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Make DSE only scan blocks that are reachable from the entry

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block.  Other blocks may have pointer cycles that will crash
basicaa and other alias analyses.  In any case, there is no
point wasting cycles optimizing dead blocks.  This fixes 
rdar://7635088

llvm-svn: 95852
This commit is contained in:
Chris Lattner 2010-02-11 05:11:54 +00:00
parent 199f4187b6
commit a087e6e82f
2 changed files with 21 additions and 1 deletions
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8
lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -44,8 +44,14 @@ namespace {
virtual bool runOnFunction(Function &F) {
bool Changed = false;
DominatorTree &DT = getAnalysis<DominatorTree>();
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
Changed |= runOnBasicBlock(*I);
// Only check non-dead blocks. Dead blocks may have strange pointer
// cycles that will confuse alias analysis.
if (DT.isReachableFromEntry(I))
Changed |= runOnBasicBlock(*I);
return Changed;
}

14
test/Transforms/DeadStoreElimination/crash.ll
View File

@ -41,3 +41,17 @@ bb14: ; preds = %bb4
}
declare void @llvm.memcpy.i64(i8* nocapture, i8* nocapture, i64, i32) nounwind
; rdar://7635088
define i32 @test3() {
entry:
ret i32 0
dead:
%P2 = getelementptr i32 *%P2, i32 52
%Q2 = getelementptr i32 *%Q2, i32 52
store i32 4, i32* %P2
store i32 4, i32* %Q2
br label %dead
}