[llvm-commits] [llvm] r139787 - /llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Thu Sep 15 01:27:32 2011
New Revision: 139787

URL: http://llvm.org/viewvc/llvm-project?rev=139787&view=rev
Log:
Revert r139782, "RemoveCopyByCommutingDef doesn't need hasPHIKill()."

It does, after all.

RemoveCopyByCommutingDef rewrites the uses of one particular value
number in A. It doesn't know how to rewrite phi uses, so there can't be
any.

Modified:
    llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp

Modified: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp?rev=139787&r1=139786&r2=139787&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp Thu Sep 15 01:27:32 2011
@@ -566,16 +566,14 @@
 }
 
 /// HasOtherReachingDefs - Return true if there are definitions of IntB
-/// other than BValNo val# that can reach uses of AValno val# of IntA, or any
-/// of its phis.
+/// other than BValNo val# that can reach uses of AValno val# of IntA.
 bool RegisterCoalescer::HasOtherReachingDefs(LiveInterval &IntA,
-                                             LiveInterval &IntB,
-                                             VNInfo *AValNo,
-                                             VNInfo *BValNo) {
+                                                    LiveInterval &IntB,
+                                                    VNInfo *AValNo,
+                                                    VNInfo *BValNo) {
   for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
        AI != AE; ++AI) {
-    if (AI->valno != AValNo && !AI->valno->isPHIDef())
-      continue;
+    if (AI->valno != AValNo) continue;
     LiveInterval::Ranges::iterator BI =
       std::upper_bound(IntB.ranges.begin(), IntB.ranges.end(), AI->start);
     if (BI != IntB.ranges.begin())
@@ -647,7 +645,9 @@
   VNInfo *AValNo = IntA.getVNInfoAt(CopyIdx.getUseIndex());
   assert(AValNo && "COPY source not live");
 
-  if (AValNo->isPHIDef() || AValNo->isUnused())
+  // If other defs can reach uses of this def, then it's not safe to perform
+  // the optimization.
+  if (AValNo->isPHIDef() || AValNo->isUnused() || AValNo->hasPHIKill())
     return false;
   MachineInstr *DefMI = LIS->getInstructionFromIndex(AValNo->def);
   if (!DefMI)