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Bug 864587 - Avoid overflowing the stack on long if/else-if chains in asm.js (r=sstangl)

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--HG--
extra : rebase_source : af47319af567ac1d6a86e67f95c5ac6d332b1713
This commit is contained in:
Luke Wagner 2013-05-08 18:34:56 -07:00
parent 3f85da200c
commit 0f6871932f
2 changed files with 54 additions and 25 deletions
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76
js/src/ion/AsmJS.cpp
View File

@ -843,7 +843,7 @@ TypedArrayStoreType(ArrayBufferView::ViewType viewType)
/*****************************************************************************/
typedef Vector<PropertyName*,1> LabelVector;
typedef Vector<MBasicBlock*,16> CaseVector;
typedef Vector<MBasicBlock*,8> BlockVector;
// ModuleCompiler encapsulates the compilation of an entire asm.js module. Over
// the course of an ModuleCompiler object's lifetime, many FunctionCompiler
@ -1546,7 +1546,6 @@ class FunctionCompiler
typedef HashMap<PropertyName*, Local> LocalMap;
private:
typedef Vector<MBasicBlock*, 2> BlockVector;
typedef HashMap<PropertyName*, BlockVector> LabeledBlockMap;
typedef HashMap<ParseNode*, BlockVector> UnlabeledBlockMap;
typedef Vector<ParseNode*, 4> NodeStack;
@ -2019,42 +2018,48 @@ class FunctionCompiler
return true;
}
void joinIf(MBasicBlock *joinBlock)
bool appendThenBlock(BlockVector *thenBlocks) {
if (!curBlock_)
return true;
return thenBlocks->append(curBlock_);
}
void joinIf(const BlockVector &thenBlocks, MBasicBlock *joinBlock)
{
if (!joinBlock)
return;
if (curBlock_) {
curBlock_->end(MGoto::New(joinBlock));
joinBlock->addPredecessor(curBlock_);
JS_ASSERT_IF(curBlock_, thenBlocks.back() == curBlock_);
for (size_t i = 0; i < thenBlocks.length(); i++) {
thenBlocks[i]->end(MGoto::New(joinBlock));
joinBlock->addPredecessor(thenBlocks[i]);
}
curBlock_ = joinBlock;
mirGraph().moveBlockToEnd(curBlock_);
}
MBasicBlock *switchToElse(MBasicBlock *elseBlock)
void switchToElse(MBasicBlock *elseBlock)
{
if (!elseBlock)
return NULL;
MBasicBlock *thenEnd = curBlock_;
return;
curBlock_ = elseBlock;
mirGraph().moveBlockToEnd(curBlock_);
return thenEnd;
}
bool joinIfElse(MBasicBlock *thenEnd)
bool joinIfElse(const BlockVector &thenBlocks)
{
if (!curBlock_ && !thenEnd)
if (!curBlock_ && thenBlocks.empty())
return true;
MBasicBlock *pred = curBlock_ ? curBlock_ : thenEnd;
MBasicBlock *pred = curBlock_ ? curBlock_ : thenBlocks[0];
MBasicBlock *join;
if (!newBlock(pred, &join))
return false;
if (curBlock_)
curBlock_->end(MGoto::New(join));
if (thenEnd)
thenEnd->end(MGoto::New(join));
if (curBlock_ && thenEnd)
join->addPredecessor(thenEnd);
for (size_t i = 0; i < thenBlocks.length(); i++) {
thenBlocks[i]->end(MGoto::New(join));
if (pred == curBlock_ || i > 0)
join->addPredecessor(thenBlocks[i]);
}
curBlock_ = join;
return true;
}
@ -2244,7 +2249,7 @@ class FunctionCompiler
return true;
}
bool startSwitchDefault(MBasicBlock *switchBlock, CaseVector *cases, MBasicBlock **defaultBlock)
bool startSwitchDefault(MBasicBlock *switchBlock, BlockVector *cases, MBasicBlock **defaultBlock)
{
if (!startSwitchCase(switchBlock, defaultBlock))
return false;
@ -2264,7 +2269,7 @@ class FunctionCompiler
return true;
}
bool joinSwitch(MBasicBlock *switchBlock, const CaseVector &cases, MBasicBlock *defaultBlock)
bool joinSwitch(MBasicBlock *switchBlock, const BlockVector &cases, MBasicBlock *defaultBlock)
{
ParseNode *pn = breakableStack_.popCopy();
if (!switchBlock)
@ -3751,8 +3756,12 @@ CheckConditional(FunctionCompiler &f, ParseNode *ternary, MDefinition **def, Typ
if (!CheckExpr(f, thenExpr, Use::NoCoercion, &thenDef, &thenType))
return false;
BlockVector thenBlocks(f.cx());
if (!f.appendThenBlock(&thenBlocks))
return false;
f.pushPhiInput(thenDef);
MBasicBlock *thenEnd = f.switchToElse(elseBlock);
f.switchToElse(elseBlock);
MDefinition *elseDef;
Type elseType;
@ -3760,7 +3769,7 @@ CheckConditional(FunctionCompiler &f, ParseNode *ternary, MDefinition **def, Typ
return false;
f.pushPhiInput(elseDef);
if (!f.joinIfElse(thenEnd))
if (!f.joinIfElse(thenBlocks))
return false;
*def = f.popPhiOutput();
@ -4243,6 +4252,13 @@ CheckLabel(FunctionCompiler &f, ParseNode *labeledStmt, LabelVector *maybeLabels
static bool
CheckIf(FunctionCompiler &f, ParseNode *ifStmt)
{
// Handle if/else-if chains using iteration instead of recursion. This
// avoids blowing the C stack quota for long if/else-if chains and also
// creates fewer MBasicBlocks at join points (by creating one join block
// for the entire if/else-if chain).
BlockVector thenBlocks(f.cx());
recurse:
JS_ASSERT(ifStmt->isKind(PNK_IF));
ParseNode *cond = TernaryKid1(ifStmt);
ParseNode *thenStmt = TernaryKid2(ifStmt);
@ -4263,13 +4279,23 @@ CheckIf(FunctionCompiler &f, ParseNode *ifStmt)
if (!CheckStatement(f, thenStmt))
return false;
if (!f.appendThenBlock(&thenBlocks))
return false;
if (!elseStmt) {
f.joinIf(elseBlock);
f.joinIf(thenBlocks, elseBlock);
} else {
MBasicBlock *thenEnd = f.switchToElse(elseBlock);
f.switchToElse(elseBlock);
if (elseStmt->isKind(PNK_IF)) {
ifStmt = elseStmt;
goto recurse;
}
if (!CheckStatement(f, elseStmt))
return false;
if (!f.joinIfElse(thenEnd))
if (!f.joinIfElse(thenBlocks))
return false;
}
@ -4374,7 +4400,7 @@ CheckSwitch(FunctionCompiler &f, ParseNode *switchStmt)
if (!CheckSwitchRange(f, stmt, &low, &high, &tableLength))
return false;
CaseVector cases(f.cx());
BlockVector cases(f.cx());
if (!cases.resize(tableLength))
return false;

3
js/src/jit-test/tests/asm.js/testControlFlow.js
View File

@ -4,6 +4,9 @@ assertAsmTypeFail(USE_ASM + "function f(i,j) { i=i|0;j=+j; if (i) return j; retu
assertEq(asmLink(asmCompile(USE_ASM + "function f(i,j) { i=i|0;j=+j; if (i) return j; return +~~i } return f"))(1,1.4), 1.4);
assertAsmTypeFail(USE_ASM + "function f(i,j) { i=i|0;j=j|0; if (i) return j^0; return i^0 } return f");
assertEq(asmLink(asmCompile(USE_ASM + "function f(i,j) { i=i|0;j=j|0; if (i) return j^0; return i|0 } return f"))(1,8), 8);
assertEq(asmLink(asmCompile(USE_ASM + "function f(i) { i=i|0; if ((i|0) == 0) return 10; else if ((i|0) == 1) return 12; else if ((i|0) == 2) return 14; return 0} return f"))(2), 14);
assertEq(asmLink(asmCompile(USE_ASM + "function f(i) { i=i|0; if ((i|0) == 0) return 10; else if ((i|0) == 1) return 12; else if ((i|0) == 2) return 14; else return 16; return 0} return f"))(3), 16);
assertEq(asmLink(asmCompile(USE_ASM + "function f(i) { i=i|0; if ((i|0) == 0) i = 10; else if ((i|0) == 1) return 12; return (i|0) } return f"))(0), 10);
assertEq(asmLink(asmCompile(USE_ASM + "function f() { while (0) {} return 0} return f"))(), 0);
assertEq(asmLink(asmCompile(USE_ASM + "function f() { for (;0;) {} return 0} return f"))(), 0);