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//===-- X86PeepholeOpt.cpp - X86 Peephole Optimizer -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a peephole optimizer for the X86.
//
//===----------------------------------------------------------------------===//
#include "X86.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
namespace {
Statistic<> NumPHOpts("x86-peephole",
"Number of peephole optimization performed");
Statistic<> NumPHMoves("x86-peephole", "Number of peephole moves folded");
struct PH : public MachineFunctionPass {
virtual bool runOnMachineFunction(MachineFunction &MF);
bool PeepholeOptimize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &I);
virtual const char *getPassName() const { return "X86 Peephole Optimizer"; }
};
}
FunctionPass *llvm::createX86PeepholeOptimizerPass() { return new PH(); }
bool PH::runOnMachineFunction(MachineFunction &MF) {
bool Changed = false;
for (MachineFunction::iterator BI = MF.begin(), E = MF.end(); BI != E; ++BI)
for (MachineBasicBlock::iterator I = BI->begin(); I != BI->end(); )
if (PeepholeOptimize(*BI, I)) {
Changed = true;
++NumPHOpts;
} else
++I;
return Changed;
}
bool PH::PeepholeOptimize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &I) {
assert(I != MBB.end());
MachineBasicBlock::iterator NextI = next(I);
MachineInstr *MI = I;
MachineInstr *Next = (NextI != MBB.end()) ? &*NextI : (MachineInstr*)0;
unsigned Size = 0;
switch (MI->getOpcode()) {
case X86::MOV8rr:
case X86::MOV16rr:
case X86::MOV32rr: // Destroy X = X copies...
if (MI->getOperand(0).getReg() == MI->getOperand(1).getReg()) {
I = MBB.erase(I);
return true;
}
return false;
// A large number of X86 instructions have forms which take an 8-bit
// immediate despite the fact that the operands are 16 or 32 bits. Because
// this can save three bytes of code size (and icache space), we want to
// shrink them if possible.
case X86::IMUL16rri: case X86::IMUL32rri:
assert(MI->getNumOperands() == 3 && "These should all have 3 operands!");
if (MI->getOperand(2).isImmediate()) {
int Val = MI->getOperand(2).getImmedValue();
// If the value is the same when signed extended from 8 bits...
if (Val == (signed int)(signed char)Val) {
unsigned Opcode;
switch (MI->getOpcode()) {
default: assert(0 && "Unknown opcode value!");
case X86::IMUL16rri: Opcode = X86::IMUL16rri8; break;
case X86::IMUL32rri: Opcode = X86::IMUL32rri8; break;
}
unsigned R0 = MI->getOperand(0).getReg();
unsigned R1 = MI->getOperand(1).getReg();
I = MBB.insert(MBB.erase(I),
BuildMI(Opcode, 2, R0).addReg(R1).addZImm((char)Val));
return true;
}
}
return false;
case X86::ADD16ri: case X86::ADD32ri: case X86::ADC32ri:
case X86::SUB16ri: case X86::SUB32ri:
case X86::SBB16ri: case X86::SBB32ri:
case X86::AND16ri: case X86::AND32ri:
case X86::OR16ri: case X86::OR32ri:
case X86::XOR16ri: case X86::XOR32ri:
assert(MI->getNumOperands() == 2 && "These should all have 2 operands!");
if (MI->getOperand(1).isImmediate()) {
int Val = MI->getOperand(1).getImmedValue();
// If the value is the same when signed extended from 8 bits...
if (Val == (signed int)(signed char)Val) {
unsigned Opcode;
switch (MI->getOpcode()) {
default: assert(0 && "Unknown opcode value!");
case X86::ADD16ri: Opcode = X86::ADD16ri8; break;
case X86::ADD32ri: Opcode = X86::ADD32ri8; break;
case X86::ADC32ri: Opcode = X86::ADC32ri8; break;
case X86::SUB16ri: Opcode = X86::SUB16ri8; break;
case X86::SUB32ri: Opcode = X86::SUB32ri8; break;
case X86::SBB16ri: Opcode = X86::SBB16ri8; break;
case X86::SBB32ri: Opcode = X86::SBB32ri8; break;
case X86::AND16ri: Opcode = X86::AND16ri8; break;
case X86::AND32ri: Opcode = X86::AND32ri8; break;
case X86::OR16ri: Opcode = X86::OR16ri8; break;
case X86::OR32ri: Opcode = X86::OR32ri8; break;
case X86::XOR16ri: Opcode = X86::XOR16ri8; break;
case X86::XOR32ri: Opcode = X86::XOR32ri8; break;
}
unsigned R0 = MI->getOperand(0).getReg();
I = MBB.insert(MBB.erase(I),
BuildMI(Opcode, 1, R0, MachineOperand::UseAndDef)
.addZImm((char)Val));
return true;
}
}
return false;
case X86::ADD16mi: case X86::ADD32mi: case X86::ADC32mi:
case X86::SUB16mi: case X86::SUB32mi:
case X86::SBB16mi: case X86::SBB32mi:
case X86::AND16mi: case X86::AND32mi:
case X86::OR16mi: case X86::OR32mi:
case X86::XOR16mi: case X86::XOR32mi:
assert(MI->getNumOperands() == 5 && "These should all have 5 operands!");
if (MI->getOperand(4).isImmediate()) {
int Val = MI->getOperand(4).getImmedValue();
// If the value is the same when signed extended from 8 bits...
if (Val == (signed int)(signed char)Val) {
unsigned Opcode;
switch (MI->getOpcode()) {
default: assert(0 && "Unknown opcode value!");
case X86::ADD16mi: Opcode = X86::ADD16mi8; break;
case X86::ADD32mi: Opcode = X86::ADD32mi8; break;
case X86::ADC32mi: Opcode = X86::ADC32mi8; break;
case X86::SUB16mi: Opcode = X86::SUB16mi8; break;
case X86::SUB32mi: Opcode = X86::SUB32mi8; break;
case X86::SBB16mi: Opcode = X86::SBB16mi8; break;
case X86::SBB32mi: Opcode = X86::SBB32mi8; break;
case X86::AND16mi: Opcode = X86::AND16mi8; break;
case X86::AND32mi: Opcode = X86::AND32mi8; break;
case X86::OR16mi: Opcode = X86::OR16mi8; break;
case X86::OR32mi: Opcode = X86::OR32mi8; break;
case X86::XOR16mi: Opcode = X86::XOR16mi8; break;
case X86::XOR32mi: Opcode = X86::XOR32mi8; break;
}
unsigned R0 = MI->getOperand(0).getReg();
unsigned Scale = MI->getOperand(1).getImmedValue();
unsigned R1 = MI->getOperand(2).getReg();
if (MI->getOperand(3).isImmediate()) {
unsigned Offset = MI->getOperand(3).getImmedValue();
I = MBB.insert(MBB.erase(I),
BuildMI(Opcode, 5).addReg(R0).addZImm(Scale).
addReg(R1).addSImm(Offset).addZImm((char)Val));
} else if (MI->getOperand(3).isGlobalAddress()) {
GlobalValue *GA = MI->getOperand(3).getGlobal();
int Offset = MI->getOperand(3).getOffset();
I = MBB.insert(
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