llvm-6502/lib/Target/Mips/MipsInstrInfo.cpp
Akira Hatanaka 648f00c2f0 Add an option to use a virtual register as the global base register instead of
reserving a physical register ($gp or $28) for that purpose.

This will completely eliminate loads that restore the value of $gp after every
function call, if the register allocator assigns a callee-saved register, or
eliminate unnecessary loads if it assigns a temporary register. 

example:

.cpload $25       // set $gp.
...
.cprestore 16     // store $gp to stack slot 16($sp).
...
jalr $25          // function call. clobbers $gp.
lw $gp, 16($sp)   // not emitted if callee-saved reg is chosen.
...
lw $2, 4($gp)
...
jalr $25          // function call.
lw $gp, 16($sp)   // not emitted if $gp is not live after this instruction.
...



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151402 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-24 22:34:47 +00:00

457 lines
15 KiB
C++

//===-- MipsInstrInfo.cpp - Mips Instruction Information ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the Mips implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "MipsInstrInfo.h"
#include "MipsTargetMachine.h"
#include "MipsMachineFunction.h"
#include "InstPrinter/MipsInstPrinter.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/ADT/STLExtras.h"
#define GET_INSTRINFO_CTOR
#include "MipsGenInstrInfo.inc"
using namespace llvm;
MipsInstrInfo::MipsInstrInfo(MipsTargetMachine &tm)
: MipsGenInstrInfo(Mips::ADJCALLSTACKDOWN, Mips::ADJCALLSTACKUP),
TM(tm), IsN64(TM.getSubtarget<MipsSubtarget>().isABI_N64()),
RI(*TM.getSubtargetImpl(), *this),
UncondBrOpc(TM.getRelocationModel() == Reloc::PIC_ ? Mips::B : Mips::J) {}
const MipsRegisterInfo &MipsInstrInfo::getRegisterInfo() const {
return RI;
}
static bool isZeroImm(const MachineOperand &op) {
return op.isImm() && op.getImm() == 0;
}
/// isLoadFromStackSlot - If the specified machine instruction is a direct
/// load from a stack slot, return the virtual or physical register number of
/// the destination along with the FrameIndex of the loaded stack slot. If
/// not, return 0. This predicate must return 0 if the instruction has
/// any side effects other than loading from the stack slot.
unsigned MipsInstrInfo::
isLoadFromStackSlot(const MachineInstr *MI, int &FrameIndex) const
{
unsigned Opc = MI->getOpcode();
if ((Opc == Mips::LW) || (Opc == Mips::LW_P8) || (Opc == Mips::LD) ||
(Opc == Mips::LD_P8) || (Opc == Mips::LWC1) || (Opc == Mips::LWC1_P8) ||
(Opc == Mips::LDC1) || (Opc == Mips::LDC164) ||
(Opc == Mips::LDC164_P8)) {
if ((MI->getOperand(1).isFI()) && // is a stack slot
(MI->getOperand(2).isImm()) && // the imm is zero
(isZeroImm(MI->getOperand(2)))) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
}
return 0;
}
/// isStoreToStackSlot - If the specified machine instruction is a direct
/// store to a stack slot, return the virtual or physical register number of
/// the source reg along with the FrameIndex of the loaded stack slot. If
/// not, return 0. This predicate must return 0 if the instruction has
/// any side effects other than storing to the stack slot.
unsigned MipsInstrInfo::
isStoreToStackSlot(const MachineInstr *MI, int &FrameIndex) const
{
unsigned Opc = MI->getOpcode();
if ((Opc == Mips::SW) || (Opc == Mips::SW_P8) || (Opc == Mips::SD) ||
(Opc == Mips::SD_P8) || (Opc == Mips::SWC1) || (Opc == Mips::SWC1_P8) ||
(Opc == Mips::SDC1) || (Opc == Mips::SDC164) ||
(Opc == Mips::SDC164_P8)) {
if ((MI->getOperand(1).isFI()) && // is a stack slot
(MI->getOperand(2).isImm()) && // the imm is zero
(isZeroImm(MI->getOperand(2)))) {
FrameIndex = MI->getOperand(1).getIndex();
return MI->getOperand(0).getReg();
}
}
return 0;
}
/// insertNoop - If data hazard condition is found insert the target nop
/// instruction.
void MipsInstrInfo::
insertNoop(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI) const
{
DebugLoc DL;
BuildMI(MBB, MI, DL, get(Mips::NOP));
}
void MipsInstrInfo::
copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, DebugLoc DL,
unsigned DestReg, unsigned SrcReg,
bool KillSrc) const {
unsigned Opc = 0, ZeroReg = 0;
if (Mips::CPURegsRegClass.contains(DestReg)) { // Copy to CPU Reg.
if (Mips::CPURegsRegClass.contains(SrcReg))
Opc = Mips::ADDu, ZeroReg = Mips::ZERO;
else if (Mips::CCRRegClass.contains(SrcReg))
Opc = Mips::CFC1;
else if (Mips::FGR32RegClass.contains(SrcReg))
Opc = Mips::MFC1;
else if (SrcReg == Mips::HI)
Opc = Mips::MFHI, SrcReg = 0;
else if (SrcReg == Mips::LO)
Opc = Mips::MFLO, SrcReg = 0;
}
else if (Mips::CPURegsRegClass.contains(SrcReg)) { // Copy from CPU Reg.
if (Mips::CCRRegClass.contains(DestReg))
Opc = Mips::CTC1;
else if (Mips::FGR32RegClass.contains(DestReg))
Opc = Mips::MTC1;
else if (DestReg == Mips::HI)
Opc = Mips::MTHI, DestReg = 0;
else if (DestReg == Mips::LO)
Opc = Mips::MTLO, DestReg = 0;
}
else if (Mips::FGR32RegClass.contains(DestReg, SrcReg))
Opc = Mips::FMOV_S;
else if (Mips::AFGR64RegClass.contains(DestReg, SrcReg))
Opc = Mips::FMOV_D32;
else if (Mips::FGR64RegClass.contains(DestReg, SrcReg))
Opc = Mips::FMOV_D64;
else if (Mips::CCRRegClass.contains(DestReg, SrcReg))
Opc = Mips::MOVCCRToCCR;
else if (Mips::CPU64RegsRegClass.contains(DestReg)) { // Copy to CPU64 Reg.
if (Mips::CPU64RegsRegClass.contains(SrcReg))
Opc = Mips::DADDu, ZeroReg = Mips::ZERO_64;
else if (SrcReg == Mips::HI64)
Opc = Mips::MFHI64, SrcReg = 0;
else if (SrcReg == Mips::LO64)
Opc = Mips::MFLO64, SrcReg = 0;
else if (Mips::FGR64RegClass.contains(SrcReg))
Opc = Mips::DMFC1;
}
else if (Mips::CPU64RegsRegClass.contains(SrcReg)) { // Copy from CPU64 Reg.
if (DestReg == Mips::HI64)
Opc = Mips::MTHI64, DestReg = 0;
else if (DestReg == Mips::LO64)
Opc = Mips::MTLO64, DestReg = 0;
else if (Mips::FGR64RegClass.contains(DestReg))
Opc = Mips::DMTC1;
}
assert(Opc && "Cannot copy registers");
MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(Opc));
if (DestReg)
MIB.addReg(DestReg, RegState::Define);
if (ZeroReg)
MIB.addReg(ZeroReg);
if (SrcReg)
MIB.addReg(SrcReg, getKillRegState(KillSrc));
}
static MachineMemOperand* GetMemOperand(MachineBasicBlock &MBB, int FI,
unsigned Flag) {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = *MF.getFrameInfo();
unsigned Align = MFI.getObjectAlignment(FI);
return MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FI), Flag,
MFI.getObjectSize(FI), Align);
}
void MipsInstrInfo::
storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned SrcReg, bool isKill, int FI,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const {
DebugLoc DL;
if (I != MBB.end()) DL = I->getDebugLoc();
MachineMemOperand *MMO = GetMemOperand(MBB, FI, MachineMemOperand::MOStore);
unsigned Opc = 0;
if (RC == Mips::CPURegsRegisterClass)
Opc = IsN64 ? Mips::SW_P8 : Mips::SW;
else if (RC == Mips::CPU64RegsRegisterClass)
Opc = IsN64 ? Mips::SD_P8 : Mips::SD;
else if (RC == Mips::FGR32RegisterClass)
Opc = IsN64 ? Mips::SWC1_P8 : Mips::SWC1;
else if (RC == Mips::AFGR64RegisterClass)
Opc = Mips::SDC1;
else if (RC == Mips::FGR64RegisterClass)
Opc = IsN64 ? Mips::SDC164_P8 : Mips::SDC164;
assert(Opc && "Register class not handled!");
BuildMI(MBB, I, DL, get(Opc)).addReg(SrcReg, getKillRegState(isKill))
.addFrameIndex(FI).addImm(0).addMemOperand(MMO);
}
void MipsInstrInfo::
loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
unsigned DestReg, int FI,
const TargetRegisterClass *RC,
const TargetRegisterInfo *TRI) const
{
DebugLoc DL;
if (I != MBB.end()) DL = I->getDebugLoc();
MachineMemOperand *MMO = GetMemOperand(MBB, FI, MachineMemOperand::MOLoad);
unsigned Opc = 0;
if (RC == Mips::CPURegsRegisterClass)
Opc = IsN64 ? Mips::LW_P8 : Mips::LW;
else if (RC == Mips::CPU64RegsRegisterClass)
Opc = IsN64 ? Mips::LD_P8 : Mips::LD;
else if (RC == Mips::FGR32RegisterClass)
Opc = IsN64 ? Mips::LWC1_P8 : Mips::LWC1;
else if (RC == Mips::AFGR64RegisterClass)
Opc = Mips::LDC1;
else if (RC == Mips::FGR64RegisterClass)
Opc = IsN64 ? Mips::LDC164_P8 : Mips::LDC164;
assert(Opc && "Register class not handled!");
BuildMI(MBB, I, DL, get(Opc), DestReg).addFrameIndex(FI).addImm(0)
.addMemOperand(MMO);
}
MachineInstr*
MipsInstrInfo::emitFrameIndexDebugValue(MachineFunction &MF, int FrameIx,
uint64_t Offset, const MDNode *MDPtr,
DebugLoc DL) const {
MachineInstrBuilder MIB = BuildMI(MF, DL, get(Mips::DBG_VALUE))
.addFrameIndex(FrameIx).addImm(0).addImm(Offset).addMetadata(MDPtr);
return &*MIB;
}
//===----------------------------------------------------------------------===//
// Branch Analysis
//===----------------------------------------------------------------------===//
static unsigned GetAnalyzableBrOpc(unsigned Opc) {
return (Opc == Mips::BEQ || Opc == Mips::BNE || Opc == Mips::BGTZ ||
Opc == Mips::BGEZ || Opc == Mips::BLTZ || Opc == Mips::BLEZ ||
Opc == Mips::BEQ64 || Opc == Mips::BNE64 || Opc == Mips::BGTZ64 ||
Opc == Mips::BGEZ64 || Opc == Mips::BLTZ64 || Opc == Mips::BLEZ64 ||
Opc == Mips::BC1T || Opc == Mips::BC1F || Opc == Mips::B ||
Opc == Mips::J) ?
Opc : 0;
}
/// GetOppositeBranchOpc - Return the inverse of the specified
/// opcode, e.g. turning BEQ to BNE.
unsigned Mips::GetOppositeBranchOpc(unsigned Opc)
{
switch (Opc) {
default: llvm_unreachable("Illegal opcode!");
case Mips::BEQ: return Mips::BNE;
case Mips::BNE: return Mips::BEQ;
case Mips::BGTZ: return Mips::BLEZ;
case Mips::BGEZ: return Mips::BLTZ;
case Mips::BLTZ: return Mips::BGEZ;
case Mips::BLEZ: return Mips::BGTZ;
case Mips::BEQ64: return Mips::BNE64;
case Mips::BNE64: return Mips::BEQ64;
case Mips::BGTZ64: return Mips::BLEZ64;
case Mips::BGEZ64: return Mips::BLTZ64;
case Mips::BLTZ64: return Mips::BGEZ64;
case Mips::BLEZ64: return Mips::BGTZ64;
case Mips::BC1T: return Mips::BC1F;
case Mips::BC1F: return Mips::BC1T;
}
}
static void AnalyzeCondBr(const MachineInstr* Inst, unsigned Opc,
MachineBasicBlock *&BB,
SmallVectorImpl<MachineOperand>& Cond) {
assert(GetAnalyzableBrOpc(Opc) && "Not an analyzable branch");
int NumOp = Inst->getNumExplicitOperands();
// for both int and fp branches, the last explicit operand is the
// MBB.
BB = Inst->getOperand(NumOp-1).getMBB();
Cond.push_back(MachineOperand::CreateImm(Opc));
for (int i=0; i<NumOp-1; i++)
Cond.push_back(Inst->getOperand(i));
}
bool MipsInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify) const
{
MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
// Skip all the debug instructions.
while (I != REnd && I->isDebugValue())
++I;
if (I == REnd || !isUnpredicatedTerminator(&*I)) {
// If this block ends with no branches (it just falls through to its succ)
// just return false, leaving TBB/FBB null.
TBB = FBB = NULL;
return false;
}
MachineInstr *LastInst = &*I;
unsigned LastOpc = LastInst->getOpcode();
// Not an analyzable branch (must be an indirect jump).
if (!GetAnalyzableBrOpc(LastOpc))
return true;
// Get the second to last instruction in the block.
unsigned SecondLastOpc = 0;
MachineInstr *SecondLastInst = NULL;
if (++I != REnd) {
SecondLastInst = &*I;
SecondLastOpc = GetAnalyzableBrOpc(SecondLastInst->getOpcode());
// Not an analyzable branch (must be an indirect jump).
if (isUnpredicatedTerminator(SecondLastInst) && !SecondLastOpc)
return true;
}
// If there is only one terminator instruction, process it.
if (!SecondLastOpc) {
// Unconditional branch
if (LastOpc == UncondBrOpc) {
TBB = LastInst->getOperand(0).getMBB();
return false;
}
// Conditional branch
AnalyzeCondBr(LastInst, LastOpc, TBB, Cond);
return false;
}
// If we reached here, there are two branches.
// If there are three terminators, we don't know what sort of block this is.
if (++I != REnd && isUnpredicatedTerminator(&*I))
return true;
// If second to last instruction is an unconditional branch,
// analyze it and remove the last instruction.
if (SecondLastOpc == UncondBrOpc) {
// Return if the last instruction cannot be removed.
if (!AllowModify)
return true;
TBB = SecondLastInst->getOperand(0).getMBB();
LastInst->eraseFromParent();
return false;
}
// Conditional branch followed by an unconditional branch.
// The last one must be unconditional.
if (LastOpc != UncondBrOpc)
return true;
AnalyzeCondBr(SecondLastInst, SecondLastOpc, TBB, Cond);
FBB = LastInst->getOperand(0).getMBB();
return false;
}
void MipsInstrInfo::BuildCondBr(MachineBasicBlock &MBB,
MachineBasicBlock *TBB, DebugLoc DL,
const SmallVectorImpl<MachineOperand>& Cond)
const {
unsigned Opc = Cond[0].getImm();
const MCInstrDesc &MCID = get(Opc);
MachineInstrBuilder MIB = BuildMI(&MBB, DL, MCID);
for (unsigned i = 1; i < Cond.size(); ++i)
MIB.addReg(Cond[i].getReg());
MIB.addMBB(TBB);
}
unsigned MipsInstrInfo::
InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
const SmallVectorImpl<MachineOperand> &Cond,
DebugLoc DL) const {
// Shouldn't be a fall through.
assert(TBB && "InsertBranch must not be told to insert a fallthrough");
// # of condition operands:
// Unconditional branches: 0
// Floating point branches: 1 (opc)
// Int BranchZero: 2 (opc, reg)
// Int Branch: 3 (opc, reg0, reg1)
assert((Cond.size() <= 3) &&
"# of Mips branch conditions must be <= 3!");
// Two-way Conditional branch.
if (FBB) {
BuildCondBr(MBB, TBB, DL, Cond);
BuildMI(&MBB, DL, get(UncondBrOpc)).addMBB(FBB);
return 2;
}
// One way branch.
// Unconditional branch.
if (Cond.empty())
BuildMI(&MBB, DL, get(UncondBrOpc)).addMBB(TBB);
else // Conditional branch.
BuildCondBr(MBB, TBB, DL, Cond);
return 1;
}
unsigned MipsInstrInfo::
RemoveBranch(MachineBasicBlock &MBB) const
{
MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
MachineBasicBlock::reverse_iterator FirstBr;
unsigned removed;
// Skip all the debug instructions.
while (I != REnd && I->isDebugValue())
++I;
FirstBr = I;
// Up to 2 branches are removed.
// Note that indirect branches are not removed.
for(removed = 0; I != REnd && removed < 2; ++I, ++removed)
if (!GetAnalyzableBrOpc(I->getOpcode()))
break;
MBB.erase(I.base(), FirstBr.base());
return removed;
}
/// ReverseBranchCondition - Return the inverse opcode of the
/// specified Branch instruction.
bool MipsInstrInfo::
ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const
{
assert( (Cond.size() && Cond.size() <= 3) &&
"Invalid Mips branch condition!");
Cond[0].setImm(Mips::GetOppositeBranchOpc(Cond[0].getImm()));
return false;
}