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gecko-dev/js/src/jsopcode.cpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set sw=4 ts=8 et tw=99:
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* JS bytecode descriptors, disassemblers, and (expression) decompilers.
*/
#include "mozilla/FloatingPoint.h"
#include "mozilla/Util.h"
#ifdef HAVE_MEMORY_H
#include <memory.h>
#endif
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsutil.h"
#include "jsprf.h"
#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsversion.h"
#include "jsfun.h"
#include "jsiter.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsopcode.h"
#include "jsscript.h"
#include "jsstr.h"
#include "ds/Sort.h"
#include "frontend/BytecodeEmitter.h"
#include "frontend/TokenStream.h"
#include "js/CharacterEncoding.h"
#include "vm/Debugger.h"
#include "vm/Shape.h"
#include "vm/StringBuffer.h"
#include "jscntxtinlines.h"
#include "jsobjinlines.h"
#include "jsopcodeinlines.h"
#include "jsautooplen.h"
#include "vm/RegExpObject-inl.h"
using namespace js;
using namespace js::gc;
using js::frontend::IsIdentifier;
using mozilla::ArrayLength;
/*
* Index limit must stay within 32 bits.
*/
JS_STATIC_ASSERT(sizeof(uint32_t) * JS_BITS_PER_BYTE >= INDEX_LIMIT_LOG2 + 1);
/* Verify JSOP_XXX_LENGTH constant definitions. */
#define OPDEF(op,val,name,token,length,nuses,ndefs,prec,format) \
JS_STATIC_ASSERT(op##_LENGTH == length);
#include "jsopcode.tbl"
#undef OPDEF
static const char js_incop_strs[][3] = {"++", "--"};
static const char js_for_each_str[] = "for each";
const JSCodeSpec js_CodeSpec[] = {
#define OPDEF(op,val,name,token,length,nuses,ndefs,prec,format) \
{length,nuses,ndefs,prec,format},
#include "jsopcode.tbl"
#undef OPDEF
};
unsigned js_NumCodeSpecs = JS_ARRAY_LENGTH(js_CodeSpec);
/*
* Each element of the array is either a source literal associated with JS
* bytecode or null.
*/
static const char *CodeToken[] = {
#define OPDEF(op,val,name,token,length,nuses,ndefs,prec,format) \
token,
#include "jsopcode.tbl"
#undef OPDEF
};
/*
* Array of JS bytecode names used by PC count JSON, DEBUG-only js_Disassemble
* and JIT debug spew.
*/
const char *js_CodeName[] = {
#define OPDEF(op,val,name,token,length,nuses,ndefs,prec,format) \
name,
#include "jsopcode.tbl"
#undef OPDEF
};
/************************************************************************/
#define COUNTS_LEN 16
size_t
js_GetVariableBytecodeLength(jsbytecode *pc)
{
JSOp op = JSOp(*pc);
JS_ASSERT(js_CodeSpec[op].length == -1);
switch (op) {
case JSOP_TABLESWITCH: {
/* Structure: default-jump case-low case-high case1-jump ... */
pc += JUMP_OFFSET_LEN;
int32_t low = GET_JUMP_OFFSET(pc);
pc += JUMP_OFFSET_LEN;
int32_t high = GET_JUMP_OFFSET(pc);
unsigned ncases = unsigned(high - low + 1);
return 1 + 3 * JUMP_OFFSET_LEN + ncases * JUMP_OFFSET_LEN;
}
default:
JS_NOT_REACHED("Unexpected op");
return 0;
}
}
static uint32_t
NumBlockSlots(JSScript *script, jsbytecode *pc)
{
JS_ASSERT(*pc == JSOP_ENTERBLOCK || *pc == JSOP_ENTERLET0 || *pc == JSOP_ENTERLET1);
JS_STATIC_ASSERT(JSOP_ENTERBLOCK_LENGTH == JSOP_ENTERLET0_LENGTH);
JS_STATIC_ASSERT(JSOP_ENTERBLOCK_LENGTH == JSOP_ENTERLET1_LENGTH);
return script->getObject(GET_UINT32_INDEX(pc))->asStaticBlock().slotCount();
}
unsigned
js::StackUses(JSScript *script, jsbytecode *pc)
{
JSOp op = (JSOp) *pc;
const JSCodeSpec &cs = js_CodeSpec[op];
if (cs.nuses >= 0)
return cs.nuses;
JS_ASSERT(js_CodeSpec[op].nuses == -1);
switch (op) {
case JSOP_POPN:
return GET_UINT16(pc);
case JSOP_LEAVEBLOCK:
return GET_UINT16(pc);
case JSOP_LEAVEBLOCKEXPR:
return GET_UINT16(pc) + 1;
case JSOP_ENTERLET0:
return NumBlockSlots(script, pc);
case JSOP_ENTERLET1:
return NumBlockSlots(script, pc) + 1;
default:
/* stack: fun, this, [argc arguments] */
JS_ASSERT(op == JSOP_NEW || op == JSOP_CALL || op == JSOP_EVAL ||
op == JSOP_FUNCALL || op == JSOP_FUNAPPLY);
return 2 + GET_ARGC(pc);
}
}
unsigned
js::StackDefs(JSScript *script, jsbytecode *pc)
{
JSOp op = (JSOp) *pc;
const JSCodeSpec &cs = js_CodeSpec[op];
if (cs.ndefs >= 0)
return cs.ndefs;
uint32_t n = NumBlockSlots(script, pc);
return op == JSOP_ENTERLET1 ? n + 1 : n;
}
static const char * countBaseNames[] = {
"interp",
"mjit",
"mjit_calls",
"mjit_code",
"mjit_pics"
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(countBaseNames) == PCCounts::BASE_LIMIT);
static const char * countAccessNames[] = {
"infer_mono",
"infer_di",
"infer_poly",
"infer_barrier",
"infer_nobarrier",
"observe_undefined",
"observe_null",
"observe_boolean",
"observe_int32",
"observe_double",
"observe_string",
"observe_object"
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(countBaseNames) +
JS_ARRAY_LENGTH(countAccessNames) == PCCounts::ACCESS_LIMIT);
static const char * countElementNames[] = {
"id_int",
"id_double",
"id_other",
"id_unknown",
"elem_typed",
"elem_packed",
"elem_dense",
"elem_other"
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(countBaseNames) +
JS_ARRAY_LENGTH(countAccessNames) +
JS_ARRAY_LENGTH(countElementNames) == PCCounts::ELEM_LIMIT);
static const char * countPropertyNames[] = {
"prop_static",
"prop_definite",
"prop_other"
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(countBaseNames) +
JS_ARRAY_LENGTH(countAccessNames) +
JS_ARRAY_LENGTH(countPropertyNames) == PCCounts::PROP_LIMIT);
static const char * countArithNames[] = {
"arith_int",
"arith_double",
"arith_other",
"arith_unknown",
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(countBaseNames) +
JS_ARRAY_LENGTH(countArithNames) == PCCounts::ARITH_LIMIT);
/* static */ const char *
PCCounts::countName(JSOp op, size_t which)
{
JS_ASSERT(which < numCounts(op));
if (which < BASE_LIMIT)
return countBaseNames[which];
if (accessOp(op)) {
if (which < ACCESS_LIMIT)
return countAccessNames[which - BASE_LIMIT];
if (elementOp(op))
return countElementNames[which - ACCESS_LIMIT];
if (propertyOp(op))
return countPropertyNames[which - ACCESS_LIMIT];
JS_NOT_REACHED("bad op");
return NULL;
}
if (arithOp(op))
return countArithNames[which - BASE_LIMIT];
JS_NOT_REACHED("bad op");
return NULL;
}
#ifdef DEBUG
void
js_DumpPCCounts(JSContext *cx, HandleScript script, js::Sprinter *sp)
{
JS_ASSERT(script->hasScriptCounts);
jsbytecode *pc = script->code;
while (pc < script->code + script->length) {
JSOp op = JSOp(*pc);
int len = js_CodeSpec[op].length;
jsbytecode *next = (len != -1) ? pc + len : pc + js_GetVariableBytecodeLength(pc);
if (!js_Disassemble1(cx, script, pc, pc - script->code, true, sp))
return;
size_t total = PCCounts::numCounts(op);
double *raw = script->getPCCounts(pc).rawCounts();
Sprint(sp, " {");
bool printed = false;
for (size_t i = 0; i < total; i++) {
double val = raw[i];
if (val) {
if (printed)
Sprint(sp, ", ");
Sprint(sp, "\"%s\": %.0f", PCCounts::countName(op, i), val);
printed = true;
}
}
Sprint(sp, "}\n");
pc = next;
}
ion::IonScriptCounts *ionCounts = script->getIonCounts();
while (ionCounts) {
Sprint(sp, "IonScript [%lu blocks]:\n", ionCounts->numBlocks());
for (size_t i = 0; i < ionCounts->numBlocks(); i++) {
const ion::IonBlockCounts &block = ionCounts->block(i);
Sprint(sp, "BB #%lu [%05u]", block.id(), block.offset());
for (size_t j = 0; j < block.numSuccessors(); j++)
Sprint(sp, " -> #%lu", block.successor(j));
Sprint(sp, " :: %llu hits %u instruction bytes %u spill bytes\n",
block.hitCount(), block.instructionBytes(), block.spillBytes());
Sprint(sp, "%s\n", block.code());
}
ionCounts = ionCounts->previous();
}
}
/*
* If pc != NULL, include a prefix indicating whether the PC is at the current line.
* If showAll is true, include the source note type and the entry stack depth.
*/
JS_FRIEND_API(JSBool)
js_DisassembleAtPC(JSContext *cx, JSScript *scriptArg, JSBool lines,
jsbytecode *pc, bool showAll, Sprinter *sp)
{
RootedScript script(cx, scriptArg);
jsbytecode *next, *end;
unsigned len;
if (showAll)
Sprint(sp, "%s:%u\n", script->filename(), script->lineno);
if (pc != NULL)
sp->put(" ");
if (showAll)
sp->put("sn stack ");
sp->put("loc ");
if (lines)
sp->put("line");
sp->put(" op\n");
if (pc != NULL)
sp->put(" ");
if (showAll)
sp->put("-- ----- ");
sp->put("----- ");
if (lines)
sp->put("----");
sp->put(" --\n");
next = script->code;
end = next + script->length;
while (next < end) {
if (next == script->main())
sp->put("main:\n");
if (pc != NULL) {
if (pc == next)
sp->put("--> ");
else
sp->put(" ");
}
if (showAll) {
jssrcnote *sn = js_GetSrcNote(cx, script, next);
if (sn) {
JS_ASSERT(!SN_IS_TERMINATOR(sn));
jssrcnote *next = SN_NEXT(sn);
while (!SN_IS_TERMINATOR(next) && SN_DELTA(next) == 0) {
Sprint(sp, "%02u\n ", SN_TYPE(sn));
sn = next;
next = SN_NEXT(sn);
}
Sprint(sp, "%02u ", SN_TYPE(sn));
}
else
sp->put(" ");
if (script->hasAnalysis() && script->analysis()->maybeCode(next))
Sprint(sp, "%05u ", script->analysis()->getCode(next).stackDepth);
else
sp->put(" ");
}
len = js_Disassemble1(cx, script, next, next - script->code, lines, sp);
if (!len)
return JS_FALSE;
next += len;
}
return JS_TRUE;
}
JSBool
js_Disassemble(JSContext *cx, HandleScript script, JSBool lines, Sprinter *sp)
{
return js_DisassembleAtPC(cx, script, lines, NULL, false, sp);
}
JS_FRIEND_API(JSBool)
js_DumpPC(JSContext *cx)
{
js::gc::AutoSuppressGC suppressGC(cx);
Sprinter sprinter(cx);
if (!sprinter.init())
return JS_FALSE;
RootedScript script(cx, cx->fp()->script());
JSBool ok = js_DisassembleAtPC(cx, script, true, cx->regs().pc, false, &sprinter);
fprintf(stdout, "%s", sprinter.string());
return ok;
}
JS_FRIEND_API(JSBool)
js_DumpScript(JSContext *cx, JSScript *scriptArg)
{
js::gc::AutoSuppressGC suppressGC(cx);
Sprinter sprinter(cx);
if (!sprinter.init())
return JS_FALSE;
RootedScript script(cx, scriptArg);
JSBool ok = js_Disassemble(cx, script, true, &sprinter);
fprintf(stdout, "%s", sprinter.string());
return ok;
}
/*
* Useful to debug ReconstructPCStack.
*/
JS_FRIEND_API(JSBool)
js_DumpScriptDepth(JSContext *cx, JSScript *scriptArg, jsbytecode *pc)
{
js::gc::AutoSuppressGC suppressGC(cx);
Sprinter sprinter(cx);
if (!sprinter.init())
return JS_FALSE;
RootedScript script(cx, scriptArg);
JSBool ok = js_DisassembleAtPC(cx, script, true, pc, true, &sprinter);
fprintf(stdout, "%s", sprinter.string());
return ok;
}
static char *
QuoteString(Sprinter *sp, JSString *str, uint32_t quote);
static bool
ToDisassemblySource(JSContext *cx, jsval v, JSAutoByteString *bytes)
{
if (JSVAL_IS_STRING(v)) {
Sprinter sprinter(cx);
if (!sprinter.init())
return false;
char *nbytes = QuoteString(&sprinter, JSVAL_TO_STRING(v), '"');
if (!nbytes)
return false;
nbytes = JS_sprintf_append(NULL, "%s", nbytes);
if (!nbytes)
return false;
bytes->initBytes(nbytes);
return true;
}
if (cx->runtime->isHeapBusy() || cx->runtime->noGCOrAllocationCheck) {
char *source = JS_sprintf_append(NULL, "<value>");
if (!source)
return false;
bytes->initBytes(source);
return true;
}
if (!JSVAL_IS_PRIMITIVE(v)) {
JSObject *obj = JSVAL_TO_OBJECT(v);
if (obj->isBlock()) {
char *source = JS_sprintf_append(NULL, "depth %d {", obj->asBlock().stackDepth());
if (!source)
return false;
Shape::Range<CanGC> r(cx, obj->lastProperty());
while (!r.empty()) {
Rooted<Shape*> shape(cx, &r.front());
JSAtom *atom = JSID_IS_INT(shape->propid())
? cx->names().empty
: JSID_TO_ATOM(shape->propid());
JSAutoByteString bytes;
if (!js_AtomToPrintableString(cx, atom, &bytes))
return false;
r.popFront();
source = JS_sprintf_append(source, "%s: %d%s",
bytes.ptr(), shape->shortid(),
!r.empty() ? ", " : "");
if (!source)
return false;
}
source = JS_sprintf_append(source, "}");
if (!source)
return false;
bytes->initBytes(source);
return true;
}
if (obj->isFunction()) {
JSString *str = JS_DecompileFunction(cx, obj->toFunction(), JS_DONT_PRETTY_PRINT);
if (!str)
return false;
return bytes->encodeLatin1(cx, str);
}
if (obj->isRegExp()) {
JSString *source = obj->asRegExp().toString(cx);
if (!source)
return false;
JS::Anchor<JSString *> anchor(source);
return bytes->encodeLatin1(cx, source);
}
}
return !!js_ValueToPrintable(cx, v, bytes, true);
}
unsigned
js_Disassemble1(JSContext *cx, HandleScript script, jsbytecode *pc,
unsigned loc, JSBool lines, Sprinter *sp)
{
JSOp op = (JSOp)*pc;
if (op >= JSOP_LIMIT) {
char numBuf1[12], numBuf2[12];
JS_snprintf(numBuf1, sizeof numBuf1, "%d", op);
JS_snprintf(numBuf2, sizeof numBuf2, "%d", JSOP_LIMIT);
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
JSMSG_BYTECODE_TOO_BIG, numBuf1, numBuf2);
return 0;
}
const JSCodeSpec *cs = &js_CodeSpec[op];
ptrdiff_t len = (ptrdiff_t) cs->length;
Sprint(sp, "%05u:", loc);
if (lines)
Sprint(sp, "%4u", JS_PCToLineNumber(cx, script, pc));
Sprint(sp, " %s", js_CodeName[op]);
switch (JOF_TYPE(cs->format)) {
case JOF_BYTE:
// Scan the trynotes to find the associated catch block
// and make the try opcode look like a jump instruction
// with an offset. This simplifies code coverage analysis
// based on this disassembled output.
if (op == JSOP_TRY) {
TryNoteArray *trynotes = script->trynotes();
uint32_t i;
for(i = 0; i < trynotes->length; i++) {
JSTryNote note = trynotes->vector[i];
if (note.kind == JSTRY_CATCH && note.start == loc + 1) {
Sprint(sp, " %u (%+d)",
(unsigned int) (loc+note.length+1),
(int) (note.length+1));
break;
}
}
}
break;
case JOF_JUMP: {
ptrdiff_t off = GET_JUMP_OFFSET(pc);
Sprint(sp, " %u (%+d)", loc + (int) off, (int) off);
break;
}
case JOF_SCOPECOORD: {
Value v = StringValue(ScopeCoordinateName(cx, script, pc));
JSAutoByteString bytes;
if (!ToDisassemblySource(cx, v, &bytes))
return 0;
ScopeCoordinate sc(pc);
Sprint(sp, " %s (hops = %u, slot = %u)", bytes.ptr(), sc.hops, sc.slot);
break;
}
case JOF_ATOM: {
Value v = StringValue(script->getAtom(GET_UINT32_INDEX(pc)));
JSAutoByteString bytes;
if (!ToDisassemblySource(cx, v, &bytes))
return 0;
Sprint(sp, " %s", bytes.ptr());
break;
}
case JOF_DOUBLE: {
Value v = script->getConst(GET_UINT32_INDEX(pc));
JSAutoByteString bytes;
if (!ToDisassemblySource(cx, v, &bytes))
return 0;
Sprint(sp, " %s", bytes.ptr());
break;
}
case JOF_OBJECT: {
/* Don't call obj.toSource if analysis/inference is active. */
if (cx->compartment->activeAnalysis) {
Sprint(sp, " object");
break;
}
JSObject *obj = script->getObject(GET_UINT32_INDEX(pc));
{
JSAutoByteString bytes;
if (!ToDisassemblySource(cx, ObjectValue(*obj), &bytes))
return 0;
Sprint(sp, " %s", bytes.ptr());
}
break;
}
case JOF_REGEXP: {
JSObject *obj = script->getRegExp(GET_UINT32_INDEX(pc));
JSAutoByteString bytes;
if (!ToDisassemblySource(cx, ObjectValue(*obj), &bytes))
return 0;
Sprint(sp, " %s", bytes.ptr());
break;
}
case JOF_TABLESWITCH:
{
int32_t i, low, high;
ptrdiff_t off = GET_JUMP_OFFSET(pc);
jsbytecode *pc2 = pc + JUMP_OFFSET_LEN;
low = GET_JUMP_OFFSET(pc2);
pc2 += JUMP_OFFSET_LEN;
high = GET_JUMP_OFFSET(pc2);
pc2 += JUMP_OFFSET_LEN;
Sprint(sp, " defaultOffset %d low %d high %d", int(off), low, high);
for (i = low; i <= high; i++) {
off = GET_JUMP_OFFSET(pc2);
Sprint(sp, "\n\t%d: %d", i, int(off));
pc2 += JUMP_OFFSET_LEN;
}
len = 1 + pc2 - pc;
break;
}
case JOF_QARG:
Sprint(sp, " %u", GET_ARGNO(pc));
break;
case JOF_LOCAL:
Sprint(sp, " %u", GET_SLOTNO(pc));
break;
case JOF_SLOTOBJECT: {
Sprint(sp, " %u", GET_SLOTNO(pc));
JSObject *obj = script->getObject(GET_UINT32_INDEX(pc + SLOTNO_LEN));
JSAutoByteString bytes;
if (!ToDisassemblySource(cx, ObjectValue(*obj), &bytes))
return 0;
Sprint(sp, " %s", bytes.ptr());
break;
}
{
int i;
case JOF_UINT16PAIR:
i = (int)GET_UINT16(pc);
Sprint(sp, " %d", i);
pc += UINT16_LEN;
/* FALL THROUGH */
case JOF_UINT16:
i = (int)GET_UINT16(pc);
goto print_int;
case JOF_UINT24:
JS_ASSERT(op == JSOP_UINT24 || op == JSOP_NEWARRAY || op == JSOP_INITELEM_ARRAY);
i = (int)GET_UINT24(pc);
goto print_int;
case JOF_UINT8:
i = GET_UINT8(pc);
goto print_int;
case JOF_INT8:
i = GET_INT8(pc);
goto print_int;
case JOF_INT32:
JS_ASSERT(op == JSOP_INT32);
i = GET_INT32(pc);
print_int:
Sprint(sp, " %d", i);
break;
}
default: {
char numBuf[12];
JS_snprintf(numBuf, sizeof numBuf, "%lx", (unsigned long) cs->format);
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
JSMSG_UNKNOWN_FORMAT, numBuf);
return 0;
}
}
sp->put("\n");
return len;
}
#endif /* DEBUG */
/************************************************************************/
const size_t Sprinter::DefaultSize = 64;
bool
Sprinter::realloc_(size_t newSize)
{
JS_ASSERT(newSize > (size_t) offset);
char *newBuf = (char *) context->realloc_(base, newSize);
if (!newBuf)
return false;
base = newBuf;
size = newSize;
base[size - 1] = 0;
return true;
}
Sprinter::Sprinter(JSContext *cx)
: context(cx),
#ifdef DEBUG
initialized(false),
#endif
base(NULL), size(0), offset(0), reportedOOM(false)
{ }
Sprinter::~Sprinter()
{
#ifdef DEBUG
if (initialized)
checkInvariants();
#endif
js_free(base);
}
bool
Sprinter::init()
{
JS_ASSERT(!initialized);
base = (char *) context->malloc_(DefaultSize);
if (!base)
return false;
#ifdef DEBUG
initialized = true;
#endif
*base = 0;
size = DefaultSize;
base[size - 1] = 0;
return true;
}
void
Sprinter::checkInvariants() const
{
JS_ASSERT(initialized);
JS_ASSERT((size_t) offset < size);
JS_ASSERT(base[size - 1] == 0);
}
const char *
Sprinter::string() const
{
return base;
}
const char *
Sprinter::stringEnd() const
{
return base + offset;
}
char *
Sprinter::stringAt(ptrdiff_t off) const
{
JS_ASSERT(off >= 0 && (size_t) off < size);
return base + off;
}
char &
Sprinter::operator[](size_t off)
{
JS_ASSERT(off < size);
return *(base + off);
}
bool
Sprinter::empty() const
{
return *base == 0;
}
char *
Sprinter::reserve(size_t len)
{
InvariantChecker ic(this);
while (len + 1 > size - offset) { /* Include trailing \0 */
if (!realloc_(size * 2))
return NULL;
}
char *sb = base + offset;
offset += len;
return sb;
}
char *
Sprinter::reserveAndClear(size_t len)
{
char *sb = reserve(len);
if (sb)
memset(sb, 0, len);
return sb;
}
ptrdiff_t
Sprinter::put(const char *s, size_t len)
{
InvariantChecker ic(this);
const char *oldBase = base;
const char *oldEnd = base + size;
ptrdiff_t oldOffset = offset;
char *bp = reserve(len);
if (!bp)
return -1;
/* s is within the buffer already */
if (s >= oldBase && s < oldEnd) {
/* buffer was realloc'ed */
if (base != oldBase)
s = stringAt(s - oldBase); /* this is where it lives now */
memmove(bp, s, len);
} else {
js_memcpy(bp, s, len);
}
bp[len] = 0;
return oldOffset;
}
ptrdiff_t
Sprinter::put(const char *s)
{
return put(s, strlen(s));
}
ptrdiff_t
Sprinter::putString(JSString *s)
{
InvariantChecker ic(this);
size_t length = s->length();
const jschar *chars = s->getChars(context);
if (!chars)
return -1;
size_t size = length;
if (size == (size_t) -1)
return -1;
ptrdiff_t oldOffset = offset;
char *buffer = reserve(size);
if (!buffer)
return -1;
DeflateStringToBuffer(context, chars, length, buffer, &size);
buffer[size] = 0;
return oldOffset;
}
int
Sprinter::printf(const char *fmt, ...)
{
InvariantChecker ic(this);
do {
va_list va;
va_start(va, fmt);
int i = vsnprintf(base + offset, size - offset, fmt, va);
va_end(va);
if (i > -1 && (size_t) i < size - offset) {
offset += i;
return i;
}
} while (realloc_(size * 2));
return -1;
}
void
Sprinter::setOffset(const char *end)
{
JS_ASSERT(end >= base && end < base + size);
offset = end - base;
}
void
Sprinter::setOffset(ptrdiff_t off)
{
JS_ASSERT(off >= 0 && (size_t) off < size);
offset = off;
}
ptrdiff_t
Sprinter::getOffset() const
{
return offset;
}
ptrdiff_t
Sprinter::getOffsetOf(const char *string) const
{
JS_ASSERT(string >= base && string < base + size);
return string - base;
}
void
Sprinter::reportOutOfMemory() {
if (reportedOOM)
return;
js_ReportOutOfMemory(context);
reportedOOM = true;
}
bool
Sprinter::hadOutOfMemory() const {
return reportedOOM;
}
ptrdiff_t
js::Sprint(Sprinter *sp, const char *format, ...)
{
va_list ap;
char *bp;
ptrdiff_t offset;
va_start(ap, format);
bp = JS_vsmprintf(format, ap); /* XXX vsaprintf */
va_end(ap);
if (!bp) {
sp->reportOutOfMemory();
return -1;
}
offset = sp->put(bp);
js_free(bp);
return offset;
}
const char js_EscapeMap[] = {
'\b', 'b',
'\f', 'f',
'\n', 'n',
'\r', 'r',
'\t', 't',
'\v', 'v',
'"', '"',
'\'', '\'',
'\\', '\\',
'\0'
};
#define DONT_ESCAPE 0x10000
static char *
QuoteString(Sprinter *sp, JSString *str, uint32_t quote)
{
/* Sample off first for later return value pointer computation. */
JSBool dontEscape = (quote & DONT_ESCAPE) != 0;
jschar qc = (jschar) quote;
ptrdiff_t offset = sp->getOffset();
if (qc && Sprint(sp, "%c", (char)qc) < 0)
return NULL;
const jschar *s = str->getChars(sp->context);
if (!s)
return NULL;
const jschar *z = s + str->length();
/* Loop control variables: z points at end of string sentinel. */
for (const jschar *t = s; t < z; s = ++t) {
/* Move t forward from s past un-quote-worthy characters. */
jschar c = *t;
while (c < 127 && isprint(c) && c != qc && c != '\\' && c != '\t') {
c = *++t;
if (t == z)
break;
}
{
ptrdiff_t len = t - s;
ptrdiff_t base = sp->getOffset();
char *bp = sp->reserve(len);
if (!bp)
return NULL;
for (ptrdiff_t i = 0; i < len; ++i)
(*sp)[base + i] = (char) *s++;
(*sp)[base + len] = 0;
}
if (t == z)
break;
/* Use js_EscapeMap, \u, or \x only if necessary. */
bool ok;
const char *e;
if (!(c >> 8) && c != 0 && (e = strchr(js_EscapeMap, (int)c)) != NULL) {
ok = dontEscape
? Sprint(sp, "%c", (char)c) >= 0
: Sprint(sp, "\\%c", e[1]) >= 0;
} else {
/*
* Use \x only if the high byte is 0 and we're in a quoted string,
* because ECMA-262 allows only \u, not \x, in Unicode identifiers
* (see bug 621814).
*/
ok = Sprint(sp, (qc && !(c >> 8)) ? "\\x%02X" : "\\u%04X", c) >= 0;
}
if (!ok)
return NULL;
}
/* Sprint the closing quote and return the quoted string. */
if (qc && Sprint(sp, "%c", (char)qc) < 0)
return NULL;
/*
* If we haven't Sprint'd anything yet, Sprint an empty string so that
* the return below gives a valid result.
*/
if (offset == sp->getOffset() && Sprint(sp, "") < 0)
return NULL;
return sp->stringAt(offset);
}
JSString *
js_QuoteString(JSContext *cx, JSString *str, jschar quote)
{
Sprinter sprinter(cx);
if (!sprinter.init())
return NULL;
char *bytes = QuoteString(&sprinter, str, quote);
JSString *escstr = bytes ? JS_NewStringCopyZ(cx, bytes) : NULL;
return escstr;
}
/************************************************************************/
static int ReconstructPCStack(JSContext*, JSScript*, jsbytecode*, jsbytecode**);
static unsigned
StackDepth(JSScript *script)
{
return script->nslots - script->nfixed;
}
static JSObject *
GetBlockChainAtPC(JSContext *cx, JSScript *script, jsbytecode *pc)
{
jsbytecode *start = script->main();
JS_ASSERT(pc >= start && pc < script->code + script->length);
JSObject *blockChain = NULL;
for (jsbytecode *p = start; p < pc; p += GetBytecodeLength(p)) {
JSOp op = JSOp(*p);
switch (op) {
case JSOP_ENTERBLOCK:
case JSOP_ENTERLET0:
case JSOP_ENTERLET1: {
JSObject *child = script->getObject(p);
JS_ASSERT_IF(blockChain, child->asBlock().stackDepth() >= blockChain->asBlock().stackDepth());
blockChain = child;
break;
}
case JSOP_LEAVEBLOCK:
case JSOP_LEAVEBLOCKEXPR:
case JSOP_LEAVEFORLETIN: {
// Some LEAVEBLOCK instructions are due to early exits via
// return/break/etc. from block-scoped loops and functions. We
// should ignore these instructions, since they don't really signal
// the end of the block.
jssrcnote *sn = js_GetSrcNote(cx, script, p);
if (!(sn && SN_TYPE(sn) == SRC_HIDDEN)) {
JS_ASSERT(blockChain);
blockChain = blockChain->asStaticBlock().enclosingBlock();
JS_ASSERT_IF(blockChain, blockChain->isBlock());
}
break;
}
default:
break;
}
}
return blockChain;
}
class PCStack
{
jsbytecode **stack;
int depth_;
public:
PCStack() : stack(NULL), depth_(0) {}
~PCStack();
bool init(JSContext *cx, JSScript *script, jsbytecode *pc);
int depth() const { return depth_; }
jsbytecode *operator[](int i) const;
};
PCStack::~PCStack()
{
js_free(stack);
}
bool
PCStack::init(JSContext *cx, JSScript *script, jsbytecode *pc)
{
stack = cx->pod_malloc<jsbytecode*>(StackDepth(script));
if (!stack)
return false;
depth_ = ReconstructPCStack(cx, script, pc, stack);
JS_ASSERT(depth_ >= 0);
return true;
}
/* Indexes the pcstack. */
jsbytecode *
PCStack::operator[](int i) const
{
if (i < 0) {
i += depth_;
JS_ASSERT(i >= 0);
}
JS_ASSERT(i < depth_);
return stack[i];
}
/*
* The expression decompiler is invoked by error handling code to produce a
* string representation of the erroring expression. As it's only a debugging
* tool, it only supports basic expressions. For anything complicated, it simply
* puts "(intermediate value)" into the error result.
*
* Here's the basic algorithm:
*
* 1. Find the stack location of the value whose expression we wish to
* decompile. The error handler can explicitly pass this as an
* argument. Otherwise, we search backwards down the stack for the offending
* value.
*
* 2. Call ReconstructPCStack with the current frame's pc. This creates a stack
* of pcs parallel to the interpreter stack; given an interpreter stack
* location, the corresponding pc stack location contains the opcode that pushed
* the value in the interpreter. Now, with the result of step 1, we have the
* opcode responsible for pushing the value we want to decompile.
*
* 3. Pass the opcode to decompilePC. decompilePC is the main decompiler
* routine, responsible for a string representation of the expression that
* generated a certain stack location. decompilePC looks at one opcode and
* returns the JS source equivalent of that opcode.
*
* 4. Expressions can, of course, contain subexpressions. For example, the
* literals "4" and "5" are subexpressions of the addition operator in "4 +
* 5". If we need to decompile a subexpression, we call decompilePC (step 2)
* recursively on the operands' pcs. The result is a depth-first traversal of
* the expression tree.
*
*/
struct ExpressionDecompiler
{
JSContext *cx;
StackFrame *fp;
RootedScript script;
RootedFunction fun;
BindingVector *localNames;
Sprinter sprinter;
ExpressionDecompiler(JSContext *cx, JSScript *script, JSFunction *fun)
: cx(cx),
script(cx, script),
fun(cx, fun),
localNames(NULL),
sprinter(cx)
{}
~ExpressionDecompiler();
bool init();
bool decompilePC(jsbytecode *pc);
JSAtom *getVar(unsigned slot);
JSAtom *getArg(unsigned slot);
JSAtom *findLetVar(jsbytecode *pc, unsigned depth);
JSAtom *loadAtom(jsbytecode *pc);
bool quote(JSString *s, uint32_t quote);
bool write(const char *s);
bool write(JSString *str);
bool getOutput(char **out);
};
bool
ExpressionDecompiler::decompilePC(jsbytecode *pc)
{
JS_ASSERT(script->code <= pc && pc < script->code + script->length);
PCStack pcstack;
if (!pcstack.init(cx, script, pc))
return false;
JSOp op = (JSOp)*pc;
if (const char *token = CodeToken[op]) {
// Handle simple cases of binary and unary operators.
switch (js_CodeSpec[op].nuses) {
case 2: {
jssrcnote *sn = js_GetSrcNote(cx, script, pc);
if (!sn || SN_TYPE(sn) != SRC_ASSIGNOP)
return write("(") &&
decompilePC(pcstack[-2]) &&
write(" ") &&
write(token) &&
write(" ") &&
decompilePC(pcstack[-1]) &&
write(")");
break;
}
case 1:
return write(token) &&
write("(") &&
decompilePC(pcstack[-1]) &&
write(")");
default:
break;
}
}
switch (op) {
case JSOP_GETGNAME:
case JSOP_CALLGNAME:
case JSOP_NAME:
case JSOP_CALLNAME:
return write(loadAtom(pc));
case JSOP_GETARG:
case JSOP_CALLARG: {
unsigned slot = GET_ARGNO(pc);
JSAtom *atom = getArg(slot);
return write(atom);
}
case JSOP_GETLOCAL:
case JSOP_CALLLOCAL: {
unsigned i = GET_SLOTNO(pc);
JSAtom *atom;
if (i >= script->nfixed) {
i -= script->nfixed;
JS_ASSERT(i < unsigned(pcstack.depth()));
atom = findLetVar(pc, i);
if (!atom)
return decompilePC(pcstack[i]); // Destructing temporary
} else {
atom = getVar(i);
}
JS_ASSERT(atom);
return write(atom);
}
case JSOP_CALLALIASEDVAR:
case JSOP_GETALIASEDVAR: {
JSAtom *atom = ScopeCoordinateName(cx, script, pc);
JS_ASSERT(atom);
return write(atom);
}
case JSOP_LENGTH:
case JSOP_GETPROP:
case JSOP_CALLPROP: {
RootedAtom prop(cx, (op == JSOP_LENGTH) ? cx->names().length : loadAtom(pc));
if (!decompilePC(pcstack[-1]))
return false;
if (IsIdentifier(prop)) {
return write(".") &&
quote(prop, '\0');
}
return write("[") &&
quote(prop, '\'') &&
write("]");
}
case JSOP_GETELEM:
case JSOP_CALLELEM:
return decompilePC(pcstack[-2]) &&
write("[") &&
decompilePC(pcstack[-1]) &&
write("]");
case JSOP_NULL:
return write(js_null_str);
case JSOP_TRUE:
return write(js_true_str);
case JSOP_FALSE:
return write(js_false_str);
case JSOP_ZERO:
case JSOP_ONE:
case JSOP_INT8:
case JSOP_UINT16:
case JSOP_UINT24:
case JSOP_INT32: {
int32_t i;
switch (op) {
case JSOP_ZERO:
i = 0;
break;
case JSOP_ONE:
i = 1;
break;
case JSOP_INT8:
i = GET_INT8(pc);
break;
case JSOP_UINT16:
i = GET_UINT16(pc);
break;
case JSOP_UINT24:
i = GET_UINT24(pc);
break;
case JSOP_INT32:
i = GET_INT32(pc);
break;
default:
JS_NOT_REACHED("wat?");
}
return sprinter.printf("%d", i) >= 0;
}
case JSOP_STRING:
return quote(loadAtom(pc), '"');
case JSOP_UNDEFINED:
return write(js_undefined_str);
case JSOP_THIS:
// |this| could convert to a very long object initialiser, so cite it by
// its keyword name.
return write(js_this_str);
case JSOP_CALL:
case JSOP_FUNCALL:
return decompilePC(pcstack[-int32_t(GET_ARGC(pc) + 2)]) &&
write("(...)");
case JSOP_NEWARRAY:
return write("[]");
case JSOP_REGEXP:
case JSOP_OBJECT: {
JSObject *obj = (op == JSOP_REGEXP)
? script->getRegExp(GET_UINT32_INDEX(pc))
: script->getObject(GET_UINT32_INDEX(pc));
JSString *str = ValueToSource(cx, ObjectValue(*obj));
if (!str)
return false;
return write(str);
}
default:
break;
}
return write("(intermediate value)");
}
ExpressionDecompiler::~ExpressionDecompiler()
{
js_delete<BindingVector>(localNames);
}
bool
ExpressionDecompiler::init()
{
assertSameCompartment(cx, script);
if (!sprinter.init())
return false;
localNames = cx->new_<BindingVector>(cx);
if (!localNames)
return false;
RootedScript script_(cx, script);
if (!FillBindingVector(script_, localNames))
return false;
return true;
}
bool
ExpressionDecompiler::write(const char *s)
{
return sprinter.put(s) >= 0;
}
bool
ExpressionDecompiler::write(JSString *str)
{
return sprinter.putString(str) >= 0;
}
bool
ExpressionDecompiler::quote(JSString *s, uint32_t quote)
{
return QuoteString(&sprinter, s, quote) >= 0;
}
JSAtom *
ExpressionDecompiler::loadAtom(jsbytecode *pc)
{
return script->getAtom(GET_UINT32_INDEX(pc));
}
JSAtom *
ExpressionDecompiler::findLetVar(jsbytecode *pc, unsigned depth)
{
if (script->hasObjects()) {
JSObject *chain = GetBlockChainAtPC(cx, script, pc);
if (!chain)
return NULL;
JS_ASSERT(chain->isBlock());
do {
BlockObject &block = chain->asBlock();
uint32_t blockDepth = block.stackDepth();
uint32_t blockCount = block.slotCount();
if (uint32_t(depth - blockDepth) < uint32_t(blockCount)) {
for (Shape::Range<NoGC> r(block.lastProperty()); !r.empty(); r.popFront()) {
const Shape &shape = r.front();
if (shape.shortid() == int(depth - blockDepth))
return JSID_TO_ATOM(shape.propid());
}
}
chain = chain->getParent();
} while (chain && chain->isBlock());
}
return NULL;
}
JSAtom *
ExpressionDecompiler::getArg(unsigned slot)
{
JS_ASSERT(fun);
JS_ASSERT(slot < script->bindings.count());
return (*localNames)[slot].name();
}
JSAtom *
ExpressionDecompiler::getVar(unsigned slot)
{
JS_ASSERT(fun);
slot += fun->nargs;
JS_ASSERT(slot < script->bindings.count());
return (*localNames)[slot].name();
}
bool
ExpressionDecompiler::getOutput(char **res)
{
ptrdiff_t len = sprinter.stringEnd() - sprinter.stringAt(0);
*res = cx->pod_malloc<char>(len + 1);
if (!*res)
return false;
js_memcpy(*res, sprinter.stringAt(0), len);
(*res)[len] = 0;
return true;
}
static bool
FindStartPC(JSContext *cx, ScriptFrameIter &iter, int spindex, int skipStackHits, Value v,
jsbytecode **valuepc)
{
jsbytecode *current = *valuepc;
if (spindex == JSDVG_IGNORE_STACK)
return true;
/*
* Fall back on *valuepc as start pc if this frame is calling .apply and
* the methodjit has "splatted" the arguments array, bumping the caller's
* stack pointer and skewing it from what static analysis in pcstack.init
* would compute.
*
* FIXME: also fall back if iter.isIon(), since the stack snapshot may be
* for the previous pc (see bug 831120).
*/
if (iter.isIon() || iter.interpFrame()->jitRevisedStack())
return true;
*valuepc = NULL;
PCStack pcstack;
if (!pcstack.init(cx, iter.script(), current))
return false;
if (spindex < 0 && spindex + pcstack.depth() < 0)
spindex = JSDVG_SEARCH_STACK;
if (spindex == JSDVG_SEARCH_STACK) {
size_t index = iter.numFrameSlots();
JS_ASSERT(index >= size_t(pcstack.depth()));
// We search from fp->sp to base to find the most recently calculated
// value matching v under assumption that it is the value that caused
// the exception.
int stackHits = 0;
Value s;
do {
if (!index)
return true;
s = iter.frameSlotValue(--index);
} while (s != v || stackHits++ != skipStackHits);
// If index is out of bounds in pcstack, the blamed value must be one
// pushed by the current bytecode, so restore *valuepc.
if (index < size_t(pcstack.depth()))
*valuepc = pcstack[index];
else
*valuepc = current;
} else {
*valuepc = pcstack[spindex];
}
return true;
}
static bool
DecompileExpressionFromStack(JSContext *cx, int spindex, int skipStackHits, HandleValue v, char **res)
{
JS_ASSERT(spindex < 0 ||
spindex == JSDVG_IGNORE_STACK ||
spindex == JSDVG_SEARCH_STACK);
*res = NULL;
#ifdef JS_MORE_DETERMINISTIC
/*
* Give up if we need deterministic behavior for differential testing.
* IonMonkey doesn't use StackFrames and this ensures we get the same
* error messages.
*/
return true;
#endif
ScriptFrameIter frameIter(cx);
if (frameIter.done())
return true;
RootedScript script(cx, frameIter.script());
AutoCompartment ac(cx, &script->global());
jsbytecode *valuepc = frameIter.pc();
RootedFunction fun(cx, frameIter.isFunctionFrame()
? frameIter.callee()
: NULL);
JS_ASSERT(script->code <= valuepc && valuepc < script->code + script->length);
// Give up if in prologue.
if (valuepc < script->main())
return true;
if (!FindStartPC(cx, frameIter, spindex, skipStackHits, v, &valuepc))
return false;
if (!valuepc)
return true;
ExpressionDecompiler ed(cx, script, fun);
if (!ed.init())
return false;
if (!ed.decompilePC(valuepc))
return false;
return ed.getOutput(res);
}
char *
js::DecompileValueGenerator(JSContext *cx, int spindex, HandleValue v,
HandleString fallbackArg, int skipStackHits)
{
RootedString fallback(cx, fallbackArg);
{
char *result;
if (!DecompileExpressionFromStack(cx, spindex, skipStackHits, v, &result))
return NULL;
if (result) {
if (strcmp(result, "(intermediate value)"))
return result;
js_free(result);
}
}
if (!fallback) {
if (v.isUndefined())
return JS_strdup(cx, js_undefined_str); // Prevent users from seeing "(void 0)"
fallback = ValueToSource(cx, v);
if (!fallback)
return NULL;
}
Rooted<JSLinearString *> linear(cx, fallback->ensureLinear(cx));
if (!linear)
return NULL;
TwoByteChars tbchars(linear->chars(), linear->length());
return LossyTwoByteCharsToNewLatin1CharsZ(cx, tbchars).c_str();
}
static bool
DecompileArgumentFromStack(JSContext *cx, int formalIndex, char **res)
{
JS_ASSERT(formalIndex >= 0);
*res = NULL;
#ifdef JS_MORE_DETERMINISTIC
/* See note in DecompileExpressionFromStack. */
return true;
#endif
/*
* Settle on the nearest script frame, which should be the builtin that
* called the intrinsic.
*/
StackIter frameIter(cx);
while (!frameIter.done() && !frameIter.isScript())
++frameIter;
JS_ASSERT(!frameIter.done());
/*
* Get the second-to-top frame, the caller of the builtin that called the
* intrinsic.
*/
++frameIter;
/* If this frame isn't a script, we can't decompile. */
if (frameIter.done() || !frameIter.isScript())
return true;
RootedScript script(cx, frameIter.script());
AutoCompartment ac(cx, &script->global());
jsbytecode *current = frameIter.pc();
RootedFunction fun(cx, frameIter.isFunctionFrame()
? frameIter.callee()
: NULL);
JS_ASSERT(script->code <= current && current < script->code + script->length);
if (current < script->main())
return true;
/* Don't handle getters, setters or calls from fun.call/fun.apply. */
if (JSOp(*current) != JSOP_CALL || static_cast<unsigned>(formalIndex) >= GET_ARGC(current))
return true;
PCStack pcStack;
if (!pcStack.init(cx, script, current))
return false;
int formalStackIndex = pcStack.depth() - GET_ARGC(current) + formalIndex;
JS_ASSERT(formalStackIndex >= 0);
if (formalStackIndex >= pcStack.depth())
return true;
ExpressionDecompiler ed(cx, script, fun);
if (!ed.init())
return false;
if (!ed.decompilePC(pcStack[formalStackIndex]))
return false;
return ed.getOutput(res);
}
char *
js::DecompileArgument(JSContext *cx, int formalIndex, HandleValue v)
{
{
char *result;
if (!DecompileArgumentFromStack(cx, formalIndex, &result))
return NULL;
if (result) {
if (strcmp(result, "(intermediate value)"))
return result;
js_free(result);
}
}
if (v.isUndefined())
return JS_strdup(cx, js_undefined_str); // Prevent users from seeing "(void 0)"
RootedString fallback(cx, ValueToSource(cx, v));
if (!fallback)
return NULL;
Rooted<JSLinearString *> linear(cx, fallback->ensureLinear(cx));
if (!linear)
return NULL;
return LossyTwoByteCharsToNewLatin1CharsZ(cx, linear->range()).c_str();
}
unsigned
js_ReconstructStackDepth(JSContext *cx, JSScript *script, jsbytecode *pc)
{
return ReconstructPCStack(cx, script, pc, NULL);
}
#define LOCAL_ASSERT_CUSTOM(expr, BAD_EXIT) \
JS_BEGIN_MACRO \
JS_ASSERT(expr); \
if (!(expr)) { BAD_EXIT; } \
JS_END_MACRO
#define LOCAL_ASSERT_RV(expr, rv) \
LOCAL_ASSERT_CUSTOM(expr, return (rv))
#define LOCAL_ASSERT(expr) LOCAL_ASSERT_RV(expr, -1);
static int
SimulateOp(JSScript *script, JSOp op, const JSCodeSpec *cs,
jsbytecode *pc, jsbytecode **pcstack, unsigned &pcdepth)
{
if (cs->format & JOF_DECOMPOSE)
return pcdepth;
unsigned nuses = StackUses(script, pc);
unsigned ndefs = StackDefs(script, pc);
LOCAL_ASSERT(pcdepth >= nuses);
pcdepth -= nuses;
LOCAL_ASSERT(pcdepth + ndefs <= StackDepth(script));
/*
* Fill the slots that the opcode defines withs its pc unless it just
* reshuffles the stack. In the latter case we want to preserve the
* opcode that generated the original value.
*/
switch (op) {
default:
if (pcstack) {
for (unsigned i = 0; i != ndefs; ++i)
pcstack[pcdepth + i] = pc;
}
break;
case JSOP_CASE:
/* Keep the switch value. */
JS_ASSERT(ndefs == 1);
break;
case JSOP_DUP:
JS_ASSERT(ndefs == 2);
if (pcstack)
pcstack[pcdepth + 1] = pcstack[pcdepth];
break;
case JSOP_DUP2:
JS_ASSERT(ndefs == 4);
if (pcstack) {
pcstack[pcdepth + 2] = pcstack[pcdepth];
pcstack[pcdepth + 3] = pcstack[pcdepth + 1];
}
break;
case JSOP_SWAP:
JS_ASSERT(ndefs == 2);
if (pcstack) {
jsbytecode *tmp = pcstack[pcdepth + 1];
pcstack[pcdepth + 1] = pcstack[pcdepth];
pcstack[pcdepth] = tmp;
}
break;
}
pcdepth += ndefs;
return pcdepth;
}
/* Ensure that script analysis reports the same stack depth. */
static void
AssertPCDepth(JSScript *script, jsbytecode *pc, unsigned pcdepth) {
/*
* If this assertion fails, run the failing test case under gdb and use the
* following gdb command to understand the execution path of this function.
*
* call js_DumpScriptDepth(cx, script, pc)
*/
JS_ASSERT_IF(script->hasAnalysis() && script->analysis()->maybeCode(pc),
script->analysis()->getCode(pc).stackDepth == pcdepth);
}
static int
ReconstructPCStack(JSContext *cx, JSScript *script, jsbytecode *target, jsbytecode **pcstack)
{
/*
* Walk forward from script->code and compute the stack depth and stack of
* operand-generating opcode PCs in pcstack.
*
* Every instruction has a statically computable stack depth before and
* after. This function returns the stack depth before the target
* instruction.
*
* The stack depth can be computed from these three common-sense rules...
*
* - The stack depth before the first instruction of the script is 0.
*
* - The stack depth after an instruction is always simply the stack
* depth before, plus whatever effect of the instruction has.
* SimulateOp computes this.
*
* - Except for three specific cases listed below, the stack depth before
* an instruction is simply the stack depth after the preceding one.
*
* ... and these three less obvious rules:
*
* - Special case 1: break, continue, or return statements that exit
* certain kinds of blocks.
*
* Rule: The stack depth before the next instruction (following the
* GOTO/RETRVAL) equals the stack depth before the first SRC_HIDDEN
* instruction.
*
* - Special case 2: The rethrow at the end of conditional catch blocks.
*
* Rule: The stack depth before the next rethrow instruction of a
* conditional catch block equals the stack depth at the end of the IFEQ
* of the catch condition (which is jumping to this re-throw).
*
* - Special case 3: Conditional expressions (A ? B : C).
*
* Rule: The code for B and C are pushing a result on the stack, so the
* stack depth before C equals the stack depth before B, which is one
* less than the stack depth after the GOTO ending B.
*/
LOCAL_ASSERT(script->code <= target && target < script->code + script->length);
/*
* Save depth of hidden instructions to recover the depth if a branch is not
* taken.
*/
unsigned hpcdepth = unsigned(-1);
/*
* Save depth of catch instructions to recover it in the rethrow path, at
* the end of a conditional catch.
*/
unsigned cpcdepth = unsigned(-1);
jsbytecode *pc;
unsigned pcdepth;
ptrdiff_t oplen;
for (pc = script->code, pcdepth = 0; ; pc += oplen) {
JSOp op = JSOp(*pc);
oplen = GetBytecodeLength(pc);
const JSCodeSpec *cs = &js_CodeSpec[op];
jssrcnote *sn = js_GetSrcNote(cx, script, pc);
/*
* *** Special case 1.a ***
*
* Hidden instructions are used to pop scoped variables (leaveblock) in
* early-exit paths and are not supposed to affect the stack depth when
* they are not taken. However, when the target is in an early-exit
* path, hidden instructions need to be taken into account.
*
* As we are not following any branch, we need to restore the stack
* depth after any instruction which is breaking the flow of the
* program. Sequences of hidden instructions are *included* in the
* following grammar:
*
* ExitSequence:
* EarlyExit // return / break / continue
* | ConditionalCatchExit // conditional catch-block exit
*
* EarlyExit:
* setrval; ExitSegment* retrval; // return stmt
* | ExitSegment* goto; // break/continue stmt
*
* ConditionalCatchExit:
* ExitSegment* hidden goto; CatchRethrow
*
* CatchRethrow:
* hidden throw; end-brace nop; // last catch-block
* | hidden throw; finally; // followed by a finally
* | hidden throwing; hidden leaveblock; catch enterblock;
* // followed by a catch-block
*
* ExitSegment:
* hidden leaveblock; // leave let-block or
* // leave catch-block
* | hidden leavewith; // leave with-block
* | hidden gosub; // leave try or
* // leave catch-block with finally
* | hidden enditer; // leave for-in/of block
* | hidden leaveforletin; hidden enditer; hidden popn;
* // leave for-let-in/of block
*
* The following code save the depth of the first hidden
* instruction. When we hit either the last instruction of the EarlyExit
* (retrval/goto) or the goto of a ConditionalCacthExit, we restore (see
* Special case 1.b) the depth after the execution of the instruction.
*
* In case of a ConditionalCacthExit, we keep the hidden depth after the
* hidden goto to again restore (see Special case 1.b) the depth after
* the throw/throwing instruction of the CatchRethrow.
*
* Note: The last instructions of the EarlyExit, such as break, continue
* and return are not hidden as they are part of the original sources,
* so we need to consider them as-if they were hidden instruction (do
* not reset the depth) and restore the depth after their execution. It
* is important to restore them after their execution, and not at the
* next instruction, because they might be followed by another sequence
* of hidden instruction.
*/
bool exitPath =
op == JSOP_GOTO ||
op == JSOP_RETRVAL ||
op == JSOP_THROW;
bool isConditionalCatchExit = false;
if (sn && SN_TYPE(sn) == SRC_HIDDEN) {
/* Only ConditionalCatchExit's goto are hidden. */
isConditionalCatchExit = op == JSOP_GOTO;
if (hpcdepth == unsigned(-1))
hpcdepth = pcdepth;
} else if (!exitPath) {
hpcdepth = unsigned(-1);
}
/*
* *** Special case 2 ***
*
* The catch depth is used to restore the depth expected in case of
* rethrow or in case of guard failure. The depth expected by throw and
* throwing instructions correspond to the result of enterblock and
* exception instructions.
*
* enterblock depth d <-- depth += d
* exception <-- depth += 1
*
* This is not a problem, except with conditional catch staements.
* Conditional catch statements are looking like:
*
* ifeq +... <-- jump to the rethrow path.
* pop <-- pop the exception value.
*
* Unfortunately, we iterate linearly over the bytecode, so we cannot
* use a stack to save the depth for each catch statement that we
* encounter. The trick done here is to save the stack depth before we
* unwind the scoped variables with leaveblock, and restore the stack
* depth plus one to account for the missing exception value.
*
* {Catch} leaveblock d <-- save depth
* ( gosub ... )?
* {Hidden} goto ...
* ( {Hidden} throw )? <-- restore depth + 1
*
* If there is no rethrow, then we should expect an end-brace nop or a
* finally.
*/
if (op == JSOP_LEAVEBLOCK && sn && SN_TYPE(sn) == SRC_CATCH) {
LOCAL_ASSERT(cpcdepth == unsigned(-1));
cpcdepth = pcdepth;
} else if (sn && SN_TYPE(sn) == SRC_HIDDEN &&
(op == JSOP_THROW || op == JSOP_THROWING))
{
/*
* The current catch block is conditional, we compensate for the pop
* of the exception added after the ifeq by adding 1 to the restored
* depth. This fake slot might not contain the right value, but
* it will be eliminated with the throw or throwing instruction.
*/
LOCAL_ASSERT(cpcdepth != unsigned(-1));
pcdepth = cpcdepth + 1;
cpcdepth = unsigned(-1);
} else if (!(op == JSOP_GOTO && sn && SN_TYPE(sn) == SRC_HIDDEN) &&
!(op == JSOP_GOSUB && cpcdepth != unsigned(-1)))
{
/*
* We need to ignore gosub and goto when we exit a catch block.
* Otherwise we might reset the catch depth before hitting the throw
* or throwing instruction.
*
* {Catch} leaveblock d
* ( gosub ... )?
* {Hidden} goto ...
* ( {Hidden} throw )?
* finally
*
* If there is no rethrow, the end-brace nop or the finally
* instruction will reset the saved depth.
*/
if (cpcdepth != unsigned(-1))
LOCAL_ASSERT(op == JSOP_NOP || op == JSOP_FINALLY);
cpcdepth = unsigned(-1);
}
/* At this point, pcdepth is the stack depth *before* the insn at pc. */
AssertPCDepth(script, pc, pcdepth);
if (pc >= target)
break;
/* Simulate the instruction at pc. */
if (SimulateOp(script, op, cs, pc, pcstack, pcdepth) < 0)
return -1;
/* At this point, pcdepth is the stack depth *after* the insn at pc. */
/*
* *** Special case 1.b ***
*
* Restore the stack depth after the execution of an EarlyExit or the
* goto of the ConditionalCatchExit.
*/
if (exitPath && hpcdepth != unsigned(-1)) {
pcdepth = hpcdepth;
/* Keep the depth if we are on the ConditionalCatchExit path. */
if (!isConditionalCatchExit)
hpcdepth = unsigned(-1);
}
/*
* *** Special case 3 ***
*
* A (C ? T : E) expression requires skipping T if target is in E or
* after the whole expression, because this expression is pushing a
* result on the stack and the goto cannot be skipped.
*
* 09 001 pc : ifeq +11
* 000 pc+ 5: null
* 001 pc+ 6: goto +... <-- The stack after the goto
* 000 pc+11: ... <-- does not have the same depth.
*
*/
if (sn && SN_TYPE(sn) == SRC_COND) {
ptrdiff_t jmplen = GET_JUMP_OFFSET(pc);
if (pc + jmplen <= target) {
/* Target does not lie in T. */
oplen = jmplen;
}
}
}
LOCAL_ASSERT(pc == target);
AssertPCDepth(script, pc, pcdepth);
return pcdepth;
}
#undef LOCAL_ASSERT
#undef LOCAL_ASSERT_RV
bool
js::CallResultEscapes(jsbytecode *pc)
{
/*
* If we see any of these sequences, the result is unused:
* - call / pop
*
* If we see any of these sequences, the result is only tested for nullness:
* - call / ifeq
* - call / not / ifeq
*/
if (*pc != JSOP_CALL)
return true;
pc += JSOP_CALL_LENGTH;
if (*pc == JSOP_POP)
return false;
if (*pc == JSOP_NOT)
pc += JSOP_NOT_LENGTH;
return (*pc != JSOP_IFEQ);
}
extern bool
js::IsValidBytecodeOffset(JSContext *cx, JSScript *script, size_t offset)
{
// This could be faster (by following jump instructions if the target is <= offset).
for (BytecodeRange r(cx, script); !r.empty(); r.popFront()) {
size_t here = r.frontOffset();
if (here >= offset)
return here == offset;
}
return false;
}
JS_FRIEND_API(size_t)
js::GetPCCountScriptCount(JSContext *cx)
{
JSRuntime *rt = cx->runtime;
if (!rt->scriptAndCountsVector)
return 0;
return rt->scriptAndCountsVector->length();
}
enum MaybeComma {NO_COMMA, COMMA};
static void
AppendJSONProperty(StringBuffer &buf, const char *name, MaybeComma comma = COMMA)
{
if (comma)
buf.append(',');
buf.append('\"');
buf.appendInflated(name, strlen(name));
buf.appendInflated("\":", 2);
}
static void
AppendArrayJSONProperties(JSContext *cx, StringBuffer &buf,
double *values, const char **names, unsigned count, MaybeComma &comma)
{
for (unsigned i = 0; i < count; i++) {
if (values[i]) {
AppendJSONProperty(buf, names[i], comma);
comma = COMMA;
NumberValueToStringBuffer(cx, DoubleValue(values[i]), buf);
}
}
}
JS_FRIEND_API(JSString *)
js::GetPCCountScriptSummary(JSContext *cx, size_t index)
{
JSRuntime *rt = cx->runtime;
if (!rt->scriptAndCountsVector || index >= rt->scriptAndCountsVector->length()) {
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_BUFFER_TOO_SMALL);
return NULL;
}
const ScriptAndCounts &sac = (*rt->scriptAndCountsVector)[index];
RootedScript script(cx, sac.script);
/*
* OOM on buffer appends here will not be caught immediately, but since
* StringBuffer uses a ContextAllocPolicy will trigger an exception on the
* context if they occur, which we'll catch before returning.
*/
StringBuffer buf(cx);
buf.append('{');
AppendJSONProperty(buf, "file", NO_COMMA);
JSString *str = JS_NewStringCopyZ(cx, script->filename());
if (!str || !(str = ValueToSource(cx, StringValue(str))))
return NULL;
buf.append(str);
AppendJSONProperty(buf, "line");
NumberValueToStringBuffer(cx, Int32Value(script->lineno), buf);
if (script->function()) {
JSAtom *atom = script->function()->displayAtom();
if (atom) {
AppendJSONProperty(buf, "name");
if (!(str = ValueToSource(cx, StringValue(atom))))
return NULL;
buf.append(str);
}
}
double baseTotals[PCCounts::BASE_LIMIT] = {0.0};
double accessTotals[PCCounts::ACCESS_LIMIT - PCCounts::BASE_LIMIT] = {0.0};
double elementTotals[PCCounts::ELEM_LIMIT - PCCounts::ACCESS_LIMIT] = {0.0};
double propertyTotals[PCCounts::PROP_LIMIT - PCCounts::ACCESS_LIMIT] = {0.0};
double arithTotals[PCCounts::ARITH_LIMIT - PCCounts::BASE_LIMIT] = {0.0};
for (unsigned i = 0; i < script->length; i++) {
PCCounts &counts = sac.getPCCounts(script->code + i);
if (!counts)
continue;
JSOp op = (JSOp)script->code[i];
unsigned numCounts = PCCounts::numCounts(op);
for (unsigned j = 0; j < numCounts; j++) {
double value = counts.get(j);
if (j < PCCounts::BASE_LIMIT) {
baseTotals[j] += value;
} else if (PCCounts::accessOp(op)) {
if (j < PCCounts::ACCESS_LIMIT)
accessTotals[j - PCCounts::BASE_LIMIT] += value;
else if (PCCounts::elementOp(op))
elementTotals[j - PCCounts::ACCESS_LIMIT] += value;
else if (PCCounts::propertyOp(op))
propertyTotals[j - PCCounts::ACCESS_LIMIT] += value;
else
JS_NOT_REACHED("Bad opcode");
} else if (PCCounts::arithOp(op)) {
arithTotals[j - PCCounts::BASE_LIMIT] += value;
} else {
JS_NOT_REACHED("Bad opcode");
}
}
}
AppendJSONProperty(buf, "totals");
buf.append('{');
MaybeComma comma = NO_COMMA;
AppendArrayJSONProperties(cx, buf, baseTotals, countBaseNames,
JS_ARRAY_LENGTH(baseTotals), comma);
AppendArrayJSONProperties(cx, buf, accessTotals, countAccessNames,
JS_ARRAY_LENGTH(accessTotals), comma);
AppendArrayJSONProperties(cx, buf, elementTotals, countElementNames,
JS_ARRAY_LENGTH(elementTotals), comma);
AppendArrayJSONProperties(cx, buf, propertyTotals, countPropertyNames,
JS_ARRAY_LENGTH(propertyTotals), comma);
AppendArrayJSONProperties(cx, buf, arithTotals, countArithNames,
JS_ARRAY_LENGTH(arithTotals), comma);
uint64_t ionActivity = 0;
ion::IonScriptCounts *ionCounts = sac.getIonCounts();
while (ionCounts) {
for (size_t i = 0; i < ionCounts->numBlocks(); i++)
ionActivity += ionCounts->block(i).hitCount();
ionCounts = ionCounts->previous();
}
if (ionActivity) {
AppendJSONProperty(buf, "ion", comma);
NumberValueToStringBuffer(cx, DoubleValue(ionActivity), buf);
}
buf.append('}');
buf.append('}');
if (cx->isExceptionPending())
return NULL;
return buf.finishString();
}
static bool
GetPCCountJSON(JSContext *cx, const ScriptAndCounts &sac, StringBuffer &buf)
{
RootedScript script(cx, sac.script);
buf.append('{');
AppendJSONProperty(buf, "text", NO_COMMA);
JSString *str = JS_DecompileScript(cx, script, NULL, 0);
if (!str || !(str = ValueToSource(cx, StringValue(str))))
return false;
buf.append(str);
AppendJSONProperty(buf, "line");
NumberValueToStringBuffer(cx, Int32Value(script->lineno), buf);
AppendJSONProperty(buf, "opcodes");
buf.append('[');
bool comma = false;
SrcNoteLineScanner scanner(script->notes(), script->lineno);
for (jsbytecode *pc = script->code;
pc < script->code + script->length;
pc += GetBytecodeLength(pc))
{
size_t offset = pc - script->code;
JSOp op = (JSOp) *pc;
if (comma)
buf.append(',');
comma = true;
buf.append('{');
AppendJSONProperty(buf, "id", NO_COMMA);
NumberValueToStringBuffer(cx, Int32Value(pc - script->code), buf);
scanner.advanceTo(offset);
AppendJSONProperty(buf, "line");
NumberValueToStringBuffer(cx, Int32Value(scanner.getLine()), buf);
{
const char *name = js_CodeName[op];
AppendJSONProperty(buf, "name");
buf.append('\"');
buf.appendInflated(name, strlen(name));
buf.append('\"');
}
{
ExpressionDecompiler ed(cx, script, script->function());
if (!ed.init())
return false;
if (!ed.decompilePC(pc))
return false;
char *text;
if (!ed.getOutput(&text))
return false;
AppendJSONProperty(buf, "text");
JSString *str = JS_NewStringCopyZ(cx, text);
js_free(text);
if (!str || !(str = ValueToSource(cx, StringValue(str))))
return false;
buf.append(str);
}
PCCounts &counts = sac.getPCCounts(pc);
unsigned numCounts = PCCounts::numCounts(op);
AppendJSONProperty(buf, "counts");
buf.append('{');
MaybeComma comma = NO_COMMA;
for (unsigned i = 0; i < numCounts; i++) {
double value = counts.get(i);
if (value > 0) {
AppendJSONProperty(buf, PCCounts::countName(op, i), comma);
comma = COMMA;
NumberValueToStringBuffer(cx, DoubleValue(value), buf);
}
}
buf.append('}');
buf.append('}');
}
buf.append(']');
ion::IonScriptCounts *ionCounts = sac.getIonCounts();
if (ionCounts) {
AppendJSONProperty(buf, "ion");
buf.append('[');
bool comma = false;
while (ionCounts) {
if (comma)
buf.append(',');
comma = true;
buf.append('[');
for (size_t i = 0; i < ionCounts->numBlocks(); i++) {
if (i)
buf.append(',');
const ion::IonBlockCounts &block = ionCounts->block(i);
buf.append('{');
AppendJSONProperty(buf, "id", NO_COMMA);
NumberValueToStringBuffer(cx, Int32Value(block.id()), buf);
AppendJSONProperty(buf, "offset");
NumberValueToStringBuffer(cx, Int32Value(block.offset()), buf);
AppendJSONProperty(buf, "successors");
buf.append('[');
for (size_t j = 0; j < block.numSuccessors(); j++) {
if (j)
buf.append(',');
NumberValueToStringBuffer(cx, Int32Value(block.successor(j)), buf);
}
buf.append(']');
AppendJSONProperty(buf, "hits");
NumberValueToStringBuffer(cx, DoubleValue(block.hitCount()), buf);
AppendJSONProperty(buf, "code");
JSString *str = JS_NewStringCopyZ(cx, block.code());
if (!str || !(str = ValueToSource(cx, StringValue(str))))
return false;
buf.append(str);
AppendJSONProperty(buf, "instructionBytes");
NumberValueToStringBuffer(cx, Int32Value(block.instructionBytes()), buf);
AppendJSONProperty(buf, "spillBytes");
NumberValueToStringBuffer(cx, Int32Value(block.spillBytes()), buf);
buf.append('}');
}
buf.append(']');
ionCounts = ionCounts->previous();
}
buf.append(']');
}
buf.append('}');
return !cx->isExceptionPending();
}
JS_FRIEND_API(JSString *)
js::GetPCCountScriptContents(JSContext *cx, size_t index)
{
JSRuntime *rt = cx->runtime;
if (!rt->scriptAndCountsVector || index >= rt->scriptAndCountsVector->length()) {
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_BUFFER_TOO_SMALL);
return NULL;
}
const ScriptAndCounts &sac = (*rt->scriptAndCountsVector)[index];
JSScript *script = sac.script;
StringBuffer buf(cx);
if (!script->function() && !script->compileAndGo)
return buf.finishString();
{
AutoCompartment ac(cx, &script->global());
if (!GetPCCountJSON(cx, sac, buf))
return NULL;
}
return buf.finishString();
}
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