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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119740 91177308-0d34-0410-b5e6-96231b3b80d8
186 lines
6.6 KiB
C++
186 lines
6.6 KiB
C++
//=======- MBlazeFrameInfo.cpp - MBlaze Frame Information ------*- C++ -*-====//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the MBlaze implementation of TargetFrameInfo class.
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//
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//===----------------------------------------------------------------------===//
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#include "MBlazeFrameInfo.h"
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#include "MBlazeInstrInfo.h"
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#include "MBlazeMachineFunction.h"
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#include "llvm/Function.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetOptions.h"
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#include "llvm/Support/CommandLine.h"
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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//
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// Stack Frame Processing methods
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// +----------------------------+
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//
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// The stack is allocated decrementing the stack pointer on
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// the first instruction of a function prologue. Once decremented,
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// all stack references are are done through a positive offset
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// from the stack/frame pointer, so the stack is considered
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// to grow up.
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//
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//===----------------------------------------------------------------------===//
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// hasFP - Return true if the specified function should have a dedicated frame
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// pointer register. This is true if the function has variable sized allocas or
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// if frame pointer elimination is disabled.
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bool MBlazeFrameInfo::hasFP(const MachineFunction &MF) const {
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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return DisableFramePointerElim(MF) || MFI->hasVarSizedObjects();
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}
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void MBlazeFrameInfo::adjustMBlazeStackFrame(MachineFunction &MF) const {
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MachineFrameInfo *MFI = MF.getFrameInfo();
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MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
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// See the description at MicroBlazeMachineFunction.h
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int TopCPUSavedRegOff = -1;
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// Adjust CPU Callee Saved Registers Area. Registers RA and FP must
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// be saved in this CPU Area there is the need. This whole Area must
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// be aligned to the default Stack Alignment requirements.
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unsigned StackOffset = MFI->getStackSize();
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unsigned RegSize = 4;
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// Replace the dummy '0' SPOffset by the negative offsets, as explained on
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// LowerFORMAL_ARGUMENTS. Leaving '0' for while is necessary to avoid
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// the approach done by calculateFrameObjectOffsets to the stack frame.
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MBlazeFI->adjustLoadArgsFI(MFI);
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MBlazeFI->adjustStoreVarArgsFI(MFI);
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if (hasFP(MF)) {
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MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
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StackOffset);
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MBlazeFI->setFPStackOffset(StackOffset);
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TopCPUSavedRegOff = StackOffset;
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StackOffset += RegSize;
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}
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if (MFI->adjustsStack()) {
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MBlazeFI->setRAStackOffset(0);
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MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
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StackOffset);
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TopCPUSavedRegOff = StackOffset;
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StackOffset += RegSize;
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}
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// Update frame info
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MFI->setStackSize(StackOffset);
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// Recalculate the final tops offset. The final values must be '0'
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// if there isn't a callee saved register for CPU or FPU, otherwise
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// a negative offset is needed.
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if (TopCPUSavedRegOff >= 0)
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MBlazeFI->setCPUTopSavedRegOff(TopCPUSavedRegOff-StackOffset);
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}
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void MBlazeFrameInfo::emitPrologue(MachineFunction &MF) const {
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MachineBasicBlock &MBB = MF.front();
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MachineFrameInfo *MFI = MF.getFrameInfo();
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const MBlazeInstrInfo &TII =
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*static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
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MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
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MachineBasicBlock::iterator MBBI = MBB.begin();
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DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
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// Get the right frame order for MBlaze.
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adjustMBlazeStackFrame(MF);
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// Get the number of bytes to allocate from the FrameInfo.
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unsigned StackSize = MFI->getStackSize();
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// No need to allocate space on the stack.
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if (StackSize == 0 && !MFI->adjustsStack()) return;
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if (StackSize < 28 && MFI->adjustsStack()) StackSize = 28;
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int FPOffset = MBlazeFI->getFPStackOffset();
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int RAOffset = MBlazeFI->getRAStackOffset();
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// Adjust stack : addi R1, R1, -imm
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BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADDI), MBlaze::R1)
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.addReg(MBlaze::R1).addImm(-StackSize);
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// Save the return address only if the function isnt a leaf one.
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// swi R15, R1, stack_loc
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if (MFI->adjustsStack()) {
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BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
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.addReg(MBlaze::R15).addReg(MBlaze::R1).addImm(RAOffset);
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}
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// if framepointer enabled, save it and set it
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// to point to the stack pointer
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if (hasFP(MF)) {
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// swi R19, R1, stack_loc
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BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
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.addReg(MBlaze::R19).addReg(MBlaze::R1).addImm(FPOffset);
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// add R19, R1, R0
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BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADD), MBlaze::R19)
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.addReg(MBlaze::R1).addReg(MBlaze::R0);
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}
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}
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void MBlazeFrameInfo::emitEpilogue(MachineFunction &MF,
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MachineBasicBlock &MBB) const {
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MachineBasicBlock::iterator MBBI = prior(MBB.end());
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MachineFrameInfo *MFI = MF.getFrameInfo();
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MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
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const MBlazeInstrInfo &TII =
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*static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
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DebugLoc dl = MBBI->getDebugLoc();
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// Get the FI's where RA and FP are saved.
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int FPOffset = MBlazeFI->getFPStackOffset();
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int RAOffset = MBlazeFI->getRAStackOffset();
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// if framepointer enabled, restore it and restore the
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// stack pointer
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if (hasFP(MF)) {
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// add R1, R19, R0
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BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADD), MBlaze::R1)
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.addReg(MBlaze::R19).addReg(MBlaze::R0);
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// lwi R19, R1, stack_loc
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BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R19)
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.addReg(MBlaze::R1).addImm(FPOffset);
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}
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// Restore the return address only if the function isnt a leaf one.
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// lwi R15, R1, stack_loc
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if (MFI->adjustsStack()) {
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BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R15)
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.addReg(MBlaze::R1).addImm(RAOffset);
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}
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// Get the number of bytes from FrameInfo
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int StackSize = (int) MFI->getStackSize();
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if (StackSize < 28 && MFI->adjustsStack()) StackSize = 28;
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// adjust stack.
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// addi R1, R1, imm
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if (StackSize) {
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BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADDI), MBlaze::R1)
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.addReg(MBlaze::R1).addImm(StackSize);
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}
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}
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