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[asan] don't unpoison redzones on function exit in use-after-return mode.

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Summary:
Before this change the instrumented code before Ret instructions looked like:
  <Unpoison Frame Redzones>
  if (Frame != OriginalFrame) // I.e. Frame is fake
     <Poison Complete Frame>

Now the instrumented code looks like:
  if (Frame != OriginalFrame) // I.e. Frame is fake
     <Poison Complete Frame>
  else
     <Unpoison Frame Redzones>

Reviewers: eugenis

Reviewed By: eugenis

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2458

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197907 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kostya Serebryany
2013-12-23 14:15:08 +00:00
parent 1fe014e5fc
commit 26f1d1cbbc
4 changed files with 120 additions and 15 deletions
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33
lib/Transforms/Utils/BasicBlockUtils.cpp
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@ -670,6 +670,39 @@ TerminatorInst *llvm::SplitBlockAndInsertIfThen(Value *Cond,
return CheckTerm;
}
/// SplitBlockAndInsertIfThenElse is similar to SplitBlockAndInsertIfThen,
/// but also creates the ElseBlock.
/// Before:
/// Head
/// SplitBefore
/// Tail
/// After:
/// Head
/// if (Cond)
/// ThenBlock
/// else
/// ElseBlock
/// SplitBefore
/// Tail
void llvm::SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
TerminatorInst **ThenTerm,
TerminatorInst **ElseTerm,
MDNode *BranchWeights) {
BasicBlock *Head = SplitBefore->getParent();
BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
TerminatorInst *HeadOldTerm = Head->getTerminator();
LLVMContext &C = Head->getContext();
BasicBlock *ThenBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
BasicBlock *ElseBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
*ThenTerm = BranchInst::Create(Tail, ThenBlock);
*ElseTerm = BranchInst::Create(Tail, ElseBlock);
BranchInst *HeadNewTerm =
BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/ElseBlock, Cond);
HeadNewTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
}
/// GetIfCondition - Given a basic block (BB) with two predecessors,
/// check to see if the merge at this block is due
/// to an "if condition". If so, return the boolean condition that determines