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Don't do code sinking on unreachable blocks. It's unprofitable and hazardous.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100455 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2010-04-05 19:17:22 +00:00
parent 54ab2e9326
commit c4ae94dee8
2 changed files with 35 additions and 0 deletions
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5
lib/CodeGen/MachineSink.cpp
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@ -126,6 +126,11 @@ bool MachineSinking::ProcessBlock(MachineBasicBlock &MBB) {
// Can't sink anything out of a block that has less than two successors.
if (MBB.succ_size() <= 1 || MBB.empty()) return false;
// Don't bother sinking code out of unreachable blocks. In addition to being
// unprofitable, it can also lead to infinite looping, because in an unreachable
// loop there may be nowhere to stop.
if (!DT->isReachableFromEntry(&MBB)) return false;
bool MadeChange = false;
// Walk the basic block bottom-up. Remember if we saw a store.