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BytecodeEmitter.cpp
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BytecodeEmitter.cpp
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 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 generation.
*/
#include "mozilla/FloatingPoint.h"
#ifdef HAVE_MEMORY_H
#include <memory.h>
#endif
#include <new>
#include <string.h>
#include "jstypes.h"
#include "jsutil.h"
#include "jsprf.h"
#include "jsapi.h"
#include "jsatom.h"
#include "jsbool.h"
#include "jscntxt.h"
#include "jsversion.h"
#include "jsfun.h"
#include "jsnum.h"
#include "jsopcode.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jsautooplen.h" // generated headers last
#include "ds/LifoAlloc.h"
#include "frontend/BytecodeEmitter.h"
#include "frontend/Parser.h"
#include "frontend/TokenStream.h"
#include "vm/RegExpObject.h"
#include "jsatominlines.h"
#include "jsscopeinlines.h"
#include "jsscriptinlines.h"
#include "frontend/ParseMaps-inl.h"
#include "frontend/ParseNode-inl.h"
#include "frontend/TreeContext-inl.h"
/* Allocation chunk counts, must be powers of two in general. */
#define BYTECODE_CHUNK_LENGTH 1024 /* initial bytecode chunk length */
#define SRCNOTE_CHUNK_LENGTH 1024 /* initial srcnote chunk length */
/* Macros to compute byte sizes from typed element counts. */
#define BYTECODE_SIZE(n) ((n) * sizeof(jsbytecode))
#define SRCNOTE_SIZE(n) ((n) * sizeof(jssrcnote))
using namespace js;
using namespace js::gc;
using namespace js::frontend;
static JSBool
NewTryNote(JSContext *cx, BytecodeEmitter *bce, JSTryNoteKind kind, unsigned stackDepth,
size_t start, size_t end);
static JSBool
SetSrcNoteOffset(JSContext *cx, BytecodeEmitter *bce, unsigned index, unsigned which, ptrdiff_t offset);
BytecodeEmitter::BytecodeEmitter(Parser *parser, SharedContext *sc, unsigned lineno,
bool noScriptRval, bool needScriptGlobal)
: sc(sc),
parent(NULL),
parser(parser),
atomIndices(sc->context),
stackDepth(0), maxStackDepth(0),
ntrynotes(0), lastTryNode(NULL),
arrayCompDepth(0),
emitLevel(0),
constMap(sc->context),
constList(sc->context),
globalScope(NULL),
closedArgs(sc->context),
closedVars(sc->context),
typesetCount(0),
noScriptRval(noScriptRval),
needScriptGlobal(needScriptGlobal),
hasSingletons(false),
inForInit(false)
{
memset(&prolog, 0, sizeof prolog);
memset(&main, 0, sizeof main);
current = &main;
firstLine = prolog.currentLine = main.currentLine = lineno;
}
bool
BytecodeEmitter::init()
{
return constMap.init() && atomIndices.ensureMap(sc->context);
}
BytecodeEmitter::~BytecodeEmitter()
{
JSContext *cx = sc->context;
cx->free_(prolog.base);
cx->free_(prolog.notes);
cx->free_(main.base);
cx->free_(main.notes);
}
static ptrdiff_t
EmitCheck(JSContext *cx, BytecodeEmitter *bce, ptrdiff_t delta)
{
jsbytecode *base = bce->base();
jsbytecode *newbase;
jsbytecode *next = bce->next();
jsbytecode *limit = bce->limit();
ptrdiff_t offset = next - base;
size_t minlength = offset + delta;
if (next + delta > limit) {
size_t newlength;
if (!base) {
JS_ASSERT(!next && !limit);
newlength = BYTECODE_CHUNK_LENGTH;
if (newlength < minlength) /* make it bigger if necessary */
newlength = RoundUpPow2(minlength);
newbase = (jsbytecode *) cx->malloc_(BYTECODE_SIZE(newlength));
} else {
JS_ASSERT(base <= next && next <= limit);
newlength = (limit - base) * 2;
if (newlength < minlength) /* make it bigger if necessary */
newlength = RoundUpPow2(minlength);
newbase = (jsbytecode *) cx->realloc_(base, BYTECODE_SIZE(newlength));
}
if (!newbase) {
js_ReportOutOfMemory(cx);
return -1;
}
JS_ASSERT(newlength >= size_t(offset + delta));
bce->current->base = newbase;
bce->current->limit = newbase + newlength;
bce->current->next = newbase + offset;
}
return offset;
}
static StaticBlockObject &
CurrentBlock(SharedContext *sc)
{
JS_ASSERT(sc->topStmt->type == STMT_BLOCK || sc->topStmt->type == STMT_SWITCH);
JS_ASSERT(sc->topStmt->blockObj->isStaticBlock());
return *sc->topStmt->blockObj;
}
static void
UpdateDepth(JSContext *cx, BytecodeEmitter *bce, ptrdiff_t target)
{
jsbytecode *pc = bce->code(target);
JSOp op = (JSOp) *pc;
const JSCodeSpec *cs = &js_CodeSpec[op];
if (cs->format & JOF_TMPSLOT_MASK) {
/*
* An opcode may temporarily consume stack space during execution.
* Account for this in maxStackDepth separately from uses/defs here.
*/
unsigned depth = (unsigned) bce->stackDepth +
((cs->format & JOF_TMPSLOT_MASK) >> JOF_TMPSLOT_SHIFT);
if (depth > bce->maxStackDepth)
bce->maxStackDepth = depth;
}
/*
* Specially handle any case that would call js_GetIndexFromBytecode since
* it requires a well-formed script. This allows us to safely pass NULL as
* the 'script' parameter.
*/
int nuses, ndefs;
if (op == JSOP_ENTERBLOCK) {
nuses = 0;
ndefs = CurrentBlock(bce->sc).slotCount();
} else if (op == JSOP_ENTERLET0) {
nuses = ndefs = CurrentBlock(bce->sc).slotCount();
} else if (op == JSOP_ENTERLET1) {
nuses = ndefs = CurrentBlock(bce->sc).slotCount() + 1;
} else {
nuses = StackUses(NULL, pc);
ndefs = StackDefs(NULL, pc);
}
bce->stackDepth -= nuses;
JS_ASSERT(bce->stackDepth >= 0);
bce->stackDepth += ndefs;
if ((unsigned)bce->stackDepth > bce->maxStackDepth)
bce->maxStackDepth = bce->stackDepth;
}
static inline void
UpdateDecomposeLength(BytecodeEmitter *bce, unsigned start)
{
unsigned end = bce->offset();
JS_ASSERT(unsigned(end - start) < 256);
bce->code(start)[-1] = end - start;
}
ptrdiff_t
frontend::Emit1(JSContext *cx, BytecodeEmitter *bce, JSOp op)
{
ptrdiff_t offset = EmitCheck(cx, bce, 1);
if (offset >= 0) {
*bce->current->next++ = (jsbytecode)op;
UpdateDepth(cx, bce, offset);
}
return offset;
}
ptrdiff_t
frontend::Emit2(JSContext *cx, BytecodeEmitter *bce, JSOp op, jsbytecode op1)
{
ptrdiff_t offset = EmitCheck(cx, bce, 2);
if (offset >= 0) {
jsbytecode *next = bce->next();
next[0] = (jsbytecode)op;
next[1] = op1;
bce->current->next = next + 2;
UpdateDepth(cx, bce, offset);
}
return offset;
}
ptrdiff_t
frontend::Emit3(JSContext *cx, BytecodeEmitter *bce, JSOp op, jsbytecode op1,
jsbytecode op2)
{
/* These should filter through EmitVarOp. */
JS_ASSERT(JOF_OPTYPE(op) != JOF_QARG);
JS_ASSERT(JOF_OPTYPE(op) != JOF_LOCAL);
ptrdiff_t offset = EmitCheck(cx, bce, 3);
if (offset >= 0) {
jsbytecode *next = bce->next();
next[0] = (jsbytecode)op;
next[1] = op1;
next[2] = op2;
bce->current->next = next + 3;
UpdateDepth(cx, bce, offset);
}
return offset;
}
ptrdiff_t
frontend::EmitN(JSContext *cx, BytecodeEmitter *bce, JSOp op, size_t extra)
{
ptrdiff_t length = 1 + (ptrdiff_t)extra;
ptrdiff_t offset = EmitCheck(cx, bce, length);
if (offset >= 0) {
jsbytecode *next = bce->next();
*next = (jsbytecode)op;
memset(next + 1, 0, BYTECODE_SIZE(extra));
bce->current->next = next + length;
/*
* Don't UpdateDepth if op's use-count comes from the immediate
* operand yet to be stored in the extra bytes after op.
*/
if (js_CodeSpec[op].nuses >= 0)
UpdateDepth(cx, bce, offset);
}
return offset;
}
static ptrdiff_t
EmitJump(JSContext *cx, BytecodeEmitter *bce, JSOp op, ptrdiff_t off)
{
ptrdiff_t offset = EmitCheck(cx, bce, 5);
if (offset >= 0) {
jsbytecode *next = bce->next();
next[0] = (jsbytecode)op;
SET_JUMP_OFFSET(next, off);
bce->current->next = next + 5;
UpdateDepth(cx, bce, offset);
}
return offset;
}
/* XXX too many "... statement" L10N gaffes below -- fix via js.msg! */
const char js_with_statement_str[] = "with statement";
const char js_finally_block_str[] = "finally block";
const char js_script_str[] = "script";
static const char *statementName[] = {
"label statement", /* LABEL */
"if statement", /* IF */
"else statement", /* ELSE */
"destructuring body", /* BODY */
"switch statement", /* SWITCH */
"block", /* BLOCK */
js_with_statement_str, /* WITH */
"catch block", /* CATCH */
"try block", /* TRY */
js_finally_block_str, /* FINALLY */
js_finally_block_str, /* SUBROUTINE */
"do loop", /* DO_LOOP */
"for loop", /* FOR_LOOP */
"for/in loop", /* FOR_IN_LOOP */
"while loop", /* WHILE_LOOP */
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(statementName) == STMT_LIMIT);
static const char *
StatementName(SharedContext *sc)
{
if (!sc->topStmt)
return js_script_str;
return statementName[sc->topStmt->type];
}
static void
ReportStatementTooLarge(JSContext *cx, SharedContext *sc)
{
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_NEED_DIET,
StatementName(sc));
}
/*
* Emit a backpatch op with offset pointing to the previous jump of this type,
* so that we can walk back up the chain fixing up the op and jump offset.
*/
static ptrdiff_t
EmitBackPatchOp(JSContext *cx, BytecodeEmitter *bce, JSOp op, ptrdiff_t *lastp)
{
ptrdiff_t offset, delta;
offset = bce->offset();
delta = offset - *lastp;
*lastp = offset;
JS_ASSERT(delta > 0);
return EmitJump(cx, bce, op, delta);
}
/* A macro for inlining at the top of EmitTree (whence it came). */
#define UPDATE_LINE_NUMBER_NOTES(cx, bce, line) \
JS_BEGIN_MACRO \
unsigned line_ = (line); \
unsigned delta_ = line_ - bce->currentLine(); \
if (delta_ != 0) { \
/* \
* Encode any change in the current source line number by using \
* either several SRC_NEWLINE notes or just one SRC_SETLINE note, \
* whichever consumes less space. \
* \
* NB: We handle backward line number deltas (possible with for \
* loops where the update part is emitted after the body, but its \
* line number is <= any line number in the body) here by letting \
* unsigned delta_ wrap to a very large number, which triggers a \
* SRC_SETLINE. \
*/ \
bce->current->currentLine = line_; \
if (delta_ >= (unsigned)(2 + ((line_ > SN_3BYTE_OFFSET_MASK)<<1))) { \
if (NewSrcNote2(cx, bce, SRC_SETLINE, (ptrdiff_t)line_) < 0) \
return JS_FALSE; \
} else { \
do { \
if (NewSrcNote(cx, bce, SRC_NEWLINE) < 0) \
return JS_FALSE; \
} while (--delta_ != 0); \
} \
} \
JS_END_MACRO
/* A function, so that we avoid macro-bloating all the other callsites. */
static JSBool
UpdateLineNumberNotes(JSContext *cx, BytecodeEmitter *bce, unsigned line)
{
UPDATE_LINE_NUMBER_NOTES(cx, bce, line);
return JS_TRUE;
}
static ptrdiff_t
EmitLoopHead(JSContext *cx, BytecodeEmitter *bce, ParseNode *nextpn)
{
if (nextpn) {
/*
* Try to give the JSOP_LOOPHEAD the same line number as the next
* instruction. nextpn is often a block, in which case the next
* instruction typically comes from the first statement inside.
*/
JS_ASSERT_IF(nextpn->isKind(PNK_STATEMENTLIST), nextpn->isArity(PN_LIST));
if (nextpn->isKind(PNK_STATEMENTLIST) && nextpn->pn_head)
nextpn = nextpn->pn_head;
if (!UpdateLineNumberNotes(cx, bce, nextpn->pn_pos.begin.lineno))
return -1;
}
return Emit1(cx, bce, JSOP_LOOPHEAD);
}
static bool
EmitLoopEntry(JSContext *cx, BytecodeEmitter *bce, ParseNode *nextpn)
{
if (nextpn) {
/* Update the line number, as for LOOPHEAD. */
JS_ASSERT_IF(nextpn->isKind(PNK_STATEMENTLIST), nextpn->isArity(PN_LIST));
if (nextpn->isKind(PNK_STATEMENTLIST) && nextpn->pn_head)
nextpn = nextpn->pn_head;
if (!UpdateLineNumberNotes(cx, bce, nextpn->pn_pos.begin.lineno))
return false;
}
return Emit1(cx, bce, JSOP_LOOPENTRY) >= 0;
}
/*
* If op is JOF_TYPESET (see the type barriers comment in jsinfer.h), reserve
* a type set to store its result.
*/
static inline void
CheckTypeSet(JSContext *cx, BytecodeEmitter *bce, JSOp op)
{
if (js_CodeSpec[op].format & JOF_TYPESET) {
if (bce->typesetCount < UINT16_MAX)
bce->typesetCount++;
}
}
/*
* Macro to emit a bytecode followed by a uint16_t immediate operand stored in
* big-endian order, used for arg and var numbers as well as for atomIndexes.
* NB: We use cx and bce from our caller's lexical environment, and return
* false on error.
*/
#define EMIT_UINT16_IMM_OP(op, i) \
JS_BEGIN_MACRO \
if (Emit3(cx, bce, op, UINT16_HI(i), UINT16_LO(i)) < 0) \
return JS_FALSE; \
CheckTypeSet(cx, bce, op); \
JS_END_MACRO
#define EMIT_UINT16PAIR_IMM_OP(op, i, j) \
JS_BEGIN_MACRO \
ptrdiff_t off_ = EmitN(cx, bce, op, 2 * UINT16_LEN); \
if (off_ < 0) \
return JS_FALSE; \
jsbytecode *pc_ = bce->code(off_); \
SET_UINT16(pc_, i); \
pc_ += UINT16_LEN; \
SET_UINT16(pc_, j); \
JS_END_MACRO
#define EMIT_UINT16_IN_PLACE(offset, op, i) \
JS_BEGIN_MACRO \
bce->code(offset)[0] = op; \
bce->code(offset)[1] = UINT16_HI(i); \
bce->code(offset)[2] = UINT16_LO(i); \
JS_END_MACRO
#define EMIT_UINT32_IN_PLACE(offset, op, i) \
JS_BEGIN_MACRO \
bce->code(offset)[0] = op; \
bce->code(offset)[1] = jsbytecode(i >> 24); \
bce->code(offset)[2] = jsbytecode(i >> 16); \
bce->code(offset)[3] = jsbytecode(i >> 8); \
bce->code(offset)[4] = jsbytecode(i); \
JS_END_MACRO
static JSBool
FlushPops(JSContext *cx, BytecodeEmitter *bce, int *npops)
{
JS_ASSERT(*npops != 0);
if (NewSrcNote(cx, bce, SRC_HIDDEN) < 0)
return JS_FALSE;
EMIT_UINT16_IMM_OP(JSOP_POPN, *npops);
*npops = 0;
return JS_TRUE;
}
static bool
PopIterator(JSContext *cx, BytecodeEmitter *bce)
{
if (NewSrcNote(cx, bce, SRC_HIDDEN) < 0)
return false;
if (Emit1(cx, bce, JSOP_ENDITER) < 0)
return false;
return true;
}
/*
* Emit additional bytecode(s) for non-local jumps.
*/
static JSBool
EmitNonLocalJumpFixup(JSContext *cx, BytecodeEmitter *bce, StmtInfo *toStmt)
{
/*
* The non-local jump fixup we emit will unbalance bce->stackDepth, because
* the fixup replicates balanced code such as JSOP_LEAVEWITH emitted at the
* end of a with statement, so we save bce->stackDepth here and restore it
* just before a successful return.
*/
int depth = bce->stackDepth;
int npops = 0;
#define FLUSH_POPS() if (npops && !FlushPops(cx, bce, &npops)) return JS_FALSE
for (StmtInfo *stmt = bce->sc->topStmt; stmt != toStmt; stmt = stmt->down) {
switch (stmt->type) {
case STMT_FINALLY:
FLUSH_POPS();
if (NewSrcNote(cx, bce, SRC_HIDDEN) < 0)
return JS_FALSE;
if (EmitBackPatchOp(cx, bce, JSOP_BACKPATCH, &GOSUBS(*stmt)) < 0)
return JS_FALSE;
break;
case STMT_WITH:
/* There's a With object on the stack that we need to pop. */
FLUSH_POPS();
if (NewSrcNote(cx, bce, SRC_HIDDEN) < 0)
return JS_FALSE;
if (Emit1(cx, bce, JSOP_LEAVEWITH) < 0)
return JS_FALSE;
break;
case STMT_FOR_IN_LOOP:
FLUSH_POPS();
if (!PopIterator(cx, bce))
return JS_FALSE;
break;
case STMT_SUBROUTINE:
/*
* There's a [exception or hole, retsub pc-index] pair on the
* stack that we need to pop.
*/
npops += 2;
break;
default:;
}
if (stmt->flags & SIF_SCOPE) {
FLUSH_POPS();
unsigned blockObjCount = stmt->blockObj->slotCount();
if (stmt->flags & SIF_FOR_BLOCK) {
/*
* For a for-let-in statement, pushing/popping the block is
* interleaved with JSOP_(END)ITER. Just handle both together
* here and skip over the enclosing STMT_FOR_IN_LOOP.
*/
JS_ASSERT(stmt->down->type == STMT_FOR_IN_LOOP);
stmt = stmt->down;
if (stmt == toStmt)
break;
if (Emit1(cx, bce, JSOP_LEAVEFORLETIN) < 0)
return JS_FALSE;
if (!PopIterator(cx, bce))
return JS_FALSE;
if (NewSrcNote(cx, bce, SRC_HIDDEN) < 0)
return JS_FALSE;
EMIT_UINT16_IMM_OP(JSOP_POPN, blockObjCount);
} else {
/* There is a Block object with locals on the stack to pop. */
if (NewSrcNote(cx, bce, SRC_HIDDEN) < 0)
return JS_FALSE;
EMIT_UINT16_IMM_OP(JSOP_LEAVEBLOCK, blockObjCount);
}
}
}
FLUSH_POPS();
bce->stackDepth = depth;
return JS_TRUE;
#undef FLUSH_POPS
}
static const jsatomid INVALID_ATOMID = -1;
static ptrdiff_t
EmitGoto(JSContext *cx, BytecodeEmitter *bce, StmtInfo *toStmt, ptrdiff_t *lastp,
jsatomid labelIndex = INVALID_ATOMID, SrcNoteType noteType = SRC_NULL)
{
int index;
if (!EmitNonLocalJumpFixup(cx, bce, toStmt))
return -1;
if (labelIndex != INVALID_ATOMID)
index = NewSrcNote2(cx, bce, noteType, ptrdiff_t(labelIndex));
else if (noteType != SRC_NULL)
index = NewSrcNote(cx, bce, noteType);
else
index = 0;
if (index < 0)
return -1;
return EmitBackPatchOp(cx, bce, JSOP_BACKPATCH, lastp);
}
static JSBool
BackPatch(JSContext *cx, BytecodeEmitter *bce, ptrdiff_t last, jsbytecode *target, jsbytecode op)
{
jsbytecode *pc, *stop;
ptrdiff_t delta, span;
pc = bce->code(last);
stop = bce->code(-1);
while (pc != stop) {
delta = GET_JUMP_OFFSET(pc);
span = target - pc;
SET_JUMP_OFFSET(pc, span);
*pc = op;
pc -= delta;
}
return JS_TRUE;
}
JSBool
frontend::PopStatementBCE(JSContext *cx, BytecodeEmitter *bce)
{
StmtInfo *stmt = bce->sc->topStmt;
if (!STMT_IS_TRYING(stmt) &&
(!BackPatch(cx, bce, stmt->breaks, bce->next(), JSOP_GOTO) ||
!BackPatch(cx, bce, stmt->continues, bce->code(stmt->update), JSOP_GOTO)))
{
return JS_FALSE;
}
PopStatementSC(bce->sc);
return JS_TRUE;
}
JSBool
frontend::DefineCompileTimeConstant(JSContext *cx, BytecodeEmitter *bce, JSAtom *atom, ParseNode *pn)
{
/* XXX just do numbers for now */
if (pn->isKind(PNK_NUMBER)) {
if (!bce->constMap.put(atom, NumberValue(pn->pn_dval)))
return JS_FALSE;
}
return JS_TRUE;
}
/*
* The function sets vp to NO_CONSTANT when the atom does not corresponds to a
* name defining a constant.
*/
static JSBool
LookupCompileTimeConstant(JSContext *cx, BytecodeEmitter *bce, JSAtom *atom, Value *constp)
{
/*
* Chase down the bce stack, but only until we reach the outermost bce.
* This enables propagating consts from top-level into switch cases in a
* function compiled along with the top-level script.
*/
constp->setMagic(JS_NO_CONSTANT);
do {
if (bce->sc->inFunction() || bce->parser->compileAndGo) {
/* XXX this will need revising if 'const' becomes block-scoped. */
StmtInfo *stmt = LexicalLookup(bce->sc, atom, NULL);
if (stmt)
return JS_TRUE;
if (BytecodeEmitter::ConstMap::Ptr p = bce->constMap.lookup(atom)) {
JS_ASSERT(!p->value.isMagic(JS_NO_CONSTANT));
*constp = p->value;
return JS_TRUE;
}
/*
* Try looking in the variable object for a direct property that
* is readonly and permanent. We know such a property can't be
* shadowed by another property on obj's prototype chain, or a
* with object or catch variable; nor can prop's value be changed,
* nor can prop be deleted.
*/
if (bce->sc->inFunction()) {
if (bce->sc->bindings.hasBinding(cx, atom))
break;
} else {
JS_ASSERT(bce->parser->compileAndGo);
JSObject *obj = bce->sc->scopeChain();
const Shape *shape = obj->nativeLookup(cx, AtomToId(atom));
if (shape) {
/*
* We're compiling code that will be executed immediately,
* not re-executed against a different scope chain and/or
* variable object. Therefore we can get constant values
* from our variable object here.
*/
if (!shape->writable() && !shape->configurable() &&
shape->hasDefaultGetter() && shape->hasSlot()) {
*constp = obj->nativeGetSlot(shape->slot());
}
}
if (shape)
break;
}
}
bce = bce->parent;
} while (bce);
return JS_TRUE;
}
static bool
EmitIndex32(JSContext *cx, JSOp op, uint32_t index, BytecodeEmitter *bce)
{
const size_t len = 1 + UINT32_INDEX_LEN;
JS_ASSERT(len == size_t(js_CodeSpec[op].length));
ptrdiff_t offset = EmitCheck(cx, bce, len);
if (offset < 0)
return false;
jsbytecode *next = bce->next();
next[0] = jsbytecode(op);
SET_UINT32_INDEX(next, index);
bce->current->next = next + len;
UpdateDepth(cx, bce, offset);
CheckTypeSet(cx, bce, op);
return true;
}
static bool
EmitIndexOp(JSContext *cx, JSOp op, uint32_t index, BytecodeEmitter *bce)
{
const size_t len = js_CodeSpec[op].length;
JS_ASSERT(len >= 1 + UINT32_INDEX_LEN);
ptrdiff_t offset = EmitCheck(cx, bce, len);
if (offset < 0)
return false;
jsbytecode *next = bce->next();
next[0] = jsbytecode(op);
SET_UINT32_INDEX(next, index);
bce->current->next = next + len;
UpdateDepth(cx, bce, offset);
CheckTypeSet(cx, bce, op);
return true;
}
static bool
EmitAtomOp(JSContext *cx, JSAtom *atom, JSOp op, BytecodeEmitter *bce)
{
JS_ASSERT(JOF_OPTYPE(op) == JOF_ATOM);
if (op == JSOP_GETPROP && atom == cx->runtime->atomState.lengthAtom) {
/* Specialize length accesses for the interpreter. */
op = JSOP_LENGTH;
}
jsatomid index;
if (!bce->makeAtomIndex(atom, &index))
return false;
return EmitIndexOp(cx, op, index, bce);
}
static bool
EmitAtomOp(JSContext *cx, ParseNode *pn, JSOp op, BytecodeEmitter *bce)
{
JS_ASSERT(pn->pn_atom != NULL);
return EmitAtomOp(cx, pn->pn_atom, op, bce);
}
static bool
EmitAtomIncDec(JSContext *cx, JSAtom *atom, JSOp op, BytecodeEmitter *bce)
{
JS_ASSERT(JOF_OPTYPE(op) == JOF_ATOM);
JS_ASSERT(js_CodeSpec[op].format & (JOF_INC | JOF_DEC));
jsatomid index;
if (!bce->makeAtomIndex(atom, &index))
return false;
const size_t len = 1 + UINT32_INDEX_LEN + 1;
JS_ASSERT(size_t(js_CodeSpec[op].length) == len);
ptrdiff_t offset = EmitCheck(cx, bce, len);
if (offset < 0)
return false;
jsbytecode *next = bce->next();
next[0] = jsbytecode(op);
SET_UINT32_INDEX(next, index);
bce->current->next = next + len;
UpdateDepth(cx, bce, offset);
CheckTypeSet(cx, bce, op);
return true;
}
static bool
EmitFunctionOp(JSContext *cx, JSOp op, uint32_t index, BytecodeEmitter *bce)
{
return EmitIndex32(cx, op, index, bce);
}
static bool
EmitObjectOp(JSContext *cx, ObjectBox *objbox, JSOp op, BytecodeEmitter *bce)
{
JS_ASSERT(JOF_OPTYPE(op) == JOF_OBJECT);
return EmitIndex32(cx, op, bce->objectList.index(objbox), bce);
}
static bool
EmitRegExp(JSContext *cx, uint32_t index, BytecodeEmitter *bce)
{
return EmitIndex32(cx, JSOP_REGEXP, index, bce);
}
/*
* To catch accidental misuse, EMIT_UINT16_IMM_OP/Emit3 assert that they are
* not used to unconditionally emit JSOP_GETLOCAL. Variable access should
* instead be emitted using EmitVarOp. In special cases, when the caller
* definitely knows that a given local slot is unaliased, this function may be
* used as a non-asserting version of EMIT_UINT16_IMM_OP.
*/
static bool
EmitUnaliasedVarOp(JSContext *cx, JSOp op, uint16_t slot, BytecodeEmitter *bce)
{
JS_ASSERT(JOF_OPTYPE(op) != JOF_SCOPECOORD);
ptrdiff_t off = EmitN(cx, bce, op, sizeof(uint16_t));
if (off < 0)
return false;
SET_UINT16(bce->code(off), slot);
return true;
}
static bool
EmitAliasedVarOp(JSContext *cx, JSOp op, uint16_t binding, JSAtom *atom, BytecodeEmitter *bce)
{
JS_ASSERT(JOF_OPTYPE(op) == JOF_SCOPECOORD);
/*
* XXX This is temporary: bug 659577 will need to compute the number of
* cloned block objects to hop over.
*/
uint16_t hops = 0;
jsatomid atomIndex;
if (!bce->makeAtomIndex(atom, &atomIndex))
return false;
bool decomposed = js_CodeSpec[op].format & JOF_DECOMPOSE;
unsigned n = 2 * sizeof(uint16_t) + sizeof(uint32_t) + (decomposed ? 1 : 0);
ptrdiff_t off = EmitN(cx, bce, op, n);
if (off < 0)
return false;
jsbytecode *pc = bce->code(off);
SET_UINT16(pc, hops);
pc += sizeof(uint16_t);
SET_UINT16(pc, binding);
pc += sizeof(uint16_t);
SET_UINT32_INDEX(pc, atomIndex);
return true;
}
static bool
EmitAliasedVarOp(JSContext *cx, JSOp op, ParseNode *pn, BytecodeEmitter *bce)
{
uint16_t binding = JOF_OPTYPE(pn->getOp()) == JOF_QARG
? bce->sc->bindings.argToBinding(pn->pn_cookie.slot())
: bce->sc->bindings.localToBinding(pn->pn_cookie.slot());
return EmitAliasedVarOp(cx, op, binding, pn->atom(), bce);
}
static bool
EmitVarOp(JSContext *cx, ParseNode *pn, JSOp op, BytecodeEmitter *bce)
{
JS_ASSERT(pn->isKind(PNK_FUNCTION) || pn->isKind(PNK_NAME));
JS_ASSERT_IF(pn->isKind(PNK_NAME), JOF_OPTYPE(op) == JOF_QARG || JOF_OPTYPE(op) == JOF_LOCAL);
JS_ASSERT(!pn->pn_cookie.isFree());
if (!bce->isAliasedName(pn))
return EmitUnaliasedVarOp(cx, op, pn->pn_cookie.slot(), bce);
switch (op) {
case JSOP_GETARG: case JSOP_GETLOCAL: op = JSOP_GETALIASEDVAR; break;
case JSOP_SETARG: case JSOP_SETLOCAL: op = JSOP_SETALIASEDVAR; break;
case JSOP_CALLARG: case JSOP_CALLLOCAL: op = JSOP_CALLALIASEDVAR; break;
default: JS_NOT_REACHED("unexpected var op");
}
return EmitAliasedVarOp(cx, op, pn, bce);
}
static bool
EmitVarIncDec(JSContext *cx, ParseNode *pn, JSOp op, BytecodeEmitter *bce)
{
JS_ASSERT(pn->isKind(PNK_NAME));
JS_ASSERT(JOF_OPTYPE(op) == JOF_QARG || JOF_OPTYPE(op) == JOF_LOCAL);
JS_ASSERT(js_CodeSpec[op].format & (JOF_INC | JOF_DEC));
JS_ASSERT(!pn->pn_cookie.isFree());
if (!bce->isAliasedName(pn))
return EmitUnaliasedVarOp(cx, op, pn->pn_cookie.slot(), bce);
switch (op) {
case JSOP_INCARG: case JSOP_INCLOCAL: op = JSOP_INCALIASEDVAR; break;
case JSOP_ARGINC: case JSOP_LOCALINC: op = JSOP_ALIASEDVARINC; break;
case JSOP_DECARG: case JSOP_DECLOCAL: op = JSOP_DECALIASEDVAR; break;
case JSOP_ARGDEC: case JSOP_LOCALDEC: op = JSOP_ALIASEDVARDEC; break;
default: JS_NOT_REACHED("unexpected var op");
}
if (!EmitAliasedVarOp(cx, op, pn, bce))
return false;
/* Remove the result to restore the stack depth before the INCALIASEDVAR. */
bce->stackDepth--;
int start = bce->offset();
const JSCodeSpec &cs = js_CodeSpec[op];
bool post = (cs.format & JOF_POST);
JSOp binop = (cs.format & JOF_INC) ? JSOP_ADD : JSOP_SUB;
if (!EmitAliasedVarOp(cx, JSOP_GETALIASEDVAR, pn, bce)) // V
return false;
if (Emit1(cx, bce, JSOP_POS) < 0) // N
return false;
if (post && Emit1(cx, bce, JSOP_DUP) < 0) // N? N
return false;
if (Emit1(cx, bce, JSOP_ONE) < 0) // N? N 1
return false;
if (Emit1(cx, bce, binop) < 0) // N? N+1
return false;
if (!EmitAliasedVarOp(cx, JSOP_SETALIASEDVAR, pn, bce)) // N? N+1
return false;
if (post && Emit1(cx, bce, JSOP_POP) < 0) // RESULT
return false;
UpdateDecomposeLength(bce, start);
return true;
}
bool
BytecodeEmitter::isAliasedName(ParseNode *pn)
{
return sc->bindingsAccessedDynamically() || shouldNoteClosedName(pn->resolve());
}
bool
BytecodeEmitter::shouldNoteClosedName(ParseNode *pn)
{
return !sc->bindingsAccessedDynamically() && pn->isDefn() && pn->isClosed();
}
bool
BytecodeEmitter::noteClosedVar(ParseNode *pn)
{
#ifdef DEBUG
JS_ASSERT(shouldNoteClosedName(pn));
Definition *dn = (Definition *)pn;
JS_ASSERT(dn->kind() == Definition::VAR || dn->kind() == Definition::CONST ||
dn->kind() == Definition::FUNCTION);
JS_ASSERT(pn->pn_cookie.slot() < sc->bindings.numVars());
for (size_t i = 0; i < closedVars.length(); ++i)
JS_ASSERT(closedVars[i] != pn->pn_cookie.slot());
#endif
sc->setFunIsHeavyweight();
return closedVars.append(pn->pn_cookie.slot());
}
bool
BytecodeEmitter::noteClosedArg(ParseNode *pn)
{
#ifdef DEBUG
JS_ASSERT(shouldNoteClosedName(pn));
Definition *dn = (Definition *)pn;
JS_ASSERT(dn->kind() == Definition::ARG);
JS_ASSERT(pn->pn_cookie.slot() < sc->bindings.numArgs());
for (size_t i = 0; i < closedArgs.length(); ++i)
JS_ASSERT(closedArgs[i] != pn->pn_cookie.slot());
#endif
sc->setFunIsHeavyweight();
return closedArgs.append(pn->pn_cookie.slot());
}
/*
* Adjust the slot for a block local to account for the number of variables
* that share the same index space with locals. Due to the incremental code
* generation for top-level script, we do the adjustment via code patching in
* js::frontend::CompileScript; see comments there.
*
* The function returns -1 on failures.
*/
static int
AdjustBlockSlot(JSContext *cx, BytecodeEmitter *bce, int slot)
{
JS_ASSERT((unsigned) slot < bce->maxStackDepth);