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llvm-6502/lib/Target/X86/X86InstrInfo.cpp
Chris Lattner 995f55036f Compile CodeGen/X86/lea-3.ll:test2 to: 
_test3:
        leaq (,%rdi,4), %rax
        orq %rdi, %rax
        ret

instead of:
_test2:
        movq %rdi, %rax
        shlq $2, %rax
        orq %rdi, %rax
        ret


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35434 91177308-0d34-0410-b5e6-96231b3b80d8
2007-03-28 18:12:31 +00:00

507 lines
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//===- X86InstrInfo.cpp - X86 Instruction Information -----------*- C++ -*-===//
//
// 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 the X86 implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "X86InstrInfo.h"
#include "X86.h"
#include "X86GenInstrInfo.inc"
#include "X86InstrBuilder.h"
#include "X86Subtarget.h"
#include "X86TargetMachine.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/LiveVariables.h"
using namespace llvm;
X86InstrInfo::X86InstrInfo(X86TargetMachine &tm)
: TargetInstrInfo(X86Insts, sizeof(X86Insts)/sizeof(X86Insts[0])),
TM(tm), RI(tm, *this) {
}
bool X86InstrInfo::isMoveInstr(const MachineInstr& MI,
unsigned& sourceReg,
unsigned& destReg) const {
MachineOpCode oc = MI.getOpcode();
if (oc == X86::MOV8rr || oc == X86::MOV16rr ||
oc == X86::MOV32rr || oc == X86::MOV64rr ||
oc == X86::MOV16to16_ || oc == X86::MOV32to32_ ||
oc == X86::FpMOV || oc == X86::MOVSSrr || oc == X86::MOVSDrr ||
oc == X86::FsMOVAPSrr || oc == X86::FsMOVAPDrr ||
oc == X86::MOVAPSrr || oc == X86::MOVAPDrr ||
oc == X86::MOVSS2PSrr || oc == X86::MOVSD2PDrr ||
oc == X86::MOVPS2SSrr || oc == X86::MOVPD2SDrr ||
oc == X86::MOVD64rr || oc == X86::MOVQ64rr) {
assert(MI.getNumOperands() == 2 &&
MI.getOperand(0).isRegister() &&
MI.getOperand(1).isRegister() &&
"invalid register-register move instruction");
sourceReg = MI.getOperand(1).getReg();
destReg = MI.getOperand(0).getReg();
return true;
}
return false;
}
unsigned X86InstrInfo::isLoadFromStackSlot(MachineInstr *MI,
int &FrameIndex) const {
switch (MI->getOpcode()) {
default: break;
case X86::MOV8rm:
case X86::MOV16rm:
case X86::MOV16_rm:
case X86::MOV32rm:
case X86::MOV32_rm:
case X86::MOV64rm:
case X86::FpLD64m:
case X86::MOVSSrm:
case X86::MOVSDrm:
case X86::MOVAPSrm:
case X86::MOVAPDrm:
case X86::MOVD64rm:
case X86::MOVQ64rm:
if (MI->getOperand(1).isFrameIndex() && MI->getOperand(2).isImmediate() &&
MI->getOperand(3).isRegister() && MI->getOperand(4).isImmediate() &&
MI->getOperand(2).getImmedValue() == 1 &&
MI->getOperand(3).getReg() == 0 &&
MI->getOperand(4).getImmedValue() == 0) {
FrameIndex = MI->getOperand(1).getFrameIndex();
return MI->getOperand(0).getReg();
}
break;
}
return 0;
}
unsigned X86InstrInfo::isStoreToStackSlot(MachineInstr *MI,
int &FrameIndex) const {
switch (MI->getOpcode()) {
default: break;
case X86::MOV8mr:
case X86::MOV16mr:
case X86::MOV16_mr:
case X86::MOV32mr:
case X86::MOV32_mr:
case X86::MOV64mr:
case X86::FpSTP64m:
case X86::MOVSSmr:
case X86::MOVSDmr:
case X86::MOVAPSmr:
case X86::MOVAPDmr:
case X86::MOVD64mr:
case X86::MOVQ64mr:
if (MI->getOperand(0).isFrameIndex() && MI->getOperand(1).isImmediate() &&
MI->getOperand(2).isRegister() && MI->getOperand(3).isImmediate() &&
MI->getOperand(1).getImmedValue() == 1 &&
MI->getOperand(2).getReg() == 0 &&
MI->getOperand(3).getImmedValue() == 0) {
FrameIndex = MI->getOperand(0).getFrameIndex();
return MI->getOperand(4).getReg();
}
break;
}
return 0;
}
/// convertToThreeAddress - This method must be implemented by targets that
/// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
/// may be able to convert a two-address instruction into a true
/// three-address instruction on demand. This allows the X86 target (for
/// example) to convert ADD and SHL instructions into LEA instructions if they
/// would require register copies due to two-addressness.
///
/// This method returns a null pointer if the transformation cannot be
/// performed, otherwise it returns the new instruction.
///
MachineInstr *
X86InstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI,
LiveVariables &LV) const {
MachineInstr *MI = MBBI;
// All instructions input are two-addr instructions. Get the known operands.
unsigned Dest = MI->getOperand(0).getReg();
unsigned Src = MI->getOperand(1).getReg();
MachineInstr *NewMI = NULL;
// FIXME: 16-bit LEA's are really slow on Athlons, but not bad on P4's. When
// we have better subtarget support, enable the 16-bit LEA generation here.
bool DisableLEA16 = true;
switch (MI->getOpcode()) {
default: return 0;
case X86::SHUFPSrri: {
assert(MI->getNumOperands() == 4 && "Unknown shufps instruction!");
if (!TM.getSubtarget<X86Subtarget>().hasSSE2()) return 0;
unsigned A = MI->getOperand(0).getReg();
unsigned B = MI->getOperand(1).getReg();
unsigned C = MI->getOperand(2).getReg();
unsigned M = MI->getOperand(3).getImm();
if (B != C) return 0;
NewMI = BuildMI(get(X86::PSHUFDri), A).addReg(B).addImm(M);
break;
}
case X86::SHL64ri: {
assert(MI->getNumOperands() == 3 && "Unknown shift instruction!");
// NOTE: LEA doesn't produce flags like shift does, but LLVM never uses
// the flags produced by a shift yet, so this is safe.
unsigned Dest = MI->getOperand(0).getReg();
unsigned Src = MI->getOperand(1).getReg();
unsigned ShAmt = MI->getOperand(2).getImm();
if (ShAmt == 0 || ShAmt >= 4) return 0;
NewMI = BuildMI(get(X86::LEA64r), Dest)
.addReg(0).addImm(1 << ShAmt).addReg(Src).addImm(0);
break;
}
case X86::SHL32ri: {
assert(MI->getNumOperands() == 3 && "Unknown shift instruction!");
// NOTE: LEA doesn't produce flags like shift does, but LLVM never uses
// the flags produced by a shift yet, so this is safe.
unsigned Dest = MI->getOperand(0).getReg();
unsigned Src = MI->getOperand(1).getReg();
unsigned ShAmt = MI->getOperand(2).getImm();
if (ShAmt == 0 || ShAmt >= 4) return 0;
unsigned Opc = TM.getSubtarget<X86Subtarget>().is64Bit() ?
X86::LEA64_32r : X86::LEA32r;
NewMI = BuildMI(get(Opc), Dest)
.addReg(0).addImm(1 << ShAmt).addReg(Src).addImm(0);
break;
}
case X86::SHL16ri: {
assert(MI->getNumOperands() == 3 && "Unknown shift instruction!");
if (DisableLEA16) return 0;
// NOTE: LEA doesn't produce flags like shift does, but LLVM never uses
// the flags produced by a shift yet, so this is safe.
unsigned Dest = MI->getOperand(0).getReg();
unsigned Src = MI->getOperand(1).getReg();
unsigned ShAmt = MI->getOperand(2).getImm();
if (ShAmt == 0 || ShAmt >= 4) return 0;
NewMI = BuildMI(get(X86::LEA16r), Dest)
.addReg(0).addImm(1 << ShAmt).addReg(Src).addImm(0);
break;
}
}
// FIXME: None of these instructions are promotable to LEAs without
// additional information. In particular, LEA doesn't set the flags that
// add and inc do. :(
if (0)
switch (MI->getOpcode()) {
case X86::INC32r:
case X86::INC64_32r:
assert(MI->getNumOperands() == 2 && "Unknown inc instruction!");
NewMI = addRegOffset(BuildMI(get(X86::LEA32r), Dest), Src, 1);
break;
case X86::INC16r:
case X86::INC64_16r:
if (DisableLEA16) return 0;
assert(MI->getNumOperands() == 2 && "Unknown inc instruction!");
NewMI = addRegOffset(BuildMI(get(X86::LEA16r), Dest), Src, 1);
break;
case X86::DEC32r:
case X86::DEC64_32r:
assert(MI->getNumOperands() == 2 && "Unknown dec instruction!");
NewMI = addRegOffset(BuildMI(get(X86::LEA32r), Dest), Src, -1);
break;
case X86::DEC16r:
case X86::DEC64_16r:
if (DisableLEA16) return 0;
assert(MI->getNumOperands() == 2 && "Unknown dec instruction!");
NewMI = addRegOffset(BuildMI(get(X86::LEA16r), Dest), Src, -1);
break;
case X86::ADD32rr:
assert(MI->getNumOperands() == 3 && "Unknown add instruction!");
NewMI = addRegReg(BuildMI(get(X86::LEA32r), Dest), Src,
MI->getOperand(2).getReg());
break;
case X86::ADD16rr:
if (DisableLEA16) return 0;
assert(MI->getNumOperands() == 3 && "Unknown add instruction!");
NewMI = addRegReg(BuildMI(get(X86::LEA16r), Dest), Src,
MI->getOperand(2).getReg());
break;
case X86::ADD32ri:
case X86::ADD32ri8:
assert(MI->getNumOperands() == 3 && "Unknown add instruction!");
if (MI->getOperand(2).isImmediate())
NewMI = addRegOffset(BuildMI(get(X86::LEA32r), Dest), Src,
MI->getOperand(2).getImmedValue());
break;
case X86::ADD16ri:
case X86::ADD16ri8:
if (DisableLEA16) return 0;
assert(MI->getNumOperands() == 3 && "Unknown add instruction!");
if (MI->getOperand(2).isImmediate())
NewMI = addRegOffset(BuildMI(get(X86::LEA16r), Dest), Src,
MI->getOperand(2).getImmedValue());
break;
case X86::SHL16ri:
if (DisableLEA16) return 0;
case X86::SHL32ri:
assert(MI->getNumOperands() == 3 && MI->getOperand(2).isImmediate() &&
"Unknown shl instruction!");
unsigned ShAmt = MI->getOperand(2).getImmedValue();
if (ShAmt == 1 || ShAmt == 2 || ShAmt == 3) {
X86AddressMode AM;
AM.Scale = 1 << ShAmt;
AM.IndexReg = Src;
unsigned Opc = MI->getOpcode() == X86::SHL32ri ? X86::LEA32r :X86::LEA16r;
NewMI = addFullAddress(BuildMI(get(Opc), Dest), AM);
}
break;
}
if (NewMI) {
NewMI->copyKillDeadInfo(MI);
LV.instructionChanged(MI, NewMI); // Update live variables
MFI->insert(MBBI, NewMI); // Insert the new inst
}
return NewMI;
}
/// commuteInstruction - We have a few instructions that must be hacked on to
/// commute them.
///
MachineInstr *X86InstrInfo::commuteInstruction(MachineInstr *MI) const {
// FIXME: Can commute cmoves by changing the condition!
switch (MI->getOpcode()) {
case X86::SHRD16rri8: // A = SHRD16rri8 B, C, I -> A = SHLD16rri8 C, B, (16-I)
case X86::SHLD16rri8: // A = SHLD16rri8 B, C, I -> A = SHRD16rri8 C, B, (16-I)
case X86::SHRD32rri8: // A = SHRD32rri8 B, C, I -> A = SHLD32rri8 C, B, (32-I)
case X86::SHLD32rri8:{// A = SHLD32rri8 B, C, I -> A = SHRD32rri8 C, B, (32-I)
unsigned Opc;
unsigned Size;
switch (MI->getOpcode()) {
default: assert(0 && "Unreachable!");
case X86::SHRD16rri8: Size = 16; Opc = X86::SHLD16rri8; break;
case X86::SHLD16rri8: Size = 16; Opc = X86::SHRD16rri8; break;
case X86::SHRD32rri8: Size = 32; Opc = X86::SHLD32rri8; break;
case X86::SHLD32rri8: Size = 32; Opc = X86::SHRD32rri8; break;
}
unsigned Amt = MI->getOperand(3).getImmedValue();
unsigned A = MI->getOperand(0).getReg();
unsigned B = MI->getOperand(1).getReg();
unsigned C = MI->getOperand(2).getReg();
bool BisKill = MI->getOperand(1).isKill();
bool CisKill = MI->getOperand(2).isKill();
return BuildMI(get(Opc), A).addReg(C, false, false, CisKill)
.addReg(B, false, false, BisKill).addImm(Size-Amt);
}
default:
return TargetInstrInfo::commuteInstruction(MI);
}
}
static X86::CondCode GetCondFromBranchOpc(unsigned BrOpc) {
switch (BrOpc) {
default: return X86::COND_INVALID;
case X86::JE: return X86::COND_E;
case X86::JNE: return X86::COND_NE;
case X86::JL: return X86::COND_L;
case X86::JLE: return X86::COND_LE;
case X86::JG: return X86::COND_G;
case X86::JGE: return X86::COND_GE;
case X86::JB: return X86::COND_B;
case X86::JBE: return X86::COND_BE;
case X86::JA: return X86::COND_A;
case X86::JAE: return X86::COND_AE;
case X86::JS: return X86::COND_S;
case X86::JNS: return X86::COND_NS;
case X86::JP: return X86::COND_P;
case X86::JNP: return X86::COND_NP;
case X86::JO: return X86::COND_O;
case X86::JNO: return X86::COND_NO;
}
}
unsigned X86::GetCondBranchFromCond(X86::CondCode CC) {
switch (CC) {
default: assert(0 && "Illegal condition code!");
case X86::COND_E: return X86::JE;
case X86::COND_NE: return X86::JNE;
case X86::COND_L: return X86::JL;
case X86::COND_LE: return X86::JLE;
case X86::COND_G: return X86::JG;
case X86::COND_GE: return X86::JGE;
case X86::COND_B: return X86::JB;
case X86::COND_BE: return X86::JBE;
case X86::COND_A: return X86::JA;
case X86::COND_AE: return X86::JAE;
case X86::COND_S: return X86::JS;
case X86::COND_NS: return X86::JNS;
case X86::COND_P: return X86::JP;
case X86::COND_NP: return X86::JNP;
case X86::COND_O: return X86::JO;
case X86::COND_NO: return X86::JNO;
}
}
/// GetOppositeBranchCondition - Return the inverse of the specified condition,
/// e.g. turning COND_E to COND_NE.
X86::CondCode X86::GetOppositeBranchCondition(X86::CondCode CC) {
switch (CC) {
default: assert(0 && "Illegal condition code!");
case X86::COND_E: return X86::COND_NE;
case X86::COND_NE: return X86::COND_E;
case X86::COND_L: return X86::COND_GE;
case X86::COND_LE: return X86::COND_G;
case X86::COND_G: return X86::COND_LE;
case X86::COND_GE: return X86::COND_L;
case X86::COND_B: return X86::COND_AE;
case X86::COND_BE: return X86::COND_A;
case X86::COND_A: return X86::COND_BE;
case X86::COND_AE: return X86::COND_B;
case X86::COND_S: return X86::COND_NS;
case X86::COND_NS: return X86::COND_S;
case X86::COND_P: return X86::COND_NP;
case X86::COND_NP: return X86::COND_P;
case X86::COND_O: return X86::COND_NO;
case X86::COND_NO: return X86::COND_O;
}
}
bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
std::vector<MachineOperand> &Cond) const {
// TODO: If FP_REG_KILL is around, ignore it.
// If the block has no terminators, it just falls into the block after it.
MachineBasicBlock::iterator I = MBB.end();
if (I == MBB.begin() || !isTerminatorInstr((--I)->getOpcode()))
return false;
// Get the last instruction in the block.
MachineInstr *LastInst = I;
// If there is only one terminator instruction, process it.
if (I == MBB.begin() || !isTerminatorInstr((--I)->getOpcode())) {
if (!isBranch(LastInst->getOpcode()))
return true;
// If the block ends with a branch there are 3 possibilities:
// it's an unconditional, conditional, or indirect branch.
if (LastInst->getOpcode() == X86::JMP) {
TBB = LastInst->getOperand(0).getMachineBasicBlock();
return false;
}
X86::CondCode BranchCode = GetCondFromBranchOpc(LastInst->getOpcode());
if (BranchCode == X86::COND_INVALID)
return true; // Can't handle indirect branch.
// Otherwise, block ends with fall-through condbranch.
TBB = LastInst->getOperand(0).getMachineBasicBlock();
Cond.push_back(MachineOperand::CreateImm(BranchCode));
return false;
}
// Get the instruction before it if it's a terminator.
MachineInstr *SecondLastInst = I;
// If there are three terminators, we don't know what sort of block this is.
if (SecondLastInst && I != MBB.begin() &&
isTerminatorInstr((--I)->getOpcode()))
return true;
// If the block ends with X86::JMP and a conditional branch, handle it.
X86::CondCode BranchCode = GetCondFromBranchOpc(SecondLastInst->getOpcode());
if (BranchCode != X86::COND_INVALID && LastInst->getOpcode() == X86::JMP) {
TBB = SecondLastInst->getOperand(0).getMachineBasicBlock();
Cond.push_back(MachineOperand::CreateImm(BranchCode));
FBB = LastInst->getOperand(0).getMachineBasicBlock();
return false;
}
// Otherwise, can't handle this.
return true;
}
void X86InstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator I = MBB.end();
if (I == MBB.begin()) return;
--I;
if (I->getOpcode() != X86::JMP &&
GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID)
return;
// Remove the branch.
I->eraseFromParent();
I = MBB.end();
if (I == MBB.begin()) return;
--I;
if (GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID)
return;
// Remove the branch.
I->eraseFromParent();
}
void X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const std::vector<MachineOperand> &Cond) const {
// Shouldn't be a fall through.
assert(TBB && "InsertBranch must not be told to insert a fallthrough");
assert((Cond.size() == 1 || Cond.size() == 0) &&
"X86 branch conditions have one component!");
if (FBB == 0) { // One way branch.
if (Cond.empty()) {
// Unconditional branch?
BuildMI(&MBB, get(X86::JMP)).addMBB(TBB);
} else {
// Conditional branch.
unsigned Opc = GetCondBranchFromCond((X86::CondCode)Cond[0].getImm());
BuildMI(&MBB, get(Opc)).addMBB(TBB);
}
return;
}
// Two-way Conditional branch.
unsigned Opc = GetCondBranchFromCond((X86::CondCode)Cond[0].getImm());
BuildMI(&MBB, get(Opc)).addMBB(TBB);
BuildMI(&MBB, get(X86::JMP)).addMBB(FBB);
}
bool X86InstrInfo::BlockHasNoFallThrough(MachineBasicBlock &MBB) const {
if (MBB.empty()) return false;
switch (MBB.back().getOpcode()) {
case X86::JMP: // Uncond branch.
case X86::JMP32r: // Indirect branch.
case X86::JMP32m: // Indirect branch through mem.
return true;
default: return false;
}
}
bool X86InstrInfo::
ReverseBranchCondition(std::vector<MachineOperand> &Cond) const {
assert(Cond.size() == 1 && "Invalid X86 branch condition!");
Cond[0].setImm(GetOppositeBranchCondition((X86::CondCode)Cond[0].getImm()));
return false;
}
const TargetRegisterClass *X86InstrInfo::getPointerRegClass() const {
const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>();
if (Subtarget->is64Bit())
return &X86::GR64RegClass;
else
return &X86::GR32RegClass;
}
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