From 041230014cfcac43b7a7204ee5ef8c4dd42f599e Mon Sep 17 00:00:00 2001 From: Bill Wendling Date: Fri, 10 Sep 2010 23:34:19 +0000 Subject: Move some of the decision logic for converting an instruction into one that sets the 'zero' bit down into the back-end. There are other cases where this logic isn't sufficient, so they should be handled separately. llvm-svn: 113665 --- llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp | 21 +++++++++++++++++---- llvm/lib/Target/ARM/ARMBaseInstrInfo.h | 3 +-- 2 files changed, 18 insertions(+), 6 deletions(-) (limited to 'llvm/lib/Target/ARM') diff --git a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp index 142633c667f..a73e7ad44db 100644 --- a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp +++ b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp @@ -1377,12 +1377,25 @@ AnalyzeCompare(const MachineInstr *MI, unsigned &SrcReg, int &CmpValue) const { return false; } -/// ConvertToSetZeroFlag - Convert the instruction to set the "zero" flag so -/// that we can remove a "comparison with zero". Update the iterator *only* if a -/// transformation took place. +/// ConvertToSetZeroFlag - Convert the instruction supplying the argument to the +/// comparison into one that sets the zero bit in the flags register. Update the +/// iterator *only* if a transformation took place. bool ARMBaseInstrInfo:: -ConvertToSetZeroFlag(MachineInstr *MI, MachineInstr *CmpInstr, +ConvertToSetZeroFlag(MachineInstr *CmpInstr, MachineBasicBlock::iterator &MII) const { + unsigned SrcReg; + int CmpValue; + if (!AnalyzeCompare(CmpInstr, SrcReg, CmpValue) || CmpValue != 0) + return false; + + MachineRegisterInfo &MRI = CmpInstr->getParent()->getParent()->getRegInfo(); + MachineRegisterInfo::def_iterator DI = MRI.def_begin(SrcReg); + if (llvm::next(DI) != MRI.def_end()) + // Only support one definition. + return false; + + MachineInstr *MI = &*DI; + // Conservatively refuse to convert an instruction which isn't in the same BB // as the comparison. if (MI->getParent() != CmpInstr->getParent()) diff --git a/llvm/lib/Target/ARM/ARMBaseInstrInfo.h b/llvm/lib/Target/ARM/ARMBaseInstrInfo.h index 622402eba35..2be0d3687d2 100644 --- a/llvm/lib/Target/ARM/ARMBaseInstrInfo.h +++ b/llvm/lib/Target/ARM/ARMBaseInstrInfo.h @@ -346,8 +346,7 @@ public: /// ConvertToSetZeroFlag - Convert the instruction to set the zero flag so /// that we can remove a "comparison with zero". - virtual bool ConvertToSetZeroFlag(MachineInstr *Instr, - MachineInstr *CmpInstr, + virtual bool ConvertToSetZeroFlag(MachineInstr *CmpInstr, MachineBasicBlock::iterator &MII) const; virtual unsigned getNumMicroOps(const MachineInstr *MI, -- cgit v1.2.3