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//===-- SparcFrameLowering.cpp - Sparc Frame 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 Sparc implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#include "SparcFrameLowering.h"
#include "SparcInstrInfo.h"
#include "SparcMachineFunctionInfo.h"
#include "SparcSubtarget.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/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
static cl::opt<bool>
DisableLeafProc("disable-sparc-leaf-proc",
cl::init(false),
cl::desc("Disable Sparc leaf procedure optimization."),
cl::Hidden);
SparcFrameLowering::SparcFrameLowering(const SparcSubtarget &ST)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown,
ST.is64Bit() ? 16 : 8, 0, ST.is64Bit() ? 16 : 8) {}
void SparcFrameLowering::emitSPAdjustment(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
int NumBytes,
unsigned ADDrr,
unsigned ADDri) const {
DebugLoc dl = (MBBI != MBB.end()) ? MBBI->getDebugLoc() : DebugLoc();
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
if (NumBytes >= -4096 && NumBytes < 4096) {
BuildMI(MBB, MBBI, dl, TII.get(ADDri), SP::O6)
.addReg(SP::O6).addImm(NumBytes);
return;
}
// Emit this the hard way. This clobbers G1 which we always know is
// available here.
if (NumBytes >= 0) {
// Emit nonnegative numbers with sethi + or.
// sethi %hi(NumBytes), %g1
// or %g1, %lo(NumBytes), %g1
// add %sp, %g1, %sp
BuildMI(MBB, MBBI, dl, TII.get(SP::SETHIi), SP::G1)
.addImm(HI22(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(SP::ORri), SP::G1)
.addReg(SP::G1).addImm(LO10(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(ADDrr), SP::O6)
.addReg(SP::O6).addReg(SP::G1);
return ;
}
// Emit negative numbers with sethi + xor.
// sethi %hix(NumBytes), %g1
// xor %g1, %lox(NumBytes), %g1
// add %sp, %g1, %sp
BuildMI(MBB, MBBI, dl, TII.get(SP::SETHIi), SP::G1)
.addImm(HIX22(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(SP::XORri), SP::G1)
.addReg(SP::G1).addImm(LOX10(NumBytes));
BuildMI(MBB, MBBI, dl, TII.get(ADDrr), SP::O6)
.addReg(SP::O6).addReg(SP::G1);
}
void SparcFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo *MFI = MF.getFrameInfo();
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
// Get the number of bytes to allocate from the FrameInfo
int NumBytes = (int) MFI->getStackSize();
unsigned SAVEri = SP::SAVEri;
unsigned SAVErr = SP::SAVErr;
if (FuncInfo->isLeafProc()) {
if (NumBytes == 0)
return;
SAVEri = SP::ADDri;
SAVErr = SP::ADDrr;
}
NumBytes = -MF.getSubtarget<SparcSubtarget>().getAdjustedFrameSize(NumBytes);
emitSPAdjustment(MF, MBB, MBBI, NumBytes, SAVErr, SAVEri);
MachineModuleInfo &MMI = MF.getMMI();
const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
unsigned regFP = MRI->getDwarfRegNum(SP::I6, true);
// Emit ".cfi_def_cfa_register 30".
unsigned CFIIndex =
MMI.addFrameInst(MCCFIInstruction::createDefCfaRegister(nullptr, regFP));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
// Emit ".cfi_window_save".
CFIIndex = MMI.addFrameInst(MCCFIInstruction::createWindowSave(nullptr));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
unsigned regInRA = MRI->getDwarfRegNum(SP::I7, true);
unsigned regOutRA = MRI->getDwarfRegNum(SP::O7, true);
// Emit ".cfi_register 15, 31".
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createRegister(nullptr, regOutRA, regInRA));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
void SparcFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
if (!hasReservedCallFrame(MF)) {
MachineInstr &MI = *I;
int Size = MI.getOperand(0).getImm();
if (MI.getOpcode() == SP::ADJCALLSTACKDOWN)
Size = -Size;
if (Size)
emitSPAdjustment(MF, MBB, I, Size, SP::ADDrr, SP::ADDri);
}
MBB.erase(I);
}
void SparcFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
DebugLoc dl = MBBI->getDebugLoc();
assert(MBBI->getOpcode() == SP::RETL &&
"Can only put epilog before 'retl' instruction!");
if (!FuncInfo->isLeafProc()) {
BuildMI(MBB, MBBI, dl, TII.get(SP::RESTORErr), SP::G0).addReg(SP::G0)
.addReg(SP::G0);
return;
}
MachineFrameInfo *MFI = MF.getFrameInfo();
int NumBytes = (int) MFI->getStackSize();
if (NumBytes == 0)
return;
NumBytes = MF.getSubtarget<SparcSubtarget>().getAdjustedFrameSize(NumBytes);
emitSPAdjustment(MF, MBB, MBBI, NumBytes, SP::ADDrr, SP::ADDri);
}
bool SparcFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
// Reserve call frame if there are no variable sized objects on the stack.
return !MF.getFrameInfo()->hasVarSizedObjects();
}
// 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 SparcFrameLowering::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken();
}
static bool LLVM_ATTRIBUTE_UNUSED verifyLeafProcRegUse(MachineRegisterInfo *MRI)
{
for (unsigned reg = SP::I0; reg <= SP::I7; ++reg)
if (MRI->isPhysRegUsed(reg))
return false;
for (unsigned reg = SP::L0; reg <= SP::L7; ++reg)
if (MRI->isPhysRegUsed(reg))
return false;
return true;
}
bool SparcFrameLowering::isLeafProc(MachineFunction &MF) const
{
MachineRegisterInfo &MRI = MF.getRegInfo();
MachineFrameInfo *MFI = MF.getFrameInfo();
return !(MFI->hasCalls() // has calls
|| MRI.isPhysRegUsed(SP::L0) // Too many registers needed
|| MRI.isPhysRegUsed(SP::O6) // %SP is used
|| hasFP(MF)); // need %FP
}
void SparcFrameLowering::remapRegsForLeafProc(MachineFunction &MF) const {
MachineRegisterInfo &MRI = MF.getRegInfo();
// Remap %i[0-7] to %o[0-7].
for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
if (!MRI.isPhysRegUsed(reg))
continue;
unsigned mapped_reg = (reg - SP::I0 + SP::O0);
assert(!MRI.isPhysRegUsed(mapped_reg));
// Replace I register with O register.
MRI.replaceRegWith(reg, mapped_reg);
// Mark the reg unused.
MRI.setPhysRegUnused(reg);
}
// Rewrite MBB's Live-ins.
for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
MBB != E; ++MBB) {
for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
if (!MBB->isLiveIn(reg))
continue;
MBB->removeLiveIn(reg);
MBB->addLiveIn(reg - SP::I0 + SP::O0);
}
}
assert(verifyLeafProcRegUse(&MRI));
#ifdef XDEBUG
MF.verify(0, "After LeafProc Remapping");
#endif
}
void SparcFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
if (!DisableLeafProc && isLeafProc(MF)) {
SparcMachineFunctionInfo *MFI = MF.getInfo<SparcMachineFunctionInfo>();
MFI->setLeafProc(true);
remapRegsForLeafProc(MF);
}
}
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