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Bug 1448089 - Make MBasicBlock::addPredecessorSameInputsAs fallible. r=tcampbell

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This commit is contained in:
Nicolas B. Pierron 2018-04-19 07:32:00 -04:00
parent d452b92931
commit 2d9966df5c
3 changed files with 39 additions and 21 deletions
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51
js/src/jit/IonAnalysis.cpp
View File

@ -714,7 +714,7 @@ BlockIsSingleTest(MBasicBlock* phiBlock, MBasicBlock* testBlock, MPhi** pphi, MT
// Change block so that it ends in a goto to the specific target block.
// existingPred is an existing predecessor of the block.
static void
static MOZ_MUST_USE bool
UpdateGotoSuccessor(TempAllocator& alloc, MBasicBlock* block, MBasicBlock* target,
MBasicBlock* existingPred)
{
@ -726,7 +726,7 @@ UpdateGotoSuccessor(TempAllocator& alloc, MBasicBlock* block, MBasicBlock* targe
MGoto* newGoto = MGoto::New(alloc, target);
block->end(newGoto);
target->addPredecessorSameInputsAs(block, existingPred);
return target->addPredecessorSameInputsAs(block, existingPred);
}
// Change block so that it ends in a test of the specified value, going to
@ -734,7 +734,7 @@ UpdateGotoSuccessor(TempAllocator& alloc, MBasicBlock* block, MBasicBlock* targe
// or ifFalse with the same values incoming to ifTrue/ifFalse as block.
// existingPred is not required to be a predecessor of ifTrue/ifFalse if block
// already ends in a test going to that block on a true/false result.
static void
static MOZ_MUST_USE bool
UpdateTestSuccessors(TempAllocator& alloc, MBasicBlock* block,
MDefinition* value, MBasicBlock* ifTrue, MBasicBlock* ifFalse,
MBasicBlock* existingPred)
@ -746,19 +746,21 @@ UpdateTestSuccessors(TempAllocator& alloc, MBasicBlock* block,
if (ifTrue != test->ifTrue()) {
test->ifTrue()->removePredecessor(block);
ifTrue->addPredecessorSameInputsAs(block, existingPred);
if (!ifTrue->addPredecessorSameInputsAs(block, existingPred))
return false;
MOZ_ASSERT(test->ifTrue() == test->getSuccessor(0));
test->replaceSuccessor(0, ifTrue);
}
if (ifFalse != test->ifFalse()) {
test->ifFalse()->removePredecessor(block);
ifFalse->addPredecessorSameInputsAs(block, existingPred);
if (!ifFalse->addPredecessorSameInputsAs(block, existingPred))
return false;
MOZ_ASSERT(test->ifFalse() == test->getSuccessor(1));
test->replaceSuccessor(1, ifFalse);
}
return;
return true;
}
MOZ_ASSERT(ins->isGoto());
@ -768,8 +770,11 @@ UpdateTestSuccessors(TempAllocator& alloc, MBasicBlock* block,
MTest* test = MTest::New(alloc, value, ifTrue, ifFalse);
block->end(test);
ifTrue->addPredecessorSameInputsAs(block, existingPred);
ifFalse->addPredecessorSameInputsAs(block, existingPred);
if (!ifTrue->addPredecessorSameInputsAs(block, existingPred))
return false;
if (!ifFalse->addPredecessorSameInputsAs(block, existingPred))
return false;
return true;
}
static bool
@ -874,10 +879,14 @@ MaybeFoldConditionBlock(MIRGraph& graph, MBasicBlock* initialBlock)
phiBlock->removePredecessor(trueBranch);
graph.removeBlock(trueBranch);
} else if (initialTest->input() == trueResult) {
UpdateGotoSuccessor(graph.alloc(), trueBranch, finalTest->ifTrue(), testBlock);
if (!UpdateGotoSuccessor(graph.alloc(), trueBranch, finalTest->ifTrue(), testBlock))
return false;
} else {
UpdateTestSuccessors(graph.alloc(), trueBranch, trueResult,
finalTest->ifTrue(), finalTest->ifFalse(), testBlock);
if (!UpdateTestSuccessors(graph.alloc(), trueBranch, trueResult,
finalTest->ifTrue(), finalTest->ifFalse(), testBlock))
{
return false;
}
}
MBasicBlock* falseTarget = falseBranch;
@ -886,15 +895,22 @@ MaybeFoldConditionBlock(MIRGraph& graph, MBasicBlock* initialBlock)
phiBlock->removePredecessor(falseBranch);
graph.removeBlock(falseBranch);
} else if (initialTest->input() == falseResult) {
UpdateGotoSuccessor(graph.alloc(), falseBranch, finalTest->ifFalse(), testBlock);
if (!UpdateGotoSuccessor(graph.alloc(), falseBranch, finalTest->ifFalse(), testBlock))
return false;
} else {
UpdateTestSuccessors(graph.alloc(), falseBranch, falseResult,
finalTest->ifTrue(), finalTest->ifFalse(), testBlock);
if (!UpdateTestSuccessors(graph.alloc(), falseBranch, falseResult,
finalTest->ifTrue(), finalTest->ifFalse(), testBlock))
{
return false;
}
}
// Short circuit the initial test to skip any constant branch eliminated above.
UpdateTestSuccessors(graph.alloc(), initialBlock, initialTest->input(),
trueTarget, falseTarget, testBlock);
if (!UpdateTestSuccessors(graph.alloc(), initialBlock, initialTest->input(),
trueTarget, falseTarget, testBlock))
{
return false;
}
// Remove phiBlock, if different from testBlock.
if (phiBlock != testBlock) {
@ -950,7 +966,8 @@ jit::FoldEmptyBlocks(MIRGraph& graph)
graph.removeBlock(block);
succ->addPredecessorSameInputsAs(pred, block);
if (!succ->addPredecessorSameInputsAs(pred, block))
return false;
succ->removePredecessor(block);
}
return true;

7
js/src/jit/MIRGraph.cpp
View File

@ -1146,7 +1146,7 @@ MBasicBlock::addPredecessorPopN(TempAllocator& alloc, MBasicBlock* pred, uint32_
return predecessors_.append(pred);
}
void
bool
MBasicBlock::addPredecessorSameInputsAs(MBasicBlock* pred, MBasicBlock* existingPred)
{
MOZ_ASSERT(pred);
@ -1162,12 +1162,13 @@ MBasicBlock::addPredecessorSameInputsAs(MBasicBlock* pred, MBasicBlock* existing
size_t existingPosition = indexForPredecessor(existingPred);
for (MPhiIterator iter = phisBegin(); iter != phisEnd(); iter++) {
if (!iter->addInputSlow(iter->getOperand(existingPosition)))
oomUnsafe.crash("MBasicBlock::addPredecessorAdjustPhis");
return false;
}
}
if (!predecessors_.append(pred))
oomUnsafe.crash("MBasicBlock::addPredecessorAdjustPhis");
return false;
return true;
}
bool

2
js/src/jit/MIRGraph.h
View File

@ -272,7 +272,7 @@ class MBasicBlock : public TempObject, public InlineListNode<MBasicBlock>
// Add a predecessor which won't introduce any new phis to this block.
// This may be called after the contents of this block have been built.
void addPredecessorSameInputsAs(MBasicBlock* pred, MBasicBlock* existingPred);
MOZ_MUST_USE bool addPredecessorSameInputsAs(MBasicBlock* pred, MBasicBlock* existingPred);
// Stranger utilities used for inlining.
MOZ_MUST_USE bool addPredecessorWithoutPhis(MBasicBlock* pred);