llvm-6502/lib/Target/Mips/MipsRegisterInfo.cpp
Bruno Cardoso Lopes 7da151cd5d Added Mips support for DYNAMIC_STACKALLOC
Fixed bug in adjustMipsStackFrame, which was breaking
while trying to access a dead stack object index. Also added
one more alignment before fixing the callee saved registers
stack offset adjustment.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54485 91177308-0d34-0410-b5e6-96231b3b80d8
2008-08-07 19:08:11 +00:00

526 lines
18 KiB
C++

//===- MipsRegisterInfo.cpp - MIPS Register Information -== -----*- C++ -*-===//
//
// 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 TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "mips-reg-info"
#include "Mips.h"
#include "MipsSubtarget.h"
#include "MipsRegisterInfo.h"
#include "MipsMachineFunction.h"
#include "llvm/Constants.h"
#include "llvm/Type.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineLocation.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
MipsRegisterInfo::MipsRegisterInfo(const MipsSubtarget &ST,
const TargetInstrInfo &tii)
: MipsGenRegisterInfo(Mips::ADJCALLSTACKDOWN, Mips::ADJCALLSTACKUP),
Subtarget(ST), TII(tii) {}
/// getRegisterNumbering - Given the enum value for some register, e.g.
/// Mips::RA, return the number that it corresponds to (e.g. 31).
unsigned MipsRegisterInfo::
getRegisterNumbering(unsigned RegEnum)
{
switch (RegEnum) {
case Mips::ZERO : case Mips::F0 : case Mips::D0 : return 0;
case Mips::AT : case Mips::F1 : return 1;
case Mips::V0 : case Mips::F2 : case Mips::D1 : return 2;
case Mips::V1 : case Mips::F3 : return 3;
case Mips::A0 : case Mips::F4 : case Mips::D2 : return 4;
case Mips::A1 : case Mips::F5 : return 5;
case Mips::A2 : case Mips::F6 : case Mips::D3 : return 6;
case Mips::A3 : case Mips::F7 : return 7;
case Mips::T0 : case Mips::F8 : case Mips::D4 : return 8;
case Mips::T1 : case Mips::F9 : return 9;
case Mips::T2 : case Mips::F10: case Mips::D5: return 10;
case Mips::T3 : case Mips::F11: return 11;
case Mips::T4 : case Mips::F12: case Mips::D6: return 12;
case Mips::T5 : case Mips::F13: return 13;
case Mips::T6 : case Mips::F14: case Mips::D7: return 14;
case Mips::T7 : case Mips::F15: return 15;
case Mips::T8 : case Mips::F16: case Mips::D8: return 16;
case Mips::T9 : case Mips::F17: return 17;
case Mips::S0 : case Mips::F18: case Mips::D9: return 18;
case Mips::S1 : case Mips::F19: return 19;
case Mips::S2 : case Mips::F20: case Mips::D10: return 20;
case Mips::S3 : case Mips::F21: return 21;
case Mips::S4 : case Mips::F22: case Mips::D11: return 22;
case Mips::S5 : case Mips::F23: return 23;
case Mips::S6 : case Mips::F24: case Mips::D12: return 24;
case Mips::S7 : case Mips::F25: return 25;
case Mips::K0 : case Mips::F26: case Mips::D13: return 26;
case Mips::K1 : case Mips::F27: return 27;
case Mips::GP : case Mips::F28: case Mips::D14: return 28;
case Mips::SP : case Mips::F29: return 29;
case Mips::FP : case Mips::F30: case Mips::D15: return 30;
case Mips::RA : case Mips::F31: return 31;
default: assert(0 && "Unknown register number!");
}
return 0; // Not reached
}
unsigned MipsRegisterInfo::getPICCallReg(void) { return Mips::T9; }
//===----------------------------------------------------------------------===//
// Callee Saved Registers methods
//===----------------------------------------------------------------------===//
/// Mips Callee Saved Registers
const unsigned* MipsRegisterInfo::
getCalleeSavedRegs(const MachineFunction *MF) const
{
// Mips callee-save register range is $16-$23, $f20-$f30
static const unsigned SingleFloatOnlyCalleeSavedRegs[] = {
Mips::S0, Mips::S1, Mips::S2, Mips::S3,
Mips::S4, Mips::S5, Mips::S6, Mips::S7,
Mips::F20, Mips::F21, Mips::F22, Mips::F23, Mips::F24, Mips::F25,
Mips::F26, Mips::F27, Mips::F28, Mips::F29, Mips::F30, 0
};
static const unsigned BitMode32CalleeSavedRegs[] = {
Mips::S0, Mips::S1, Mips::S2, Mips::S3,
Mips::S4, Mips::S5, Mips::S6, Mips::S7,
Mips::F20, Mips::F22, Mips::F24, Mips::F26, Mips::F28, Mips::F30,
Mips::D10, Mips::D11, Mips::D12, Mips::D13, Mips::D14, Mips::D15,0
};
if (Subtarget.isSingleFloat())
return SingleFloatOnlyCalleeSavedRegs;
else
return BitMode32CalleeSavedRegs;
}
/// Mips Callee Saved Register Classes
const TargetRegisterClass* const*
MipsRegisterInfo::getCalleeSavedRegClasses(const MachineFunction *MF) const
{
static const TargetRegisterClass * const SingleFloatOnlyCalleeSavedRC[] = {
&Mips::CPURegsRegClass, &Mips::CPURegsRegClass, &Mips::CPURegsRegClass,
&Mips::CPURegsRegClass, &Mips::CPURegsRegClass, &Mips::CPURegsRegClass,
&Mips::CPURegsRegClass, &Mips::CPURegsRegClass,
&Mips::FGR32RegClass, &Mips::FGR32RegClass, &Mips::FGR32RegClass,
&Mips::FGR32RegClass, &Mips::FGR32RegClass, &Mips::FGR32RegClass,
&Mips::FGR32RegClass, &Mips::FGR32RegClass, &Mips::FGR32RegClass,
&Mips::FGR32RegClass, &Mips::FGR32RegClass, 0
};
static const TargetRegisterClass * const BitMode32CalleeSavedRC[] = {
&Mips::CPURegsRegClass, &Mips::CPURegsRegClass, &Mips::CPURegsRegClass,
&Mips::CPURegsRegClass, &Mips::CPURegsRegClass, &Mips::CPURegsRegClass,
&Mips::CPURegsRegClass, &Mips::CPURegsRegClass,
&Mips::AFGR32RegClass, &Mips::AFGR32RegClass, &Mips::AFGR32RegClass,
&Mips::AFGR32RegClass, &Mips::AFGR32RegClass, &Mips::AFGR32RegClass,
&Mips::AFGR64RegClass, &Mips::AFGR64RegClass, &Mips::AFGR64RegClass,
&Mips::AFGR64RegClass, &Mips::AFGR64RegClass, &Mips::AFGR64RegClass, 0
};
if (Subtarget.isSingleFloat())
return SingleFloatOnlyCalleeSavedRC;
else
return BitMode32CalleeSavedRC;
}
BitVector MipsRegisterInfo::
getReservedRegs(const MachineFunction &MF) const
{
BitVector Reserved(getNumRegs());
Reserved.set(Mips::ZERO);
Reserved.set(Mips::AT);
Reserved.set(Mips::K0);
Reserved.set(Mips::K1);
Reserved.set(Mips::GP);
Reserved.set(Mips::SP);
Reserved.set(Mips::FP);
Reserved.set(Mips::RA);
return Reserved;
}
//===----------------------------------------------------------------------===//
//
// Stack Frame Processing methods
// +----------------------------+
//
// The stack is allocated decrementing the stack pointer on
// the first instruction of a function prologue. Once decremented,
// all stack referencesare are done thought a positive offset
// from the stack/frame pointer, so the stack is considering
// to grow up! Otherwise terrible hacks would have to be made
// to get this stack ABI compliant :)
//
// The stack frame required by the ABI (after call):
// Offset
//
// 0 ----------
// 4 Args to pass
// . saved $GP (used in PIC)
// . Alloca allocations
// . Local Area
// . CPU "Callee Saved" Registers
// . saved FP
// . saved RA
// . FPU "Callee Saved" Registers
// StackSize -----------
//
// Offset - offset from sp after stack allocation on function prologue
//
// The sp is the stack pointer subtracted/added from the stack size
// at the Prologue/Epilogue
//
// References to the previous stack (to obtain arguments) are done
// with offsets that exceeds the stack size: (stacksize+(4*(num_arg-1))
//
// Examples:
// - reference to the actual stack frame
// for any local area var there is smt like : FI >= 0, StackOffset: 4
// sw REGX, 4(SP)
//
// - reference to previous stack frame
// suppose there's a load to the 5th arguments : FI < 0, StackOffset: 16.
// The emitted instruction will be something like:
// lw REGX, 16+StackSize(SP)
//
// Since the total stack size is unknown on LowerFORMAL_ARGUMENTS, all
// stack references (ObjectOffset) created to reference the function
// arguments, are negative numbers. This way, on eliminateFrameIndex it's
// possible to detect those references and the offsets are adjusted to
// their real location.
//
//===----------------------------------------------------------------------===//
void MipsRegisterInfo::adjustMipsStackFrame(MachineFunction &MF) const
{
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
unsigned StackAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
// Min and Max CSI FrameIndex.
int MinCSFI = -1, MaxCSFI = -1;
// See the description at MipsMachineFunction.h
int TopCPUSavedRegOff = -1, TopFPUSavedRegOff = -1;
// Replace the dummy '0' SPOffset by the negative offsets, as explained on
// LowerFORMAL_ARGUMENTS. Leaving '0' for while is necessary to avoid
// the approach done by calculateFrameObjectOffsets to the stack frame.
MipsFI->adjustLoadArgsFI(MFI);
MipsFI->adjustStoreVarArgsFI(MFI);
// It happens that the default stack frame allocation order does not directly
// map to the convention used for mips. So we must fix it. We move the callee
// save register slots after the local variables area, as described in the
// stack frame above.
unsigned CalleeSavedAreaSize = 0;
if (!CSI.empty()) {
MinCSFI = CSI[0].getFrameIdx();
MaxCSFI = CSI[CSI.size()-1].getFrameIdx();
}
for (unsigned i = 0, e = CSI.size(); i != e; ++i)
CalleeSavedAreaSize += MFI->getObjectAlignment(CSI[i].getFrameIdx());
// Adjust local variables. They should come on the stack right
// after the arguments.
int LastOffsetFI = -1;
for (int i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
if (i >= MinCSFI && i <= MaxCSFI)
continue;
if (MFI->isDeadObjectIndex(i))
continue;
unsigned Offset = MFI->getObjectOffset(i) - CalleeSavedAreaSize;
if (LastOffsetFI == -1)
LastOffsetFI = i;
if (Offset > MFI->getObjectOffset(LastOffsetFI))
LastOffsetFI = i;
MFI->setObjectOffset(i, Offset);
}
// Adjust CPU Callee Saved Registers Area. Registers RA and FP must
// be saved in this CPU Area there is the need. This whole Area must
// be aligned to the default Stack Alignment requirements.
unsigned StackOffset = 0;
unsigned RegSize = Subtarget.isGP32bit() ? 4 : 8;
if (LastOffsetFI >= 0)
StackOffset = MFI->getObjectOffset(LastOffsetFI)+
MFI->getObjectAlignment(LastOffsetFI);
StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
for (unsigned i = 0, e = CSI.size(); i != e ; ++i) {
if (CSI[i].getRegClass() != Mips::CPURegsRegisterClass)
break;
MFI->setObjectOffset(CSI[i].getFrameIdx(), StackOffset);
TopCPUSavedRegOff = StackOffset;
StackOffset += MFI->getObjectAlignment(CSI[i].getFrameIdx());
}
if (hasFP(MF)) {
MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize),
StackOffset);
MipsFI->setFPStackOffset(StackOffset);
TopCPUSavedRegOff = StackOffset;
StackOffset += RegSize;
}
if (MFI->hasCalls()) {
MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize),
StackOffset);
MipsFI->setRAStackOffset(StackOffset);
TopCPUSavedRegOff = StackOffset;
StackOffset += RegSize;
}
StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
// Adjust FPU Callee Saved Registers Area. This Area must be
// aligned to the default Stack Alignment requirements.
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
if (CSI[i].getRegClass() == Mips::CPURegsRegisterClass)
continue;
MFI->setObjectOffset(CSI[i].getFrameIdx(), StackOffset);
TopFPUSavedRegOff = StackOffset;
StackOffset += MFI->getObjectAlignment(CSI[i].getFrameIdx());
}
StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
// Update frame info
MFI->setStackSize(StackOffset);
// Recalculate the final tops offset. The final values must be '0'
// if there isn't a callee saved register for CPU or FPU, otherwise
// a negative offset is needed.
if (TopCPUSavedRegOff >= 0)
MipsFI->setCPUTopSavedRegOff(TopCPUSavedRegOff-StackOffset);
if (TopFPUSavedRegOff >= 0)
MipsFI->setFPUTopSavedRegOff(TopFPUSavedRegOff-StackOffset);
}
// hasFP - Return true if the specified function should have a dedicated frame
// pointer register. This is true if the function has variable sized allocas or
// if frame pointer elimination is disabled.
bool MipsRegisterInfo::
hasFP(const MachineFunction &MF) const {
return (NoFramePointerElim || MF.getFrameInfo()->hasVarSizedObjects());
}
// This function eliminate ADJCALLSTACKDOWN,
// ADJCALLSTACKUP pseudo instructions
void MipsRegisterInfo::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
// Simply discard ADJCALLSTACKDOWN, ADJCALLSTACKUP instructions.
MBB.erase(I);
}
// FrameIndex represent objects inside a abstract stack.
// We must replace FrameIndex with an stack/frame pointer
// direct reference.
void MipsRegisterInfo::
eliminateFrameIndex(MachineBasicBlock::iterator II, int SPAdj,
RegScavenger *RS) const
{
MachineInstr &MI = *II;
MachineFunction &MF = *MI.getParent()->getParent();
unsigned i = 0;
while (!MI.getOperand(i).isFrameIndex()) {
++i;
assert(i < MI.getNumOperands() &&
"Instr doesn't have FrameIndex operand!");
}
#ifndef NDEBUG
DOUT << "\nFunction : " << MF.getFunction()->getName() << "\n";
DOUT << "<--------->\n";
MI.print(DOUT);
#endif
int FrameIndex = MI.getOperand(i).getIndex();
int stackSize = MF.getFrameInfo()->getStackSize();
int spOffset = MF.getFrameInfo()->getObjectOffset(FrameIndex);
#ifndef NDEBUG
DOUT << "FrameIndex : " << FrameIndex << "\n";
DOUT << "spOffset : " << spOffset << "\n";
DOUT << "stackSize : " << stackSize << "\n";
#endif
// as explained on LowerFORMAL_ARGUMENTS, detect negative offsets
// and adjust SPOffsets considering the final stack size.
int Offset = ((spOffset < 0) ? (stackSize + (-(spOffset+4))) : (spOffset));
Offset += MI.getOperand(i-1).getImm();
#ifndef NDEBUG
DOUT << "Offset : " << Offset << "\n";
DOUT << "<--------->\n";
#endif
MI.getOperand(i-1).ChangeToImmediate(Offset);
MI.getOperand(i).ChangeToRegister(getFrameRegister(MF), false);
}
void MipsRegisterInfo::
emitPrologue(MachineFunction &MF) const
{
MachineBasicBlock &MBB = MF.front();
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.begin();
bool isPIC = (MF.getTarget().getRelocationModel() == Reloc::PIC_);
// Get the right frame order for Mips.
adjustMipsStackFrame(MF);
// Get the number of bytes to allocate from the FrameInfo.
unsigned StackSize = MFI->getStackSize();
// No need to allocate space on the stack.
if (StackSize == 0 && !MFI->hasCalls()) return;
int FPOffset = MipsFI->getFPStackOffset();
int RAOffset = MipsFI->getRAStackOffset();
BuildMI(MBB, MBBI, TII.get(Mips::NOREORDER));
// TODO: check need from GP here.
if (isPIC && Subtarget.isABI_O32())
BuildMI(MBB, MBBI, TII.get(Mips::CPLOAD)).addReg(getPICCallReg());
BuildMI(MBB, MBBI, TII.get(Mips::NOMACRO));
// Adjust stack : addi sp, sp, (-imm)
BuildMI(MBB, MBBI, TII.get(Mips::ADDiu), Mips::SP)
.addReg(Mips::SP).addImm(-StackSize);
// Save the return address only if the function isnt a leaf one.
// sw $ra, stack_loc($sp)
if (MFI->hasCalls()) {
BuildMI(MBB, MBBI, TII.get(Mips::SW))
.addReg(Mips::RA).addImm(RAOffset).addReg(Mips::SP);
}
// if framepointer enabled, save it and set it
// to point to the stack pointer
if (hasFP(MF)) {
// sw $fp,stack_loc($sp)
BuildMI(MBB, MBBI, TII.get(Mips::SW))
.addReg(Mips::FP).addImm(FPOffset).addReg(Mips::SP);
// move $fp, $sp
BuildMI(MBB, MBBI, TII.get(Mips::ADDu), Mips::FP)
.addReg(Mips::SP).addReg(Mips::ZERO);
}
// PIC speficic function prologue
if ((isPIC) && (MFI->hasCalls())) {
BuildMI(MBB, MBBI, TII.get(Mips::CPRESTORE))
.addImm(MipsFI->getGPStackOffset());
}
}
void MipsRegisterInfo::
emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const
{
MachineBasicBlock::iterator MBBI = prior(MBB.end());
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
// Get the number of bytes from FrameInfo
int NumBytes = (int) MFI->getStackSize();
// Get the FI's where RA and FP are saved.
int FPOffset = MipsFI->getFPStackOffset();
int RAOffset = MipsFI->getRAStackOffset();
// if framepointer enabled, restore it and restore the
// stack pointer
if (hasFP(MF)) {
// move $sp, $fp
BuildMI(MBB, MBBI, TII.get(Mips::ADDu), Mips::SP)
.addReg(Mips::FP).addReg(Mips::ZERO);
// lw $fp,stack_loc($sp)
BuildMI(MBB, MBBI, TII.get(Mips::LW))
.addReg(Mips::FP).addImm(FPOffset).addReg(Mips::SP);
}
// Restore the return address only if the function isnt a leaf one.
// lw $ra, stack_loc($sp)
if (MFI->hasCalls()) {
BuildMI(MBB, MBBI, TII.get(Mips::LW))
.addReg(Mips::RA).addImm(RAOffset).addReg(Mips::SP);
}
// adjust stack : insert addi sp, sp, (imm)
if (NumBytes) {
BuildMI(MBB, MBBI, TII.get(Mips::ADDiu), Mips::SP)
.addReg(Mips::SP).addImm(NumBytes);
}
}
void MipsRegisterInfo::
processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
// Set the SPOffset on the FI where GP must be saved/loaded.
MachineFrameInfo *MFI = MF.getFrameInfo();
bool isPIC = (MF.getTarget().getRelocationModel() == Reloc::PIC_);
if (MFI->hasCalls() && isPIC) {
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
MFI->setObjectOffset(MipsFI->getGPFI(), MipsFI->getGPStackOffset());
}
}
unsigned MipsRegisterInfo::
getRARegister() const {
return Mips::RA;
}
unsigned MipsRegisterInfo::
getFrameRegister(MachineFunction &MF) const {
return hasFP(MF) ? Mips::FP : Mips::SP;
}
unsigned MipsRegisterInfo::
getEHExceptionRegister() const {
assert(0 && "What is the exception register");
return 0;
}
unsigned MipsRegisterInfo::
getEHHandlerRegister() const {
assert(0 && "What is the exception handler register");
return 0;
}
int MipsRegisterInfo::
getDwarfRegNum(unsigned RegNum, bool isEH) const {
assert(0 && "What is the dwarf register number");
return -1;
}
#include "MipsGenRegisterInfo.inc"