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LoopSimplify bug fix. Handle indirect loop back edges.

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Do not call SplitBlockPredecessors on a loop preheader when one of the
predecessors is an indirectbr. Otherwise, you will hit this assert:
!isa<IndirectBrInst>(Preds[i]->getTerminator()) && "Cannot split an edge from an IndirectBrInst"

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153134 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick
2012-03-20 21:24:52 +00:00
parent cd1142ef7f
commit 7edc277f72
2 changed files with 49 additions and 5 deletions
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13
lib/Transforms/Utils/LoopSimplify.cpp
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@ -538,8 +538,7 @@ void LoopSimplify::PlaceSplitBlockCarefully(BasicBlock *NewBB,
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L, LPPassManager &LPM,
BasicBlock *Preheader) {
// Don't try to separate loops without a preheader (this excludes
// loop headers which are targeted by an indirectbr).
// Don't try to separate loops without a preheader.
if (!Preheader)
return 0;
@ -554,11 +553,15 @@ Loop *LoopSimplify::SeparateNestedLoop(Loop *L, LPPassManager &LPM,
// handles the case when a PHI node has multiple instances of itself as
// arguments.
SmallVector<BasicBlock*, 8> OuterLoopPreds;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
if (PN->getIncomingValue(i) != PN ||
!L->contains(PN->getIncomingBlock(i)))
!L->contains(PN->getIncomingBlock(i))) {
// We can't split indirectbr edges.
if (isa<IndirectBrInst>(PN->getIncomingBlock(i)->getTerminator()))
return 0;
OuterLoopPreds.push_back(PN->getIncomingBlock(i));
}
}
DEBUG(dbgs() << "LoopSimplify: Splitting out a new outer loop\n");
// If ScalarEvolution is around and knows anything about values in