If all sources of a PHI node are defined by an implicit_def, just emit an implicit_def instead of a copy.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50927 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index a82e78e..8b1f307 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -127,11 +127,15 @@
return true;
}
-static bool isSourceDefinedByImplicitDef(MachineInstr *MPhi, unsigned SrcIdx,
+static bool isSourceDefinedByImplicitDef(MachineInstr *MPhi,
MachineRegisterInfo *MRI) {
- unsigned SrcReg = MPhi->getOperand(SrcIdx*2+1).getReg();
- MachineInstr *DefMI = MRI->getVRegDef(SrcReg);
- return DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF;
+ for (unsigned i = 1; i != MPhi->getNumOperands(); i += 2) {
+ unsigned SrcReg = MPhi->getOperand(i).getReg();
+ MachineInstr *DefMI = MRI->getVRegDef(SrcReg);
+ if (!DefMI || DefMI->getOpcode() != TargetInstrInfo::IMPLICIT_DEF)
+ return false;
+ }
+ return true;
}
/// LowerAtomicPHINode - Lower the PHI node at the top of the specified block,
@@ -156,9 +160,9 @@
// into the phi node destination.
//
const TargetInstrInfo *TII = MF.getTarget().getInstrInfo();
- if (NumSrcs == 1 && isSourceDefinedByImplicitDef(MPhi, 0, MRI))
- // If the only source of a PHI node is an implicit_def, just emit an
- // implicit_def instead of a copy.
+ if (isSourceDefinedByImplicitDef(MPhi, MRI))
+ // If all sources of a PHI node are implicit_def, just emit an implicit_def
+ // instead of a copy.
BuildMI(MBB, AfterPHIsIt, TII->get(TargetInstrInfo::IMPLICIT_DEF), DestReg);
else
TII->copyRegToReg(MBB, AfterPHIsIt, DestReg, IncomingReg, RC, RC);