diff options
-rw-r--r-- | lib/CodeGen/StrongPHIElimination.cpp | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp index b276e80..11b8ca3 100644 --- a/lib/CodeGen/StrongPHIElimination.cpp +++ b/lib/CodeGen/StrongPHIElimination.cpp @@ -421,6 +421,7 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) { while (P != MBB->end() && P->getOpcode() == TargetInstrInfo::PHI) { unsigned DestReg = P->getOperand(0).getReg(); + // Don't both doing PHI elimination for dead PHI's. if (P->registerDefIsDead(DestReg)) { ++P; @@ -442,6 +443,12 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) { // Iterate over the operands of the PHI node for (int i = P->getNumOperands() - 1; i >= 2; i-=2) { unsigned SrcReg = P->getOperand(i-1).getReg(); + + // Don't need to try to coalesce a register with itself. + if (SrcReg == DestReg) { + ProcessedNames.insert(SrcReg); + continue; + } // Check for trivial interferences via liveness information, allowing us // to avoid extra work later. Any registers that interfere cannot both |