llvm-6502/lib/Target/Hexagon/HexagonFrameLowering.cpp
2015-02-09 21:56:37 +00:00

347 lines
12 KiB
C++

//===-- HexagonFrameLowering.cpp - Define frame lowering ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//
//===----------------------------------------------------------------------===//
#include "HexagonFrameLowering.h"
#include "Hexagon.h"
#include "HexagonInstrInfo.h"
#include "HexagonMachineFunctionInfo.h"
#include "HexagonRegisterInfo.h"
#include "HexagonSubtarget.h"
#include "HexagonTargetMachine.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
static cl::opt<bool> DisableDeallocRet(
"disable-hexagon-dealloc-ret",
cl::Hidden,
cl::desc("Disable Dealloc Return for Hexagon target"));
/// determineFrameLayout - Determine the size of the frame and maximum call
/// frame size.
void HexagonFrameLowering::determineFrameLayout(MachineFunction &MF) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
// Get the number of bytes to allocate from the FrameInfo.
unsigned FrameSize = MFI->getStackSize();
// Get the alignments provided by the target.
unsigned TargetAlign =
MF.getSubtarget().getFrameLowering()->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 = RoundUpToAlignment(maxCallFrameSize, TargetAlign);
// Update maximum call frame size.
MFI->setMaxCallFrameSize(maxCallFrameSize);
// Include call frame size in total.
FrameSize += maxCallFrameSize;
// Make sure the frame is aligned.
FrameSize = RoundUpToAlignment(FrameSize, TargetAlign);
// Update frame info.
MFI->setStackSize(FrameSize);
}
void HexagonFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineBasicBlock::iterator MBBI = MBB.begin();
const HexagonRegisterInfo *QRI =
MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
determineFrameLayout(MF);
// Get the number of bytes to allocate from the FrameInfo.
int NumBytes = (int) MFI->getStackSize();
// LLVM expects allocframe not to be the first instruction in the
// basic block.
MachineBasicBlock::iterator InsertPt = MBB.begin();
//
// ALLOCA adjust regs. Iterate over ADJDYNALLOC nodes and change the offset.
//
HexagonMachineFunctionInfo *FuncInfo =
MF.getInfo<HexagonMachineFunctionInfo>();
const std::vector<MachineInstr*>& AdjustRegs =
FuncInfo->getAllocaAdjustInsts();
for (std::vector<MachineInstr*>::const_iterator i = AdjustRegs.begin(),
e = AdjustRegs.end();
i != e; ++i) {
MachineInstr* MI = *i;
assert((MI->getOpcode() == Hexagon::ADJDYNALLOC) &&
"Expected adjust alloca node");
MachineOperand& MO = MI->getOperand(2);
assert(MO.isImm() && "Expected immediate");
MO.setImm(MFI->getMaxCallFrameSize());
}
//
// Only insert ALLOCFRAME if we need to.
//
if (hasFP(MF)) {
// Check for overflow.
// Hexagon_TODO: Ugh! hardcoding. Is there an API that can be used?
const int ALLOCFRAME_MAX = 16384;
const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
if (NumBytes >= ALLOCFRAME_MAX) {
// Emit allocframe(#0).
BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::S2_allocframe)).addImm(0);
// Subtract offset from frame pointer.
BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::CONST32_Int_Real),
HEXAGON_RESERVED_REG_1).addImm(NumBytes);
BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::A2_sub),
QRI->getStackRegister()).
addReg(QRI->getStackRegister()).
addReg(HEXAGON_RESERVED_REG_1);
} else {
BuildMI(MBB, InsertPt, dl, TII.get(Hexagon::S2_allocframe)).addImm(NumBytes);
}
}
}
// Returns true if MBB has a machine instructions that indicates a tail call
// in the block.
bool HexagonFrameLowering::hasTailCall(MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
unsigned RetOpcode = MBBI->getOpcode();
return RetOpcode == Hexagon::TCRETURNtg || RetOpcode == Hexagon::TCRETURNtext;
}
void HexagonFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = std::prev(MBB.end());
DebugLoc dl = MBBI->getDebugLoc();
//
// Only insert deallocframe if we need to. Also at -O0. See comment
// in emitPrologue above.
//
if (hasFP(MF) || MF.getTarget().getOptLevel() == CodeGenOpt::None) {
MachineBasicBlock::iterator MBBI = std::prev(MBB.end());
MachineBasicBlock::iterator MBBI_end = MBB.end();
const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
// Handle EH_RETURN.
if (MBBI->getOpcode() == Hexagon::EH_RETURN_JMPR) {
assert(MBBI->getOperand(0).isReg() && "Offset should be in register!");
BuildMI(MBB, MBBI, dl, TII.get(Hexagon::L2_deallocframe));
BuildMI(MBB, MBBI, dl, TII.get(Hexagon::A2_add),
Hexagon::R29).addReg(Hexagon::R29).addReg(Hexagon::R28);
return;
}
// Replace 'jumpr r31' instruction with dealloc_return for V4 and higher
// versions.
if (MBBI->getOpcode() == Hexagon::JMPret && !DisableDeallocRet) {
// Check for RESTORE_DEALLOC_RET_JMP_V4 call. Don't emit an extra DEALLOC
// instruction if we encounter it.
MachineBasicBlock::iterator BeforeJMPR =
MBB.begin() == MBBI ? MBBI : std::prev(MBBI);
if (BeforeJMPR != MBBI &&
BeforeJMPR->getOpcode() == Hexagon::RESTORE_DEALLOC_RET_JMP_V4) {
// Remove the JMPR node.
MBB.erase(MBBI);
return;
}
// Add dealloc_return.
MachineInstrBuilder MIB =
BuildMI(MBB, MBBI_end, dl, TII.get(Hexagon::L4_return));
// Transfer the function live-out registers.
MIB->copyImplicitOps(*MBB.getParent(), &*MBBI);
// Remove the JUMPR node.
MBB.erase(MBBI);
} else { // Add deallocframe for V2 and V3, and V4 tail calls.
// Check for RESTORE_DEALLOC_BEFORE_TAILCALL_V4. We don't need an extra
// DEALLOCFRAME instruction after it.
MachineBasicBlock::iterator Term = MBB.getFirstTerminator();
MachineBasicBlock::iterator I =
Term == MBB.begin() ? MBB.end() : std::prev(Term);
if (I != MBB.end() &&
I->getOpcode() == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4)
return;
BuildMI(MBB, MBBI, dl, TII.get(Hexagon::L2_deallocframe));
}
}
}
bool HexagonFrameLowering::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const HexagonMachineFunctionInfo *FuncInfo =
MF.getInfo<HexagonMachineFunctionInfo>();
return (MFI->hasCalls() || (MFI->getStackSize() > 0) ||
FuncInfo->hasClobberLR() );
}
static inline
unsigned uniqueSuperReg(unsigned Reg, const TargetRegisterInfo *TRI) {
MCSuperRegIterator SRI(Reg, TRI);
assert(SRI.isValid() && "Expected a superreg");
unsigned SuperReg = *SRI;
++SRI;
assert(!SRI.isValid() && "Expected exactly one superreg");
return SuperReg;
}
bool
HexagonFrameLowering::spillCalleeSavedRegisters(
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
if (CSI.empty()) {
return false;
}
// We can only schedule double loads if we spill contiguous callee-saved regs
// For instance, we cannot scheduled double-word loads if we spill r24,
// r26, and r27.
// Hexagon_TODO: We can try to double-word align odd registers for -O2 and
// above.
bool ContiguousRegs = true;
for (unsigned i = 0; i < CSI.size(); ++i) {
unsigned Reg = CSI[i].getReg();
//
// Check if we can use a double-word store.
//
unsigned SuperReg = uniqueSuperReg(Reg, TRI);
bool CanUseDblStore = false;
const TargetRegisterClass* SuperRegClass = nullptr;
if (ContiguousRegs && (i < CSI.size()-1)) {
unsigned SuperRegNext = uniqueSuperReg(CSI[i+1].getReg(), TRI);
SuperRegClass = TRI->getMinimalPhysRegClass(SuperReg);
CanUseDblStore = (SuperRegNext == SuperReg);
}
if (CanUseDblStore) {
TII.storeRegToStackSlot(MBB, MI, SuperReg, true,
CSI[i+1].getFrameIdx(), SuperRegClass, TRI);
MBB.addLiveIn(SuperReg);
++i;
} else {
// Cannot use a double-word store.
ContiguousRegs = false;
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i].getFrameIdx(), RC,
TRI);
MBB.addLiveIn(Reg);
}
}
return true;
}
bool HexagonFrameLowering::restoreCalleeSavedRegisters(
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
if (CSI.empty()) {
return false;
}
// We can only schedule double loads if we spill contiguous callee-saved regs
// For instance, we cannot scheduled double-word loads if we spill r24,
// r26, and r27.
// Hexagon_TODO: We can try to double-word align odd registers for -O2 and
// above.
bool ContiguousRegs = true;
for (unsigned i = 0; i < CSI.size(); ++i) {
unsigned Reg = CSI[i].getReg();
//
// Check if we can use a double-word load.
//
unsigned SuperReg = uniqueSuperReg(Reg, TRI);
const TargetRegisterClass* SuperRegClass = nullptr;
bool CanUseDblLoad = false;
if (ContiguousRegs && (i < CSI.size()-1)) {
unsigned SuperRegNext = uniqueSuperReg(CSI[i+1].getReg(), TRI);
SuperRegClass = TRI->getMinimalPhysRegClass(SuperReg);
CanUseDblLoad = (SuperRegNext == SuperReg);
}
if (CanUseDblLoad) {
TII.loadRegFromStackSlot(MBB, MI, SuperReg, CSI[i+1].getFrameIdx(),
SuperRegClass, TRI);
MBB.addLiveIn(SuperReg);
++i;
} else {
// Cannot use a double-word load.
ContiguousRegs = false;
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(), RC, TRI);
MBB.addLiveIn(Reg);
}
}
return true;
}
void HexagonFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
MachineInstr &MI = *I;
if (MI.getOpcode() == Hexagon::ADJCALLSTACKDOWN) {
// Hexagon_TODO: add code
} else if (MI.getOpcode() == Hexagon::ADJCALLSTACKUP) {
// Hexagon_TODO: add code
} else {
llvm_unreachable("Cannot handle this call frame pseudo instruction");
}
MBB.erase(I);
}
int HexagonFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
int FI) const {
return MF.getFrameInfo()->getObjectOffset(FI);
}