diff options
Diffstat (limited to 'llvm/lib/CodeGen/RegisterCoalescer.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/RegisterCoalescer.cpp | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp index 2ca67d63257..75920744782 100644 --- a/llvm/lib/CodeGen/RegisterCoalescer.cpp +++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp @@ -1492,6 +1492,20 @@ JoinVals::analyzeValue(unsigned ValNo, JoinVals &Other) { if ((V.WriteLanes & OtherV.ValidLanes) == 0) return CR_Replace; + // If the other live range is killed by DefMI and the live ranges are still + // overlapping, it must be because we're looking at an early clobber def: + // + // %dst<def,early-clobber> = ASM %src<kill> + // + // In this case, it is illegal to merge the two live ranges since the early + // clobber def would clobber %src before it was read. + if (OtherLRQ.isKill()) { + // This case where the def doesn't overlap the kill is handled above. + assert(VNI->def.isEarlyClobber() && + "Only early clobber defs can overlap a kill"); + return CR_Impossible; + } + // VNI is clobbering live lanes in OtherVNI, but there is still the // possibility that no instructions actually read the clobbered lanes. // If we're clobbering all the lanes in OtherVNI, at least one must be read. |
