From: Cameron Zwarich <zwarich@apple.com>
Date: Fri, 24 Dec 2010 03:09:36 +0000 (+0000)
Subject: Simplify a check for implicit defs and remove a FIXME.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=ef485d86585123b5e31a7f88aef22725ebd07e7a;p=oota-llvm.git

Simplify a check for implicit defs and remove a FIXME.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122537 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp
index b475432bcfb..a0ad2fb0c0b 100644
--- a/lib/CodeGen/StrongPHIElimination.cpp
+++ b/lib/CodeGen/StrongPHIElimination.cpp
@@ -189,20 +189,18 @@ void StrongPHIElimination::InsertCopiesForPHI(MachineInstr* PHI,
   SmallPtrSet<MachineBasicBlock*, 8> MBBsInsertedInto;
   for (unsigned i = 1; i < PHI->getNumOperands(); i += 2) {
     MachineOperand& SrcMO = PHI->getOperand(i);
+
+    // If a source is defined by an implicit def, there is no need to insert a
+    // copy in the predecessor.
+    if (SrcMO.isUndef())
+      continue;
+
     unsigned SrcReg = SrcMO.getReg();
     unsigned SrcSubReg = SrcMO.getSubReg();
 
     assert(TargetRegisterInfo::isVirtualRegister(SrcReg) &&
            "Machine PHI Operands must all be virtual registers!");
 
-    // If source is defined by an implicit def, there is no need to insert a
-    // copy.
-    // FIXME: For some reason, if LiveIntervals is run prior to PHI elimination
-    // implcit defs have no defining instruction. Is this expected?
-    MachineInstr* DefMI = MRI->getVRegDef(SrcReg);
-    if (!DefMI)
-      continue;
-
     MachineBasicBlock* PredBB = PHI->getOperand(i + 1).getMBB();
 
     // A copy may have already been inserted in the predecessor in the case of a