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7744 lines (6990 loc) · 262 KB
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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:
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Communicator client code, released
* March 31, 1998.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* JS bytecode generation.
*/
#ifdef HAVE_MEMORY_H
#include <memory.h>
#endif
#include <new>
#include <string.h>
#include "jstypes.h"
#include "jsstdint.h"
#include "jsarena.h"
#include "jsutil.h"
#include "jsbit.h"
#include "jsprf.h"
#include "jsapi.h"
#include "jsatom.h"
#include "jsbool.h"
#include "jscntxt.h"
#include "jsversion.h"
#include "jsemit.h"
#include "jsfun.h"
#include "jsnum.h"
#include "jsopcode.h"
#include "jsparse.h"
#include "jsregexp.h"
#include "jsscan.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jsautooplen.h" // generated headers last
#include "jsstaticcheck.h"
#include "jsatominlines.h"
#include "jsobjinlines.h"
#include "jsscopeinlines.h"
#include "jsscriptinlines.h"
/* Allocation chunk counts, must be powers of two in general. */
#define BYTECODE_CHUNK 256 /* code allocation increment */
#define SRCNOTE_CHUNK 64 /* initial srcnote allocation increment */
#define TRYNOTE_CHUNK 64 /* trynote allocation increment */
/* Macros to compute byte sizes from typed element counts. */
#define BYTECODE_SIZE(n) ((n) * sizeof(jsbytecode))
#define SRCNOTE_SIZE(n) ((n) * sizeof(jssrcnote))
#define TRYNOTE_SIZE(n) ((n) * sizeof(JSTryNote))
using namespace js;
using namespace js::gc;
static JSBool
NewTryNote(JSContext *cx, JSCodeGenerator *cg, JSTryNoteKind kind,
uintN stackDepth, size_t start, size_t end);
static JSBool
EmitIndexOp(JSContext *cx, JSOp op, uintN index, JSCodeGenerator *cg);
static JSBool
EmitLeaveBlock(JSContext *cx, JSCodeGenerator *cg, JSOp op, JSObjectBox *box);
void
JSTreeContext::trace(JSTracer *trc)
{
bindings.trace(trc);
}
JSCodeGenerator::JSCodeGenerator(Parser *parser,
JSArenaPool *cpool, JSArenaPool *npool,
uintN lineno)
: JSTreeContext(parser),
codePool(cpool), notePool(npool),
codeMark(JS_ARENA_MARK(cpool)), noteMark(JS_ARENA_MARK(npool)),
stackDepth(0), maxStackDepth(0),
ntrynotes(0), lastTryNode(NULL),
spanDeps(NULL), jumpTargets(NULL), jtFreeList(NULL),
numSpanDeps(0), numJumpTargets(0), spanDepTodo(0),
arrayCompDepth(0),
emitLevel(0),
constMap(parser->context),
constList(parser->context),
globalUses(ContextAllocPolicy(parser->context)),
closedArgs(ContextAllocPolicy(parser->context)),
closedVars(ContextAllocPolicy(parser->context)),
traceIndex(0)
{
flags = TCF_COMPILING;
memset(&prolog, 0, sizeof prolog);
memset(&main, 0, sizeof main);
current = &main;
firstLine = prolog.currentLine = main.currentLine = lineno;
prolog.noteMask = main.noteMask = SRCNOTE_CHUNK - 1;
memset(&upvarMap, 0, sizeof upvarMap);
}
bool JSCodeGenerator::init()
{
return constMap.init();
}
JSCodeGenerator::~JSCodeGenerator()
{
JS_ARENA_RELEASE(codePool, codeMark);
JS_ARENA_RELEASE(notePool, noteMark);
/* NB: non-null only after OOM. */
if (spanDeps)
parser->context->free(spanDeps);
if (upvarMap.vector)
parser->context->free(upvarMap.vector);
}
static ptrdiff_t
EmitCheck(JSContext *cx, JSCodeGenerator *cg, JSOp op, ptrdiff_t delta)
{
jsbytecode *base, *limit, *next;
ptrdiff_t offset, length;
size_t incr, size;
base = CG_BASE(cg);
next = CG_NEXT(cg);
limit = CG_LIMIT(cg);
offset = next - base;
if (next + delta > limit) {
length = offset + delta;
length = (length <= BYTECODE_CHUNK)
? BYTECODE_CHUNK
: JS_BIT(JS_CeilingLog2(length));
incr = BYTECODE_SIZE(length);
if (!base) {
JS_ARENA_ALLOCATE_CAST(base, jsbytecode *, cg->codePool, incr);
} else {
size = BYTECODE_SIZE(limit - base);
incr -= size;
JS_ARENA_GROW_CAST(base, jsbytecode *, cg->codePool, size, incr);
}
if (!base) {
js_ReportOutOfScriptQuota(cx);
return -1;
}
CG_BASE(cg) = base;
CG_LIMIT(cg) = base + length;
CG_NEXT(cg) = base + offset;
}
return offset;
}
static void
UpdateDepth(JSContext *cx, JSCodeGenerator *cg, ptrdiff_t target)
{
jsbytecode *pc;
JSOp op;
const JSCodeSpec *cs;
uintN extra, depth, nuses;
intN ndefs;
pc = CG_CODE(cg, target);
op = (JSOp) *pc;
cs = &js_CodeSpec[op];
#ifdef JS_TRACER
extern uint8 js_opcode2extra[];
extra = js_opcode2extra[op];
#else
extra = 0;
#endif
if ((cs->format & JOF_TMPSLOT_MASK) || extra) {
depth = (uintN) cg->stackDepth +
((cs->format & JOF_TMPSLOT_MASK) >> JOF_TMPSLOT_SHIFT) +
extra;
/* :TODO: hack - remove later. */
switch (op) {
case JSOP_PROPINC:
case JSOP_PROPDEC:
depth += 1;
break;
case JSOP_NAMEINC:
case JSOP_NAMEDEC:
case JSOP_INCNAME:
case JSOP_DECNAME:
case JSOP_GNAMEINC:
case JSOP_GNAMEDEC:
case JSOP_INCGNAME:
case JSOP_DECGNAME:
depth += 2;
break;
default:
break;
}
if (depth > cg->maxStackDepth)
cg->maxStackDepth = depth;
}
nuses = js_GetStackUses(cs, op, pc);
cg->stackDepth -= nuses;
JS_ASSERT(cg->stackDepth >= 0);
if (cg->stackDepth < 0) {
char numBuf[12];
TokenStream *ts;
JS_snprintf(numBuf, sizeof numBuf, "%d", target);
ts = &cg->parser->tokenStream;
JS_ReportErrorFlagsAndNumber(cx, JSREPORT_WARNING,
js_GetErrorMessage, NULL,
JSMSG_STACK_UNDERFLOW,
ts->getFilename() ? ts->getFilename() : "stdin",
numBuf);
}
ndefs = cs->ndefs;
if (ndefs < 0) {
JSObject *blockObj;
/* We just executed IndexParsedObject */
JS_ASSERT(op == JSOP_ENTERBLOCK);
JS_ASSERT(nuses == 0);
blockObj = cg->objectList.lastbox->object;
JS_ASSERT(blockObj->isStaticBlock());
JS_ASSERT(blockObj->getSlot(JSSLOT_BLOCK_DEPTH).isUndefined());
OBJ_SET_BLOCK_DEPTH(cx, blockObj, cg->stackDepth);
ndefs = OBJ_BLOCK_COUNT(cx, blockObj);
}
cg->stackDepth += ndefs;
if ((uintN)cg->stackDepth > cg->maxStackDepth)
cg->maxStackDepth = cg->stackDepth;
}
ptrdiff_t
js_Emit1(JSContext *cx, JSCodeGenerator *cg, JSOp op)
{
ptrdiff_t offset = EmitCheck(cx, cg, op, 1);
if (offset >= 0) {
*CG_NEXT(cg)++ = (jsbytecode)op;
UpdateDepth(cx, cg, offset);
}
return offset;
}
ptrdiff_t
js_Emit2(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1)
{
ptrdiff_t offset = EmitCheck(cx, cg, op, 2);
if (offset >= 0) {
jsbytecode *next = CG_NEXT(cg);
next[0] = (jsbytecode)op;
next[1] = op1;
CG_NEXT(cg) = next + 2;
UpdateDepth(cx, cg, offset);
}
return offset;
}
ptrdiff_t
js_Emit3(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1,
jsbytecode op2)
{
ptrdiff_t offset = EmitCheck(cx, cg, op, 3);
if (offset >= 0) {
jsbytecode *next = CG_NEXT(cg);
next[0] = (jsbytecode)op;
next[1] = op1;
next[2] = op2;
CG_NEXT(cg) = next + 3;
UpdateDepth(cx, cg, offset);
}
return offset;
}
ptrdiff_t
js_Emit5(JSContext *cx, JSCodeGenerator *cg, JSOp op, uint16 op1, uint16 op2)
{
ptrdiff_t offset = EmitCheck(cx, cg, op, 5);
if (offset >= 0) {
jsbytecode *next = CG_NEXT(cg);
next[0] = (jsbytecode)op;
next[1] = UINT16_HI(op1);
next[2] = UINT16_LO(op1);
next[3] = UINT16_HI(op2);
next[4] = UINT16_LO(op2);
CG_NEXT(cg) = next + 5;
UpdateDepth(cx, cg, offset);
}
return offset;
}
ptrdiff_t
js_EmitN(JSContext *cx, JSCodeGenerator *cg, JSOp op, size_t extra)
{
ptrdiff_t length = 1 + (ptrdiff_t)extra;
ptrdiff_t offset = EmitCheck(cx, cg, op, length);
if (offset >= 0) {
jsbytecode *next = CG_NEXT(cg);
*next = (jsbytecode)op;
memset(next + 1, 0, BYTECODE_SIZE(extra));
CG_NEXT(cg) = 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, cg, 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(JSCodeGenerator *cg)
{
if (!cg->topStmt)
return js_script_str;
return statementName[cg->topStmt->type];
}
static void
ReportStatementTooLarge(JSContext *cx, JSCodeGenerator *cg)
{
JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_NEED_DIET,
StatementName(cg));
}
/**
Span-dependent instructions in JS bytecode consist of the jump (JOF_JUMP)
and switch (JOF_LOOKUPSWITCH, JOF_TABLESWITCH) format opcodes, subdivided
into unconditional (gotos and gosubs), and conditional jumps or branches
(which pop a value, test it, and jump depending on its value). Most jumps
have just one immediate operand, a signed offset from the jump opcode's pc
to the target bytecode. The lookup and table switch opcodes may contain
many jump offsets.
Mozilla bug #80981 (http://bugzilla.mozilla.org/show_bug.cgi?id=80981) was
fixed by adding extended "X" counterparts to the opcodes/formats (NB: X is
suffixed to prefer JSOP_ORX thereby avoiding a JSOP_XOR name collision for
the extended form of the JSOP_OR branch opcode). The unextended or short
formats have 16-bit signed immediate offset operands, the extended or long
formats have 32-bit signed immediates. The span-dependency problem consists
of selecting as few long instructions as possible, or about as few -- since
jumps can span other jumps, extending one jump may cause another to need to
be extended.
Most JS scripts are short, so need no extended jumps. We optimize for this
case by generating short jumps until we know a long jump is needed. After
that point, we keep generating short jumps, but each jump's 16-bit immediate
offset operand is actually an unsigned index into cg->spanDeps, an array of
JSSpanDep structs. Each struct tells the top offset in the script of the
opcode, the "before" offset of the jump (which will be the same as top for
simplex jumps, but which will index further into the bytecode array for a
non-initial jump offset in a lookup or table switch), the after "offset"
adjusted during span-dependent instruction selection (initially the same
value as the "before" offset), and the jump target (more below).
Since we generate cg->spanDeps lazily, from within js_SetJumpOffset, we must
ensure that all bytecode generated so far can be inspected to discover where
the jump offset immediate operands lie within CG_CODE(cg). But the bonus is
that we generate span-dependency records sorted by their offsets, so we can
binary-search when trying to find a JSSpanDep for a given bytecode offset,
or the nearest JSSpanDep at or above a given pc.
To avoid limiting scripts to 64K jumps, if the cg->spanDeps index overflows
65534, we store SPANDEP_INDEX_HUGE in the jump's immediate operand. This
tells us that we need to binary-search for the cg->spanDeps entry by the
jump opcode's bytecode offset (sd->before).
Jump targets need to be maintained in a data structure that lets us look
up an already-known target by its address (jumps may have a common target),
and that also lets us update the addresses (script-relative, a.k.a. absolute
offsets) of targets that come after a jump target (for when a jump below
that target needs to be extended). We use an AVL tree, implemented using
recursion, but with some tricky optimizations to its height-balancing code
(see http://www.cmcrossroads.com/bradapp/ftp/src/libs/C++/AvlTrees.html).
A final wrinkle: backpatch chains are linked by jump-to-jump offsets with
positive sign, even though they link "backward" (i.e., toward lower bytecode
address). We don't want to waste space and search time in the AVL tree for
such temporary backpatch deltas, so we use a single-bit wildcard scheme to
tag true JSJumpTarget pointers and encode untagged, signed (positive) deltas
in JSSpanDep.target pointers, depending on whether the JSSpanDep has a known
target, or is still awaiting backpatching.
Note that backpatch chains would present a problem for BuildSpanDepTable,
which inspects bytecode to build cg->spanDeps on demand, when the first
short jump offset overflows. To solve this temporary problem, we emit a
proxy bytecode (JSOP_BACKPATCH; JSOP_BACKPATCH_POP for branch ops) whose
nuses/ndefs counts help keep the stack balanced, but whose opcode format
distinguishes its backpatch delta immediate operand from a normal jump
offset.
*/
static int
BalanceJumpTargets(JSJumpTarget **jtp)
{
JSJumpTarget *jt, *jt2, *root;
int dir, otherDir, heightChanged;
JSBool doubleRotate;
jt = *jtp;
JS_ASSERT(jt->balance != 0);
if (jt->balance < -1) {
dir = JT_RIGHT;
doubleRotate = (jt->kids[JT_LEFT]->balance > 0);
} else if (jt->balance > 1) {
dir = JT_LEFT;
doubleRotate = (jt->kids[JT_RIGHT]->balance < 0);
} else {
return 0;
}
otherDir = JT_OTHER_DIR(dir);
if (doubleRotate) {
jt2 = jt->kids[otherDir];
*jtp = root = jt2->kids[dir];
jt->kids[otherDir] = root->kids[dir];
root->kids[dir] = jt;
jt2->kids[dir] = root->kids[otherDir];
root->kids[otherDir] = jt2;
heightChanged = 1;
root->kids[JT_LEFT]->balance = -JS_MAX(root->balance, 0);
root->kids[JT_RIGHT]->balance = -JS_MIN(root->balance, 0);
root->balance = 0;
} else {
*jtp = root = jt->kids[otherDir];
jt->kids[otherDir] = root->kids[dir];
root->kids[dir] = jt;
heightChanged = (root->balance != 0);
jt->balance = -((dir == JT_LEFT) ? --root->balance : ++root->balance);
}
return heightChanged;
}
typedef struct AddJumpTargetArgs {
JSContext *cx;
JSCodeGenerator *cg;
ptrdiff_t offset;
JSJumpTarget *node;
} AddJumpTargetArgs;
static int
AddJumpTarget(AddJumpTargetArgs *args, JSJumpTarget **jtp)
{
JSJumpTarget *jt;
int balanceDelta;
jt = *jtp;
if (!jt) {
JSCodeGenerator *cg = args->cg;
jt = cg->jtFreeList;
if (jt) {
cg->jtFreeList = jt->kids[JT_LEFT];
} else {
JS_ARENA_ALLOCATE_CAST(jt, JSJumpTarget *, &args->cx->tempPool,
sizeof *jt);
if (!jt) {
js_ReportOutOfScriptQuota(args->cx);
return 0;
}
}
jt->offset = args->offset;
jt->balance = 0;
jt->kids[JT_LEFT] = jt->kids[JT_RIGHT] = NULL;
cg->numJumpTargets++;
args->node = jt;
*jtp = jt;
return 1;
}
if (jt->offset == args->offset) {
args->node = jt;
return 0;
}
if (args->offset < jt->offset)
balanceDelta = -AddJumpTarget(args, &jt->kids[JT_LEFT]);
else
balanceDelta = AddJumpTarget(args, &jt->kids[JT_RIGHT]);
if (!args->node)
return 0;
jt->balance += balanceDelta;
return (balanceDelta && jt->balance)
? 1 - BalanceJumpTargets(jtp)
: 0;
}
#ifdef DEBUG_brendan
static int AVLCheck(JSJumpTarget *jt)
{
int lh, rh;
if (!jt) return 0;
JS_ASSERT(-1 <= jt->balance && jt->balance <= 1);
lh = AVLCheck(jt->kids[JT_LEFT]);
rh = AVLCheck(jt->kids[JT_RIGHT]);
JS_ASSERT(jt->balance == rh - lh);
return 1 + JS_MAX(lh, rh);
}
#endif
static JSBool
SetSpanDepTarget(JSContext *cx, JSCodeGenerator *cg, JSSpanDep *sd,
ptrdiff_t off)
{
AddJumpTargetArgs args;
if (off < JUMPX_OFFSET_MIN || JUMPX_OFFSET_MAX < off) {
ReportStatementTooLarge(cx, cg);
return JS_FALSE;
}
args.cx = cx;
args.cg = cg;
args.offset = sd->top + off;
args.node = NULL;
AddJumpTarget(&args, &cg->jumpTargets);
if (!args.node)
return JS_FALSE;
#ifdef DEBUG_brendan
AVLCheck(cg->jumpTargets);
#endif
SD_SET_TARGET(sd, args.node);
return JS_TRUE;
}
#define SPANDEPS_MIN 256
#define SPANDEPS_SIZE(n) ((n) * sizeof(JSSpanDep))
#define SPANDEPS_SIZE_MIN SPANDEPS_SIZE(SPANDEPS_MIN)
static JSBool
AddSpanDep(JSContext *cx, JSCodeGenerator *cg, jsbytecode *pc, jsbytecode *pc2,
ptrdiff_t off)
{
uintN index;
JSSpanDep *sdbase, *sd;
size_t size;
index = cg->numSpanDeps;
if (index + 1 == 0) {
ReportStatementTooLarge(cx, cg);
return JS_FALSE;
}
if ((index & (index - 1)) == 0 &&
(!(sdbase = cg->spanDeps) || index >= SPANDEPS_MIN)) {
size = sdbase ? SPANDEPS_SIZE(index) : SPANDEPS_SIZE_MIN / 2;
sdbase = (JSSpanDep *) cx->realloc(sdbase, size + size);
if (!sdbase)
return JS_FALSE;
cg->spanDeps = sdbase;
}
cg->numSpanDeps = index + 1;
sd = cg->spanDeps + index;
sd->top = pc - CG_BASE(cg);
sd->offset = sd->before = pc2 - CG_BASE(cg);
if (js_CodeSpec[*pc].format & JOF_BACKPATCH) {
/* Jump offset will be backpatched if off is a non-zero "bpdelta". */
if (off != 0) {
JS_ASSERT(off >= 1 + JUMP_OFFSET_LEN);
if (off > BPDELTA_MAX) {
ReportStatementTooLarge(cx, cg);
return JS_FALSE;
}
}
SD_SET_BPDELTA(sd, off);
} else if (off == 0) {
/* Jump offset will be patched directly, without backpatch chaining. */
SD_SET_TARGET(sd, 0);
} else {
/* The jump offset in off is non-zero, therefore it's already known. */
if (!SetSpanDepTarget(cx, cg, sd, off))
return JS_FALSE;
}
if (index > SPANDEP_INDEX_MAX)
index = SPANDEP_INDEX_HUGE;
SET_SPANDEP_INDEX(pc2, index);
return JS_TRUE;
}
static jsbytecode *
AddSwitchSpanDeps(JSContext *cx, JSCodeGenerator *cg, jsbytecode *pc)
{
JSOp op;
jsbytecode *pc2;
ptrdiff_t off;
jsint low, high;
uintN njumps, indexlen;
op = (JSOp) *pc;
JS_ASSERT(op == JSOP_TABLESWITCH || op == JSOP_LOOKUPSWITCH);
pc2 = pc;
off = GET_JUMP_OFFSET(pc2);
if (!AddSpanDep(cx, cg, pc, pc2, off))
return NULL;
pc2 += JUMP_OFFSET_LEN;
if (op == JSOP_TABLESWITCH) {
low = GET_JUMP_OFFSET(pc2);
pc2 += JUMP_OFFSET_LEN;
high = GET_JUMP_OFFSET(pc2);
pc2 += JUMP_OFFSET_LEN;
njumps = (uintN) (high - low + 1);
indexlen = 0;
} else {
njumps = GET_UINT16(pc2);
pc2 += UINT16_LEN;
indexlen = INDEX_LEN;
}
while (njumps) {
--njumps;
pc2 += indexlen;
off = GET_JUMP_OFFSET(pc2);
if (!AddSpanDep(cx, cg, pc, pc2, off))
return NULL;
pc2 += JUMP_OFFSET_LEN;
}
return 1 + pc2;
}
static JSBool
BuildSpanDepTable(JSContext *cx, JSCodeGenerator *cg)
{
jsbytecode *pc, *end;
JSOp op;
const JSCodeSpec *cs;
ptrdiff_t off;
pc = CG_BASE(cg) + cg->spanDepTodo;
end = CG_NEXT(cg);
while (pc != end) {
JS_ASSERT(pc < end);
op = (JSOp)*pc;
cs = &js_CodeSpec[op];
switch (JOF_TYPE(cs->format)) {
case JOF_TABLESWITCH:
case JOF_LOOKUPSWITCH:
pc = AddSwitchSpanDeps(cx, cg, pc);
if (!pc)
return JS_FALSE;
break;
case JOF_JUMP:
off = GET_JUMP_OFFSET(pc);
if (!AddSpanDep(cx, cg, pc, pc, off))
return JS_FALSE;
/* FALL THROUGH */
default:
pc += cs->length;
break;
}
}
return JS_TRUE;
}
static JSSpanDep *
GetSpanDep(JSCodeGenerator *cg, jsbytecode *pc)
{
uintN index;
ptrdiff_t offset;
int lo, hi, mid;
JSSpanDep *sd;
index = GET_SPANDEP_INDEX(pc);
if (index != SPANDEP_INDEX_HUGE)
return cg->spanDeps + index;
offset = pc - CG_BASE(cg);
lo = 0;
hi = cg->numSpanDeps - 1;
while (lo <= hi) {
mid = (lo + hi) / 2;
sd = cg->spanDeps + mid;
if (sd->before == offset)
return sd;
if (sd->before < offset)
lo = mid + 1;
else
hi = mid - 1;
}
JS_ASSERT(0);
return NULL;
}
static JSBool
SetBackPatchDelta(JSContext *cx, JSCodeGenerator *cg, jsbytecode *pc,
ptrdiff_t delta)
{
JSSpanDep *sd;
JS_ASSERT(delta >= 1 + JUMP_OFFSET_LEN);
if (!cg->spanDeps && delta < JUMP_OFFSET_MAX) {
SET_JUMP_OFFSET(pc, delta);
return JS_TRUE;
}
if (delta > BPDELTA_MAX) {
ReportStatementTooLarge(cx, cg);
return JS_FALSE;
}
if (!cg->spanDeps && !BuildSpanDepTable(cx, cg))
return JS_FALSE;
sd = GetSpanDep(cg, pc);
JS_ASSERT(SD_GET_BPDELTA(sd) == 0);
SD_SET_BPDELTA(sd, delta);
return JS_TRUE;
}
static void
UpdateJumpTargets(JSJumpTarget *jt, ptrdiff_t pivot, ptrdiff_t delta)
{
if (jt->offset > pivot) {
jt->offset += delta;
if (jt->kids[JT_LEFT])
UpdateJumpTargets(jt->kids[JT_LEFT], pivot, delta);
}
if (jt->kids[JT_RIGHT])
UpdateJumpTargets(jt->kids[JT_RIGHT], pivot, delta);
}
static JSSpanDep *
FindNearestSpanDep(JSCodeGenerator *cg, ptrdiff_t offset, int lo,
JSSpanDep *guard)
{
int num, hi, mid;
JSSpanDep *sdbase, *sd;
num = cg->numSpanDeps;
JS_ASSERT(num > 0);
hi = num - 1;
sdbase = cg->spanDeps;
while (lo <= hi) {
mid = (lo + hi) / 2;
sd = sdbase + mid;
if (sd->before == offset)
return sd;
if (sd->before < offset)
lo = mid + 1;
else
hi = mid - 1;
}
if (lo == num)
return guard;
sd = sdbase + lo;
JS_ASSERT(sd->before >= offset && (lo == 0 || sd[-1].before < offset));
return sd;
}
static void
FreeJumpTargets(JSCodeGenerator *cg, JSJumpTarget *jt)
{
if (jt->kids[JT_LEFT])
FreeJumpTargets(cg, jt->kids[JT_LEFT]);
if (jt->kids[JT_RIGHT])
FreeJumpTargets(cg, jt->kids[JT_RIGHT]);
jt->kids[JT_LEFT] = cg->jtFreeList;
cg->jtFreeList = jt;
}
static JSBool
OptimizeSpanDeps(JSContext *cx, JSCodeGenerator *cg)
{
jsbytecode *pc, *oldpc, *base, *limit, *next;
JSSpanDep *sd, *sd2, *sdbase, *sdlimit, *sdtop, guard;
ptrdiff_t offset, growth, delta, top, pivot, span, length, target;
JSBool done;
JSOp op;
uint32 type;
size_t size, incr;
jssrcnote *sn, *snlimit;
JSSrcNoteSpec *spec;
uintN i, n, noteIndex;
JSTryNode *tryNode;
#ifdef DEBUG_brendan
int passes = 0;
#endif
base = CG_BASE(cg);
sdbase = cg->spanDeps;
sdlimit = sdbase + cg->numSpanDeps;
offset = CG_OFFSET(cg);
growth = 0;
do {
done = JS_TRUE;
delta = 0;
top = pivot = -1;
sdtop = NULL;
pc = NULL;
op = JSOP_NOP;
type = 0;
#ifdef DEBUG_brendan
passes++;
#endif
for (sd = sdbase; sd < sdlimit; sd++) {
JS_ASSERT(JT_HAS_TAG(sd->target));
sd->offset += delta;
if (sd->top != top) {
sdtop = sd;
top = sd->top;
JS_ASSERT(top == sd->before);
pivot = sd->offset;
pc = base + top;
op = (JSOp) *pc;
type = JOF_OPTYPE(op);
if (JOF_TYPE_IS_EXTENDED_JUMP(type)) {
/*
* We already extended all the jump offset operands for
* the opcode at sd->top. Jumps and branches have only
* one jump offset operand, but switches have many, all
* of which are adjacent in cg->spanDeps.
*/
continue;
}
JS_ASSERT(type == JOF_JUMP ||
type == JOF_TABLESWITCH ||
type == JOF_LOOKUPSWITCH);
}
if (!JOF_TYPE_IS_EXTENDED_JUMP(type)) {
span = SD_SPAN(sd, pivot);
if (span < JUMP_OFFSET_MIN || JUMP_OFFSET_MAX < span) {
ptrdiff_t deltaFromTop = 0;
done = JS_FALSE;
switch (op) {
case JSOP_GOTO: op = JSOP_GOTOX; break;
case JSOP_IFEQ: op = JSOP_IFEQX; break;
case JSOP_IFNE: op = JSOP_IFNEX; break;
case JSOP_OR: op = JSOP_ORX; break;
case JSOP_AND: op = JSOP_ANDX; break;
case JSOP_GOSUB: op = JSOP_GOSUBX; break;
case JSOP_CASE: op = JSOP_CASEX; break;
case JSOP_DEFAULT: op = JSOP_DEFAULTX; break;
case JSOP_TABLESWITCH: op = JSOP_TABLESWITCHX; break;
case JSOP_LOOKUPSWITCH: op = JSOP_LOOKUPSWITCHX; break;
default:
ReportStatementTooLarge(cx, cg);
return JS_FALSE;
}
*pc = (jsbytecode) op;
for (sd2 = sdtop; sd2 < sdlimit && sd2->top == top; sd2++) {
if (sd2 <= sd) {
/*
* sd2->offset already includes delta as it stood
* before we entered this loop, but it must also
* include the delta relative to top due to all the
* extended jump offset immediates for the opcode
* starting at top, which we extend in this loop.
*
* If there is only one extended jump offset, then
* sd2->offset won't change and this for loop will
* iterate once only.
*/
sd2->offset += deltaFromTop;
deltaFromTop += JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN;
} else {
/*
* sd2 comes after sd, and won't be revisited by
* the outer for loop, so we have to increase its
* offset by delta, not merely by deltaFromTop.
*/
sd2->offset += delta;
}
delta += JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN;
UpdateJumpTargets(cg->jumpTargets, sd2->offset,
JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN);
}
sd = sd2 - 1;
}
}
}
growth += delta;
} while (!done);
if (growth) {
#ifdef DEBUG_brendan
TokenStream *ts = &cg->parser->tokenStream;
printf("%s:%u: %u/%u jumps extended in %d passes (%d=%d+%d)\n",
ts->filename ? ts->filename : "stdin", cg->firstLine,
growth / (JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN), cg->numSpanDeps,
passes, offset + growth, offset, growth);
#endif
/*
* Ensure that we have room for the extended jumps, but don't round up
* to a power of two -- we're done generating code, so we cut to fit.
*/
limit = CG_LIMIT(cg);
length = offset + growth;
next = base + length;
if (next > limit) {
JS_ASSERT(length > BYTECODE_CHUNK);
size = BYTECODE_SIZE(limit - base);
incr = BYTECODE_SIZE(length) - size;
JS_ARENA_GROW_CAST(base, jsbytecode *, cg->codePool, size, incr);
if (!base) {
js_ReportOutOfScriptQuota(cx);
return JS_FALSE;
}
CG_BASE(cg) = base;
CG_LIMIT(cg) = next = base + length;
}
CG_NEXT(cg) = next;
/*
* Set up a fake span dependency record to guard the end of the code
* being generated. This guard record is returned as a fencepost by
* FindNearestSpanDep if there is no real spandep at or above a given
* unextended code offset.
*/
guard.top = -1;
guard.offset = offset + growth;