/*
 * Copyright 1994-2007 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */
 
/*-
 *      Verify that the code within a method block doesn't exploit any 
 *      security holes.
 */
/*
   Exported function:

   jboolean 
   VerifyClass(JNIEnv *env, jclass cb, char *message_buffer,
               jint buffer_length)
   jboolean 
   VerifyClassForMajorVersion(JNIEnv *env, jclass cb, char *message_buffer,
                              jint buffer_length, jint major_version)

   This file now only uses the standard JNI and the following VM functions
   exported in jvm.h:

   JVM_FindClassFromClass
   JVM_IsInterface
   JVM_GetClassNameUTF
   JVM_GetClassCPEntriesCount
   JVM_GetClassCPTypes
   JVM_GetClassFieldsCount
   JVM_GetClassMethodsCount

   JVM_GetFieldIxModifiers

   JVM_GetMethodIxModifiers
   JVM_GetMethodIxExceptionTableLength
   JVM_GetMethodIxLocalsCount
   JVM_GetMethodIxArgsSize
   JVM_GetMethodIxMaxStack
   JVM_GetMethodIxNameUTF
   JVM_GetMethodIxSignatureUTF
   JVM_GetMethodIxExceptionsCount
   JVM_GetMethodIxExceptionIndexes
   JVM_GetMethodIxByteCodeLength
   JVM_GetMethodIxByteCode
   JVM_GetMethodIxExceptionTableEntry
   JVM_IsConstructorIx
   
   JVM_GetCPClassNameUTF
   JVM_GetCPFieldNameUTF
   JVM_GetCPMethodNameUTF
   JVM_GetCPFieldSignatureUTF
   JVM_GetCPMethodSignatureUTF
   JVM_GetCPFieldClassNameUTF
   JVM_GetCPMethodClassNameUTF
   JVM_GetCPFieldModifiers
   JVM_GetCPMethodModifiers

   JVM_ReleaseUTF
   JVM_IsSameClassPackage

 */

#include <string.h>
#include <setjmp.h>
#include <assert.h>
#include <limits.h>
#include <stdlib.h>

#include "jni.h"
#include "jvm.h"
#include "typedefs.h"

#include "opcodes.h"
#include "opcodes.length"
#include "opcodes.in_out"

#define MAX_ARRAY_DIMENSIONS 255
/* align byte code */
#ifndef ALIGN_UP
#define ALIGN_UP(n,align_grain) (((n) + ((align_grain) - 1)) & ~((align_grain)-1))
#endif /* ALIGN_UP */
#define UCALIGN(n) ((unsigned char *)ALIGN_UP((uintptr_t)(n),sizeof(int)))

#ifdef DEBUG

int verify_verbose = 0;
static struct context_type *GlobalContext;
#endif

enum {
    ITEM_Bogus,
    ITEM_Void,			/* only as a function return value */
    ITEM_Integer,
    ITEM_Float,
    ITEM_Double,
    ITEM_Double_2,		/* 2nd word of double in register */
    ITEM_Long,
    ITEM_Long_2,		/* 2nd word of long in register */
    ITEM_Array,
    ITEM_Object,		/* Extra info field gives name. */
    ITEM_NewObject,		/* Like object, but uninitialized. */
    ITEM_InitObject,		/* "this" is init method, before call 
				    to super() */
    ITEM_ReturnAddress,		/* Extra info gives instr # of start pc */
    /* The following three are only used within array types. 
     * Normally, we use ITEM_Integer, instead. */
    ITEM_Byte,
    ITEM_Short,
    ITEM_Char
};


#define UNKNOWN_STACK_SIZE -1
#define UNKNOWN_REGISTER_COUNT -1
#define UNKNOWN_RET_INSTRUCTION -1

#undef MAX
#undef MIN 
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))

#define BITS_PER_INT   (CHAR_BIT * sizeof(int)/sizeof(char))
#define SET_BIT(flags, i)  (flags[(i)/BITS_PER_INT] |= \
			               ((unsigned)1 << ((i) % BITS_PER_INT)))
#define	IS_BIT_SET(flags, i) (flags[(i)/BITS_PER_INT] & \
			               ((unsigned)1 << ((i) % BITS_PER_INT)))

typedef unsigned int fullinfo_type;
typedef unsigned int *bitvector;

#define GET_ITEM_TYPE(thing) ((thing) & 0x1F)
#define GET_INDIRECTION(thing) (((thing) & 0xFFFF) >> 5)
#define GET_EXTRA_INFO(thing) ((thing) >> 16)
#define WITH_ZERO_INDIRECTION(thing) ((thing) & ~(0xFFE0))
#define WITH_ZERO_EXTRA_INFO(thing) ((thing) & 0xFFFF)

#define MAKE_FULLINFO(type, indirect, extra) \
     ((type) + ((indirect) << 5) + ((extra) << 16))

#define MAKE_Object_ARRAY(indirect) \
       (context->object_info + ((indirect) << 5))

#define NULL_FULLINFO MAKE_FULLINFO(ITEM_Object, 0, 0)

/* opc_invokespecial calls to <init> need to be treated special */
#define opc_invokeinit 0x100	

/* A hash mechanism used by the verifier.
 * Maps class names to unique 16 bit integers.
 */

#define HASH_TABLE_SIZE 503

/* The buckets are managed as a 256 by 256 matrix. We allocate an entire
 * row (256 buckets) at a time to minimize fragmentation. Rows are 
 * allocated on demand so that we don't waste too much space.
 */
 
#define MAX_HASH_ENTRIES 65536
#define HASH_ROW_SIZE 256

typedef struct hash_bucket_type {
    char *name;
    unsigned int hash;
    jclass class;
    unsigned short ID;
    unsigned short next;
    unsigned loadable:1;  /* from context->class loader */
} hash_bucket_type;

typedef struct {
    hash_bucket_type **buckets;
    unsigned short *table;
    int entries_used;
} hash_table_type;

#define GET_BUCKET(class_hash, ID)\
    (class_hash->buckets[ID / HASH_ROW_SIZE] + ID % HASH_ROW_SIZE)

/* 
 * There are currently two types of resources that we need to keep
 * track of (in addition to the CCalloc pool). 
 */
enum {
    VM_STRING_UTF, /* VM-allocated UTF strings */
    VM_MALLOC_BLK  /* malloc'ed blocks */
};

#define LDC_CLASS_MAJOR_VERSION 49

#define ALLOC_STACK_SIZE 16 /* big enough */

typedef struct alloc_stack_type {
    void *ptr;
    int kind;
    struct alloc_stack_type *next;
} alloc_stack_type;

/* The context type encapsulates the current invocation of the byte
 * code verifier.
 */
struct context_type {

    JNIEnv *env;                /* current JNIEnv */

    /* buffers etc. */
    char *message;
    jint message_buf_len;
    jboolean err_code;

    alloc_stack_type *allocated_memory; /* all memory blocks that we have not
					   had a chance to free */
    /* Store up to ALLOC_STACK_SIZE number of handles to allocated memory
       blocks here, to save mallocs. */
    alloc_stack_type alloc_stack[ALLOC_STACK_SIZE];
    int alloc_stack_top;

    /* these fields are per class */
    jclass class;		/* current class */
    jint major_version;
    jint nconstants;
    unsigned char *constant_types;
    hash_table_type class_hash;

    fullinfo_type object_info;	/* fullinfo for java/lang/Object */
    fullinfo_type string_info;	/* fullinfo for java/lang/String */
    fullinfo_type throwable_info; /* fullinfo for java/lang/Throwable */
    fullinfo_type cloneable_info; /* fullinfo for java/lang/Cloneable */
    fullinfo_type serializable_info; /* fullinfo for java/io/Serializable */

    fullinfo_type currentclass_info; /* fullinfo for context->class */
    fullinfo_type superclass_info;   /* fullinfo for superclass */

    /* these fields are per method */
    int method_index;	/* current method */
    unsigned short *exceptions; /* exceptions */
    unsigned char *code;	/* current code object */
    jint code_length;
    int *code_data;		/* offset to instruction number */
    struct instruction_data_type *instruction_data; /* info about each */
    struct handler_info_type *handler_info;
    fullinfo_type *superclasses; /* null terminated superclasses */
    int instruction_count;	/* number of instructions */
    fullinfo_type return_type;	/* function return type */
    fullinfo_type swap_table[4]; /* used for passing information */
    int bitmask_size;		/* words needed to hold bitmap of arguments */

    /* these fields are per field */
    int field_index;

    /* Used by the space allocator */
    struct CCpool *CCroot, *CCcurrent;
    char *CCfree_ptr;
    int CCfree_size;

    /* Jump here on any error. */
    jmp_buf jump_buffer;

#ifdef DEBUG
    /* keep track of how many global refs are allocated. */
    int n_globalrefs;
#endif
};

struct stack_info_type {
    struct stack_item_type *stack;
    int stack_size;
};

struct register_info_type {
    int register_count;		/* number of registers used */
    fullinfo_type *registers;
    int mask_count;		/* number of masks in the following */
    struct mask_type *masks;
};

struct mask_type {
    int entry;
    int *modifies;
};

typedef unsigned short flag_type;

struct instruction_data_type {
    opcode_type opcode;		/* may turn into "canonical" opcode */
    unsigned changed:1;		/* has it changed */
    unsigned protected:1;	/* must accessor be a subclass of "this" */
    union {
	int i;			/* operand to the opcode */
	int *ip;
	fullinfo_type fi;
    } operand, operand2;
    fullinfo_type p;
    struct stack_info_type stack_info;
    struct register_info_type register_info;
#define FLAG_REACHED            0x01 /* instruction reached */
#define FLAG_NEED_CONSTRUCTOR   0x02 /* must call this.<init> or super.<init> */
#define FLAG_NO_RETURN          0x04 /* must throw out of method */
    flag_type or_flags;		/* true for at least one path to this inst */
#define FLAG_CONSTRUCTED        0x01 /* this.<init> or super.<init> called */
    flag_type and_flags;	/* true for all paths to this instruction */
};

struct handler_info_type {
    int start, end, handler;
    struct stack_info_type stack_info;
};

struct stack_item_type {
    fullinfo_type item;
    struct stack_item_type *next;
};

typedef struct context_type context_type;
typedef struct instruction_data_type instruction_data_type;
typedef struct stack_item_type stack_item_type;
typedef struct register_info_type register_info_type;
typedef struct stack_info_type stack_info_type;
typedef struct mask_type mask_type;

static void read_all_code(context_type *context, jclass cb, int num_methods,
                          int** code_lengths, unsigned char*** code);
static void verify_method(context_type *context, jclass cb, int index,
                          int code_length, unsigned char* code);
static void free_all_code(int num_methods, int* lengths, unsigned char** code);
static void verify_field(context_type *context, jclass cb, int index);

static void verify_opcode_operands (context_type *, unsigned int inumber, int offset);
static void set_protected(context_type *, unsigned int inumber, int key, opcode_type);
static jboolean is_superclass(context_type *, fullinfo_type);

static void initialize_exception_table(context_type *);
static int instruction_length(unsigned char *iptr, unsigned char *end);
static jboolean isLegalTarget(context_type *, int offset);
static void verify_constant_pool_type(context_type *, int, unsigned);

static void initialize_dataflow(context_type *);
static void run_dataflow(context_type *context);
static void check_register_values(context_type *context, unsigned int inumber);
static void check_flags(context_type *context, unsigned int inumber);
static void pop_stack(context_type *, unsigned int inumber, stack_info_type *);
static void update_registers(context_type *, unsigned int inumber, register_info_type *);
static void update_flags(context_type *, unsigned int inumber, 
			 flag_type *new_and_flags, flag_type *new_or_flags);
static void push_stack(context_type *, unsigned int inumber, stack_info_type *stack);

static void merge_into_successors(context_type *, unsigned int inumber, 
				  register_info_type *register_info,
				  stack_info_type *stack_info, 
				  flag_type and_flags, flag_type or_flags);
static void merge_into_one_successor(context_type *context, 
				     unsigned int from_inumber,
				     unsigned int inumber, 
				     register_info_type *register_info,
				     stack_info_type *stack_info, 
				     flag_type and_flags, flag_type or_flags,
				     jboolean isException);
static void merge_stack(context_type *, unsigned int inumber,
			unsigned int to_inumber, stack_info_type *);
static void merge_registers(context_type *, unsigned int inumber,
			    unsigned int to_inumber, 
			    register_info_type *);
static void merge_flags(context_type *context, unsigned int from_inumber,
			unsigned int to_inumber,
			flag_type new_and_flags, flag_type new_or_flags);

static stack_item_type *copy_stack(context_type *, stack_item_type *);
static mask_type *copy_masks(context_type *, mask_type *masks, int mask_count);
static mask_type *add_to_masks(context_type *, mask_type *, int , int);

static fullinfo_type decrement_indirection(fullinfo_type);

static fullinfo_type merge_fullinfo_types(context_type *context, 
					  fullinfo_type a, 
					  fullinfo_type b,
					  jboolean assignment);
static jboolean isAssignableTo(context_type *,
			       fullinfo_type a, 
			       fullinfo_type b);

static jclass object_fullinfo_to_classclass(context_type *, fullinfo_type);


#define NEW(type, count) \
        ((type *)CCalloc(context, (count)*(sizeof(type)), JNI_FALSE))
#define ZNEW(type, count) \
        ((type *)CCalloc(context, (count)*(sizeof(type)), JNI_TRUE))

static void CCinit(context_type *context);
static void CCreinit(context_type *context);
static void CCdestroy(context_type *context);
static void *CCalloc(context_type *context, int size, jboolean zero);

static fullinfo_type cp_index_to_class_fullinfo(context_type *, int, int);

static char signature_to_fieldtype(context_type *context, 
				   const char **signature_p, fullinfo_type *info);

static void CCerror (context_type *, char *format, ...);
static void CFerror (context_type *, char *format, ...);
static void CCout_of_memory (context_type *);

/* Because we can longjmp any time, we need to be very careful about
 * remembering what needs to be freed. */

static void check_and_push(context_type *context, const void *ptr, int kind);
static void pop_and_free(context_type *context);

static int signature_to_args_size(const char *method_signature);

#ifdef DEBUG
static void print_stack (context_type *, stack_info_type *stack_info);
static void print_registers(context_type *, register_info_type *register_info);
static void print_flags(context_type *, flag_type, flag_type);
static void print_formatted_fieldname(context_type *context, int index);
static void print_formatted_methodname(context_type *context, int index);
#endif

void initialize_class_hash(context_type *context) 
{
    hash_table_type *class_hash = &(context->class_hash);
    class_hash->buckets = (hash_bucket_type **)
        calloc(MAX_HASH_ENTRIES / HASH_ROW_SIZE, sizeof(hash_bucket_type *));
    class_hash->table = (unsigned short *)
        calloc(HASH_TABLE_SIZE, sizeof(unsigned short));
    if (class_hash->buckets == 0 ||
	class_hash->table == 0)
        CCout_of_memory(context);
    class_hash->entries_used = 0;
}

static void finalize_class_hash(context_type *context)
{
    hash_table_type *class_hash = &(context->class_hash);
    JNIEnv *env = context->env;
    int i;
    /* 4296677: bucket index starts from 1. */
    for (i=1;i<=class_hash->entries_used;i++) {
        hash_bucket_type *bucket = GET_BUCKET(class_hash, i);
        assert(bucket != NULL);
	free(bucket->name);
	if (bucket->class) {
	    (*env)->DeleteGlobalRef(env, bucket->class);
#ifdef DEBUG
	    context->n_globalrefs--;
#endif
	}
    }
    if (class_hash->buckets) {
        for (i=0;i<MAX_HASH_ENTRIES / HASH_ROW_SIZE; i++) {
	    if (class_hash->buckets[i] == 0)
	        break;
	    free(class_hash->buckets[i]);
	}
    }
    free(class_hash->buckets);
    free(class_hash->table);
}

static hash_bucket_type * 
new_bucket(context_type *context, unsigned short *pID)
{
    hash_table_type *class_hash = &(context->class_hash);
    int i = *pID = class_hash->entries_used + 1;
    int row = i / HASH_ROW_SIZE;
    if (i >= MAX_HASH_ENTRIES)
        CCerror(context, "Exceeded verifier's limit of 65535 referred classes");
    if (class_hash->buckets[row] == 0) {
        class_hash->buckets[row] = (hash_bucket_type*)
	    calloc(HASH_ROW_SIZE, sizeof(hash_bucket_type));
	if (class_hash->buckets[row] == 0)
	    CCout_of_memory(context);
    }
    class_hash->entries_used++; /* only increment when we are sure there
				   is no overflow. */
    return GET_BUCKET(class_hash, i);
}

static unsigned int
class_hash_fun(const char *s)
{
    int i;
    unsigned raw_hash;
    for (raw_hash = 0; (i = *s) != '\0'; ++s) 
	raw_hash = raw_hash * 37 + i;
    return raw_hash;
}

/*
 * Find a class using the defining loader of the current class
 * and return a local reference to it.
 */
static jclass load_class_local(context_type *context,const char *classname)
{
    jclass cb = JVM_FindClassFromClass(context->env, classname, 
				 JNI_FALSE, context->class);
    if (cb == 0)
	 CCerror(context, "Cannot find class %s", classname);
    return cb;
} 

/*
 * Find a class using the defining loader of the current class
 * and return a global reference to it.
 */
static jclass load_class_global(context_type *context, const char *classname)
{
    JNIEnv *env = context->env;
    jclass local, global;

    local = load_class_local(context, classname);
    global = (*env)->NewGlobalRef(env, local);
    if (global == 0)
	CCout_of_memory(context);
#ifdef DEBUG
    context->n_globalrefs++;
#endif
    (*env)->DeleteLocalRef(env, local);
    return global;
} 

/*
 * Return a unique ID given a local class reference. The loadable
 * flag is true if the defining class loader of context->class
 * is known to be capable of loading the class.
 */
static unsigned short 
class_to_ID(context_type *context, jclass cb, jboolean loadable)
{
    JNIEnv *env = context->env;
    hash_table_type *class_hash = &(context->class_hash);
    unsigned int hash;
    hash_bucket_type *bucket;
    unsigned short *pID;
    const char *name = JVM_GetClassNameUTF(env, cb);

    check_and_push(context, name, VM_STRING_UTF);
    hash = class_hash_fun(name);
    pID = &(class_hash->table[hash % HASH_TABLE_SIZE]);
    while (*pID) {
        bucket = GET_BUCKET(class_hash, *pID);
        if (bucket->hash == hash && strcmp(name, bucket->name) == 0) {
	    /*
	     * There is an unresolved entry with our name
	     * so we're forced to load it in case it matches us.
	     */
	    if (bucket->class == 0) {
		assert(bucket->loadable == JNI_TRUE);
		bucket->class = load_class_global(context, name);
	    }

	    /*
	     * It's already in the table. Update the loadable
	     * state if it's known and then we're done.
	     */
	    if ((*env)->IsSameObject(env, cb, bucket->class)) {
		if (loadable && !bucket->loadable)
		    bucket->loadable = JNI_TRUE;
	        goto done;
	    }
	}
	pID = &bucket->next;
    }
    bucket = new_bucket(context, pID);
    bucket->next = 0;
    bucket->hash = hash;
    bucket->name = malloc(strlen(name) + 1);
    if (bucket->name == 0)
        CCout_of_memory(context);
    strcpy(bucket->name, name);
    bucket->loadable = loadable;
    bucket->class = (*env)->NewGlobalRef(env, cb);
    if (bucket->class == 0)
        CCout_of_memory(context);
#ifdef DEBUG
    context->n_globalrefs++;
#endif

done:
    pop_and_free(context);
    return *pID;
}

/*
 * Return a unique ID given a class name from the constant pool.
 * All classes are lazily loaded from the defining loader of
 * context->class.
 */
static unsigned short 
class_name_to_ID(context_type *context, const char *name)
{
    hash_table_type *class_hash = &(context->class_hash);
    unsigned int hash = class_hash_fun(name);
    hash_bucket_type *bucket;
    unsigned short *pID;
    jboolean force_load = JNI_FALSE;

    pID = &(class_hash->table[hash % HASH_TABLE_SIZE]);
    while (*pID) {
        bucket = GET_BUCKET(class_hash, *pID);
        if (bucket->hash == hash && strcmp(name, bucket->name) == 0) {
	    if (bucket->loadable)
	        goto done;
	    force_load = JNI_TRUE;
	}
	pID = &bucket->next;
    }

    if (force_load) {
	/*
	 * We found at least one matching named entry for a class that
	 * was not known to be loadable through the defining class loader
	 * of context->class. We must load our named class and update
	 * the hash table in case one these entries matches our class.
	 */
        JNIEnv *env = context->env;
	jclass cb = load_class_local(context, name);
	unsigned short id = class_to_ID(context, cb, JNI_TRUE);
        (*env)->DeleteLocalRef(env, cb);
	return id;
    }

    bucket = new_bucket(context, pID);
    bucket->next = 0;
    bucket->class = 0;
    bucket->loadable = JNI_TRUE; /* name-only IDs are implicitly loadable */
    bucket->hash = hash;
    bucket->name = malloc(strlen(name) + 1);
    if (bucket->name == 0)
        CCout_of_memory(context);
    strcpy(bucket->name, name);

done:
    return *pID;
}

static const char * 
ID_to_class_name(context_type *context, unsigned short ID)
{
    hash_table_type *class_hash = &(context->class_hash);
    hash_bucket_type *bucket = GET_BUCKET(class_hash, ID);
    return bucket->name;
}

static jclass
ID_to_class(context_type *context, unsigned short ID)
{
    hash_table_type *class_hash = &(context->class_hash);
    hash_bucket_type *bucket = GET_BUCKET(class_hash, ID);
    if (bucket->class == 0) {
	assert(bucket->loadable == JNI_TRUE);
	bucket->class = load_class_global(context, bucket->name);
    }
    return bucket->class;
}

static fullinfo_type 
make_loadable_class_info(context_type *context, jclass cb)
{
    return MAKE_FULLINFO(ITEM_Object, 0,
			   class_to_ID(context, cb, JNI_TRUE));
}

static fullinfo_type 
make_class_info(context_type *context, jclass cb)
{
    return MAKE_FULLINFO(ITEM_Object, 0,
                         class_to_ID(context, cb, JNI_FALSE));
}

static fullinfo_type
make_class_info_from_name(context_type *context, const char *name)
{
    return MAKE_FULLINFO(ITEM_Object, 0,
			 class_name_to_ID(context, name));
}

/* RETURNS
 * 1: on success       chosen to be consistent with previous VerifyClass
 * 0: verify error 
 * 2: out of memory
 * 3: class format error
 *
 * Called by verify_class.  Verify the code of each of the methods
 * in a class.  Note that this function apparently can't be JNICALL,
 * because if it is the dynamic linker doesn't appear to be able to
 * find it on Win32. 
 */

#define CC_OK 1
#define CC_VerifyError 0
#define CC_OutOfMemory 2
#define CC_ClassFormatError 3

JNIEXPORT jboolean
VerifyClassForMajorVersion(JNIEnv *env, jclass cb, char *buffer, jint len,
                           jint major_version)
{
    context_type context_structure;
    context_type *context = &context_structure;
    jboolean result = CC_OK;
    int i;
    int num_methods;
    int* code_lengths;
    unsigned char** code;

#ifdef DEBUG
    GlobalContext = context;
#endif

    memset(context, 0, sizeof(context_type));
    context->message = buffer;
    context->message_buf_len = len;

    context->env = env;
    context->class = cb;

    /* Set invalid method/field index of the context, in case anyone 
       calls CCerror */
    context->method_index = -1;
    context->field_index = -1;

    /* Don't call CCerror or anything that can call it above the setjmp! */
    if (!setjmp(context->jump_buffer)) {
	jclass super;

	CCinit(context);		/* initialize heap; may throw */

	initialize_class_hash(context);

	context->major_version = major_version;
	context->nconstants = JVM_GetClassCPEntriesCount(env, cb);
	context->constant_types = (unsigned char *)
	    malloc(sizeof(unsigned char) * context->nconstants + 1);
 
	if (context->constant_types == 0)
	    CCout_of_memory(context);

	JVM_GetClassCPTypes(env, cb, context->constant_types);

	if (context->constant_types == 0)
	    CCout_of_memory(context);

	context->object_info = 
	    make_class_info_from_name(context, "java/lang/Object");
	context->string_info = 
	    make_class_info_from_name(context, "java/lang/String");
	context->throwable_info = 
	    make_class_info_from_name(context, "java/lang/Throwable");
	context->cloneable_info = 
	    make_class_info_from_name(context, "java/lang/Cloneable");
	context->serializable_info = 
	    make_class_info_from_name(context, "java/io/Serializable");

	context->currentclass_info = make_loadable_class_info(context, cb);

	super = (*env)->GetSuperclass(env, cb);

	if (super != 0) {
	    fullinfo_type *gptr;
	    int i = 0;

	    context->superclass_info = make_loadable_class_info(context, super);

	    while(super != 0) {
	        jclass tmp_cb = (*env)->GetSuperclass(env, super);
		(*env)->DeleteLocalRef(env, super);
		super = tmp_cb;
		i++;
	    }
	    (*env)->DeleteLocalRef(env, super);
	    super = 0;

	    /* Can't go on context heap since it survives more than 
	       one method */
	    context->superclasses = gptr =
	        malloc(sizeof(fullinfo_type)*(i + 1));
	    if (gptr == 0) {
	        CCout_of_memory(context);
	    }

	    super = (*env)->GetSuperclass(env, context->class);
	    while(super != 0) {
	        jclass tmp_cb;
		*gptr++ = make_class_info(context, super);
		tmp_cb = (*env)->GetSuperclass(env, super); 
		(*env)->DeleteLocalRef(env, super);
		super = tmp_cb;
	    }
	    *gptr = 0;
	} else { 
	    context->superclass_info = 0;
	}

	(*env)->DeleteLocalRef(env, super);
    
	/* Look at each method */
	for (i = JVM_GetClassFieldsCount(env, cb); --i >= 0;)  
	    verify_field(context, cb, i);
  num_methods = JVM_GetClassMethodsCount(env, cb);
  read_all_code(context, cb, num_methods, &code_lengths, &code);
  for (i = num_methods - 1; i >= 0; --i) 
	    verify_method(context, cb, i, code_lengths[i], code[i]);
  free_all_code(num_methods, code_lengths, code);
	result = CC_OK;
    } else {
	result = context->err_code;
    }

    /* Cleanup */
    finalize_class_hash(context);

    while(context->allocated_memory)
        pop_and_free(context);

#ifdef DEBUG
    GlobalContext = 0;
#endif

    if (context->exceptions)
        free(context->exceptions);

    if (context->code)
        free(context->code);

    if (context->constant_types)
        free(context->constant_types);

    if (context->superclasses)
	free(context->superclasses);

#ifdef DEBUG
    /* Make sure all global refs created in the verifier are freed */
    assert(context->n_globalrefs == 0);
#endif

    CCdestroy(context);		/* destroy heap */
    return result;
}

#define OLD_FORMAT_MAX_MAJOR_VERSION 48

JNIEXPORT jboolean
VerifyClass(JNIEnv *env, jclass cb, char *buffer, jint len)
{
    static int warned = 0;
    if (!warned) {
      jio_fprintf(stdout, "Warning! An old version of jvm is used. This is not supported.\n");
      warned = 1;
    }
    return VerifyClassForMajorVersion(env, cb, buffer, len,
                                      OLD_FORMAT_MAX_MAJOR_VERSION);
}

static void
verify_field(context_type *context, jclass cb, int field_index)
{
    JNIEnv *env = context->env;
    int access_bits = JVM_GetFieldIxModifiers(env, cb, field_index);
    context->field_index = field_index;

    if (  ((access_bits & JVM_ACC_PUBLIC) != 0) && 
	  ((access_bits & (JVM_ACC_PRIVATE | JVM_ACC_PROTECTED)) != 0)) {
        CCerror(context, "Inconsistent access bits.");
    } 
    context->field_index = -1;
}


/**
 * We read all of the class's methods' code because it is possible that
 * the verification of one method could resulting in linking further 
 * down the stack (due to class loading), which could end up rewriting
 * some of the bytecode of methods we haven't verified yet.  Since we 
 * don't want to see the rewritten bytecode, cache all the code and 
 * operate only on that.
 */
static void
read_all_code(context_type* context, jclass cb, int num_methods, 
              int** lengths_addr, unsigned char*** code_addr) 
{
  int* lengths = malloc(sizeof(int) * num_methods);
  unsigned char** code = malloc(sizeof(unsigned char*) * num_methods);

  *(lengths_addr) = lengths;
  *(code_addr) = code;

  if (lengths == 0 || code == 0) {
    CCout_of_memory(context);
  } else {
    int i;
    for (i = 0; i < num_methods; ++i) {
      lengths[i] = JVM_GetMethodIxByteCodeLength(context->env, cb, i);
      if (lengths[i] != 0) {
        code[i] = malloc(sizeof(unsigned char) * (lengths[i] + 1));
        if (code[i] == NULL) {
          CCout_of_memory(context);
        } else {
          JVM_GetMethodIxByteCode(context->env, cb, i, code[i]);
        }
      } else { 
        code[i] = NULL;
      }
    }
  }
}

static void 
free_all_code(int num_methods, int* lengths, unsigned char** code) 
{
  int i;
  for (i = 0; i < num_methods; ++i) {
    free(code[i]);
  }
  free(lengths);
  free(code);
}

/* Verify the code of one method */
static void
verify_method(context_type *context, jclass cb, int method_index, 
              int code_length, unsigned char* code)
{
    JNIEnv *env = context->env;
    int access_bits = JVM_GetMethodIxModifiers(env, cb, method_index);
    int *code_data;
    instruction_data_type *idata = 0;
    int instruction_count;
    int i, offset;
    unsigned int inumber;
    jint nexceptions;

    if ((access_bits & (JVM_ACC_NATIVE | JVM_ACC_ABSTRACT)) != 0) { 
	/* not much to do for abstract and native methods */
	return;
    }

    context->code_length = code_length;
    context->code = code;
 
    /* CCerror can give method-specific info once this is set */
    context->method_index = method_index;

    CCreinit(context);		/* initial heap */
    code_data = NEW(int, code_length);

#ifdef DEBUG
    if (verify_verbose) {
        const char *classname = JVM_GetClassNameUTF(env, cb);
	const char *methodname = 
	    JVM_GetMethodIxNameUTF(env, cb, method_index);
	const char *signature = 
	    JVM_GetMethodIxSignatureUTF(env, cb, method_index);
	jio_fprintf(stdout, "Looking at %s.%s%s\n", 
		    (classname ? classname : ""),
		    (methodname ? methodname : ""), 
		    (signature ? signature : ""));
	JVM_ReleaseUTF(classname);
	JVM_ReleaseUTF(methodname);
	JVM_ReleaseUTF(signature);
    }
#endif

    if (((access_bits & JVM_ACC_PUBLIC) != 0) && 
	((access_bits & (JVM_ACC_PRIVATE | JVM_ACC_PROTECTED)) != 0)) {
	CCerror(context, "Inconsistent access bits.");
    } 

    /* Run through the code.  Mark the start of each instruction, and give
     * the instruction a number */
    for (i = 0, offset = 0; offset < code_length; i++) {
	int length = instruction_length(&code[offset], code + code_length);
	int next_offset = offset + length;
	if (length <= 0) 
	    CCerror(context, "Illegal instruction found at offset %d", offset);
	if (next_offset > code_length) 
	    CCerror(context, "Code stops in the middle of instruction "
		    " starting at offset %d", offset);
	code_data[offset] = i;
	while (++offset < next_offset)
	    code_data[offset] = -1; /* illegal location */
    }
    instruction_count = i;	/* number of instructions in code */
    
    /* Allocate a structure to hold info about each instruction. */
    idata = NEW(instruction_data_type, instruction_count);

    /* Initialize the heap, and other info in the context structure. */
    context->code = code;
    context->instruction_data = idata;
    context->code_data = code_data;
    context->instruction_count = instruction_count;
    context->handler_info = 
        NEW(struct handler_info_type, 
	    JVM_GetMethodIxExceptionTableLength(env, cb, method_index));
    context->bitmask_size = 
        (JVM_GetMethodIxLocalsCount(env, cb, method_index)
	 + (BITS_PER_INT - 1))/BITS_PER_INT;
    
    if (instruction_count == 0) 
	CCerror(context, "Empty code");
	
    for (inumber = 0, offset = 0; offset < code_length; inumber++) {
	int length = instruction_length(&code[offset], code + code_length);
	instruction_data_type *this_idata = &idata[inumber];
	this_idata->opcode = code[offset];
	this_idata->stack_info.stack = NULL;
	this_idata->stack_info.stack_size  = UNKNOWN_STACK_SIZE;
	this_idata->register_info.register_count = UNKNOWN_REGISTER_COUNT;
	this_idata->changed = JNI_FALSE;  /* no need to look at it yet. */
	this_idata->protected = JNI_FALSE;  /* no need to look at it yet. */
	this_idata->and_flags = (flag_type) -1;	/* "bottom" and value */
	this_idata->or_flags = 0; /* "bottom" or value*/
	/* This also sets up this_data->operand.  It also makes the 
	 * xload_x and xstore_x instructions look like the generic form. */
	verify_opcode_operands(context, inumber, offset);
	offset += length;
    }
    
    
    /* make sure exception table is reasonable. */
    initialize_exception_table(context);
    /* Set up first instruction, and start of exception handlers. */
    initialize_dataflow(context);
    /* Run data flow analysis on the instructions. */
    run_dataflow(context);

    /* verify checked exceptions, if any */
    nexceptions = JVM_GetMethodIxExceptionsCount(env, cb, method_index);
    context->exceptions = (unsigned short *)
        malloc(sizeof(unsigned short) * nexceptions + 1);
    if (context->exceptions == 0)
        CCout_of_memory(context);
    JVM_GetMethodIxExceptionIndexes(env, cb, method_index, 
				    context->exceptions);
    for (i = 0; i < nexceptions; i++) {
        /* Make sure the constant pool item is JVM_CONSTANT_Class */
        verify_constant_pool_type(context, (int)context->exceptions[i],
				  1 << JVM_CONSTANT_Class);
    }
    free(context->exceptions);
    context->exceptions = 0;
    context->code = 0;
    context->method_index = -1;
}


/* Look at a single instruction, and verify its operands.  Also, for 
 * simplicity, move the operand into the ->operand field.
 * Make sure that branches don't go into the middle of nowhere.
 */

static jint ntohl(jint n)
{
    unsigned char *p = (unsigned char *)&n;
    return (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
}

static void
verify_opcode_operands(context_type *context, unsigned int inumber, int offset)
{
    JNIEnv *env = context->env;
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    int *code_data = context->code_data;
    int mi = context->method_index;
    unsigned char *code = context->code;
    opcode_type opcode = this_idata->opcode;
    int var; 
    
    /*
     * Set the ip fields to 0 not the i fields because the ip fields
     * are 64 bits on 64 bit architectures, the i field is only 32
     */
    this_idata->operand.ip = 0;
    this_idata->operand2.ip = 0;

    switch (opcode) {

    case opc_jsr:
	/* instruction of ret statement */
	this_idata->operand2.i = UNKNOWN_RET_INSTRUCTION;
	/* FALLTHROUGH */
    case opc_ifeq: case opc_ifne: case opc_iflt: 
    case opc_ifge: case opc_ifgt: case opc_ifle:
    case opc_ifnull: case opc_ifnonnull:
    case opc_if_icmpeq: case opc_if_icmpne: case opc_if_icmplt: 
    case opc_if_icmpge: case opc_if_icmpgt: case opc_if_icmple:
    case opc_if_acmpeq: case opc_if_acmpne:   
    case opc_goto: {
	/* Set the ->operand to be the instruction number of the target. */
	int jump = (((signed char)(code[offset+1])) << 8) + code[offset+2];
	int target = offset + jump;
	if (!isLegalTarget(context, target))
	    CCerror(context, "Illegal target of jump or branch");
	this_idata->operand.i = code_data[target];
	break;
    }
	
    case opc_jsr_w:
	/* instruction of ret statement */
	this_idata->operand2.i = UNKNOWN_RET_INSTRUCTION;
	/* FALLTHROUGH */
    case opc_goto_w: {
	/* Set the ->operand to be the instruction number of the target. */
	int jump = (((signed char)(code[offset+1])) << 24) + 
	             (code[offset+2] << 16) + (code[offset+3] << 8) + 
	             (code[offset + 4]);
	int target = offset + jump;
	if (!isLegalTarget(context, target))
	    CCerror(context, "Illegal target of jump or branch");
	this_idata->operand.i = code_data[target];
	break;
    }

    case opc_tableswitch: 
    case opc_lookupswitch: {
	/* Set the ->operand to be a table of possible instruction targets. */
	int *lpc = (int *) UCALIGN(code + offset + 1);
	int *lptr;
	int *saved_operand;
	int keys;
	int k, delta;
	/* 4639449, 4647081: Padding bytes must be zero. */
	unsigned char* bptr = (unsigned char*) (code + offset + 1);
	for (; bptr < (unsigned char*)lpc; bptr++) {
	    if (*bptr != 0) {
		CCerror(context, "Non zero padding bytes in switch");
	    }
	}
	if (opcode == opc_tableswitch) {
	    keys = ntohl(lpc[2]) -  ntohl(lpc[1]) + 1;
	    delta = 1;
	} else { 
	    keys = ntohl(lpc[1]); /* number of pairs */
	    delta = 2;
	    /* Make sure that the tableswitch items are sorted */
	    for (k = keys - 1, lptr = &lpc[2]; --k >= 0; lptr += 2) {
		int this_key = ntohl(lptr[0]);	/* NB: ntohl may be unsigned */
		int next_key = ntohl(lptr[2]);
		if (this_key >= next_key) { 
		    CCerror(context, "Unsorted lookup switch");
		}
	    }
	}
	saved_operand = NEW(int, keys + 2);
	if (!isLegalTarget(context, offset + ntohl(lpc[0]))) 
	    CCerror(context, "Illegal default target in switch");
	saved_operand[keys + 1] = code_data[offset + ntohl(lpc[0])];
	for (k = keys, lptr = &lpc[3]; --k >= 0; lptr += delta) {
	    int target = offset + ntohl(lptr[0]);
	    if (!isLegalTarget(context, target))
		CCerror(context, "Illegal branch in opc_tableswitch");
	    saved_operand[k + 1] = code_data[target];
	}
	saved_operand[0] = keys + 1; /* number of successors */
	this_idata->operand.ip = saved_operand;
	break;
    }
	
    case opc_ldc: {   
	/* Make sure the constant pool item is the right type. */
	int key = code[offset + 1];
	int types = (1 << JVM_CONSTANT_Integer) | (1 << JVM_CONSTANT_Float) |
		    (1 << JVM_CONSTANT_String);
	if (context->major_version >= LDC_CLASS_MAJOR_VERSION) {
	    types |= 1 << JVM_CONSTANT_Class;
	}
	this_idata->operand.i = key;
	verify_constant_pool_type(context, key, types);
	break;
    }
	  
    case opc_ldc_w: {   
	/* Make sure the constant pool item is the right type. */
	int key = (code[offset + 1] << 8) + code[offset + 2];
	int types = (1 << JVM_CONSTANT_Integer) | (1 << JVM_CONSTANT_Float) |
		    (1 << JVM_CONSTANT_String);
	if (context->major_version >= LDC_CLASS_MAJOR_VERSION) {
	    types |= 1 << JVM_CONSTANT_Class;
	}
	this_idata->operand.i = key;
	verify_constant_pool_type(context, key, types);
	break;
    }
	  
    case opc_ldc2_w: { 
	/* Make sure the constant pool item is the right type. */
	int key = (code[offset + 1] << 8) + code[offset + 2];
	int types = (1 << JVM_CONSTANT_Double) | (1 << JVM_CONSTANT_Long);
	this_idata->operand.i = key;
	verify_constant_pool_type(context, key, types);
	break;
    }

    case opc_getfield: case opc_putfield:
    case opc_getstatic: case opc_putstatic: {
	/* Make sure the constant pool item is the right type. */
	int key = (code[offset + 1] << 8) + code[offset + 2];
	this_idata->operand.i = key;
	verify_constant_pool_type(context, key, 1 << JVM_CONSTANT_Fieldref);	
	if (opcode == opc_getfield || opcode == opc_putfield) 
	    set_protected(context, inumber, key, opcode);
	break;
    }

    case opc_invokevirtual:
    case opc_invokespecial: 
    case opc_invokestatic:
    case opc_invokeinterface: {
	/* Make sure the constant pool item is the right type. */
	int key = (code[offset + 1] << 8) + code[offset + 2];
	const char *methodname;
	jclass cb = context->class;
	fullinfo_type clazz_info;
	int is_constructor, is_internal;
	int kind = (opcode == opc_invokeinterface 
	                    ? 1 << JVM_CONSTANT_InterfaceMethodref
	                    : 1 << JVM_CONSTANT_Methodref);
	/* Make sure the constant pool item is the right type. */
	verify_constant_pool_type(context, key, kind);
	methodname = JVM_GetCPMethodNameUTF(env, cb, key);
	check_and_push(context, methodname, VM_STRING_UTF);
	is_constructor = !strcmp(methodname, "<init>");
	is_internal = methodname[0] == '<';
	pop_and_free(context);

	clazz_info = cp_index_to_class_fullinfo(context, key,
						JVM_CONSTANT_Methodref);
	this_idata->operand.i = key;
	this_idata->operand2.fi = clazz_info;
	if (is_constructor) {
	    if (opcode != opc_invokespecial) {
		CCerror(context, 
			"Must call initializers using invokespecial");
	    }
	    this_idata->opcode = opc_invokeinit;
	} else {
	    if (is_internal) {
		CCerror(context, "Illegal call to internal method");
	    }
	    if (opcode == opc_invokespecial 
		   && clazz_info != context->currentclass_info  
		   && clazz_info != context->superclass_info) {
		int not_found = 1;

		jclass super = (*env)->GetSuperclass(env, context->class);
		while(super != 0) {
		    jclass tmp_cb;
		    fullinfo_type new_info = make_class_info(context, super);
		    if (clazz_info == new_info) {
		        not_found = 0;
			break;
		    }
		    tmp_cb = (*env)->GetSuperclass(env, super);
		    (*env)->DeleteLocalRef(env, super);
		    super = tmp_cb;
		}
		(*env)->DeleteLocalRef(env, super);
		
		/* The optimizer make cause this to happen on local code */
		if (not_found) {
#ifdef BROKEN_JAVAC
		    jobject loader = JVM_GetClassLoader(env, context->class);
		    int has_loader = (loader != 0);
		    (*env)->DeleteLocalRef(env, loader);
		    if (has_loader)
#endif /* BROKEN_JAVAC */
		        CCerror(context, 
				"Illegal use of nonvirtual function call");
		}
	    }
	}
	if (opcode == opc_invokeinterface) { 
	    unsigned int args1;
	    unsigned int args2;
	    const char *signature = 
	        JVM_GetCPMethodSignatureUTF(env, context->class, key);
	    check_and_push(context, signature, VM_STRING_UTF);
	    args1 = signature_to_args_size(signature) + 1;
	    args2 = code[offset + 3];
	    if (args1 != args2) {
		CCerror(context, 
			"Inconsistent args_size for opc_invokeinterface");
	    } 
            if (code[offset + 4] != 0) {
                CCerror(context,
                        "Fourth operand byte of invokeinterface must be zero");
            }
	    pop_and_free(context);
	} else if (opcode == opc_invokevirtual 
		      || opcode == opc_invokespecial) 
	    set_protected(context, inumber, key, opcode);
	break;
    }
	

    case opc_instanceof: 
    case opc_checkcast: 
    case opc_new:
    case opc_anewarray: 
    case opc_multianewarray: {
	/* Make sure the constant pool item is a class */
	int key = (code[offset + 1] << 8) + code[offset + 2];
	fullinfo_type target;
	verify_constant_pool_type(context, key, 1 << JVM_CONSTANT_Class);
	target = cp_index_to_class_fullinfo(context, key, JVM_CONSTANT_Class);
	if (GET_ITEM_TYPE(target) == ITEM_Bogus) 
	    CCerror(context, "Illegal type");
	switch(opcode) {
	case opc_anewarray:
	    if ((GET_INDIRECTION(target)) >= MAX_ARRAY_DIMENSIONS)
		CCerror(context, "Array with too many dimensions");
	    this_idata->operand.fi = MAKE_FULLINFO(GET_ITEM_TYPE(target),
						   GET_INDIRECTION(target) + 1,
						   GET_EXTRA_INFO(target));
	    break;
	case opc_new:
	    if (WITH_ZERO_EXTRA_INFO(target) !=
		             MAKE_FULLINFO(ITEM_Object, 0, 0))
		CCerror(context, "Illegal creation of multi-dimensional array");
	    /* operand gets set to the "unitialized object".  operand2 gets
	     * set to what the value will be after it's initialized. */
	    this_idata->operand.fi = MAKE_FULLINFO(ITEM_NewObject, 0, inumber);
	    this_idata->operand2.fi = target;
	    break;
	case opc_multianewarray:
	    this_idata->operand.fi = target;
	    this_idata->operand2.i = code[offset + 3];
	    if (    (this_idata->operand2.i > GET_INDIRECTION(target))
		 || (this_idata->operand2.i == 0))
		CCerror(context, "Illegal dimension argument");
	    break;
	default:
	    this_idata->operand.fi = target;
	}
	break;
    }
	
    case opc_newarray: {
	/* Cache the result of the opc_newarray into the operand slot */
	fullinfo_type full_info;
	switch (code[offset + 1]) {
	    case JVM_T_INT:    
	        full_info = MAKE_FULLINFO(ITEM_Integer, 1, 0); break;
	    case JVM_T_LONG:   
		full_info = MAKE_FULLINFO(ITEM_Long, 1, 0); break;
	    case JVM_T_FLOAT:  
		full_info = MAKE_FULLINFO(ITEM_Float, 1, 0); break;
	    case JVM_T_DOUBLE: 
		full_info = MAKE_FULLINFO(ITEM_Double, 1, 0); break;
	    case JVM_T_BYTE: case JVM_T_BOOLEAN:
		full_info = MAKE_FULLINFO(ITEM_Byte, 1, 0); break;
	    case JVM_T_CHAR:   
		full_info = MAKE_FULLINFO(ITEM_Char, 1, 0); break;
	    case JVM_T_SHORT:  
		full_info = MAKE_FULLINFO(ITEM_Short, 1, 0); break;
	    default:
		full_info = 0;		/* Keep lint happy */
		CCerror(context, "Bad type passed to opc_newarray");
	}
	this_idata->operand.fi = full_info;
	break;
    }
	  
    /* Fudge iload_x, aload_x, etc to look like their generic cousin. */
    case opc_iload_0: case opc_iload_1: case opc_iload_2: case opc_iload_3:
	this_idata->opcode = opc_iload;
	var = opcode - opc_iload_0;
	goto check_local_variable;
	  
    case opc_fload_0: case opc_fload_1: case opc_fload_2: case opc_fload_3:
	this_idata->opcode = opc_fload;
	var = opcode - opc_fload_0;
	goto check_local_variable;

    case opc_aload_0: case opc_aload_1: case opc_aload_2: case opc_aload_3:
	this_idata->opcode = opc_aload;
	var = opcode - opc_aload_0;
	goto check_local_variable;

    case opc_lload_0: case opc_lload_1: case opc_lload_2: case opc_lload_3:
	this_idata->opcode = opc_lload;
	var = opcode - opc_lload_0;
	goto check_local_variable2;

    case opc_dload_0: case opc_dload_1: case opc_dload_2: case opc_dload_3:
	this_idata->opcode = opc_dload;
	var = opcode - opc_dload_0;
	goto check_local_variable2;

    case opc_istore_0: case opc_istore_1: case opc_istore_2: case opc_istore_3:
	this_idata->opcode = opc_istore;
	var = opcode - opc_istore_0;
	goto check_local_variable;
	
    case opc_fstore_0: case opc_fstore_1: case opc_fstore_2: case opc_fstore_3:
	this_idata->opcode = opc_fstore;
	var = opcode - opc_fstore_0;
	goto check_local_variable;

    case opc_astore_0: case opc_astore_1: case opc_astore_2: case opc_astore_3:
	this_idata->opcode = opc_astore;
	var = opcode - opc_astore_0;
	goto check_local_variable;

    case opc_lstore_0: case opc_lstore_1: case opc_lstore_2: case opc_lstore_3:
	this_idata->opcode = opc_lstore;
	var = opcode - opc_lstore_0;
	goto check_local_variable2;

    case opc_dstore_0: case opc_dstore_1: case opc_dstore_2: case opc_dstore_3:
	this_idata->opcode = opc_dstore;
	var = opcode - opc_dstore_0;
	goto check_local_variable2;

    case opc_wide: 
	this_idata->opcode = code[offset + 1];
	var = (code[offset + 2] << 8) + code[offset + 3];
	switch(this_idata->opcode) {
	    case opc_lload:  case opc_dload: 
	    case opc_lstore: case opc_dstore:
	        goto check_local_variable2;
	    default:
	        goto check_local_variable;
	}

    case opc_iinc:		/* the increment amount doesn't matter */
    case opc_ret: 
    case opc_aload: case opc_iload: case opc_fload:
    case opc_astore: case opc_istore: case opc_fstore:
	var = code[offset + 1];
    check_local_variable:
	/* Make sure that the variable number isn't illegal. */
	this_idata->operand.i = var;
	if (var >= JVM_GetMethodIxLocalsCount(env, context->class, mi))
	    CCerror(context, "Illegal local variable number");
	break;
	    
    case opc_lload: case opc_dload: case opc_lstore: case opc_dstore: 
	var = code[offset + 1];
    check_local_variable2:
	/* Make sure that the variable number isn't illegal. */
	this_idata->operand.i = var;
	if ((var + 1) >= JVM_GetMethodIxLocalsCount(env, context->class, mi))
	    CCerror(context, "Illegal local variable number");
	break;
	
    default:
	if (opcode >= opc_breakpoint) 
	    CCerror(context, "Quick instructions shouldn't appear yet.");
	break;
    } /* of switch */
}


static void 
set_protected(context_type *context, unsigned int inumber, int key, opcode_type opcode) 
{
    JNIEnv *env = context->env;
    fullinfo_type clazz_info;
    if (opcode != opc_invokevirtual && opcode != opc_invokespecial) {
        clazz_info = cp_index_to_class_fullinfo(context, key, 
						JVM_CONSTANT_Fieldref);
    } else {
        clazz_info = cp_index_to_class_fullinfo(context, key, 
						JVM_CONSTANT_Methodref);
    }
    if (is_superclass(context, clazz_info)) {
	jclass calledClass = 
	    object_fullinfo_to_classclass(context, clazz_info);
	int access;
	/* 4734966: JVM_GetCPFieldModifiers() or JVM_GetCPMethodModifiers() only
	   searches the referenced field or method in calledClass. The following
	   while loop is added to search up the superclass chain to make this
	   symbolic resolution consistent with the field/method resolution 
	   specified in VM spec 5.4.3. */
	calledClass = (*env)->NewLocalRef(env, calledClass);
	do {
	    jclass tmp_cb;
	    if (opcode != opc_invokevirtual && opcode != opc_invokespecial) {
	        access = JVM_GetCPFieldModifiers
	            (env, context->class, key, calledClass);
	    } else {
	        access = JVM_GetCPMethodModifiers
	            (env, context->class, key, calledClass);
	    }
	    if (access != -1) {
	        break;
	    }
	    tmp_cb = (*env)->GetSuperclass(env, calledClass);
	    (*env)->DeleteLocalRef(env, calledClass);
	    calledClass = tmp_cb;
	} while (calledClass != 0);

	if (access == -1) {
	    /* field/method not found, detected at runtime. */ 
	} else if (access & JVM_ACC_PROTECTED) {
	    if (!JVM_IsSameClassPackage(env, calledClass, context->class))
		context->instruction_data[inumber].protected = JNI_TRUE;
	}
	(*env)->DeleteLocalRef(env, calledClass);
    }
}


static jboolean 
is_superclass(context_type *context, fullinfo_type clazz_info) { 
    fullinfo_type *fptr = context->superclasses;

    if (fptr == 0)
        return JNI_FALSE;
    for (; *fptr != 0; fptr++) { 
	if (*fptr == clazz_info)
	    return JNI_TRUE;
    }
    return JNI_FALSE;
}


/* Look through each item on the exception table.  Each of the fields must 
 * refer to a legal instruction. 
 */
static void
initialize_exception_table(context_type *context)
{
    JNIEnv *env = context->env;
    int mi = context->method_index;
    struct handler_info_type *handler_info = context->handler_info;
    int *code_data = context->code_data;
    int code_length = context->code_length;
    int max_stack_size = JVM_GetMethodIxMaxStack(env, context->class, mi);
    int i = JVM_GetMethodIxExceptionTableLength(env, context->class, mi);
    if (max_stack_size < 1 && i > 0) {
        // If the method contains exception handlers, it must have room
        // on the expression stack for the exception that the VM could push
        CCerror(context, "Stack size too large");
    }
    for (; --i >= 0; handler_info++) {
        JVM_ExceptionTableEntryType einfo;
	stack_item_type *stack_item = NEW(stack_item_type, 1);

	JVM_GetMethodIxExceptionTableEntry(env, context->class, mi, 
					   i, &einfo);

	if (!(einfo.start_pc < einfo.end_pc &&
	      einfo.start_pc >= 0 &&
	      isLegalTarget(context, einfo.start_pc) &&
	      (einfo.end_pc ==  code_length || 
	       isLegalTarget(context, einfo.end_pc)))) {
	    CFerror(context, "Illegal exception table range");
	}
	if (!((einfo.handler_pc > 0) && 
	      isLegalTarget(context, einfo.handler_pc))) {
	    CFerror(context, "Illegal exception table handler");
	}

	handler_info->start = code_data[einfo.start_pc];
	/* einfo.end_pc may point to one byte beyond the end of bytecodes. */
	handler_info->end = (einfo.end_pc == context->code_length) ? 
	    context->instruction_count : code_data[einfo.end_pc];
	handler_info->handler = code_data[einfo.handler_pc];
	handler_info->stack_info.stack = stack_item;
	handler_info->stack_info.stack_size = 1;
	stack_item->next = NULL;
	if (einfo.catchType != 0) {
	    const char *classname;
	    /* Constant pool entry type has been checked in format checker */
	    classname = JVM_GetCPClassNameUTF(env,
					      context->class,
					      einfo.catchType);
	    check_and_push(context, classname, VM_STRING_UTF);
	    stack_item->item = make_class_info_from_name(context, classname);
	    if (!isAssignableTo(context, 
				stack_item->item, 
				context->throwable_info))
	        CCerror(context, "catch_type not a subclass of Throwable");
	    pop_and_free(context);
	} else {
	    stack_item->item = context->throwable_info;
	}
    }
}


/* Given a pointer to an instruction, return its length.  Use the table
 * opcode_length[] which is automatically built.
 */
static int instruction_length(unsigned char *iptr, unsigned char *end)
{
    int instruction = *iptr;
    switch (instruction) {
        case opc_tableswitch: {
 	    int *lpc = (int *)UCALIGN(iptr + 1);
	    int index;
	    if (lpc + 2 >= (int *)end) {
	        return -1; /* do not read pass the end */
            }
	    index = ntohl(lpc[2]) - ntohl(lpc[1]);
	    if ((index < 0) || (index > 65535)) {
		return -1;	/* illegal */
	    } else { 
		return (unsigned char *)(&lpc[index + 4]) - iptr;
            }
	}
	    
	case opc_lookupswitch: {
	    int *lpc = (int *) UCALIGN(iptr + 1);
	    int npairs;
	    if (lpc + 1 >= (int *)end)
	        return -1; /* do not read pass the end */
	    npairs = ntohl(lpc[1]);
	    /* There can't be more than 64K labels because of the limit
	     * on per-method byte code length.
	     */
	    if (npairs < 0 || npairs >= 65536) 
		return  -1;
	    else 
		return (unsigned char *)(&lpc[2 * (npairs + 1)]) - iptr;
	}

	case opc_wide: 
	    if (iptr + 1 >= end)
	        return -1; /* do not read pass the end */
	    switch(iptr[1]) {
	        case opc_ret:
	        case opc_iload: case opc_istore: 
	        case opc_fload: case opc_fstore:
	        case opc_aload: case opc_astore:
	        case opc_lload: case opc_lstore:
	        case opc_dload: case opc_dstore: 
		    return 4;
		case opc_iinc:
		    return 6;
		default: 
		    return -1;
	    }

	default: {
	    /* A length of 0 indicates an error. */
	    int length = opcode_length[instruction];
	    return (length <= 0) ? -1 : length;
	}
    }
}


/* Given the target of a branch, make sure that it's a legal target. */
static jboolean 
isLegalTarget(context_type *context, int offset)
{
    int code_length = context->code_length;
    int *code_data = context->code_data;
    return (offset >= 0 && offset < code_length && code_data[offset] >= 0);
}


/* Make sure that an element of the constant pool really is of the indicated 
 * type.
 */
static void
verify_constant_pool_type(context_type *context, int index, unsigned mask)
{
    int nconstants = context->nconstants;
    unsigned char *type_table = context->constant_types;
    unsigned type;

    if ((index <= 0) || (index >= nconstants))
	CCerror(context, "Illegal constant pool index");

    type = type_table[index];
    if ((mask & (1 << type)) == 0) 
	CCerror(context, "Illegal type in constant pool");
}
        

static void
initialize_dataflow(context_type *context) 
{
    JNIEnv *env = context->env;
    instruction_data_type *idata = context->instruction_data;
    int mi = context->method_index;
    jclass cb = context->class;
    int args_size = JVM_GetMethodIxArgsSize(env, cb, mi);
    fullinfo_type *reg_ptr;
    fullinfo_type full_info;
    const char *p;
    const char *signature;

    /* Initialize the function entry, since we know everything about it. */
    idata[0].stack_info.stack_size = 0;
    idata[0].stack_info.stack = NULL;
    idata[0].register_info.register_count = args_size;
    idata[0].register_info.registers = NEW(fullinfo_type, args_size);
    idata[0].register_info.mask_count = 0;
    idata[0].register_info.masks = NULL;
    idata[0].and_flags = 0;	/* nothing needed */
    idata[0].or_flags = FLAG_REACHED; /* instruction reached */
    reg_ptr = idata[0].register_info.registers;

    if ((JVM_GetMethodIxModifiers(env, cb, mi) & JVM_ACC_STATIC) == 0) {
	/* A non static method.  If this is an <init> method, the first
	 * argument is an uninitialized object.  Otherwise it is an object of
	 * the given class type.  java.lang.Object.<init> is special since
	 * we don't call its superclass <init> method.
	 */
	if (JVM_IsConstructorIx(env, cb, mi)
	        && context->currentclass_info != context->object_info) {
	    *reg_ptr++ = MAKE_FULLINFO(ITEM_InitObject, 0, 0);
	    idata[0].or_flags |= FLAG_NEED_CONSTRUCTOR;
	} else {
	    *reg_ptr++ = context->currentclass_info;
	}
    }
    signature = JVM_GetMethodIxSignatureUTF(env, cb, mi);
    check_and_push(context, signature, VM_STRING_UTF);
    /* Fill in each of the arguments into the registers. */
    for (p = signature + 1; *p != JVM_SIGNATURE_ENDFUNC; ) {
	char fieldchar = signature_to_fieldtype(context, &p, &full_info);
	switch (fieldchar) {
	    case 'D': case 'L': 
	        *reg_ptr++ = full_info;
	        *reg_ptr++ = full_info + 1;
		break;
	    default:
	        *reg_ptr++ = full_info;
		break;
	}
    }
    p++;			/* skip over right parenthesis */
    if (*p == 'V') {
	context->return_type = MAKE_FULLINFO(ITEM_Void, 0, 0);
    } else {
	signature_to_fieldtype(context, &p, &full_info);
	context->return_type = full_info;
    }
    pop_and_free(context);
    /* Indicate that we need to look at the first instruction. */
    idata[0].changed = JNI_TRUE;
}	


/* Run the data flow analysis, as long as there are things to change. */
static void
run_dataflow(context_type *context) {
    JNIEnv *env = context->env;
    int mi = context->method_index;
    jclass cb = context->class;
    int max_stack_size = JVM_GetMethodIxMaxStack(env, cb, mi);
    instruction_data_type *idata = context->instruction_data;
    int icount = context->instruction_count;
    jboolean work_to_do = JNI_TRUE;
    unsigned int inumber;

    /* Run through the loop, until there is nothing left to do. */
    while (work_to_do) {
	work_to_do = JNI_FALSE;
	for (inumber = 0; inumber < icount; inumber++) {
	    instruction_data_type *this_idata = &idata[inumber];
	    if (this_idata->changed) {
		register_info_type new_register_info;
		stack_info_type new_stack_info;
		flag_type new_and_flags, new_or_flags;
		
		this_idata->changed = JNI_FALSE;
		work_to_do = JNI_TRUE;
#ifdef DEBUG
		if (verify_verbose) {
		    int opcode = this_idata->opcode;
		    jio_fprintf(stdout, "Instruction %d: ", inumber);
		    print_stack(context, &this_idata->stack_info);
		    print_registers(context, &this_idata->register_info);
		    print_flags(context, 
				this_idata->and_flags, this_idata->or_flags);
		    fflush(stdout);
		}
#endif
		/* Make sure the registers and flags are appropriate */
		check_register_values(context, inumber);
		check_flags(context, inumber);

		/* Make sure the stack can deal with this instruction */
		pop_stack(context, inumber, &new_stack_info);

		/* Update the registers  and flags */
		update_registers(context, inumber, &new_register_info);
		update_flags(context, inumber, &new_and_flags, &new_or_flags);

		/* Update the stack. */
		push_stack(context, inumber, &new_stack_info);

		if (new_stack_info.stack_size > max_stack_size) 
		    CCerror(context, "Stack size too large");
#ifdef DEBUG
		if (verify_verbose) {
		    jio_fprintf(stdout, "  ");
		    print_stack(context, &new_stack_info);
		    print_registers(context, &new_register_info);
		    print_flags(context, new_and_flags, new_or_flags);
		    fflush(stdout);
		}
#endif
		/* Add the new stack and register information to any
		 * instructions that can follow this instruction.     */
		merge_into_successors(context, inumber, 
				      &new_register_info, &new_stack_info,
				      new_and_flags, new_or_flags);
	    }
	}
    }
}


/* Make sure that the registers contain a legitimate value for the given
 * instruction.
*/

static void
check_register_values(context_type *context, unsigned int inumber)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    opcode_type opcode = this_idata->opcode;
    int operand = this_idata->operand.i;
    int register_count = this_idata->register_info.register_count;
    fullinfo_type *registers = this_idata->register_info.registers;
    jboolean double_word = JNI_FALSE;	/* default value */
    int type;
    
    switch (opcode) {
        default:
	    return;
        case opc_iload: case opc_iinc:
	    type = ITEM_Integer; break;
        case opc_fload:
	    type = ITEM_Float; break;
        case opc_aload:
	    type = ITEM_Object; break;
        case opc_ret:
	    type = ITEM_ReturnAddress; break;
        case opc_lload:	
	    type = ITEM_Long; double_word = JNI_TRUE; break;
        case opc_dload:
	    type = ITEM_Double; double_word = JNI_TRUE; break;
    }
    if (!double_word) {
	fullinfo_type reg;
	/* Make sure we don't have an illegal register or one with wrong type */
	if (operand >= register_count) {
	    CCerror(context, 
		    "Accessing value from uninitialized register %d", operand);
	}
	reg = registers[operand];
	
	if (WITH_ZERO_EXTRA_INFO(reg) == MAKE_FULLINFO(type, 0, 0)) {
	    /* the register is obviously of the given type */
	    return;
	} else if (GET_INDIRECTION(reg) > 0 && type == ITEM_Object) {
	    /* address type stuff be used on all arrays */
	    return;
	} else if (GET_ITEM_TYPE(reg) == ITEM_ReturnAddress) { 
	    CCerror(context, "Cannot load return address from register %d", 
		              operand);
	    /* alternatively
	              (GET_ITEM_TYPE(reg) == ITEM_ReturnAddress)
                   && (opcode == opc_iload) 
		   && (type == ITEM_Object || type == ITEM_Integer)
	       but this never occurs
	    */
	} else if (reg == ITEM_InitObject && type == ITEM_Object) {
	    return;
	} else if (WITH_ZERO_EXTRA_INFO(reg) == 
		        MAKE_FULLINFO(ITEM_NewObject, 0, 0) && 
		   type == ITEM_Object) {
	    return;
        } else {
	    CCerror(context, "Register %d contains wrong type", operand);
	}
    } else {
	/* Make sure we don't have an illegal register or one with wrong type */
	if ((operand + 1) >= register_count) {
	    CCerror(context, 
		    "Accessing value from uninitialized register pair %d/%d", 
		    operand, operand+1);
	} else {
	    if ((registers[operand] == MAKE_FULLINFO(type, 0, 0)) &&
		(registers[operand + 1] == MAKE_FULLINFO(type + 1, 0, 0))) {
		return;
	    } else {
		CCerror(context, "Register pair %d/%d contains wrong type", 
		        operand, operand+1);
	    }
	}
    } 
}


/* Make sure the flags contain legitimate values for this instruction.
*/

static void
check_flags(context_type *context, unsigned int inumber)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    opcode_type opcode = this_idata->opcode;
    switch (opcode) {
        case opc_return:
	    /* We need a constructor, but we aren't guaranteed it's called */
	    if ((this_idata->or_flags & FLAG_NEED_CONSTRUCTOR) && 
		   !(this_idata->and_flags & FLAG_CONSTRUCTED))
		CCerror(context, "Constructor must call super() or this()");
	    /* fall through */
        case opc_ireturn: case opc_lreturn: 
        case opc_freturn: case opc_dreturn: case opc_areturn: 
	    if (this_idata->or_flags & FLAG_NO_RETURN)
		/* This method cannot exit normally */
		CCerror(context, "Cannot return normally");
        default:
	    break; /* nothing to do. */
    }
}

/* Make sure that the top of the stack contains reasonable values for the 
 * given instruction.  The post-pop values of the stack and its size are 
 * returned in *new_stack_info.
 */

static void 
pop_stack(context_type *context, unsigned int inumber, stack_info_type *new_stack_info)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    opcode_type opcode = this_idata->opcode;
    stack_item_type *stack = this_idata->stack_info.stack;
    int stack_size = this_idata->stack_info.stack_size;
    char *stack_operands, *p;
    char buffer[257];		/* for holding manufactured argument lists */
    fullinfo_type stack_extra_info_buffer[256]; /* save info popped off stack */
    fullinfo_type *stack_extra_info = &stack_extra_info_buffer[256];
    fullinfo_type full_info;    /* only used in case of invoke instructions */
    fullinfo_type put_full_info; /* only used in case opc_putstatic and opc_putfield */
    
    switch(opcode) {
        default:
	    /* For most instructions, we just use a built-in table */
	    stack_operands = opcode_in_out[opcode][0];
	    break;

        case opc_putstatic: case opc_putfield: {
	    /* The top thing on the stack depends on the signature of
	     * the object.                         */
	    int operand = this_idata->operand.i;
	    const char *signature = 
	        JVM_GetCPFieldSignatureUTF(context->env,
					   context->class,
					   operand);
	    char *ip = buffer;
	    check_and_push(context, signature, VM_STRING_UTF);
#ifdef DEBUG
	    if (verify_verbose) {
		print_formatted_fieldname(context, operand);
	    }
#endif
	    if (opcode == opc_putfield)
		*ip++ = 'A';	/* object for putfield */
	    *ip++ = signature_to_fieldtype(context, &signature, &put_full_info);
	    *ip = '\0';
	    stack_operands = buffer;
	    pop_and_free(context);
	    break;
	}

	case opc_invokevirtual: case opc_invokespecial:        
        case opc_invokeinit:	/* invokespecial call to <init> */
	case opc_invokestatic: case opc_invokeinterface: {
	    /* The top stuff on the stack depends on the method signature */
	    int operand = this_idata->operand.i;
	    const char *signature = 
	        JVM_GetCPMethodSignatureUTF(context->env, 
					    context->class, 
					    operand);
	    char *ip = buffer;
	    const char *p;
	    check_and_push(context, signature, VM_STRING_UTF);
#ifdef DEBUG
	    if (verify_verbose) {
		print_formatted_methodname(context, operand);
	    }
#endif
	    if (opcode != opc_invokestatic) 
		/* First, push the object */
		*ip++ = (opcode == opc_invokeinit ? '@' : 'A');
	    for (p = signature + 1; *p != JVM_SIGNATURE_ENDFUNC; ) {
		*ip++ = signature_to_fieldtype(context, &p, &full_info);
		if (ip >= buffer + sizeof(buffer) - 1)
		    CCerror(context, "Signature %s has too many arguments", 
			    signature);
	    }
	    *ip = 0;
	    stack_operands = buffer;
	    pop_and_free(context);
	    break;
	}

	case opc_multianewarray: {
	    /* Count can't be larger than 255. So can't overflow buffer */
	    int count = this_idata->operand2.i;	/* number of ints on stack */
	    memset(buffer, 'I', count);
	    buffer[count] = '\0';
	    stack_operands = buffer;
	    break;
	}

    } /* of switch */

    /* Run through the list of operands >>backwards<< */
    for (   p = stack_operands + strlen(stack_operands);
	    p > stack_operands; 
	    stack = stack->next) {
	int type = *--p;
	fullinfo_type top_type = stack ? stack->item : 0;
	int size = (type == 'D' || type == 'L') ? 2 : 1;
	*--stack_extra_info = top_type;
	if (stack == NULL) 
	    CCerror(context, "Unable to pop operand off an empty stack");

	switch (type) {
	    case 'I': 
	        if (top_type != MAKE_FULLINFO(ITEM_Integer, 0, 0))
		    CCerror(context, "Expecting to find integer on stack");
		break;
		
	    case 'F': 
		if (top_type != MAKE_FULLINFO(ITEM_Float, 0, 0))
		    CCerror(context, "Expecting to find float on stack");
		break;
		
	    case 'A':		/* object or array */
		if (   (GET_ITEM_TYPE(top_type) != ITEM_Object) 
		    && (GET_INDIRECTION(top_type) == 0)) { 
		    /* The thing isn't an object or an array.  Let's see if it's
		     * one of the special cases  */
		    if (  (WITH_ZERO_EXTRA_INFO(top_type) == 
			        MAKE_FULLINFO(ITEM_ReturnAddress, 0, 0))
			&& (opcode == opc_astore)) 
			break;
		    if (   (GET_ITEM_TYPE(top_type) == ITEM_NewObject 
			    || (GET_ITEM_TYPE(top_type) == ITEM_InitObject))
			&& ((opcode == opc_astore) || (opcode == opc_aload)
                            || (opcode == opc_ifnull) || (opcode == opc_ifnonnull)))
			break;
		    /* The 2nd edition VM of the specification allows field
		     * initializations before the superclass initializer,
		     * if the field is defined within the current class.
                     */
		     if (   (GET_ITEM_TYPE(top_type) == ITEM_InitObject)
			 && (opcode == opc_putfield)) {
			int operand = this_idata->operand.i;
			int access_bits = JVM_GetCPFieldModifiers(context->env,
								  context->class,
								  operand,
								  context->class);
			/* Note: This relies on the fact that 
			 * JVM_GetCPFieldModifiers retrieves only local fields,
			 * and does not respect inheritance.
			 */
			if (access_bits != -1) {
			    if ( cp_index_to_class_fullinfo(context, operand, JVM_CONSTANT_Fieldref) ==
			         context->currentclass_info ) {
				top_type = context->currentclass_info;
				*stack_extra_info = top_type;
				break;
			    }
			}
		    }
		    CCerror(context, "Expecting to find object/array on stack");
		}
		break;

	    case '@': {		/* unitialized object, for call to <init> */
		int item_type = GET_ITEM_TYPE(top_type);
		if (item_type != ITEM_NewObject && item_type != ITEM_InitObject)
		    CCerror(context, 
			    "Expecting to find unitialized object on stack");
		break;
	    }

	    case 'O':		/* object, not array */
		if (WITH_ZERO_EXTRA_INFO(top_type) != 
		       MAKE_FULLINFO(ITEM_Object, 0, 0))
		    CCerror(context, "Expecting to find object on stack");
		break;

	    case 'a':		/* integer, object, or array */
		if (      (top_type != MAKE_FULLINFO(ITEM_Integer, 0, 0)) 
		       && (GET_ITEM_TYPE(top_type) != ITEM_Object)
		       && (GET_INDIRECTION(top_type) == 0))
		    CCerror(context, 
			    "Expecting to find object, array, or int on stack");
		break;

	    case 'D':		/* double */
		if (top_type != MAKE_FULLINFO(ITEM_Double, 0, 0))
		    CCerror(context, "Expecting to find double on stack");
		break;

	    case 'L':		/* long */
		if (top_type != MAKE_FULLINFO(ITEM_Long, 0, 0))
		    CCerror(context, "Expecting to find long on stack");
		break;

	    case ']':		/* array of some type */
		if (top_type == NULL_FULLINFO) { 
		    /* do nothing */
		} else switch(p[-1]) {
		    case 'I':	/* array of integers */
		        if (top_type != MAKE_FULLINFO(ITEM_Integer, 1, 0) && 
			    top_type != NULL_FULLINFO)
			    CCerror(context, 
				    "Expecting to find array of ints on stack");
			break;

		    case 'L':	/* array of longs */
		        if (top_type != MAKE_FULLINFO(ITEM_Long, 1, 0))
			    CCerror(context, 
				   "Expecting to find array of longs on stack");
			break;

		    case 'F':	/* array of floats */
		        if (top_type != MAKE_FULLINFO(ITEM_Float, 1, 0))
			    CCerror(context, 
				 "Expecting to find array of floats on stack");
			break;

		    case 'D':	/* array of doubles */
		        if (top_type != MAKE_FULLINFO(ITEM_Double, 1, 0))
			    CCerror(context, 
				"Expecting to find array of doubles on stack");
			break;

		    case 'A': {	/* array of addresses (arrays or objects) */
			int indirection = GET_INDIRECTION(top_type);
			if ((indirection == 0) || 
			    ((indirection == 1) && 
			        (GET_ITEM_TYPE(top_type) != ITEM_Object)))
			    CCerror(context, 
				"Expecting to find array of objects or arrays "
				    "on stack");
			break;
		    }
			
		    case 'B':	/* array of bytes */
		        if (top_type != MAKE_FULLINFO(ITEM_Byte, 1, 0))
			    CCerror(context, 
				  "Expecting to find array of bytes on stack");
			break;

		    case 'C':	/* array of characters */
		        if (top_type != MAKE_FULLINFO(ITEM_Char, 1, 0))
			    CCerror(context, 
				  "Expecting to find array of chars on stack");
			break;

		    case 'S':	/* array of shorts */
		        if (top_type != MAKE_FULLINFO(ITEM_Short, 1, 0))
			    CCerror(context, 
				 "Expecting to find array of shorts on stack");
			break;

		    case '?':	/* any type of array is okay */
		        if (GET_INDIRECTION(top_type) == 0) 
			    CCerror(context, 
				    "Expecting to find array on stack");
			break;

		    default:
			CCerror(context, "Internal error #1");
			break;
		}
		p -= 2;		/* skip over [ <char> */
		break;

	    case '1': case '2': case '3': case '4': /* stack swapping */
		if (top_type == MAKE_FULLINFO(ITEM_Double, 0, 0) 
		    || top_type == MAKE_FULLINFO(ITEM_Long, 0, 0)) {
		    if ((p > stack_operands) && (p[-1] == '+')) {
			context->swap_table[type - '1'] = top_type + 1;
			context->swap_table[p[-2] - '1'] = top_type;
			size = 2;
			p -= 2;
		    } else {
			CCerror(context, 
				"Attempt to split long or double on the stack");
		    }
		} else {
		    context->swap_table[type - '1'] = stack->item;
		    if ((p > stack_operands) && (p[-1] == '+')) 
			p--;	/* ignore */
		}
		break;
	    case '+':		/* these should have been caught. */
	    default:
		CCerror(context, "Internal error #2");
	}
	stack_size -= size;
    }
    
    /* For many of the opcodes that had an "A" in their field, we really 
     * need to go back and do a little bit more accurate testing.  We can, of
     * course, assume that the minimal type checking has already been done. 
     */
    switch (opcode) {
	default: break;
	case opc_aastore: {	/* array index object  */
	    fullinfo_type array_type = stack_extra_info[0];
	    fullinfo_type object_type = stack_extra_info[2];
	    fullinfo_type target_type = decrement_indirection(array_type);
	    if ((GET_ITEM_TYPE(object_type) != ITEM_Object) 
		    && (GET_INDIRECTION(object_type) == 0)) { 
		CCerror(context, "Expecting reference type on operand stack in aastore");
	    }
	    if ((GET_ITEM_TYPE(target_type) != ITEM_Object)
		    && (GET_INDIRECTION(target_type) == 0)) {
		CCerror(context, "Component type of the array must be reference type in aastore");
	    }
	    break;
	}

	case opc_putfield: 
	case opc_getfield: 
        case opc_putstatic: {	
	    int operand = this_idata->operand.i;
	    fullinfo_type stack_object = stack_extra_info[0];
	    if (opcode == opc_putfield || opcode == opc_getfield) {
		if (!isAssignableTo
		        (context, 
			 stack_object, 
			 cp_index_to_class_fullinfo
			     (context, operand, JVM_CONSTANT_Fieldref))) {
		    CCerror(context, 
			    "Incompatible type for getting or setting field");
		}
		if (this_idata->protected && 
		    !isAssignableTo(context, stack_object, 
				    context->currentclass_info)) { 
		    CCerror(context, "Bad access to protected data");
		}
	    }
	    if (opcode == opc_putfield || opcode == opc_putstatic) { 
		int item = (opcode == opc_putfield ? 1 : 0);
		if (!isAssignableTo(context, 
				    stack_extra_info[item], put_full_info)) { 
		    CCerror(context, "Bad type in putfield/putstatic");
		}
	    }
	    break;
	}

        case opc_athrow: 
	    if (!isAssignableTo(context, stack_extra_info[0], 
				context->throwable_info)) {
		CCerror(context, "Can only throw Throwable objects");
	    }
	    break;

	case opc_aaload: {	/* array index */
	    /* We need to pass the information to the stack updater */
	    fullinfo_type array_type = stack_extra_info[0];
	    context->swap_table[0] = decrement_indirection(array_type);
	    break;
	}
	    
        case opc_invokevirtual: case opc_invokespecial: 
        case opc_invokeinit:
	case opc_invokeinterface: case opc_invokestatic: {
	    int operand = this_idata->operand.i;
	    const char *signature = 
	        JVM_GetCPMethodSignatureUTF(context->env,
					    context->class,
					    operand);
	    int item;
	    const char *p;
	    check_and_push(context, signature, VM_STRING_UTF);
	    if (opcode == opc_invokestatic) {
		item = 0;
	    } else if (opcode == opc_invokeinit) {
		fullinfo_type init_type = this_idata->operand2.fi;
		fullinfo_type object_type = stack_extra_info[0];
		context->swap_table[0] = object_type; /* save value */
		if (GET_ITEM_TYPE(stack_extra_info[0]) == ITEM_NewObject) {
		    /* We better be calling the appropriate init.  Find the
		     * inumber of the "opc_new" instruction", and figure 
		     * out what the type really is. 
		     */
		    unsigned int new_inumber = GET_EXTRA_INFO(stack_extra_info[0]);
		    fullinfo_type target_type = idata[new_inumber].operand2.fi;
		    context->swap_table[1] = target_type;

		    if (target_type != init_type) {
			CCerror(context, "Call to wrong initialization method");
		    }
		    if (this_idata->protected 
		        && context->major_version > LDC_CLASS_MAJOR_VERSION
		        && !isAssignableTo(context, object_type, 
				           context->currentclass_info)) { 
		      CCerror(context, "Bad access to protected data");
		    }
		} else {
		    /* We better be calling super() or this(). */
		    if (init_type != context->superclass_info && 
			init_type != context->currentclass_info) {
			CCerror(context, "Call to wrong initialization method");
		    }
		    context->swap_table[1] = context->currentclass_info;
		}
		item = 1;
	    } else {
		fullinfo_type target_type = this_idata->operand2.fi;
		fullinfo_type object_type = stack_extra_info[0];
		if (!isAssignableTo(context, object_type, target_type)){
		    CCerror(context, 
		            "Incompatible object argument for function call");
		} 
		if (opcode == opc_invokespecial 
		    && !isAssignableTo(context, object_type, 
				       context->currentclass_info)) {
		    /* Make sure object argument is assignment compatible to current class */
		    CCerror(context,
			    "Incompatible object argument for invokespecial");
		}
		if (this_idata->protected
		    && !isAssignableTo(context, object_type, 
				       context->currentclass_info)) { 
		    /* This is ugly. Special dispensation.  Arrays pretend to
		       implement public Object clone() even though they don't */
		    const char *utfName = 
		        JVM_GetCPMethodNameUTF(context->env, 
					       context->class,
					       this_idata->operand.i);
		    int is_clone = utfName && (strcmp(utfName, "clone") == 0);
		    JVM_ReleaseUTF(utfName);

		    if ((target_type == context->object_info) && 
			(GET_INDIRECTION(object_type) > 0) &&
			is_clone) {
		    } else { 
			CCerror(context, "Bad access to protected data");
		    }
		}
		item = 1;
	    }
	    for (p = signature + 1; *p != JVM_SIGNATURE_ENDFUNC; item++)
		if (signature_to_fieldtype(context, &p, &full_info) == 'A') {
		    if (!isAssignableTo(context, 
					stack_extra_info[item], full_info)) {
			CCerror(context, "Incompatible argument to function");
		    }
		}

	    pop_and_free(context);
	    break;
	}
	    
        case opc_return:
	    if (context->return_type != MAKE_FULLINFO(ITEM_Void, 0, 0)) 
		CCerror(context, "Wrong return type in function");
	    break;

	case opc_ireturn: case opc_lreturn: case opc_freturn: 
        case opc_dreturn: case opc_areturn: {
	    fullinfo_type target_type = context->return_type;
	    fullinfo_type object_type = stack_extra_info[0];
	    if (!isAssignableTo(context, object_type, target_type)) {
		CCerror(context, "Wrong return type in function");
	    }
	    break;
	}

        case opc_new: {
	    /* Make sure that nothing on the stack already looks like what
	     * we want to create.  I can't image how this could possibly happen
	     * but we should test for it anyway, since if it could happen, the
	     * result would be an unitialized object being able to masquerade
	     * as an initialized one. 
	     */
	    stack_item_type *item;
	    for (item = stack; item != NULL; item = item->next) { 
		if (item->item == this_idata->operand.fi) { 
		    CCerror(context, 
			    "Uninitialized object on stack at creating point");
		}
	    }
	    /* Info for update_registers */
	    context->swap_table[0] = this_idata->operand.fi;
	    context->swap_table[1] = MAKE_FULLINFO(ITEM_Bogus, 0, 0);
	    
	    break;
	}
    }
    new_stack_info->stack = stack;
    new_stack_info->stack_size = stack_size;
}


/* We've already determined that the instruction is legal.  Perform the 
 * operation on the registers, and return the updated results in
 * new_register_count_p and new_registers.
 */

static void
update_registers(context_type *context, unsigned int inumber, 
		 register_info_type *new_register_info)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    opcode_type opcode = this_idata->opcode;
    int operand = this_idata->operand.i;
    int register_count = this_idata->register_info.register_count;
    fullinfo_type *registers = this_idata->register_info.registers;
    stack_item_type *stack = this_idata->stack_info.stack;
    int mask_count = this_idata->register_info.mask_count;
    mask_type *masks = this_idata->register_info.masks;

    /* Use these as default new values. */
    int            new_register_count = register_count;
    int            new_mask_count = mask_count;
    fullinfo_type *new_registers = registers;
    mask_type     *new_masks = masks;

    enum { ACCESS_NONE, ACCESS_SINGLE, ACCESS_DOUBLE } access = ACCESS_NONE;
    int i;
    
    /* Remember, we've already verified the type at the top of the stack. */
    switch (opcode) {
	default: break;
        case opc_istore: case opc_fstore: case opc_astore:
	    access = ACCESS_SINGLE;
	    goto continue_store;

        case opc_lstore: case opc_dstore:
	    access = ACCESS_DOUBLE;
	    goto continue_store;

	continue_store: {
	    /* We have a modification to the registers.  Copy them if needed. */
	    fullinfo_type stack_top_type = stack->item;
	    int max_operand = operand + ((access == ACCESS_DOUBLE) ? 1 : 0);
	    
	    if (     max_operand < register_count 
		  && registers[operand] == stack_top_type
		  && ((access == ACCESS_SINGLE) || 
		         (registers[operand + 1]== stack_top_type + 1))) 
		/* No changes have been made to the registers. */
		break;
	    new_register_count = MAX(max_operand + 1, register_count);
	    new_registers = NEW(fullinfo_type, new_register_count);
	    for (i = 0; i < register_count; i++) 
		new_registers[i] = registers[i];
	    for (i = register_count; i < new_register_count; i++) 
		new_registers[i] = MAKE_FULLINFO(ITEM_Bogus, 0, 0);
	    new_registers[operand] = stack_top_type;
	    if (access == ACCESS_DOUBLE)
		new_registers[operand + 1] = stack_top_type + 1;
	    break;
	}
	 
        case opc_iload: case opc_fload: case opc_aload:
        case opc_iinc: case opc_ret:
	    access = ACCESS_SINGLE;
	    break;

        case opc_lload: case opc_dload:	
	    access = ACCESS_DOUBLE;
	    break;

        case opc_jsr: case opc_jsr_w:
	    for (i = 0; i < new_mask_count; i++) 
		if (new_masks[i].entry == operand) 
		    CCerror(context, "Recursive call to jsr entry");
	    new_masks = add_to_masks(context, masks, mask_count, operand);
	    new_mask_count++; 
	    break;
	    
        case opc_invokeinit: 
        case opc_new: {
	    /* For invokeinit, an uninitialized object has been initialized.
	     * For new, all previous occurrences of an uninitialized object
	     * from the same instruction must be made bogus.  
	     * We find all occurrences of swap_table[0] in the registers, and
	     * replace them with swap_table[1];   
	     */
	    fullinfo_type from = context->swap_table[0];
	    fullinfo_type to = context->swap_table[1];

	    int i;
	    for (i = 0; i < register_count; i++) {
		if (new_registers[i] == from) {
		    /* Found a match */
		    break;
		}
	    }
	    if (i < register_count) { /* We broke out loop for match */
		/* We have to change registers, and possibly a mask */
		jboolean copied_mask = JNI_FALSE;
		int k;
		new_registers = NEW(fullinfo_type, register_count);
		memcpy(new_registers, registers, 
		       register_count * sizeof(registers[0]));
		for ( ; i < register_count; i++) { 
		    if (new_registers[i] == from) { 
			new_registers[i] = to;
			for (k = 0; k < new_mask_count; k++) {
			    if (!IS_BIT_SET(new_masks[k].modifies, i)) { 
				if (!copied_mask) { 
				    new_masks = copy_masks(context, new_masks, 
							   mask_count);
				    copied_mask = JNI_TRUE;
				}
				SET_BIT(new_masks[k].modifies, i);
			    }
			}
		    }
		}
	    }
	    break;
	} 
    } /* of switch */

    if ((access != ACCESS_NONE) && (new_mask_count > 0)) {
	int i, j;
	for (i = 0; i < new_mask_count; i++) {
	    int *mask = new_masks[i].modifies;
	    if ((!IS_BIT_SET(mask, operand)) || 
		  ((access == ACCESS_DOUBLE) && 
		   !IS_BIT_SET(mask, operand + 1))) {
		new_masks = copy_masks(context, new_masks, mask_count);
		for (j = i; j < new_mask_count; j++) {
		    SET_BIT(new_masks[j].modifies, operand);
		    if (access == ACCESS_DOUBLE) 
			SET_BIT(new_masks[j].modifies, operand + 1);
		} 
		break;
	    }
	}
    }

    new_register_info->register_count = new_register_count;
    new_register_info->registers = new_registers;
    new_register_info->masks = new_masks;
    new_register_info->mask_count = new_mask_count;
}



/* We've already determined that the instruction is legal, and have updated 
 * the registers.  Update the flags, too. 
 */


static void
update_flags(context_type *context, unsigned int inumber, 
	     flag_type *new_and_flags, flag_type *new_or_flags)

{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    flag_type and_flags = this_idata->and_flags;
    flag_type or_flags = this_idata->or_flags;

    /* Set the "we've done a constructor" flag */
    if (this_idata->opcode == opc_invokeinit) {
	fullinfo_type from = context->swap_table[0];
	if (from == MAKE_FULLINFO(ITEM_InitObject, 0, 0))
	    and_flags |= FLAG_CONSTRUCTED;
    }
    *new_and_flags = and_flags;
    *new_or_flags = or_flags;
}



/* We've already determined that the instruction is legal.  Perform the 
 * operation on the stack;
 *
 * new_stack_size_p and new_stack_p point to the results after the pops have
 * already been done.  Do the pushes, and then put the results back there. 
 */

static void
push_stack(context_type *context, unsigned int inumber, stack_info_type *new_stack_info)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    opcode_type opcode = this_idata->opcode;
    int operand = this_idata->operand.i;

    int stack_size = new_stack_info->stack_size;
    stack_item_type *stack = new_stack_info->stack;
    char *stack_results;
	
    fullinfo_type full_info = 0;
    char buffer[5], *p;		/* actually [2] is big enough */

    /* We need to look at all those opcodes in which either we can't tell the
     * value pushed onto the stack from the opcode, or in which the value
     * pushed onto the stack is an object or array.  For the latter, we need
     * to make sure that full_info is set to the right value.
     */
    switch(opcode) {
        default:
	    stack_results = opcode_in_out[opcode][1]; 
	    break;

	case opc_ldc: case opc_ldc_w: case opc_ldc2_w: {
	    /* Look to constant pool to determine correct result. */
	    unsigned char *type_table = context->constant_types;
	    switch (type_table[operand]) {
		case JVM_CONSTANT_Integer:   
		    stack_results = "I"; break;
		case JVM_CONSTANT_Float:     
		    stack_results = "F"; break;
		case JVM_CONSTANT_Double:    
		    stack_results = "D"; break;
		case JVM_CONSTANT_Long:      
		    stack_results = "L"; break;
		case JVM_CONSTANT_String: 
		    stack_results = "A"; 
		    full_info = context->string_info;
		    break;
		case JVM_CONSTANT_Class: 
		    if (context->major_version < LDC_CLASS_MAJOR_VERSION)
			CCerror(context, "Internal error #3");
		    stack_results = "A";
		    full_info = make_class_info_from_name(context,
							  "java/lang/Class");
		    break;
		default:
		    CCerror(context, "Internal error #3");
		    stack_results = "";	/* Never reached: keep lint happy */
	    }
	    break;
	}

        case opc_getstatic: case opc_getfield: {
	    /* Look to signature to determine correct result. */
	    int operand = this_idata->operand.i;
	    const char *signature = JVM_GetCPFieldSignatureUTF(context->env,
							       context->class, 
							       operand);
	    check_and_push(context, signature, VM_STRING_UTF);
#ifdef DEBUG
	    if (verify_verbose) {
		print_formatted_fieldname(context, operand);
	    }
#endif
	    buffer[0] = signature_to_fieldtype(context, &signature, &full_info);
	    buffer[1] = '\0';
	    stack_results = buffer;
	    pop_and_free(context);
	    break;
	}

	case opc_invokevirtual: case opc_invokespecial:
        case opc_invokeinit:
	case opc_invokestatic: case opc_invokeinterface: {
	    /* Look to signature to determine correct result. */
	    int operand = this_idata->operand.i;
	    const char *signature = JVM_GetCPMethodSignatureUTF(context->env,
								context->class,
								operand);
	    const char *result_signature;
	    check_and_push(context, signature, VM_STRING_UTF);
	    result_signature = strchr(signature, JVM_SIGNATURE_ENDFUNC) + 1;
	    if (result_signature[0] == JVM_SIGNATURE_VOID) {
		stack_results = "";
	    } else {
		buffer[0] = signature_to_fieldtype(context, &result_signature, 
						   &full_info);
		buffer[1] = '\0';
		stack_results = buffer;
	    }
	    pop_and_free(context);
	    break;
	}
	    
	case opc_aconst_null:
	    stack_results = opcode_in_out[opcode][1]; 
	    full_info = NULL_FULLINFO; /* special NULL */
	    break;

	case opc_new: 
	case opc_checkcast: 
	case opc_newarray: 
	case opc_anewarray: 
        case opc_multianewarray:
	    stack_results = opcode_in_out[opcode][1]; 
	    /* Conveniently, this result type is stored here */
	    full_info = this_idata->operand.fi;
	    break;
			
	case opc_aaload:
	    stack_results = opcode_in_out[opcode][1]; 
	    /* pop_stack() saved value for us. */
	    full_info = context->swap_table[0];
	    break;
		
	case opc_aload:
	    stack_results = opcode_in_out[opcode][1]; 
	    /* The register hasn't been modified, so we can use its value. */
	    full_info = this_idata->register_info.registers[operand];
	    break;
    } /* of switch */
    
    for (p = stack_results; *p != 0; p++) {
	int type = *p;
	stack_item_type *new_item = NEW(stack_item_type, 1);
	new_item->next = stack;
	stack = new_item;
	switch (type) {
	    case 'I': 
	        stack->item = MAKE_FULLINFO(ITEM_Integer, 0, 0); break;
	    case 'F': 
		stack->item = MAKE_FULLINFO(ITEM_Float, 0, 0); break;
	    case 'D': 
		stack->item = MAKE_FULLINFO(ITEM_Double, 0, 0); 
		stack_size++; break;
	    case 'L': 
		stack->item = MAKE_FULLINFO(ITEM_Long, 0, 0); 
		stack_size++; break;
	    case 'R': 
		stack->item = MAKE_FULLINFO(ITEM_ReturnAddress, 0, operand);
		break;
	    case '1': case '2': case '3': case '4': {
		/* Get the info saved in the swap_table */
		fullinfo_type stype = context->swap_table[type - '1'];
		stack->item = stype;
		if (stype == MAKE_FULLINFO(ITEM_Long, 0, 0) || 
		    stype == MAKE_FULLINFO(ITEM_Double, 0, 0)) {
		    stack_size++; p++;
		}
		break;
	    }
	    case 'A': 
		/* full_info should have the appropriate value. */
		assert(full_info != 0);
		stack->item = full_info;
		break;
	    default:
		CCerror(context, "Internal error #4");

	    } /* switch type */
	stack_size++;
    } /* outer for loop */

    if (opcode == opc_invokeinit) {
	/* If there are any instances of "from" on the stack, we need to
	 * replace it with "to", since calling <init> initializes all versions
	 * of the object, obviously.     */
	fullinfo_type from = context->swap_table[0];
	stack_item_type *ptr;
	for (ptr = stack; ptr != NULL; ptr = ptr->next) {
	    if (ptr->item == from) {
		fullinfo_type to = context->swap_table[1];
		stack = copy_stack(context, stack);
		for (ptr = stack; ptr != NULL; ptr = ptr->next) 
		    if (ptr->item == from) ptr->item = to;
		break;
	    }
	}
    }

    new_stack_info->stack_size = stack_size;
    new_stack_info->stack = stack;
}


/* We've performed an instruction, and determined the new registers and stack 
 * value.  Look at all of the possibly subsequent instructions, and merge
 * this stack value into theirs. 
 */

static void
merge_into_successors(context_type *context, unsigned int inumber, 
		      register_info_type *register_info,
		      stack_info_type *stack_info, 
		      flag_type and_flags, flag_type or_flags)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[inumber];
    opcode_type opcode = this_idata->opcode;
    int operand = this_idata->operand.i;
    struct handler_info_type *handler_info = context->handler_info;
    int handler_info_length = 
        JVM_GetMethodIxExceptionTableLength(context->env, 
					    context->class, 
					    context->method_index); 


    int buffer[2];		/* default value for successors */
    int *successors = buffer;	/* table of successors */
    int successors_count;
    int i;
    
    switch (opcode) {
    default:
	successors_count = 1; 
	buffer[0] = inumber + 1;
	break;

    case opc_ifeq: case opc_ifne: case opc_ifgt: 
    case opc_ifge: case opc_iflt: case opc_ifle:
    case opc_ifnull: case opc_ifnonnull:
    case opc_if_icmpeq: case opc_if_icmpne: case opc_if_icmpgt: 
    case opc_if_icmpge: case opc_if_icmplt: case opc_if_icmple:
    case opc_if_acmpeq: case opc_if_acmpne:
	successors_count = 2;
	buffer[0] = inumber + 1; 
	buffer[1] = operand;
	break;

    case opc_jsr: case opc_jsr_w: 
	if (this_idata->operand2.i != UNKNOWN_RET_INSTRUCTION) 
	    idata[this_idata->operand2.i].changed = JNI_TRUE;
	/* FALLTHROUGH */
    case opc_goto: case opc_goto_w:
	successors_count = 1;
	buffer[0] = operand;
	break;


    case opc_ireturn: case opc_lreturn: case opc_return:	
    case opc_freturn: case opc_dreturn: case opc_areturn: 
    case opc_athrow:
	/* The testing for the returns is handled in pop_stack() */
	successors_count = 0;
	break;

    case opc_ret: {
	/* This is slightly slow, but good enough for a seldom used instruction.
	 * The EXTRA_ITEM_INFO of the ITEM_ReturnAddress indicates the
	 * address of the first instruction of the subroutine.  We can return
	 * to 1 after any instruction that jsr's to that instruction.
	 */
	if (this_idata->operand2.ip == NULL) {
	    fullinfo_type *registers = this_idata->register_info.registers;
	    int called_instruction = GET_EXTRA_INFO(registers[operand]);
	    int i, count, *ptr;;
	    for (i = context->instruction_count, count = 0; --i >= 0; ) {
		if (((idata[i].opcode == opc_jsr) ||
		     (idata[i].opcode == opc_jsr_w)) && 
		    (idata[i].operand.i == called_instruction)) 
		    count++;
	    }
	    this_idata->operand2.ip = ptr = NEW(int, count + 1);
	    *ptr++ = count;
	    for (i = context->instruction_count, count = 0; --i >= 0; ) {
		if (((idata[i].opcode == opc_jsr) ||
		     (idata[i].opcode == opc_jsr_w)) && 
		    (idata[i].operand.i == called_instruction)) 
		    *ptr++ = i + 1;
	    }
	}
	successors = this_idata->operand2.ip; /* use this instead */
	successors_count = *successors++;
	break;

    }

    case opc_tableswitch:
    case opc_lookupswitch: 
	successors = this_idata->operand.ip; /* use this instead */
	successors_count = *successors++;
	break;
    }

#ifdef DEBUG
    if (verify_verbose) { 
	jio_fprintf(stdout, " [");
	for (i = handler_info_length; --i >= 0; handler_info++)
	    if (handler_info->start <= inumber && handler_info->end > inumber)
		jio_fprintf(stdout, "%d* ", handler_info->handler);
	for (i = 0; i < successors_count; i++)
	    jio_fprintf(stdout, "%d ", successors[i]);
	jio_fprintf(stdout,   "]\n");
    }
#endif

    handler_info = context->handler_info;
    for (i = handler_info_length; --i >= 0; handler_info++) {
	if (handler_info->start <= inumber && handler_info->end > inumber) {
	    int handler = handler_info->handler;
	    if (opcode != opc_invokeinit) {
		merge_into_one_successor(context, inumber, handler, 
					 &this_idata->register_info, /* old */
					 &handler_info->stack_info, 
					 (flag_type) (and_flags
						      & this_idata->and_flags),
					 (flag_type) (or_flags
						      | this_idata->or_flags),
					 JNI_TRUE);
	    } else {
		/* We need to be a little bit more careful with this 
		 * instruction.  Things could either be in the state before
		 * the instruction or in the state afterwards */
		fullinfo_type from = context->swap_table[0];
		flag_type temp_or_flags = or_flags;
		if (from == MAKE_FULLINFO(ITEM_InitObject, 0, 0))
		    temp_or_flags |= FLAG_NO_RETURN;
		merge_into_one_successor(context, inumber, handler, 
					 &this_idata->register_info, /* old */
					 &handler_info->stack_info, 
					 this_idata->and_flags,
					 this_idata->or_flags,
					 JNI_TRUE);
		merge_into_one_successor(context, inumber, handler, 
					 register_info, 
					 &handler_info->stack_info, 
					 and_flags, temp_or_flags, JNI_TRUE);
	    }
	}
    }
    for (i = 0; i < successors_count; i++) {
	int target = successors[i];
	if (target >= context->instruction_count) 
	    CCerror(context, "Falling off the end of the code");
	merge_into_one_successor(context, inumber, target, 
				 register_info, stack_info, and_flags, or_flags,
				 JNI_FALSE);
    }
}

/* We have a new set of registers and stack values for a given instruction.
 * Merge this new set into the values that are already there. 
 */

static void
merge_into_one_successor(context_type *context, 
			 unsigned int from_inumber, unsigned int to_inumber, 
			 register_info_type *new_register_info,
			 stack_info_type *new_stack_info,
			 flag_type new_and_flags, flag_type new_or_flags,
			 jboolean isException)
{
    instruction_data_type *idata = context->instruction_data;
    register_info_type register_info_buf;
    stack_info_type stack_info_buf;
#ifdef DEBUG
    instruction_data_type *this_idata = &idata[to_inumber];
    register_info_type old_reg_info;
    stack_info_type old_stack_info;
    flag_type old_and_flags, old_or_flags;
#endif

#ifdef DEBUG
    if (verify_verbose) {
	old_reg_info = this_idata->register_info;
	old_stack_info = this_idata->stack_info;
	old_and_flags = this_idata->and_flags;
	old_or_flags = this_idata->or_flags;
    }
#endif

    /* All uninitialized objects are set to "bogus" when jsr and
     * ret are executed. Thus uninitialized objects can't propagate
     * into or out of a subroutine.
     */
    if (idata[from_inumber].opcode == opc_ret ||
	idata[from_inumber].opcode == opc_jsr ||
	idata[from_inumber].opcode == opc_jsr_w) {
	int new_register_count = new_register_info->register_count;
	fullinfo_type *new_registers = new_register_info->registers;
        int i;
	stack_item_type *item;

	for (item = new_stack_info->stack; item != NULL; item = item->next) {
	    if (GET_ITEM_TYPE(item->item) == ITEM_NewObject) {
	        /* This check only succeeds for hand-contrived code.
		 * Efficiency is not an issue.
		 */
	        stack_info_buf.stack = copy_stack(context, 
						  new_stack_info->stack);
		stack_info_buf.stack_size = new_stack_info->stack_size;
		new_stack_info = &stack_info_buf;
		for (item = new_stack_info->stack; item != NULL; 
		     item = item->next) {
		    if (GET_ITEM_TYPE(item->item) == ITEM_NewObject) {
		        item->item = MAKE_FULLINFO(ITEM_Bogus, 0, 0);
		    }
		}
	        break;
	    }
	}
	for (i = 0; i < new_register_count; i++) {
	    if (GET_ITEM_TYPE(new_registers[i]) == ITEM_NewObject) {
	        /* This check only succeeds for hand-contrived code.
		 * Efficiency is not an issue.
		 */
	        fullinfo_type *new_set = NEW(fullinfo_type, 
					     new_register_count);
		for (i = 0; i < new_register_count; i++) {
		    fullinfo_type t = new_registers[i];
		    new_set[i] = GET_ITEM_TYPE(t) != ITEM_NewObject ?
		        t : MAKE_FULLINFO(ITEM_Bogus, 0, 0);
		}
		register_info_buf.register_count = new_register_count;
		register_info_buf.registers = new_set;
		register_info_buf.mask_count = new_register_info->mask_count;
		register_info_buf.masks = new_register_info->masks;
		new_register_info = &register_info_buf;
		break;
	    }
	}
    }

    /* Returning from a subroutine is somewhat ugly.  The actual thing
     * that needs to get merged into the new instruction is a joining
     * of info from the ret instruction with stuff in the jsr instruction 
     */
    if (idata[from_inumber].opcode == opc_ret && !isException) {
	int new_register_count = new_register_info->register_count;
	fullinfo_type *new_registers = new_register_info->registers;
	int new_mask_count = new_register_info->mask_count;
	mask_type *new_masks = new_register_info->masks;
	int operand = idata[from_inumber].operand.i;
	int called_instruction = GET_EXTRA_INFO(new_registers[operand]);
	instruction_data_type *jsr_idata = &idata[to_inumber - 1];
	register_info_type *jsr_reginfo = &jsr_idata->register_info;
	if (jsr_idata->operand2.i != from_inumber) {
	    if (jsr_idata->operand2.i != UNKNOWN_RET_INSTRUCTION)
		CCerror(context, "Multiple returns to single jsr");
	    jsr_idata->operand2.i = from_inumber;
	}
	if (jsr_reginfo->register_count == UNKNOWN_REGISTER_COUNT) {
	    /* We don't want to handle the returned-to instruction until 
	     * we've dealt with the jsr instruction.   When we get to the
	     * jsr instruction (if ever), we'll re-mark the ret instruction
	     */
	    ;
	} else { 
	    int register_count = jsr_reginfo->register_count;
	    fullinfo_type *registers = jsr_reginfo->registers;
	    int max_registers = MAX(register_count, new_register_count);
	    fullinfo_type *new_set = NEW(fullinfo_type, max_registers);
	    int *return_mask;
	    struct register_info_type new_new_register_info;
	    int i;
	    /* Make sure the place we're returning from is legal! */
	    for (i = new_mask_count; --i >= 0; ) 
		if (new_masks[i].entry == called_instruction) 
		    break;
	    if (i < 0)
		CCerror(context, "Illegal return from subroutine");
	    /* pop the masks down to the indicated one.  Remember the mask
	     * we're popping off. */
	    return_mask = new_masks[i].modifies;
	    new_mask_count = i;
	    for (i = 0; i < max_registers; i++) {
		if (IS_BIT_SET(return_mask, i)) 
		    new_set[i] = i < new_register_count ? 
			  new_registers[i] : MAKE_FULLINFO(ITEM_Bogus, 0, 0);
		else 
		    new_set[i] = i < register_count ? 
			registers[i] : MAKE_FULLINFO(ITEM_Bogus, 0, 0);
	    }
	    new_new_register_info.register_count = max_registers;
	    new_new_register_info.registers      = new_set;
	    new_new_register_info.mask_count     = new_mask_count;
	    new_new_register_info.masks          = new_masks;


	    merge_stack(context, from_inumber, to_inumber, new_stack_info);
	    merge_registers(context, to_inumber - 1, to_inumber, 
			    &new_new_register_info);
            merge_flags(context, from_inumber, to_inumber, new_and_flags, new_or_flags);
	}
    } else {
	merge_stack(context, from_inumber, to_inumber, new_stack_info);
	merge_registers(context, from_inumber, to_inumber, new_register_info);
	merge_flags(context, from_inumber, to_inumber, 
		    new_and_flags, new_or_flags);
    }

#ifdef DEBUG
    if (verify_verbose && idata[to_inumber].changed) {
	register_info_type *register_info = &this_idata->register_info;
	stack_info_type *stack_info = &this_idata->stack_info;
	if (memcmp(&old_reg_info, register_info, sizeof(old_reg_info)) ||
	    memcmp(&old_stack_info, stack_info, sizeof(old_stack_info)) || 
	    (old_and_flags != this_idata->and_flags) || 
	    (old_or_flags != this_idata->or_flags)) {
	    jio_fprintf(stdout, "   %2d:", to_inumber);
	    print_stack(context, &old_stack_info);
	    print_registers(context, &old_reg_info);
	    print_flags(context, old_and_flags, old_or_flags);
	    jio_fprintf(stdout, " => ");
	    print_stack(context, &this_idata->stack_info);
	    print_registers(context, &this_idata->register_info);
	    print_flags(context, this_idata->and_flags, this_idata->or_flags);
	    jio_fprintf(stdout, "\n");
	}
    }
#endif

}

static void
merge_stack(context_type *context, unsigned int from_inumber,
	    unsigned int to_inumber, stack_info_type *new_stack_info)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[to_inumber];

    int new_stack_size =  new_stack_info->stack_size;
    stack_item_type *new_stack = new_stack_info->stack;

    int stack_size = this_idata->stack_info.stack_size;

    if (stack_size == UNKNOWN_STACK_SIZE) {
	/* First time at this instruction.  Just copy. */
	this_idata->stack_info.stack_size = new_stack_size;
	this_idata->stack_info.stack = new_stack;
	this_idata->changed = JNI_TRUE;
    } else if (new_stack_size != stack_size) {
	CCerror(context, "Inconsistent stack height %d != %d",
		new_stack_size, stack_size);
    } else { 
	stack_item_type *stack = this_idata->stack_info.stack;
	stack_item_type *old, *new;
	jboolean change = JNI_FALSE;
	for (old = stack, new = new_stack; old != NULL; 
	           old = old->next, new = new->next) {
	    if (!isAssignableTo(context, new->item, old->item)) {
		change = JNI_TRUE;
		break;
	    }
	}
	if (change) {
	    stack = copy_stack(context, stack);
	    for (old = stack, new = new_stack; old != NULL; 
		          old = old->next, new = new->next) {
	        if (new == NULL) {
		    break;
		}
		old->item = merge_fullinfo_types(context, old->item, new->item, 
						 JNI_FALSE);
		if (GET_ITEM_TYPE(old->item) == ITEM_Bogus) {
			CCerror(context, "Mismatched stack types");
		}
	    }
	    if (old != NULL || new != NULL) {
	        CCerror(context, "Mismatched stack types");
	    }
	    this_idata->stack_info.stack = stack;
	    this_idata->changed = JNI_TRUE;
	}
    }
}

static void
merge_registers(context_type *context, unsigned int from_inumber,
		unsigned int to_inumber, register_info_type *new_register_info)
{
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[to_inumber];
    register_info_type	  *this_reginfo = &this_idata->register_info;

    int            new_register_count = new_register_info->register_count;
    fullinfo_type *new_registers = new_register_info->registers;
    int            new_mask_count = new_register_info->mask_count;
    mask_type     *new_masks = new_register_info->masks;
    

    if (this_reginfo->register_count == UNKNOWN_REGISTER_COUNT) {
	this_reginfo->register_count = new_register_count;
	this_reginfo->registers = new_registers;
	this_reginfo->mask_count = new_mask_count;
	this_reginfo->masks = new_masks;
	this_idata->changed = JNI_TRUE;
    } else {
	/* See if we've got new information on the register set. */
	int register_count = this_reginfo->register_count;
	fullinfo_type *registers = this_reginfo->registers;
	int mask_count = this_reginfo->mask_count;
	mask_type *masks = this_reginfo->masks;
	
	jboolean copy = JNI_FALSE;
	int i, j;
	if (register_count > new_register_count) {
	    /* Any register larger than new_register_count is now bogus */
	    this_reginfo->register_count = new_register_count;
	    register_count = new_register_count;
	    this_idata->changed = JNI_TRUE;
	}
	for (i = 0; i < register_count; i++) {
	    fullinfo_type prev_value = registers[i];
	    if ((i < new_register_count) 
		  ? (!isAssignableTo(context, new_registers[i], prev_value))
		  : (prev_value != MAKE_FULLINFO(ITEM_Bogus, 0, 0))) {
		copy = JNI_TRUE; 
		break;
	    }
	}
	
	if (copy) {
	    /* We need a copy.  So do it. */
	    fullinfo_type *new_set = NEW(fullinfo_type, register_count);
	    for (j = 0; j < i; j++) 
		new_set[j] =  registers[j];
	    for (j = i; j < register_count; j++) {
		if (i >= new_register_count) 
		    new_set[j] = MAKE_FULLINFO(ITEM_Bogus, 0, 0);
		else 
		    new_set[j] = merge_fullinfo_types(context, 
						      new_registers[j], 
						      registers[j], JNI_FALSE);
	    }
	    /* Some of the end items might now be bogus. This step isn't 
	     * necessary, but it may save work later. */
	    while (   register_count > 0
		   && GET_ITEM_TYPE(new_set[register_count-1]) == ITEM_Bogus) 
		register_count--;
	    this_reginfo->register_count = register_count;
	    this_reginfo->registers = new_set;
	    this_idata->changed = JNI_TRUE;
	}
	if (mask_count > 0) { 
	    /* If the target instruction already has a sequence of masks, then
	     * we need to merge new_masks into it.  We want the entries on
	     * the mask to be the longest common substring of the two.
	     *   (e.g.   a->b->d merged with a->c->d should give a->d)
	     * The bits set in the mask should be the or of the corresponding
	     * entries in each of the original masks.
	     */
	    int i, j, k;
	    int matches = 0;
	    int last_match = -1;
	    jboolean copy_needed = JNI_FALSE;
	    for (i = 0; i < mask_count; i++) {
		int entry = masks[i].entry;
		for (j = last_match + 1; j < new_mask_count; j++) {
		    if (new_masks[j].entry == entry) {
			/* We have a match */
			int *prev = masks[i].modifies;
			int *new = new_masks[j].modifies;
			matches++; 
			/* See if new_mask has bits set for "entry" that 
			 * weren't set for mask.  If so, need to copy. */
			for (k = context->bitmask_size - 1;
			       !copy_needed && k >= 0;
			       k--) 
			    if (~prev[k] & new[k])
				copy_needed = JNI_TRUE;
			last_match = j;
			break;
		    }
		}
	    }
	    if ((matches < mask_count) || copy_needed) { 
		/* We need to make a copy for the new item, since either the
		 * size has decreased, or new bits are set. */
		mask_type *copy = NEW(mask_type, matches);
		for (i = 0; i < matches; i++) {
		    copy[i].modifies = NEW(int, context->bitmask_size);
		}
		this_reginfo->masks = copy;
		this_reginfo->mask_count = matches;
		this_idata->changed = JNI_TRUE;
		matches = 0;
		last_match = -1;
		for (i = 0; i < mask_count; i++) {
		    int entry = masks[i].entry;
		    for (j = last_match + 1; j < new_mask_count; j++) {
			if (new_masks[j].entry == entry) {
			    int *prev1 = masks[i].modifies;
			    int *prev2 = new_masks[j].modifies;
			    int *new = copy[matches].modifies;
			    copy[matches].entry = entry;
			    for (k = context->bitmask_size - 1; k >= 0; k--) 
				new[k] = prev1[k] | prev2[k];
			    matches++;
			    last_match = j;
			    break;
			}
		    }
		}
	    }
	}
    }
}


static void 
merge_flags(context_type *context, unsigned int from_inumber,
	    unsigned int to_inumber,
	    flag_type new_and_flags, flag_type new_or_flags) 
{
    /* Set this_idata->and_flags &= new_and_flags
           this_idata->or_flags |= new_or_flags
     */
    instruction_data_type *idata = context->instruction_data;
    instruction_data_type *this_idata = &idata[to_inumber];
    flag_type this_and_flags = this_idata->and_flags;
    flag_type this_or_flags = this_idata->or_flags;
    flag_type merged_and = this_and_flags & new_and_flags;
    flag_type merged_or = this_or_flags | new_or_flags;
    
    if ((merged_and != this_and_flags) || (merged_or != this_or_flags)) {
	this_idata->and_flags = merged_and;
	this_idata->or_flags = merged_or;
	this_idata->changed = JNI_TRUE;
    }
}


/* Make a copy of a stack */

static stack_item_type *
copy_stack(context_type *context, stack_item_type *stack)
{
    int length;
    stack_item_type *ptr;
    
    /* Find the length */
    for (ptr = stack, length = 0; ptr != NULL; ptr = ptr->next, length++);
    
    if (length > 0) { 
	stack_item_type *new_stack = NEW(stack_item_type, length);
	stack_item_type *new_ptr;
	for (    ptr = stack, new_ptr = new_stack; 
	         ptr != NULL;
	         ptr = ptr->next, new_ptr++) {
	    new_ptr->item = ptr->item;
	    new_ptr->next = new_ptr + 1;
	}
	new_stack[length - 1].next = NULL;
	return new_stack;
    } else {
	return NULL;
    }
}


static mask_type *
copy_masks(context_type *context, mask_type *masks, int mask_count)
{
    mask_type *result = NEW(mask_type, mask_count);
    int bitmask_size = context->bitmask_size;
    int *bitmaps = NEW(int, mask_count * bitmask_size);
    int i;
    for (i = 0; i < mask_count; i++) { 
	result[i].entry = masks[i].entry;
	result[i].modifies = &bitmaps[i * bitmask_size];
	memcpy(result[i].modifies, masks[i].modifies, bitmask_size * sizeof(int));
    }
    return result;
}


static mask_type *
add_to_masks(context_type *context, mask_type *masks, int mask_count, int d)
{
    mask_type *result = NEW(mask_type, mask_count + 1);
    int bitmask_size = context->bitmask_size;
    int *bitmaps = NEW(int, (mask_count + 1) * bitmask_size);
    int i;
    for (i = 0; i < mask_count; i++) { 
	result[i].entry = masks[i].entry;
	result[i].modifies = &bitmaps[i * bitmask_size];
	memcpy(result[i].modifies, masks[i].modifies, bitmask_size * sizeof(int));
    }
    result[mask_count].entry = d;
    result[mask_count].modifies = &bitmaps[mask_count * bitmask_size];
    memset(result[mask_count].modifies, 0, bitmask_size * sizeof(int));
    return result;
}
    


/* We create our own storage manager, since we malloc lots of little items, 
 * and I don't want to keep trace of when they become free.  I sure wish that
 * we had heaps, and I could just free the heap when done. 
 */

#define CCSegSize 2000

struct CCpool {			/* a segment of allocated memory in the pool */
    struct CCpool *next;
    int segSize;		/* almost always CCSegSize */
    int poolPad;
    char space[CCSegSize];
};

/* Initialize the context's heap. */
static void CCinit(context_type *context)
{
    struct CCpool *new = (struct CCpool *) malloc(sizeof(struct CCpool));
    /* Set context->CCroot to 0 if new == 0 to tell CCdestroy to lay off */
    context->CCroot = context->CCcurrent = new;
    if (new == 0) {
	CCout_of_memory(context);
    }
    new->next = NULL;
    new->segSize = CCSegSize;
    context->CCfree_size = CCSegSize;
    context->CCfree_ptr = &new->space[0];
}


/* Reuse all the space that we have in the context's heap. */
static void CCreinit(context_type *context)
{
    struct CCpool *first = context->CCroot;
    context->CCcurrent = first;
    context->CCfree_size = CCSegSize;
    context->CCfree_ptr = &first->space[0];
}

/* Destroy the context's heap. */
static void CCdestroy(context_type *context)
{
    struct CCpool *this = context->CCroot;
    while (this) {
	struct CCpool *next = this->next;
	free(this);
	this = next;
    }
    /* These two aren't necessary.  But can't hurt either */
    context->CCroot = context->CCcurrent = NULL;
    context->CCfree_ptr = 0;
}

/* Allocate an object of the given size from the context's heap. */
static void *
CCalloc(context_type *context, int size, jboolean zero)
{

    register char *p;
    /* Round CC to the size of a pointer */
    size = (size + (sizeof(void *) - 1)) & ~(sizeof(void *) - 1);

    if (context->CCfree_size <  size) {
	struct CCpool *current = context->CCcurrent;
	struct CCpool *new;
	if (size > CCSegSize) {	/* we need to allocate a special block */
	    new = (struct CCpool *)malloc(sizeof(struct CCpool) + 
					  (size - CCSegSize));
	    if (new == 0) {
		CCout_of_memory(context);
	    }
	    new->next = current->next;
	    new->segSize = size;
	    current->next = new;
	} else {
	    new = current->next;
	    if (new == NULL) {
		new = (struct CCpool *) malloc(sizeof(struct CCpool));
		if (new == 0) {
		    CCout_of_memory(context);
		}
		current->next = new;
		new->next = NULL;
		new->segSize = CCSegSize;
	    }
	}
	context->CCcurrent = new;
	context->CCfree_ptr = &new->space[0];
	context->CCfree_size = new->segSize;
    }
    p = context->CCfree_ptr;
    context->CCfree_ptr += size;
    context->CCfree_size -= size;
    if (zero) 
	memset(p, 0, size);
    return p;
}

/* Get the class associated with a particular field or method or class in the
 * constant pool.  If is_field is true, we've got a field or method.  If 
 * false, we've got a class.
 */
static fullinfo_type
cp_index_to_class_fullinfo(context_type *context, int cp_index, int kind)
{
    JNIEnv *env = context->env;
    fullinfo_type result;
    const char *classname;
    switch (kind) {
    case JVM_CONSTANT_Class: 
        classname = JVM_GetCPClassNameUTF(env, 
					  context->class,
					  cp_index);
	break;
    case JVM_CONSTANT_Methodref:
        classname = JVM_GetCPMethodClassNameUTF(env, 
						context->class,
						cp_index);
	break;
    case JVM_CONSTANT_Fieldref:
        classname = JVM_GetCPFieldClassNameUTF(env, 
					       context->class,
					       cp_index);
	break;
    default:
        classname = NULL;
        CCerror(context, "Internal error #5");
    }

    check_and_push(context, classname, VM_STRING_UTF);
    if (classname[0] == JVM_SIGNATURE_ARRAY) {
	/* This make recursively call us, in case of a class array */
	signature_to_fieldtype(context, &classname, &result);
    } else {
	result = make_class_info_from_name(context, classname);
    }
    pop_and_free(context);
    return result;
}


static int
print_CCerror_info(context_type *context)
{
    JNIEnv *env = context->env;
    jclass cb = context->class;
    const char *classname = JVM_GetClassNameUTF(env, cb);
    const char *name = 0;
    const char *signature = 0;
    int n = 0;
    if (context->method_index != -1) {
        name = JVM_GetMethodIxNameUTF(env, cb, context->method_index);
        signature = 
	    JVM_GetMethodIxSignatureUTF(env, cb, context->method_index);
	n += jio_snprintf(context->message, context->message_buf_len,
			  "(class: %s, method: %s signature: %s) ", 
			  (classname ? classname : ""),
			  (name ? name : ""), 
			  (signature ? signature : ""));
    } else if (context->field_index != -1 ) {
        name = JVM_GetMethodIxNameUTF(env, cb, context->field_index);
	n += jio_snprintf(context->message, context->message_buf_len,
			  "(class: %s, field: %s) ", 
			  (classname ? classname : 0), 
			  (name ? name : 0));
    } else {
        n += jio_snprintf(context->message, context->message_buf_len,
			  "(class: %s) ", classname ? classname : "");
    }
    JVM_ReleaseUTF(classname);
    JVM_ReleaseUTF(name);
    JVM_ReleaseUTF(signature);
    return n;
}

static void 
CCerror (context_type *context, char *format, ...)
{
    int n = print_CCerror_info(context);
    va_list args;
    if (n >= 0 && n < context->message_buf_len) {
        va_start(args, format);
	jio_vsnprintf(context->message + n, context->message_buf_len - n,
		      format, args);        
	va_end(args);
    }
    context->err_code = CC_VerifyError;
    longjmp(context->jump_buffer, 1);
}

static void
CCout_of_memory(context_type *context)
{
    int n = print_CCerror_info(context);
    context->err_code = CC_OutOfMemory;
    longjmp(context->jump_buffer, 1);
}

static void
CFerror(context_type *context, char *format, ...)
{
    int n = print_CCerror_info(context);
    va_list args;
    if (n >= 0 && n < context->message_buf_len) {
        va_start(args, format);
	jio_vsnprintf(context->message + n, context->message_buf_len - n,
		      format, args);        
	va_end(args);
    }
    context->err_code = CC_ClassFormatError;
    longjmp(context->jump_buffer, 1);
}

static char 
signature_to_fieldtype(context_type *context, 
		       const char **signature_p, fullinfo_type *full_info_p)
{
    const char *p = *signature_p;
    fullinfo_type full_info = MAKE_FULLINFO(0, 0, 0);
    char result;
    int array_depth = 0;
    
    for (;;) { 
	switch(*p++) {
            default:
		full_info = MAKE_FULLINFO(ITEM_Bogus, 0, 0);
		result = 0; 
		break;

            case JVM_SIGNATURE_BOOLEAN: case JVM_SIGNATURE_BYTE: 
		full_info = (array_depth > 0)
		              ? MAKE_FULLINFO(ITEM_Byte, 0, 0)
		              : MAKE_FULLINFO(ITEM_Integer, 0, 0);
		result = 'I'; 
		break;

            case JVM_SIGNATURE_CHAR:
		full_info = (array_depth > 0)
		              ? MAKE_FULLINFO(ITEM_Char, 0, 0)
			      : MAKE_FULLINFO(ITEM_Integer, 0, 0);
		result = 'I'; 
		break;

            case JVM_SIGNATURE_SHORT: 
		full_info = (array_depth > 0)
		              ? MAKE_FULLINFO(ITEM_Short, 0, 0)
			      : MAKE_FULLINFO(ITEM_Integer, 0, 0);
		result = 'I'; 
		break;

            case JVM_SIGNATURE_INT:
		full_info = MAKE_FULLINFO(ITEM_Integer, 0, 0);
		result = 'I'; 
		break;

            case JVM_SIGNATURE_FLOAT:
		full_info = MAKE_FULLINFO(ITEM_Float, 0, 0);
		result = 'F'; 
		break;

            case JVM_SIGNATURE_DOUBLE:
		full_info = MAKE_FULLINFO(ITEM_Double, 0, 0);
		result = 'D'; 
		break;

	    case JVM_SIGNATURE_LONG:
		full_info = MAKE_FULLINFO(ITEM_Long, 0, 0);
		result = 'L'; 
		break;

            case JVM_SIGNATURE_ARRAY:
		array_depth++;
		continue;	/* only time we ever do the loop > 1 */

            case JVM_SIGNATURE_CLASS: {
		char buffer_space[256];
		char *buffer = buffer_space;
		char *finish = strchr(p, JVM_SIGNATURE_ENDCLASS);
		int length = finish - p;
		if (length + 1 > sizeof(buffer_space)) {
		    buffer = malloc(length + 1);
		    check_and_push(context, buffer, VM_MALLOC_BLK);
		}
	        memcpy(buffer, p, length);
		buffer[length] = '\0';
		full_info = make_class_info_from_name(context, buffer);
		result = 'A';
		p = finish + 1;
		if (buffer != buffer_space) 
		    pop_and_free(context);
		break;
	    }
	} /* end of switch */
	break;
    }
    *signature_p = p;
    if (array_depth == 0 || result == 0) { 
	/* either not an array, or result is bogus */
	*full_info_p = full_info;
	return result;
    } else {
	if (array_depth > MAX_ARRAY_DIMENSIONS) 
	    CCerror(context, "Array with too many dimensions");
	*full_info_p = MAKE_FULLINFO(GET_ITEM_TYPE(full_info),
				     array_depth, 
				     GET_EXTRA_INFO(full_info));
	return 'A';
    }
}


/* Given an array type, create the type that has one less level of 
 * indirection.
 */

static fullinfo_type
decrement_indirection(fullinfo_type array_info)
{
    if (array_info == NULL_FULLINFO) { 
	return NULL_FULLINFO;
    } else { 
	int type = GET_ITEM_TYPE(array_info);
	int indirection = GET_INDIRECTION(array_info) - 1;
	int extra_info = GET_EXTRA_INFO(array_info);
	if (   (indirection == 0) 
	       && ((type == ITEM_Short || type == ITEM_Byte || type == ITEM_Char)))
	    type = ITEM_Integer;
	return MAKE_FULLINFO(type, indirection, extra_info);
    }
}


/* See if we can assign an object of the "from" type to an object
 * of the "to" type.
 */

static jboolean isAssignableTo(context_type *context, 
			     fullinfo_type from, fullinfo_type to)
{
    return (merge_fullinfo_types(context, from, to, JNI_TRUE) == to);
}

/* Given two fullinfo_type's, find their lowest common denominator.  If
 * the assignable_p argument is non-null, we're really just calling to find
 * out if "<target> := <value>" is a legitimate assignment.  
 *
 * We treat all interfaces as if they were of type java/lang/Object, since the
 * runtime will do the full checking.
 */
static fullinfo_type 
merge_fullinfo_types(context_type *context, 
		     fullinfo_type value, fullinfo_type target,
		     jboolean for_assignment)
{
    JNIEnv *env = context->env;
    if (value == target) {
	/* If they're identical, clearly just return what we've got */
	return value;
    }

    /* Both must be either arrays or objects to go further */
    if (GET_INDIRECTION(value) == 0 && GET_ITEM_TYPE(value) != ITEM_Object)
	return MAKE_FULLINFO(ITEM_Bogus, 0, 0);
    if (GET_INDIRECTION(target) == 0 && GET_ITEM_TYPE(target) != ITEM_Object)
	return MAKE_FULLINFO(ITEM_Bogus, 0, 0);
    
    /* If either is NULL, return the other. */
    if (value == NULL_FULLINFO) 
	return target;
    else if (target == NULL_FULLINFO)
	return value;

    /* If either is java/lang/Object, that's the result. */
    if (target == context->object_info)
	return target;
    else if (value == context->object_info) {
	/* Minor hack.  For assignments, Interface := Object, return Interface
	 * rather than Object, so that isAssignableTo() will get the right
	 * result.      */
	if (for_assignment && (WITH_ZERO_EXTRA_INFO(target) == 
			          MAKE_FULLINFO(ITEM_Object, 0, 0))) {
	    jclass cb = object_fullinfo_to_classclass(context, 
						      target);
	    int is_interface = cb && JVM_IsInterface(env, cb);
	    if (is_interface)
		return target;
	}
	return value;
    }
    if (GET_INDIRECTION(value) > 0 || GET_INDIRECTION(target) > 0) {
	/* At least one is an array.  Neither is java/lang/Object or NULL.
	 * Moreover, the types are not identical.
	 * The result must either be Object, or an array of some object type.
	 */
	fullinfo_type value_base, target_base;
	int dimen_value = GET_INDIRECTION(value);
	int dimen_target = GET_INDIRECTION(target);

	if (target == context->cloneable_info || 
	    target == context->serializable_info) {
	    return target;
	}

	if (value == context->cloneable_info || 
	    value == context->serializable_info) {
	    return value;
	}
	
	/* First, if either item's base type isn't ITEM_Object, promote it up
         * to an object or array of object.  If either is elemental, we can
	 * punt.
    	 */
	if (GET_ITEM_TYPE(value) != ITEM_Object) { 
	    if (dimen_value == 0)
		return MAKE_FULLINFO(ITEM_Bogus, 0, 0);
	    dimen_value--;
	    value = MAKE_Object_ARRAY(dimen_value);
	    
	}
	if (GET_ITEM_TYPE(target) != ITEM_Object) { 
	    if (dimen_target == 0)
		return MAKE_FULLINFO(ITEM_Bogus, 0, 0);
	    dimen_target--;
	    target = MAKE_Object_ARRAY(dimen_target);
	}
	/* Both are now objects or arrays of some sort of object type */
	value_base = WITH_ZERO_INDIRECTION(value);
	target_base = WITH_ZERO_INDIRECTION(target);
	if (dimen_value == dimen_target) { 
            /* Arrays of the same dimension.  Merge their base types. */
	    fullinfo_type  result_base = 
		merge_fullinfo_types(context, value_base, target_base,
					    for_assignment);
	    if (result_base == MAKE_FULLINFO(ITEM_Bogus, 0, 0))
		/* bogus in, bogus out */
		return result_base;
	    return MAKE_FULLINFO(ITEM_Object, dimen_value,
				 GET_EXTRA_INFO(result_base));
	} else { 
	    /* Arrays of different sizes. If the smaller dimension array's base
	     * type is java/lang/Cloneable or java/io/Serializable, return it.
	     * Otherwise return java/lang/Object with a dimension of the smaller
	     * of the two */
	    if (dimen_value < dimen_target) {
		if (value_base == context->cloneable_info ||
		    value_base == context ->serializable_info) {
		    return value;
		}
		return MAKE_Object_ARRAY(dimen_value);
	    } else {
		if (target_base == context->cloneable_info ||
		    target_base == context->serializable_info) {
		    return target;
		}
		return MAKE_Object_ARRAY(dimen_target);
	    }                                                     
	}
    } else {
	/* Both are non-array objects. Neither is java/lang/Object or NULL */
	jclass cb_value, cb_target, cb_super_value, cb_super_target;
	fullinfo_type result_info;

	/* Let's get the classes corresponding to each of these.  Treat 
	 * interfaces as if they were java/lang/Object.  See hack note above. */
	cb_target = object_fullinfo_to_classclass(context, target);
	if (cb_target == 0) 
	    return MAKE_FULLINFO(ITEM_Bogus, 0, 0);
	if (JVM_IsInterface(env, cb_target)) 
	    return for_assignment ? target : context->object_info;
	cb_value = object_fullinfo_to_classclass(context, value);
	if (cb_value == 0) 
	    return MAKE_FULLINFO(ITEM_Bogus, 0, 0);
	if (JVM_IsInterface(env, cb_value))
	    return context->object_info;
	
	/* If this is for assignment of target := value, we just need to see if
	 * cb_target is a superclass of cb_value.  Save ourselves a lot of 
	 * work.
	 */
	if (for_assignment) {
	    cb_super_value = (*env)->GetSuperclass(env, cb_value); 
	    while (cb_super_value != 0) {
	        jclass tmp_cb;
	        if ((*env)->IsSameObject(env, cb_super_value, cb_target)) {
		    (*env)->DeleteLocalRef(env, cb_super_value);
		    return target;
		}
		tmp_cb =  (*env)->GetSuperclass(env, cb_super_value); 
		(*env)->DeleteLocalRef(env, cb_super_value);
		cb_super_value = tmp_cb;
	    }
	    (*env)->DeleteLocalRef(env, cb_super_value);
	    return context->object_info;
	}

	/* Find out whether cb_value or cb_target is deeper in the class
	 * tree by moving both toward the root, and seeing who gets there
	 * first.                                                          */
	cb_super_value = (*env)->GetSuperclass(env, cb_value);
	cb_super_target = (*env)->GetSuperclass(env, cb_target);
	while((cb_super_value != 0) &&
	      (cb_super_target != 0)) {
	    jclass tmp_cb;
	    /* Optimization.  If either hits the other when going up looking
	     * for a parent, then might as well return the parent immediately */
	    if ((*env)->IsSameObject(env, cb_super_value, cb_target)) {
	        (*env)->DeleteLocalRef(env, cb_super_value);
	        (*env)->DeleteLocalRef(env, cb_super_target);
		return target;
	    }
	    if ((*env)->IsSameObject(env, cb_super_target, cb_value)) {
	        (*env)->DeleteLocalRef(env, cb_super_value);
	        (*env)->DeleteLocalRef(env, cb_super_target);
		return value;
	    }
	    tmp_cb = (*env)->GetSuperclass(env, cb_super_value);
	    (*env)->DeleteLocalRef(env, cb_super_value);
	    cb_super_value = tmp_cb;

	    tmp_cb = (*env)->GetSuperclass(env, cb_super_target);
	    (*env)->DeleteLocalRef(env, cb_super_target);
	    cb_super_target = tmp_cb;
	} 
	cb_value = (*env)->NewLocalRef(env, cb_value);
	cb_target = (*env)->NewLocalRef(env, cb_target);
	/* At most one of the following two while clauses will be executed. 
	 * Bring the deeper of cb_target and cb_value to the depth of the 
	 * shallower one. 
	 */
	while (cb_super_value != 0) { 
	  /* cb_value is deeper */
	    jclass cb_tmp;

	    cb_tmp = (*env)->GetSuperclass(env, cb_super_value);
	    (*env)->DeleteLocalRef(env, cb_super_value);
	    cb_super_value = cb_tmp;

	    cb_tmp = (*env)->GetSuperclass(env, cb_value);
	    (*env)->DeleteLocalRef(env, cb_value);
	    cb_value = cb_tmp;
	}
	while (cb_super_target != 0) { 
	  /* cb_target is deeper */
	    jclass cb_tmp;
	    
	    cb_tmp = (*env)->GetSuperclass(env, cb_super_target);
	    (*env)->DeleteLocalRef(env, cb_super_target);
	    cb_super_target = cb_tmp;

	    cb_tmp = (*env)->GetSuperclass(env, cb_target);
	    (*env)->DeleteLocalRef(env, cb_target);
	    cb_target = cb_tmp;
	}
    
	/* Walk both up, maintaining equal depth, until a join is found.  We
	 * know that we will find one.  */
	while (!(*env)->IsSameObject(env, cb_value, cb_target)) { 
	    jclass cb_tmp;
	    cb_tmp = (*env)->GetSuperclass(env, cb_value);
	    (*env)->DeleteLocalRef(env, cb_value);
	    cb_value = cb_tmp;
	    cb_tmp = (*env)->GetSuperclass(env, cb_target);
	    (*env)->DeleteLocalRef(env, cb_target);
	    cb_target = cb_tmp;
	}
	result_info = make_class_info(context, cb_value);
	(*env)->DeleteLocalRef(env, cb_value);
	(*env)->DeleteLocalRef(env, cb_super_value);
	(*env)->DeleteLocalRef(env, cb_target);
	(*env)->DeleteLocalRef(env, cb_super_target);
	return result_info;
    } /* both items are classes */
}


/* Given a fullinfo_type corresponding to an Object, return the jclass
 * of that type.
 *
 * This function always returns a global reference!
 */

static jclass
object_fullinfo_to_classclass(context_type *context, fullinfo_type classinfo)
{
    unsigned short info = GET_EXTRA_INFO(classinfo);
    return ID_to_class(context, info);
}

static void free_block(void *ptr, int kind)
{
    switch (kind) {
    case VM_STRING_UTF:
        JVM_ReleaseUTF(ptr);
	break;
    case VM_MALLOC_BLK:
        free(ptr);
	break;
    }
}

static void check_and_push(context_type *context, const void *ptr, int kind)
{
    alloc_stack_type *p;
    if (ptr == 0)
        CCout_of_memory(context);
    if (context->alloc_stack_top < ALLOC_STACK_SIZE)
        p = &(context->alloc_stack[context->alloc_stack_top++]);
    else {
        /* Otherwise we have to malloc */ 
        p = malloc(sizeof(alloc_stack_type));
	if (p == 0) {
	    /* Make sure we clean up. */ 
	    free_block((void *)ptr, kind);
	    CCout_of_memory(context);
	}
    }
    p->kind = kind;
    p->ptr = (void *)ptr;
    p->next = context->allocated_memory;
    context->allocated_memory = p;
}

static void pop_and_free(context_type *context)
{
    alloc_stack_type *p = context->allocated_memory;
    context->allocated_memory = p->next;
    free_block(p->ptr, p->kind);
    if (p < context->alloc_stack + ALLOC_STACK_SIZE &&
	p >= context->alloc_stack)
        context->alloc_stack_top--;
    else
        free(p);
}

static int signature_to_args_size(const char *method_signature)
{
    const char *p;
    int args_size = 0;
    for (p = method_signature; *p != JVM_SIGNATURE_ENDFUNC; p++) {
        switch (*p) {
          case JVM_SIGNATURE_BOOLEAN:
          case JVM_SIGNATURE_BYTE:
          case JVM_SIGNATURE_CHAR:
          case JVM_SIGNATURE_SHORT:
          case JVM_SIGNATURE_INT:
          case JVM_SIGNATURE_FLOAT:
            args_size += 1;
            break;
          case JVM_SIGNATURE_CLASS:
            args_size += 1;
            while (*p != JVM_SIGNATURE_ENDCLASS) p++;
            break;
          case JVM_SIGNATURE_ARRAY:
            args_size += 1;
            while ((*p == JVM_SIGNATURE_ARRAY)) p++;
            /* If an array of classes, skip over class name, too. */
            if (*p == JVM_SIGNATURE_CLASS) {
                while (*p != JVM_SIGNATURE_ENDCLASS)
                  p++;
            }
            break;
          case JVM_SIGNATURE_DOUBLE:
          case JVM_SIGNATURE_LONG:
            args_size += 2;
            break;
          case JVM_SIGNATURE_FUNC:  /* ignore initial (, if given */
            break;
          default:
            /* Indicate an error. */
            return 0;
        }
    }
    return args_size;
}

#ifdef DEBUG

/* Below are for debugging. */

static void print_fullinfo_type(context_type *, fullinfo_type, jboolean);

static void 
print_stack(context_type *context, stack_info_type *stack_info)
{
    stack_item_type *stack = stack_info->stack;
    if (stack_info->stack_size == UNKNOWN_STACK_SIZE) {
	jio_fprintf(stdout, "x");
    } else {
	jio_fprintf(stdout, "(");
	for ( ; stack != 0; stack = stack->next) 
	    print_fullinfo_type(context, stack->item, 
	       	(jboolean)(verify_verbose > 1 ? JNI_TRUE : JNI_FALSE));
	jio_fprintf(stdout, ")");
    }
}	

static void
print_registers(context_type *context, register_info_type *register_info)
{
    int register_count = register_info->register_count;
    if (register_count == UNKNOWN_REGISTER_COUNT) {
	jio_fprintf(stdout, "x");
    } else {
	fullinfo_type *registers = register_info->registers;
	int mask_count = register_info->mask_count;
	mask_type *masks = register_info->masks;
	int i, j;

	jio_fprintf(stdout, "{");
	for (i = 0; i < register_count; i++) 
	    print_fullinfo_type(context, registers[i], 
		(jboolean)(verify_verbose > 1 ? JNI_TRUE : JNI_FALSE));
	jio_fprintf(stdout, "}");
	for (i = 0; i < mask_count; i++) { 
	    char *separator = "";
	    int *modifies = masks[i].modifies;
	    jio_fprintf(stdout, "<%d: ", masks[i].entry);
	    for (j = 0; 
		 j < JVM_GetMethodIxLocalsCount(context->env, 
						context->class, 
						context->method_index); 
		 j++) 
		if (IS_BIT_SET(modifies, j)) {
		    jio_fprintf(stdout, "%s%d", separator, j);
		    separator = ",";
		}
	    jio_fprintf(stdout, ">");
	}
    }
}


static void
print_flags(context_type *context, flag_type and_flags, flag_type or_flags)
{ 
    if (and_flags != ((flag_type)-1) || or_flags != 0) {
	jio_fprintf(stdout, "<%x %x>", and_flags, or_flags);
    }
}	    

static void 
print_fullinfo_type(context_type *context, fullinfo_type type, jboolean verbose) 
{
    int i;
    int indirection = GET_INDIRECTION(type);
    for (i = indirection; i-- > 0; )
	jio_fprintf(stdout, "[");
    switch (GET_ITEM_TYPE(type)) {
        case ITEM_Integer:       
	    jio_fprintf(stdout, "I"); break;
	case ITEM_Float:         
	    jio_fprintf(stdout, "F"); break;
	case ITEM_Double:        
	    jio_fprintf(stdout, "D"); break;
	case ITEM_Double_2:      
	    jio_fprintf(stdout, "d"); break;
	case ITEM_Long:          
	    jio_fprintf(stdout, "L"); break;
	case ITEM_Long_2:        
	    jio_fprintf(stdout, "l"); break;
	case ITEM_ReturnAddress: 
	    jio_fprintf(stdout, "a"); break;
	case ITEM_Object:        
	    if (!verbose) {
		jio_fprintf(stdout, "A");
	    } else {
		unsigned short extra = GET_EXTRA_INFO(type);
		if (extra == 0) {
		    jio_fprintf(stdout, "/Null/");
		} else {
		    const char *name = ID_to_class_name(context, extra);
		    const char *name2 = strrchr(name, '/');
		    jio_fprintf(stdout, "/%s/", name2 ? name2 + 1 : name);
		}
	    }
	    break;
	case ITEM_Char:
	    jio_fprintf(stdout, "C"); break;
	case ITEM_Short:
	    jio_fprintf(stdout, "S"); break;
	case ITEM_Byte:
	    jio_fprintf(stdout, "B"); break;
        case ITEM_NewObject:
	    if (!verbose) {
		jio_fprintf(stdout, "@");
	    } else {
		int inum = GET_EXTRA_INFO(type);
		fullinfo_type real_type = 
		    context->instruction_data[inum].operand2.fi;
		jio_fprintf(stdout, ">");
		print_fullinfo_type(context, real_type, JNI_TRUE);
		jio_fprintf(stdout, "<");
	    }
	    break;
        case ITEM_InitObject:
	    jio_fprintf(stdout, verbose ? ">/this/<" : "@");
	    break;

	default: 
	    jio_fprintf(stdout, "?"); break;
    }
    for (i = indirection; i-- > 0; )
	jio_fprintf(stdout, "]");
}


static void 
print_formatted_fieldname(context_type *context, int index)
{
    JNIEnv *env = context->env;
    jclass cb = context->class;
    const char *classname = JVM_GetCPFieldClassNameUTF(env, cb, index);
    const char *fieldname = JVM_GetCPFieldNameUTF(env, cb, index);
    jio_fprintf(stdout, "  <%s.%s>", 
		classname ? classname : "", fieldname ? fieldname : "");
    JVM_ReleaseUTF(classname);
    JVM_ReleaseUTF(fieldname);
}

static void 
print_formatted_methodname(context_type *context, int index)
{
    JNIEnv *env = context->env;
    jclass cb = context->class;
    const char *classname = JVM_GetCPMethodClassNameUTF(env, cb, index);
    const char *methodname = JVM_GetCPMethodNameUTF(env, cb, index);
    jio_fprintf(stdout, "  <%s.%s>", 
		classname ? classname : "", methodname ? methodname : "");
    JVM_ReleaseUTF(classname);
    JVM_ReleaseUTF(methodname);
}

#endif /*DEBUG*/