Author: evancheng
Date: Wed Feb 13 02:41:08 2008
New Revision: 47056
URL: http://llvm.org/viewvc/llvm-project?rev=47056&view=rev
Log:
* Cannot safely commute an instruction there are other defs which can reach its
uses.
* Ignore copy instructions which have already been coalesced.
Modified:
llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
Modified: llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp?rev=47056&r1=47055&r2=47056&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp (original)
+++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp Wed Feb 13 02:41:08 2008
@@ -237,7 +237,9 @@
// AValNo is the value number in A that defines the copy, A3 in the example.
LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
VNInfo *AValNo = ALR->valno;
- if (AValNo->def == ~0U || AValNo->def == ~1U)
+ // If other defs can reach uses of this def, then it's not safe to perform
+ // the optimization.
+ if (AValNo->def == ~0U || AValNo->def == ~1U || AValNo->hasPHIKill)
return false;
MachineInstr *DefMI = li_->getInstructionFromIndex(AValNo->def);
const TargetInstrDesc &TID = DefMI->getDesc();
@@ -312,6 +314,8 @@
MachineOperand &UseMO = UI.getOperand();
++UI;
MachineInstr *UseMI = UseMO.getParent();
+ if (JoinedCopies.count(UseMI))
+ continue;
unsigned UseIdx = li_->getInstructionIndex(UseMI);
LiveInterval::iterator ULR = IntA.FindLiveRangeContaining(UseIdx);
if (ULR->valno != AValNo)
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