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Bug 766004 - Remove LookupCompileTimeConstant(). r=bhackett.

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--HG--
extra : rebase_source : 27e505a79158eb87fd38adf700bc21a666415733
This commit is contained in:
Nicholas Nethercote 2012-06-19 18:05:43 -07:00
parent 401cf770e8
commit 338d8ebabd
1 changed files with 3 additions and 138 deletions
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141
js/src/frontend/BytecodeEmitter.cpp
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@ -646,70 +646,6 @@ frontend::DefineCompileTimeConstant(JSContext *cx, BytecodeEmitter *bce, JSAtom
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->script->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->script->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)
{
@ -2122,7 +2058,7 @@ MOZ_NEVER_INLINE static JSBool
EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
{
JSOp switchOp;
JSBool ok, hasDefault, constPropagated;
JSBool ok, hasDefault;
ptrdiff_t top, off, defaultOffset;
ParseNode *pn2, *pn3, *pn4;
uint32_t caseCount, tableLength;
@ -2130,13 +2066,13 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
int32_t i, low, high;
int noteIndex;
size_t switchSize, tableSize;
jsbytecode *pc, *savepc;
jsbytecode *pc;
StmtInfo stmtInfo(cx);
/* Try for most optimal, fall back if not dense ints, and per ECMAv2. */
switchOp = JSOP_TABLESWITCH;
ok = JS_TRUE;
hasDefault = constPropagated = JS_FALSE;
hasDefault = JS_FALSE;
defaultOffset = -1;
pn2 = pn->pn_right;
@ -2239,32 +2175,6 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
constVal.setNull();
break;
case PNK_NAME:
if (!pn4->maybeExpr()) {
ok = LookupCompileTimeConstant(cx, bce, pn4->pn_atom, &constVal);
if (!ok)
goto release;
if (!constVal.isMagic(JS_NO_CONSTANT)) {
if (constVal.isObject()) {
/*
* XXX JSOP_LOOKUPSWITCH does not support const-
* propagated object values, see bug 407186.
*/
switchOp = JSOP_CONDSWITCH;
continue;
}
if (constVal.isString()) {
JSAtom *atom = js_AtomizeString(cx, constVal.toString());
if (!atom) {
ok = JS_FALSE;
goto release;
}
constVal.setString(atom);
}
constPropagated = JS_TRUE;
break;
}
}
/* FALL THROUGH */
default:
switchOp = JSOP_CONDSWITCH;
continue;
@ -2486,51 +2396,6 @@ EmitSwitch(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn)
* simple, all switchOp cases exit that way.
*/
MUST_FLOW_THROUGH("out");
if (constPropagated) {
/*
* Skip switchOp, as we are not setting jump offsets in the two
* for loops below. We'll restore bce->next() from savepc after,
* unless there was an error.
*/
savepc = bce->next();
bce->current->next = pc + 1;
if (switchOp == JSOP_TABLESWITCH) {
for (i = 0; i < (int)tableLength; i++) {
pn3 = table[i];
if (pn3 &&
(pn4 = pn3->pn_left) != NULL &&
pn4->isKind(PNK_NAME))
{
/* Note a propagated constant with the const's name. */
JS_ASSERT(!pn4->maybeExpr());
jsatomid index;
if (!bce->makeAtomIndex(pn4->pn_atom, &index))
goto bad;
bce->current->next = pc;
if (NewSrcNote2(cx, bce, SRC_LABEL, ptrdiff_t(index)) < 0)
goto bad;
}
pc += JUMP_OFFSET_LEN;
}
} else {
for (pn3 = pn2->pn_head; pn3; pn3 = pn3->pn_next) {
pn4 = pn3->pn_left;
if (pn4 && pn4->isKind(PNK_NAME)) {
/* Note a propagated constant with the const's name. */
JS_ASSERT(!pn4->maybeExpr());
jsatomid index;
if (!bce->makeAtomIndex(pn4->pn_atom, &index))
goto bad;
bce->current->next = pc;
if (NewSrcNote2(cx, bce, SRC_LABEL, ptrdiff_t(index)) < 0)
goto bad;
}
pc += UINT32_INDEX_LEN + JUMP_OFFSET_LEN;
}
}
bce->current->next = savepc;
}
}
/* Emit code for each case's statements, copying pn_offset up to pn3. */