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//=======- MBlazeFrameInfo.cpp - MBlaze Frame 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 MBlaze implementation of TargetFrameInfo class.
//
//===----------------------------------------------------------------------===//
#include "MBlazeFrameInfo.h"
#include "MBlazeInstrInfo.h"
#include "MBlazeMachineFunction.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
//
// Stack Frame Processing methods
// +----------------------------+
//
// The stack is allocated decrementing the stack pointer on
// the first instruction of a function prologue. Once decremented,
// all stack references are are done through a positive offset
// from the stack/frame pointer, so the stack is considered
// to grow up.
//
//===----------------------------------------------------------------------===//
// 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 MBlazeFrameInfo::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
return DisableFramePointerElim(MF) || MFI->hasVarSizedObjects();
}
void MBlazeFrameInfo::adjustMBlazeStackFrame(MachineFunction &MF) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
// See the description at MicroBlazeMachineFunction.h
int TopCPUSavedRegOff = -1;
// 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 = MFI->getStackSize();
unsigned RegSize = 4;
// 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.
MBlazeFI->adjustLoadArgsFI(MFI);
MBlazeFI->adjustStoreVarArgsFI(MFI);
if (hasFP(MF)) {
MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
StackOffset);
MBlazeFI->setFPStackOffset(StackOffset);
TopCPUSavedRegOff = StackOffset;
StackOffset += RegSize;
}
if (MFI->adjustsStack()) {
MBlazeFI->setRAStackOffset(0);
MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
StackOffset);
TopCPUSavedRegOff = StackOffset;
StackOffset += RegSize;
}
// 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)
MBlazeFI->setCPUTopSavedRegOff(TopCPUSavedRegOff-StackOffset);
}
void MBlazeFrameInfo::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
MachineFrameInfo *MFI = MF.getFrameInfo();
const MBlazeInstrInfo &TII =
*static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
// Get the right frame order for MBlaze.
adjustMBlazeStackFrame(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->adjustsStack()) return;
if (StackSize < 28 && MFI->adjustsStack()) StackSize = 28;
int FPOffset = MBlazeFI->getFPStackOffset();
int RAOffset = MBlazeFI->getRAStackOffset();
// Adjust stack : addi R1, R1, -imm
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADDI), MBlaze::R1)
.addReg(MBlaze::R1).addImm(-StackSize);
// Save the return address only if the function isnt a leaf one.
// swi R15, R1, stack_loc
if (MFI->adjustsStack()) {
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
.addReg(MBlaze::R15).addReg(MBlaze::R1).addImm(RAOffset);
}
// if framepointer enabled, save it and set it
// to point to the stack pointer
if (hasFP(MF)) {
// swi R19, R1, stack_loc
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
.addReg(MBlaze::R19).addReg(MBlaze::R1).addImm(FPOffset);
// add R19, R1, R0
BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADD), MBlaze::R19)
.addReg(MBlaze::R1).addReg(MBlaze::R0);
}
}
void MBlazeFrameInfo::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = prior(MBB.end());
MachineFrameInfo *MFI = MF.getFrameInfo();
MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
const MBlazeInstrInfo &TII =
*static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
DebugLoc dl = MBBI->getDebugLoc();
// Get the FI's where RA and FP are saved.
int FPOffset = MBlazeFI->getFPStackOffset();
int RAOffset = MBlazeFI->getRAStackOffset();
// if framepointer enabled, restore it and restore the
// stack pointer
if (hasFP(MF)) {
// add R1, R19, R0
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADD), MBlaze::R1)
.addReg(MBlaze::R19).addReg(MBlaze::R0);
// lwi R19, R1, stack_loc
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R19)
.addReg(MBlaze::R1).addImm(FPOffset);
}
// Restore the return address only if the function isnt a leaf one.
// lwi R15, R1, stack_loc
if (MFI->adjustsStack()) {
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R15)
.addReg(MBlaze::R1).addImm(RAOffset);
}
// Get the number of bytes from FrameInfo
int StackSize = (int) MFI->getStackSize();
if (StackSize < 28 && MFI->adjustsStack()) StackSize = 28;
// adjust stack.
// addi R1, R1, imm
if (StackSize) {
BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADDI), MBlaze::R1)
.addReg(MBlaze::R1).addImm(StackSize);
}
}
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