diff options
Diffstat (limited to 'lib/CodeGen/EarlyIfConversion.cpp')
| -rw-r--r-- | lib/CodeGen/EarlyIfConversion.cpp | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/lib/CodeGen/EarlyIfConversion.cpp b/lib/CodeGen/EarlyIfConversion.cpp index d3687b98b344..fbc4d97c4987 100644 --- a/lib/CodeGen/EarlyIfConversion.cpp +++ b/lib/CodeGen/EarlyIfConversion.cpp @@ -479,11 +479,20 @@ void SSAIfConv::rewritePHIOperands() { // Convert all PHIs to select instructions inserted before FirstTerm. for (unsigned i = 0, e = PHIs.size(); i != e; ++i) { PHIInfo &PI = PHIs[i]; + unsigned DstReg = 0; + DEBUG(dbgs() << "If-converting " << *PI.PHI); - unsigned PHIDst = PI.PHI->getOperand(0).getReg(); - unsigned DstReg = MRI->createVirtualRegister(MRI->getRegClass(PHIDst)); - TII->insertSelect(*Head, FirstTerm, HeadDL, DstReg, Cond, PI.TReg, PI.FReg); - DEBUG(dbgs() << " --> " << *std::prev(FirstTerm)); + if (PI.TReg == PI.FReg) { + // We do not need the select instruction if both incoming values are + // equal. + DstReg = PI.TReg; + } else { + unsigned PHIDst = PI.PHI->getOperand(0).getReg(); + DstReg = MRI->createVirtualRegister(MRI->getRegClass(PHIDst)); + TII->insertSelect(*Head, FirstTerm, HeadDL, + DstReg, Cond, PI.TReg, PI.FReg); + DEBUG(dbgs() << " --> " << *std::prev(FirstTerm)); + } // Rewrite PHI operands TPred -> (DstReg, Head), remove FPred. for (unsigned i = PI.PHI->getNumOperands(); i != 1; i -= 2) { |