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Indvars: Don't recursively delete instruction during BB iteration.

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This can invalidate the iterators leading to use after frees and crashes.
Fixes PR12536.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166291 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2012-10-19 17:53:54 +00:00
parent de7c37efe2
commit 7182126b0f
2 changed files with 23 additions and 3 deletions
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8
lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -551,15 +551,17 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter) {
PN->setIncomingValue(i, ExitVal);
// If this instruction is dead now, delete it.
RecursivelyDeleteTriviallyDeadInstructions(Inst, TLI);
// If this instruction is dead now, delete it. Don't do it now to avoid
// invalidating iterators.
if (isInstructionTriviallyDead(Inst, TLI))
DeadInsts.push_back(Inst);
if (NumPreds == 1) {
// Completely replace a single-pred PHI. This is safe, because the
// NewVal won't be variant in the loop, so we don't need an LCSSA phi
// node anymore.
PN->replaceAllUsesWith(ExitVal);
RecursivelyDeleteTriviallyDeadInstructions(PN, TLI);
PN->eraseFromParent();
}
}
if (NumPreds != 1) {

18
test/Transforms/IndVarSimplify/crash.ll
View File

@ -113,3 +113,21 @@ bb9:
ret void
}
; PR12536
define void @fn1() noreturn nounwind {
entry:
br label %for.cond
for.cond: ; preds = %for.end, %entry
%b.0 = phi i32 [ undef, %entry ], [ %conv, %for.end ]
br label %for.cond1
for.cond1: ; preds = %for.cond1, %for.cond
%c.0 = phi i32 [ %b.0, %for.cond1 ], [ 0, %for.cond ]
br i1 undef, label %for.cond1, label %for.end
for.end: ; preds = %for.cond1
%cmp2 = icmp slt i32 %c.0, 1
%conv = zext i1 %cmp2 to i32
br label %for.cond
}