From b2e4b7adde3bb45bae3bf887d5185789280fe79b Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Mon, 18 Feb 2008 18:56:31 +0000 Subject: - 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). llvm-svn: 47281 --- llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp') diff --git a/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp b/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp index 199c89ef55a..7c512ed368a 100644 --- a/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp +++ b/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp @@ -247,11 +247,11 @@ bool SimpleRegisterCoalescing::RemoveCopyByCommutingDef(LiveInterval &IntA, 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 -- cgit v1.2.3