From 9860b71b6a23bc0ae620d7dfc621ea1ffafbf8d8 Mon Sep 17 00:00:00 2001 From: Owen Anderson Date: Wed, 6 Aug 2008 20:29:20 +0000 Subject: [PATCH] We don't need to try to coalesce input vregs that are the same as the output vreg. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54422 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/StrongPHIElimination.cpp | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp index b276e80e92b..11b8ca361c6 100644 --- a/lib/CodeGen/StrongPHIElimination.cpp +++ b/lib/CodeGen/StrongPHIElimination.cpp @@ -421,6 +421,7 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) { while (P != MBB->end() && P->getOpcode() == TargetInstrInfo::PHI) { unsigned DestReg = P->getOperand(0).getReg(); + // Don't both doing PHI elimination for dead PHI's. if (P->registerDefIsDead(DestReg)) { ++P; @@ -442,6 +443,12 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) { // Iterate over the operands of the PHI node for (int i = P->getNumOperands() - 1; i >= 2; i-=2) { unsigned SrcReg = P->getOperand(i-1).getReg(); + + // Don't need to try to coalesce a register with itself. + if (SrcReg == DestReg) { + ProcessedNames.insert(SrcReg); + continue; + } // Check for trivial interferences via liveness information, allowing us // to avoid extra work later. Any registers that interfere cannot both -- 2.34.1