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Fix 12513: Loop unrolling breaks with indirect branches.

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Take this opportunity to generalize the indirectbr bailout logic for
loop transformations. CFG transformations will never get indirectbr
right, and there's no point trying.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154386 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick
2012-04-10 05:14:42 +00:00
parent 64c0748eb3
commit d9fc1ce809
6 changed files with 75 additions and 37 deletions
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11
lib/Analysis/LoopInfo.cpp
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@ -205,6 +205,17 @@ bool Loop::isLoopSimplifyForm() const {
return getLoopPreheader() && getLoopLatch() && hasDedicatedExits();
}
/// isSafeToClone - Return true if the loop body is safe to clone in practice.
/// Routines that reform the loop CFG and split edges often fail on indirectbr.
bool Loop::isSafeToClone() const {
// Return false if any loop blocks contain indirectbrs.
for (Loop::block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
if (isa<IndirectBrInst>((*I)->getTerminator()))
return false;
}
return true;
}
/// hasDedicatedExits - Return true if no exit block for the loop
/// has a predecessor that is outside the loop.
bool Loop::hasDedicatedExits() const {