Target/X86/X86InstrInfo.cpp

3492 optimizeCompareInstr(MachineInstr *CmpInstr, unsigned SrcReg, unsigned SrcReg2,
3497   switch (CmpInstr->getOpcode()) {
3514     if (!MRI->use_nodbg_empty(CmpInstr->getOperand(0).getReg()))
3517     switch (CmpInstr->getOpcode()) {
3535     CmpInstr->setDesc(get(NewOpcode));
3536     CmpInstr->RemoveOperand(0);
3548   // CmpInstr is the first instruction of the BB.
3549   MachineBasicBlock::iterator I = CmpInstr, Def = MI;
3552   // EFLAGS. If MI is not in the same BB as CmpInstr, do not optimize.
3554   if (IsCmpZero && (MI->getParent() != CmpInstr->getParent() ||
3558   // We are searching for an earlier instruction that can make CmpInstr
3563   // We iterate backward, starting from the instruction before CmpInstr and
3565   // RI points to the instruction before CmpInstr.
3570       RE = CmpInstr->getParent() == MI->getParent() ?
3572            CmpInstr->getParent()->rend();
3576     // Check whether CmpInstr can be made redundant by the current instruction.
3578         isRedundantFlagInstr(CmpInstr, SrcReg, SrcReg2, CmpValue, Instr)) {
3596       // We can't remove CmpInstr.
3608   // Scan forward from the instruction after CmpInstr for uses of EFLAGS.
3609   // It is safe to remove CmpInstr if EFLAGS is redefined or killed.
3614   MachineBasicBlock::iterator E = CmpInstr->getParent()->end();
3621       // It is safe to remove CmpInstr if EFLAGS is updated again.
3676       // If it is safe to remove CmpInstr, the condition code of these
3681       // It is safe to remove CmpInstr if EFLAGS is updated again or killed.
3690     MachineBasicBlock *MBB = CmpInstr->getParent();
3731   CmpInstr->eraseFromParent();