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Don't try to loop on iterators that are potentially invalidated inside the loop. Fixes PR11361!

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144454 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2011-11-12 03:09:12 +00:00
parent 7386612a16
commit d7ecff49d9
2 changed files with 60 additions and 0 deletions
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18
lib/Analysis/ScalarEvolution.cpp
View File

@ -4853,10 +4853,18 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
// Also evaluate the other PHI nodes. However, we don't get to stop if we
// cease to be able to evaluate one of them or if they stop evolving,
// because that doesn't necessarily prevent us from computing PN.
SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
for (DenseMap<Instruction *, Constant *>::const_iterator
I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){
PHINode *PHI = dyn_cast<PHINode>(I->first);
if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
PHIsToCompute.push_back(std::make_pair(PHI, I->second));
}
// We use two distinct loops because EvaluateExpression may invalidate any
// iterators into CurrentIterVals.
for (SmallVectorImpl<std::pair<PHINode *, Constant*> >::const_iterator
I = PHIsToCompute.begin(), E = PHIsToCompute.end(); I != E; ++I) {
PHINode *PHI = I->first;
Constant *&NextPHI = NextIterVals[PHI];
if (!NextPHI) { // Not already computed.
Value *BEValue = PHI->getIncomingValue(SecondIsBackedge);
@ -4928,10 +4936,20 @@ const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L,
// Update all the PHI nodes for the next iteration.
DenseMap<Instruction *, Constant *> NextIterVals;
// Create a list of which PHIs we need to compute. We want to do this before
// calling EvaluateExpression on them because that may invalidate iterators
// into CurrentIterVals.
SmallVector<PHINode *, 8> PHIsToCompute;
for (DenseMap<Instruction *, Constant *>::const_iterator
I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){
PHINode *PHI = dyn_cast<PHINode>(I->first);
if (!PHI || PHI->getParent() != Header) continue;
PHIsToCompute.push_back(PHI);
}
for (SmallVectorImpl<PHINode *>::const_iterator I = PHIsToCompute.begin(),
E = PHIsToCompute.end(); I != E; ++I) {
PHINode *PHI = *I;
Constant *&NextPHI = NextIterVals[PHI];
if (NextPHI) continue; // Already computed!

42
test/Transforms/LoopUnroll/pr11361.ll Normal file
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@ -0,0 +1,42 @@
; RUN: opt -loop-unroll -disable-output
; PR11361
; This tests for an iterator invalidation issue.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define void @func_1() nounwind uwtable {
entry:
br label %for.cond8.preheader
for.cond8.preheader: ; preds = %for.inc15, %entry
%l_1264.04 = phi i32 [ 0, %entry ], [ %add.i, %for.inc15 ]
%l_1330.0.03 = phi i80 [ undef, %entry ], [ %ins.lcssa, %for.inc15 ]
br label %for.body9
for.body9: ; preds = %for.body9, %for.cond8.preheader
%l_1330.0.12 = phi i80 [ %l_1330.0.03, %for.cond8.preheader ], [ %ins, %for.body9 ]
%storemerge1 = phi i32 [ 7, %for.cond8.preheader ], [ %sub, %for.body9 ]
%tmp = lshr i80 %l_1330.0.12, 8
%tmp1 = trunc i80 %tmp to i8
%inc12 = add i8 %tmp1, 1
%tmp2 = zext i8 %inc12 to i80
%tmp3 = shl nuw nsw i80 %tmp2, 8
%mask = and i80 %l_1330.0.12, -65281
%ins = or i80 %tmp3, %mask
%sub = add nsw i32 %storemerge1, -1
%tobool = icmp eq i32 %sub, 0
br i1 %tobool, label %for.inc15, label %for.body9
for.inc15: ; preds = %for.body9
%ins.lcssa = phi i80 [ %ins, %for.body9 ]
%sext = shl i32 %l_1264.04, 24
%conv.i = ashr exact i32 %sext, 24
%add.i = add nsw i32 %conv.i, 1
%cmp = icmp slt i32 %add.i, 3
br i1 %cmp, label %for.cond8.preheader, label %for.end16
for.end16: ; preds = %for.inc15
ret void
}