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Accept instructions that read undefined values.

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This is not supposed to happen, but I have seen the x86 rematter getting
confused when rematerializing partial redefs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127857 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-03-18 03:06:04 +00:00
parent 7cec179a64
commit 9ef931e71c
1 changed files with 9 additions and 1 deletions
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10
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -761,7 +761,15 @@ bool LiveIntervals::shrinkToUses(LiveInterval *li,
continue;
SlotIndex Idx = getInstructionIndex(UseMI).getUseIndex();
VNInfo *VNI = li->getVNInfoAt(Idx);
assert(VNI && "Live interval not live into reading instruction");
if (!VNI) {
// This shouldn't happen: readsVirtualRegister returns true, but there is
// no live value. It is likely caused by a target getting <undef> flags
// wrong.
DEBUG(dbgs() << Idx << '\t' << *UseMI
<< "Warning: Instr claims to read non-existent value in "
<< *li << '\n');
continue;
}
if (VNI->def == Idx) {
// Special case: An early-clobber tied operand reads and writes the
// register one slot early.