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Don't optimize the landing pad exit block.

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One way to exit the loop is through an unwind edge. However, that may involve
splitting the critical edge of the landing pad, which is non-trivial. Prevent
the transformation from rewriting the landing pad exit loop block.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137871 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2011-08-17 21:20:43 +00:00
parent 490606e613
commit 0906a7c46c
1 changed files with 18 additions and 4 deletions
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22
lib/Transforms/Utils/LoopSimplify.cpp
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@ -398,6 +398,9 @@ BasicBlock *LoopSimplify::InsertPreheaderForLoop(Loop *L) {
/// blocks. This method is used to split exit blocks that have predecessors /// blocks. This method is used to split exit blocks that have predecessors
/// outside of the loop. /// outside of the loop.
BasicBlock *LoopSimplify::RewriteLoopExitBlock(Loop *L, BasicBlock *Exit) { BasicBlock *LoopSimplify::RewriteLoopExitBlock(Loop *L, BasicBlock *Exit) {
// Don't split a landing pad block.
if (Exit->isLandingPad()) return 0;
SmallVector<BasicBlock*, 8> LoopBlocks; SmallVector<BasicBlock*, 8> LoopBlocks;
for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit); I != E; ++I) { for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit); I != E; ++I) {
BasicBlock *P = *I; BasicBlock *P = *I;
@ -746,18 +749,29 @@ void LoopSimplify::verifyAnalysis() const {
(void)HasIndBrPred; (void)HasIndBrPred;
} }
// Indirectbr can interfere with exit block canonicalization. // Indirectbr and LandingPad can interfere with exit block canonicalization.
if (!L->hasDedicatedExits()) { if (!L->hasDedicatedExits()) {
bool HasIndBrExiting = false; bool HasIndBrExiting = false;
bool HasLPadExiting = false;
SmallVector<BasicBlock*, 8> ExitingBlocks; SmallVector<BasicBlock*, 8> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks); L->getExitingBlocks(ExitingBlocks);
for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
if (isa<IndirectBrInst>((ExitingBlocks[i])->getTerminator())) { if (isa<IndirectBrInst>((ExitingBlocks[i])->getTerminator())) {
HasIndBrExiting = true; HasIndBrExiting = true;
break; break;
} }
assert(HasIndBrExiting && if (const InvokeInst *II =
dyn_cast<InvokeInst>(ExitingBlocks[i]->getTerminator())) {
if (L->contains(II->getNormalDest()) &&
!L->contains(II->getUnwindDest())) {
HasLPadExiting = true;
break;
}
}
}
assert((HasIndBrExiting || HasLPadExiting) &&
"LoopSimplify has no excuse for missing exit block info!"); "LoopSimplify has no excuse for missing exit block info!");
(void)HasIndBrExiting; (void)HasIndBrExiting; (void)HasLPadExiting;
} }
} }