Author: evancheng
Date: Mon Feb 18 12:56:31 2008
New Revision: 47281
URL: http://llvm.org/viewvc/llvm-project?rev=47281&view=rev
Log:
- Remove the previous check which broke coalescer-commute3.ll
- For now, conservatively ignore copy MI whose source is a physical register.
Commuting its def MI can cause a physical register live interval to be live
through a loop (since we know it's live coming into the def MI).
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=47281&r1=47280&r2=47281&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp (original)
+++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp Mon Feb 18 12:56:31 2008
@@ -247,11 +247,11 @@
unsigned CopyIdx = li_->getDefIndex(li_->getInstructionIndex(CopyMI));
- // FIXME: For now, only eliminate the copy by commuting its def is the source
- // does not live pass the move. Coalescing those copies may end up may simply
- // end up swapping a live interval for another. That and because usually only
- // the non-two address operand can be folded can end up pessimizing the code.
- if (CopyMI->findRegisterUseOperandIdx(IntA.reg, true) != -1)
+ // FIXME: For now, only eliminate the copy by commuting its def when the
+ // source register is a virtual register. We want to guard against cases
+ // where the copy is a back edge copy and commuting the def lengthen the
+ // live interval of the source register to the entire loop.
+ if (TargetRegisterInfo::isPhysicalRegister(IntA.reg))
return false;
// BValNo is a value number in B that is defined by a copy from A. 'B3' in
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