/// a side.
///
/// @param MI Optimizable select instruction.
+ /// @param SeenMIs Set that record all MIs in the basic block up to \p
+ /// MI. Has to be updated with any newly created MI or deleted ones.
/// @param PreferFalse Try to optimize FalseOp instead of TrueOp.
/// @returns Optimized instruction or NULL.
virtual MachineInstr *optimizeSelect(MachineInstr *MI,
+ SmallPtrSetImpl<MachineInstr *> &NewMIs,
bool PreferFalse = false) const {
// This function must be implemented if Optimizable is ever set.
llvm_unreachable("Target must implement TargetInstrInfo::optimizeSelect!");
bool optimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB);
bool optimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
SmallPtrSetImpl<MachineInstr*> &LocalMIs);
- bool optimizeSelect(MachineInstr *MI);
+ bool optimizeSelect(MachineInstr *MI,
+ SmallPtrSetImpl<MachineInstr *> &LocalMIs);
bool optimizeCondBranch(MachineInstr *MI);
bool optimizeCopyOrBitcast(MachineInstr *MI);
bool optimizeCoalescableCopy(MachineInstr *MI);
}
/// Optimize a select instruction.
-bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI) {
+bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI,
+ SmallPtrSetImpl<MachineInstr *> &LocalMIs) {
unsigned TrueOp = 0;
unsigned FalseOp = 0;
bool Optimizable = false;
return false;
if (!Optimizable)
return false;
- if (!TII->optimizeSelect(MI))
+ if (!TII->optimizeSelect(MI, LocalMIs))
return false;
MI->eraseFromParent();
++NumSelects;
MachineBasicBlock *MBB = &*I;
bool SeenMoveImm = false;
+
+ // During this forward scan, at some point it needs to answer the question
+ // "given a pointer to an MI in the current BB, is it located before or
+ // after the current instruction".
+ // To perform this, the following set keeps track of the MIs already seen
+ // during the scan, if a MI is not in the set, it is assumed to be located
+ // after. Newly created MIs have to be inserted in the set as well.
SmallPtrSet<MachineInstr*, 16> LocalMIs;
SmallSet<unsigned, 4> ImmDefRegs;
DenseMap<unsigned, MachineInstr*> ImmDefMIs;
if ((isUncoalescableCopy(*MI) &&
optimizeUncoalescableCopy(MI, LocalMIs)) ||
(MI->isCompare() && optimizeCmpInstr(MI, MBB)) ||
- (MI->isSelect() && optimizeSelect(MI))) {
+ (MI->isSelect() && optimizeSelect(MI, LocalMIs))) {
// MI is deleted.
LocalMIs.erase(MI);
Changed = true;
return false;
}
-MachineInstr *ARMBaseInstrInfo::optimizeSelect(MachineInstr *MI,
- bool PreferFalse) const {
+MachineInstr *
+ARMBaseInstrInfo::optimizeSelect(MachineInstr *MI,
+ SmallPtrSetImpl<MachineInstr *> &SeenMIs,
+ bool PreferFalse) const {
assert((MI->getOpcode() == ARM::MOVCCr || MI->getOpcode() == ARM::t2MOVCCr) &&
"Unknown select instruction");
MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
NewMI.addOperand(FalseReg);
NewMI->tieOperands(0, NewMI->getNumOperands() - 1);
+ // Update SeenMIs set: register newly created MI and erase removed DefMI.
+ SeenMIs.insert(NewMI);
+ SeenMIs.erase(DefMI);
+
// The caller will erase MI, but not DefMI.
DefMI->eraseFromParent();
return NewMI;
unsigned &TrueOp, unsigned &FalseOp,
bool &Optimizable) const override;
- MachineInstr *optimizeSelect(MachineInstr *MI, bool) const override;
+ MachineInstr *optimizeSelect(MachineInstr *MI,
+ SmallPtrSetImpl<MachineInstr *> &SeenMIs,
+ bool) const override;
/// FoldImmediate - 'Reg' is known to be defined by a move immediate
/// instruction, try to fold the immediate into the use instruction.