2946cd7010
to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
220 lines
8.1 KiB
C++
220 lines
8.1 KiB
C++
//===-- LanaiFrameLowering.cpp - Lanai Frame Information ------------------===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file contains the Lanai implementation of TargetFrameLowering class.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "LanaiFrameLowering.h"
|
|
|
|
#include "LanaiInstrInfo.h"
|
|
#include "LanaiMachineFunctionInfo.h"
|
|
#include "LanaiSubtarget.h"
|
|
#include "llvm/CodeGen/MachineFrameInfo.h"
|
|
#include "llvm/CodeGen/MachineFunction.h"
|
|
#include "llvm/CodeGen/MachineInstrBuilder.h"
|
|
#include "llvm/CodeGen/MachineRegisterInfo.h"
|
|
#include "llvm/IR/Function.h"
|
|
|
|
using namespace llvm;
|
|
|
|
// Determines the size of the frame and maximum call frame size.
|
|
void LanaiFrameLowering::determineFrameLayout(MachineFunction &MF) const {
|
|
MachineFrameInfo &MFI = MF.getFrameInfo();
|
|
const LanaiRegisterInfo *LRI = STI.getRegisterInfo();
|
|
|
|
// Get the number of bytes to allocate from the FrameInfo.
|
|
unsigned FrameSize = MFI.getStackSize();
|
|
|
|
// Get the alignment.
|
|
unsigned StackAlign = LRI->needsStackRealignment(MF) ? MFI.getMaxAlignment()
|
|
: getStackAlignment();
|
|
|
|
// Get the maximum call frame size of all the calls.
|
|
unsigned MaxCallFrameSize = MFI.getMaxCallFrameSize();
|
|
|
|
// If we have dynamic alloca then MaxCallFrameSize needs to be aligned so
|
|
// that allocations will be aligned.
|
|
if (MFI.hasVarSizedObjects())
|
|
MaxCallFrameSize = alignTo(MaxCallFrameSize, StackAlign);
|
|
|
|
// Update maximum call frame size.
|
|
MFI.setMaxCallFrameSize(MaxCallFrameSize);
|
|
|
|
// Include call frame size in total.
|
|
if (!(hasReservedCallFrame(MF) && MFI.adjustsStack()))
|
|
FrameSize += MaxCallFrameSize;
|
|
|
|
// Make sure the frame is aligned.
|
|
FrameSize = alignTo(FrameSize, StackAlign);
|
|
|
|
// Update frame info.
|
|
MFI.setStackSize(FrameSize);
|
|
}
|
|
|
|
// Iterates through each basic block in a machine function and replaces
|
|
// ADJDYNALLOC pseudo instructions with a Lanai:ADDI with the
|
|
// maximum call frame size as the immediate.
|
|
void LanaiFrameLowering::replaceAdjDynAllocPseudo(MachineFunction &MF) const {
|
|
const LanaiInstrInfo &LII =
|
|
*static_cast<const LanaiInstrInfo *>(STI.getInstrInfo());
|
|
unsigned MaxCallFrameSize = MF.getFrameInfo().getMaxCallFrameSize();
|
|
|
|
for (MachineFunction::iterator MBB = MF.begin(), E = MF.end(); MBB != E;
|
|
++MBB) {
|
|
MachineBasicBlock::iterator MBBI = MBB->begin();
|
|
while (MBBI != MBB->end()) {
|
|
MachineInstr &MI = *MBBI++;
|
|
if (MI.getOpcode() == Lanai::ADJDYNALLOC) {
|
|
DebugLoc DL = MI.getDebugLoc();
|
|
unsigned Dst = MI.getOperand(0).getReg();
|
|
unsigned Src = MI.getOperand(1).getReg();
|
|
|
|
BuildMI(*MBB, MI, DL, LII.get(Lanai::ADD_I_LO), Dst)
|
|
.addReg(Src)
|
|
.addImm(MaxCallFrameSize);
|
|
MI.eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Generates the following sequence for function entry:
|
|
// st %fp,-4[*%sp] !push old FP
|
|
// add %sp,8,%fp !generate new FP
|
|
// sub %sp,0x4,%sp !allocate stack space (as needed)
|
|
void LanaiFrameLowering::emitPrologue(MachineFunction &MF,
|
|
MachineBasicBlock &MBB) const {
|
|
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
|
|
|
|
MachineFrameInfo &MFI = MF.getFrameInfo();
|
|
const LanaiInstrInfo &LII =
|
|
*static_cast<const LanaiInstrInfo *>(STI.getInstrInfo());
|
|
MachineBasicBlock::iterator MBBI = MBB.begin();
|
|
|
|
// Debug location must be unknown since the first debug location is used
|
|
// to determine the end of the prologue.
|
|
DebugLoc DL;
|
|
|
|
// Determine the correct frame layout
|
|
determineFrameLayout(MF);
|
|
|
|
// FIXME: This appears to be overallocating. Needs investigation.
|
|
// Get the number of bytes to allocate from the FrameInfo.
|
|
unsigned StackSize = MFI.getStackSize();
|
|
|
|
// Push old FP
|
|
// st %fp,-4[*%sp]
|
|
BuildMI(MBB, MBBI, DL, LII.get(Lanai::SW_RI))
|
|
.addReg(Lanai::FP)
|
|
.addReg(Lanai::SP)
|
|
.addImm(-4)
|
|
.addImm(LPAC::makePreOp(LPAC::ADD))
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
|
|
// Generate new FP
|
|
// add %sp,8,%fp
|
|
BuildMI(MBB, MBBI, DL, LII.get(Lanai::ADD_I_LO), Lanai::FP)
|
|
.addReg(Lanai::SP)
|
|
.addImm(8)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
|
|
// Allocate space on the stack if needed
|
|
// sub %sp,StackSize,%sp
|
|
if (StackSize != 0) {
|
|
BuildMI(MBB, MBBI, DL, LII.get(Lanai::SUB_I_LO), Lanai::SP)
|
|
.addReg(Lanai::SP)
|
|
.addImm(StackSize)
|
|
.setMIFlag(MachineInstr::FrameSetup);
|
|
}
|
|
|
|
// Replace ADJDYNANALLOC
|
|
if (MFI.hasVarSizedObjects())
|
|
replaceAdjDynAllocPseudo(MF);
|
|
}
|
|
|
|
MachineBasicBlock::iterator LanaiFrameLowering::eliminateCallFramePseudoInstr(
|
|
MachineFunction & /*MF*/, MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator I) const {
|
|
// Discard ADJCALLSTACKDOWN, ADJCALLSTACKUP instructions.
|
|
return MBB.erase(I);
|
|
}
|
|
|
|
// The function epilogue should not depend on the current stack pointer!
|
|
// It should use the frame pointer only. This is mandatory because
|
|
// of alloca; we also take advantage of it to omit stack adjustments
|
|
// before returning.
|
|
//
|
|
// Note that when we go to restore the preserved register values we must
|
|
// not try to address their slots by using offsets from the stack pointer.
|
|
// That's because the stack pointer may have been moved during the function
|
|
// execution due to a call to alloca(). Rather, we must restore all
|
|
// preserved registers via offsets from the frame pointer value.
|
|
//
|
|
// Note also that when the current frame is being "popped" (by adjusting
|
|
// the value of the stack pointer) on function exit, we must (for the
|
|
// sake of alloca) set the new value of the stack pointer based upon
|
|
// the current value of the frame pointer. We can't just add what we
|
|
// believe to be the (static) frame size to the stack pointer because
|
|
// if we did that, and alloca() had been called during this function,
|
|
// we would end up returning *without* having fully deallocated all of
|
|
// the space grabbed by alloca. If that happened, and a function
|
|
// containing one or more alloca() calls was called over and over again,
|
|
// then the stack would grow without limit!
|
|
//
|
|
// RET is lowered to
|
|
// ld -4[%fp],%pc # modify %pc (two delay slots)
|
|
// as the return address is in the stack frame and mov to pc is allowed.
|
|
// emitEpilogue emits
|
|
// mov %fp,%sp # restore the stack pointer
|
|
// ld -8[%fp],%fp # restore the caller's frame pointer
|
|
// before RET and the delay slot filler will move RET such that these
|
|
// instructions execute in the delay slots of the load to PC.
|
|
void LanaiFrameLowering::emitEpilogue(MachineFunction & /*MF*/,
|
|
MachineBasicBlock &MBB) const {
|
|
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
|
|
const LanaiInstrInfo &LII =
|
|
*static_cast<const LanaiInstrInfo *>(STI.getInstrInfo());
|
|
DebugLoc DL = MBBI->getDebugLoc();
|
|
|
|
// Restore the stack pointer using the callee's frame pointer value.
|
|
BuildMI(MBB, MBBI, DL, LII.get(Lanai::ADD_I_LO), Lanai::SP)
|
|
.addReg(Lanai::FP)
|
|
.addImm(0);
|
|
|
|
// Restore the frame pointer from the stack.
|
|
BuildMI(MBB, MBBI, DL, LII.get(Lanai::LDW_RI), Lanai::FP)
|
|
.addReg(Lanai::FP)
|
|
.addImm(-8)
|
|
.addImm(LPAC::ADD);
|
|
}
|
|
|
|
void LanaiFrameLowering::determineCalleeSaves(MachineFunction &MF,
|
|
BitVector &SavedRegs,
|
|
RegScavenger *RS) const {
|
|
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
|
|
|
|
MachineFrameInfo &MFI = MF.getFrameInfo();
|
|
const LanaiRegisterInfo *LRI =
|
|
static_cast<const LanaiRegisterInfo *>(STI.getRegisterInfo());
|
|
int Offset = -4;
|
|
|
|
// Reserve 4 bytes for the saved RCA
|
|
MFI.CreateFixedObject(4, Offset, true);
|
|
Offset -= 4;
|
|
|
|
// Reserve 4 bytes for the saved FP
|
|
MFI.CreateFixedObject(4, Offset, true);
|
|
Offset -= 4;
|
|
|
|
if (LRI->hasBasePointer(MF)) {
|
|
MFI.CreateFixedObject(4, Offset, true);
|
|
SavedRegs.reset(LRI->getBaseRegister());
|
|
}
|
|
}
|