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llvm-6502/lib/Target/ARM/ARMBaseRegisterInfo.cpp
Nick Lewycky 8a8d479214 Move global variables in TargetMachine into new TargetOptions class. As an API 
change, now you need a TargetOptions object to create a TargetMachine. Clang
patch to follow.

One small functionality change in PTX. PTX had commented out the machine
verifier parts in their copy of printAndVerify. That now calls the version in
LLVMTargetMachine. Users of PTX who need verification disabled should rely on
not passing the command-line flag to enable it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145714 91177308-0d34-0410-b5e6-96231b3b80d8
2011-12-02 22:16:29 +00:00

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//===- ARMBaseRegisterInfo.cpp - ARM Register 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 base ARM implementation of TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//
#include "ARM.h"
#include "ARMBaseInstrInfo.h"
#include "ARMBaseRegisterInfo.h"
#include "ARMFrameLowering.h"
#include "ARMInstrInfo.h"
#include "ARMMachineFunctionInfo.h"
#include "ARMSubtarget.h"
#include "MCTargetDesc/ARMAddressingModes.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/LLVMContext.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/CommandLine.h"
#define GET_REGINFO_TARGET_DESC
#include "ARMGenRegisterInfo.inc"
using namespace llvm;
static cl::opt<bool>
ForceAllBaseRegAlloc("arm-force-base-reg-alloc", cl::Hidden, cl::init(false),
cl::desc("Force use of virtual base registers for stack load/store"));
static cl::opt<bool>
EnableLocalStackAlloc("enable-local-stack-alloc", cl::init(true), cl::Hidden,
cl::desc("Enable pre-regalloc stack frame index allocation"));
static cl::opt<bool>
EnableBasePointer("arm-use-base-pointer", cl::Hidden, cl::init(true),
cl::desc("Enable use of a base pointer for complex stack frames"));
ARMBaseRegisterInfo::ARMBaseRegisterInfo(const ARMBaseInstrInfo &tii,
const ARMSubtarget &sti)
: ARMGenRegisterInfo(ARM::LR), TII(tii), STI(sti),
FramePtr((STI.isTargetDarwin() || STI.isThumb()) ? ARM::R7 : ARM::R11),
BasePtr(ARM::R6) {
}
const unsigned*
ARMBaseRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
static const unsigned CalleeSavedRegs[] = {
ARM::LR, ARM::R11, ARM::R10, ARM::R9, ARM::R8,
ARM::R7, ARM::R6, ARM::R5, ARM::R4,
ARM::D15, ARM::D14, ARM::D13, ARM::D12,
ARM::D11, ARM::D10, ARM::D9, ARM::D8,
0
};
static const unsigned DarwinCalleeSavedRegs[] = {
// Darwin ABI deviates from ARM standard ABI. R9 is not a callee-saved
// register.
ARM::LR, ARM::R7, ARM::R6, ARM::R5, ARM::R4,
ARM::R11, ARM::R10, ARM::R8,
ARM::D15, ARM::D14, ARM::D13, ARM::D12,
ARM::D11, ARM::D10, ARM::D9, ARM::D8,
0
};
return STI.isTargetDarwin() ? DarwinCalleeSavedRegs : CalleeSavedRegs;
}
BitVector ARMBaseRegisterInfo::
getReservedRegs(const MachineFunction &MF) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
// FIXME: avoid re-calculating this every time.
BitVector Reserved(getNumRegs());
Reserved.set(ARM::SP);
Reserved.set(ARM::PC);
Reserved.set(ARM::FPSCR);
if (TFI->hasFP(MF))
Reserved.set(FramePtr);
if (hasBasePointer(MF))
Reserved.set(BasePtr);
// Some targets reserve R9.
if (STI.isR9Reserved())
Reserved.set(ARM::R9);
// Reserve D16-D31 if the subtarget doesn't support them.
if (!STI.hasVFP3() || STI.hasD16()) {
assert(ARM::D31 == ARM::D16 + 15);
for (unsigned i = 0; i != 16; ++i)
Reserved.set(ARM::D16 + i);
}
return Reserved;
}
bool ARMBaseRegisterInfo::isReservedReg(const MachineFunction &MF,
unsigned Reg) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
switch (Reg) {
default: break;
case ARM::SP:
case ARM::PC:
return true;
case ARM::R6:
if (hasBasePointer(MF))
return true;
break;
case ARM::R7:
case ARM::R11:
if (FramePtr == Reg && TFI->hasFP(MF))
return true;
break;
case ARM::R9:
return STI.isR9Reserved();
}
return false;
}
const TargetRegisterClass *
ARMBaseRegisterInfo::getMatchingSuperRegClass(const TargetRegisterClass *A,
const TargetRegisterClass *B,
unsigned SubIdx) const {
switch (SubIdx) {
default: return 0;
case ARM::ssub_0:
case ARM::ssub_1:
case ARM::ssub_2:
case ARM::ssub_3: {
// S sub-registers.
if (A->getSize() == 8) {
if (B == &ARM::SPR_8RegClass)
return &ARM::DPR_8RegClass;
assert(B == &ARM::SPRRegClass && "Expecting SPR register class!");
if (A == &ARM::DPR_8RegClass)
return A;
return &ARM::DPR_VFP2RegClass;
}
if (A->getSize() == 16) {
if (B == &ARM::SPR_8RegClass)
return &ARM::QPR_8RegClass;
return &ARM::QPR_VFP2RegClass;
}
if (A->getSize() == 32) {
if (B == &ARM::SPR_8RegClass)
return 0; // Do not allow coalescing!
return &ARM::QQPR_VFP2RegClass;
}
assert(A->getSize() == 64 && "Expecting a QQQQ register class!");
return 0; // Do not allow coalescing!
}
case ARM::dsub_0:
case ARM::dsub_1:
case ARM::dsub_2:
case ARM::dsub_3: {
// D sub-registers.
if (A->getSize() == 16) {
if (B == &ARM::DPR_VFP2RegClass)
return &ARM::QPR_VFP2RegClass;
if (B == &ARM::DPR_8RegClass)
return 0; // Do not allow coalescing!
return A;
}
if (A->getSize() == 32) {
if (B == &ARM::DPR_VFP2RegClass)
return &ARM::QQPR_VFP2RegClass;
if (B == &ARM::DPR_8RegClass)
return 0; // Do not allow coalescing!
return A;
}
assert(A->getSize() == 64 && "Expecting a QQQQ register class!");
if (B != &ARM::DPRRegClass)
return 0; // Do not allow coalescing!
return A;
}
case ARM::dsub_4:
case ARM::dsub_5:
case ARM::dsub_6:
case ARM::dsub_7: {
// D sub-registers of QQQQ registers.
if (A->getSize() == 64 && B == &ARM::DPRRegClass)
return A;
return 0; // Do not allow coalescing!
}
case ARM::qsub_0:
case ARM::qsub_1: {
// Q sub-registers.
if (A->getSize() == 32) {
if (B == &ARM::QPR_VFP2RegClass)
return &ARM::QQPR_VFP2RegClass;
if (B == &ARM::QPR_8RegClass)
return 0; // Do not allow coalescing!
return A;
}
assert(A->getSize() == 64 && "Expecting a QQQQ register class!");
if (B == &ARM::QPRRegClass)
return A;
return 0; // Do not allow coalescing!
}
case ARM::qsub_2:
case ARM::qsub_3: {
// Q sub-registers of QQQQ registers.
if (A->getSize() == 64 && B == &ARM::QPRRegClass)
return A;
return 0; // Do not allow coalescing!
}
}
return 0;
}
bool
ARMBaseRegisterInfo::canCombineSubRegIndices(const TargetRegisterClass *RC,
SmallVectorImpl<unsigned> &SubIndices,
unsigned &NewSubIdx) const {
unsigned Size = RC->getSize() * 8;
if (Size < 6)
return 0;
NewSubIdx = 0; // Whole register.
unsigned NumRegs = SubIndices.size();
if (NumRegs == 8) {
// 8 D registers -> 1 QQQQ register.
return (Size == 512 &&
SubIndices[0] == ARM::dsub_0 &&
SubIndices[1] == ARM::dsub_1 &&
SubIndices[2] == ARM::dsub_2 &&
SubIndices[3] == ARM::dsub_3 &&
SubIndices[4] == ARM::dsub_4 &&
SubIndices[5] == ARM::dsub_5 &&
SubIndices[6] == ARM::dsub_6 &&
SubIndices[7] == ARM::dsub_7);
} else if (NumRegs == 4) {
if (SubIndices[0] == ARM::qsub_0) {
// 4 Q registers -> 1 QQQQ register.
return (Size == 512 &&
SubIndices[1] == ARM::qsub_1 &&
SubIndices[2] == ARM::qsub_2 &&
SubIndices[3] == ARM::qsub_3);
} else if (SubIndices[0] == ARM::dsub_0) {
// 4 D registers -> 1 QQ register.
if (Size >= 256 &&
SubIndices[1] == ARM::dsub_1 &&
SubIndices[2] == ARM::dsub_2 &&
SubIndices[3] == ARM::dsub_3) {
if (Size == 512)
NewSubIdx = ARM::qqsub_0;
return true;
}
} else if (SubIndices[0] == ARM::dsub_4) {
// 4 D registers -> 1 QQ register (2nd).
if (Size == 512 &&
SubIndices[1] == ARM::dsub_5 &&
SubIndices[2] == ARM::dsub_6 &&
SubIndices[3] == ARM::dsub_7) {
NewSubIdx = ARM::qqsub_1;
return true;
}
} else if (SubIndices[0] == ARM::ssub_0) {
// 4 S registers -> 1 Q register.
if (Size >= 128 &&
SubIndices[1] == ARM::ssub_1 &&
SubIndices[2] == ARM::ssub_2 &&
SubIndices[3] == ARM::ssub_3) {
if (Size >= 256)
NewSubIdx = ARM::qsub_0;
return true;
}
}
} else if (NumRegs == 2) {
if (SubIndices[0] == ARM::qsub_0) {
// 2 Q registers -> 1 QQ register.
if (Size >= 256 && SubIndices[1] == ARM::qsub_1) {
if (Size == 512)
NewSubIdx = ARM::qqsub_0;
return true;
}
} else if (SubIndices[0] == ARM::qsub_2) {
// 2 Q registers -> 1 QQ register (2nd).
if (Size == 512 && SubIndices[1] == ARM::qsub_3) {
NewSubIdx = ARM::qqsub_1;
return true;
}
} else if (SubIndices[0] == ARM::dsub_0) {
// 2 D registers -> 1 Q register.
if (Size >= 128 && SubIndices[1] == ARM::dsub_1) {
if (Size >= 256)
NewSubIdx = ARM::qsub_0;
return true;
}
} else if (SubIndices[0] == ARM::dsub_2) {
// 2 D registers -> 1 Q register (2nd).
if (Size >= 256 && SubIndices[1] == ARM::dsub_3) {
NewSubIdx = ARM::qsub_1;
return true;
}
} else if (SubIndices[0] == ARM::dsub_4) {
// 2 D registers -> 1 Q register (3rd).
if (Size == 512 && SubIndices[1] == ARM::dsub_5) {
NewSubIdx = ARM::qsub_2;
return true;
}
} else if (SubIndices[0] == ARM::dsub_6) {
// 2 D registers -> 1 Q register (3rd).
if (Size == 512 && SubIndices[1] == ARM::dsub_7) {
NewSubIdx = ARM::qsub_3;
return true;
}
} else if (SubIndices[0] == ARM::ssub_0) {
// 2 S registers -> 1 D register.
if (SubIndices[1] == ARM::ssub_1) {
if (Size >= 128)
NewSubIdx = ARM::dsub_0;
return true;
}
} else if (SubIndices[0] == ARM::ssub_2) {
// 2 S registers -> 1 D register (2nd).
if (Size >= 128 && SubIndices[1] == ARM::ssub_3) {
NewSubIdx = ARM::dsub_1;
return true;
}
}
}
return false;
}
const TargetRegisterClass*
ARMBaseRegisterInfo::getLargestLegalSuperClass(const TargetRegisterClass *RC)
const {
const TargetRegisterClass *Super = RC;
TargetRegisterClass::sc_iterator I = RC->getSuperClasses();
do {
switch (Super->getID()) {
case ARM::GPRRegClassID:
case ARM::SPRRegClassID:
case ARM::DPRRegClassID:
case ARM::QPRRegClassID:
case ARM::QQPRRegClassID:
case ARM::QQQQPRRegClassID:
return Super;
}
Super = *I++;
} while (Super);
return RC;
}
const TargetRegisterClass *
ARMBaseRegisterInfo::getPointerRegClass(unsigned Kind) const {
return ARM::GPRRegisterClass;
}
const TargetRegisterClass *
ARMBaseRegisterInfo::getCrossCopyRegClass(const TargetRegisterClass *RC) const {
if (RC == &ARM::CCRRegClass)
return 0; // Can't copy CCR registers.
return RC;
}
unsigned
ARMBaseRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
MachineFunction &MF) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
switch (RC->getID()) {
default:
return 0;
case ARM::tGPRRegClassID:
return TFI->hasFP(MF) ? 4 : 5;
case ARM::GPRRegClassID: {
unsigned FP = TFI->hasFP(MF) ? 1 : 0;
return 10 - FP - (STI.isR9Reserved() ? 1 : 0);
}
case ARM::SPRRegClassID: // Currently not used as 'rep' register class.
case ARM::DPRRegClassID:
return 32 - 10;
}
}
/// getRawAllocationOrder - Returns the register allocation order for a
/// specified register class with a target-dependent hint.
ArrayRef<unsigned>
ARMBaseRegisterInfo::getRawAllocationOrder(const TargetRegisterClass *RC,
unsigned HintType, unsigned HintReg,
const MachineFunction &MF) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
// Alternative register allocation orders when favoring even / odd registers
// of register pairs.
// No FP, R9 is available.
static const unsigned GPREven1[] = {
ARM::R0, ARM::R2, ARM::R4, ARM::R6, ARM::R8, ARM::R10,
ARM::R1, ARM::R3, ARM::R12,ARM::LR, ARM::R5, ARM::R7,
ARM::R9, ARM::R11
};
static const unsigned GPROdd1[] = {
ARM::R1, ARM::R3, ARM::R5, ARM::R7, ARM::R9, ARM::R11,
ARM::R0, ARM::R2, ARM::R12,ARM::LR, ARM::R4, ARM::R6,
ARM::R8, ARM::R10
};
// FP is R7, R9 is available.
static const unsigned GPREven2[] = {
ARM::R0, ARM::R2, ARM::R4, ARM::R8, ARM::R10,
ARM::R1, ARM::R3, ARM::R12,ARM::LR, ARM::R5, ARM::R6,
ARM::R9, ARM::R11
};
static const unsigned GPROdd2[] = {
ARM::R1, ARM::R3, ARM::R5, ARM::R9, ARM::R11,
ARM::R0, ARM::R2, ARM::R12,ARM::LR, ARM::R4, ARM::R6,
ARM::R8, ARM::R10
};
// FP is R11, R9 is available.
static const unsigned GPREven3[] = {
ARM::R0, ARM::R2, ARM::R4, ARM::R6, ARM::R8,
ARM::R1, ARM::R3, ARM::R10,ARM::R12,ARM::LR, ARM::R5, ARM::R7,
ARM::R9
};
static const unsigned GPROdd3[] = {
ARM::R1, ARM::R3, ARM::R5, ARM::R6, ARM::R9,
ARM::R0, ARM::R2, ARM::R10,ARM::R12,ARM::LR, ARM::R4, ARM::R7,
ARM::R8
};
// No FP, R9 is not available.
static const unsigned GPREven4[] = {
ARM::R0, ARM::R2, ARM::R4, ARM::R6, ARM::R10,
ARM::R1, ARM::R3, ARM::R12,ARM::LR, ARM::R5, ARM::R7, ARM::R8,
ARM::R11
};
static const unsigned GPROdd4[] = {
ARM::R1, ARM::R3, ARM::R5, ARM::R7, ARM::R11,
ARM::R0, ARM::R2, ARM::R12,ARM::LR, ARM::R4, ARM::R6, ARM::R8,
ARM::R10
};
// FP is R7, R9 is not available.
static const unsigned GPREven5[] = {
ARM::R0, ARM::R2, ARM::R4, ARM::R10,
ARM::R1, ARM::R3, ARM::R12,ARM::LR, ARM::R5, ARM::R6, ARM::R8,
ARM::R11
};
static const unsigned GPROdd5[] = {
ARM::R1, ARM::R3, ARM::R5, ARM::R11,
ARM::R0, ARM::R2, ARM::R12,ARM::LR, ARM::R4, ARM::R6, ARM::R8,
ARM::R10
};
// FP is R11, R9 is not available.
static const unsigned GPREven6[] = {
ARM::R0, ARM::R2, ARM::R4, ARM::R6,
ARM::R1, ARM::R3, ARM::R10,ARM::R12,ARM::LR, ARM::R5, ARM::R7, ARM::R8
};
static const unsigned GPROdd6[] = {
ARM::R1, ARM::R3, ARM::R5, ARM::R7,
ARM::R0, ARM::R2, ARM::R10,ARM::R12,ARM::LR, ARM::R4, ARM::R6, ARM::R8
};
// We only support even/odd hints for GPR and rGPR.
if (RC != ARM::GPRRegisterClass && RC != ARM::rGPRRegisterClass)
return RC->getRawAllocationOrder(MF);
if (HintType == ARMRI::RegPairEven) {
if (isPhysicalRegister(HintReg) && getRegisterPairEven(HintReg, MF) == 0)
// It's no longer possible to fulfill this hint. Return the default
// allocation order.
return RC->getRawAllocationOrder(MF);
if (!TFI->hasFP(MF)) {
if (!STI.isR9Reserved())
return makeArrayRef(GPREven1);
else
return makeArrayRef(GPREven4);
} else if (FramePtr == ARM::R7) {
if (!STI.isR9Reserved())
return makeArrayRef(GPREven2);
else
return makeArrayRef(GPREven5);
} else { // FramePtr == ARM::R11
if (!STI.isR9Reserved())
return makeArrayRef(GPREven3);
else
return makeArrayRef(GPREven6);
}
} else if (HintType == ARMRI::RegPairOdd) {
if (isPhysicalRegister(HintReg) && getRegisterPairOdd(HintReg, MF) == 0)
// It's no longer possible to fulfill this hint. Return the default
// allocation order.
return RC->getRawAllocationOrder(MF);
if (!TFI->hasFP(MF)) {
if (!STI.isR9Reserved())
return makeArrayRef(GPROdd1);
else
return makeArrayRef(GPROdd4);
} else if (FramePtr == ARM::R7) {
if (!STI.isR9Reserved())
return makeArrayRef(GPROdd2);
else
return makeArrayRef(GPROdd5);
} else { // FramePtr == ARM::R11
if (!STI.isR9Reserved())
return makeArrayRef(GPROdd3);
else
return makeArrayRef(GPROdd6);
}
}
return RC->getRawAllocationOrder(MF);
}
/// ResolveRegAllocHint - Resolves the specified register allocation hint
/// to a physical register. Returns the physical register if it is successful.
unsigned
ARMBaseRegisterInfo::ResolveRegAllocHint(unsigned Type, unsigned Reg,
const MachineFunction &MF) const {
if (Reg == 0 || !isPhysicalRegister(Reg))
return 0;
if (Type == 0)
return Reg;
else if (Type == (unsigned)ARMRI::RegPairOdd)
// Odd register.
return getRegisterPairOdd(Reg, MF);
else if (Type == (unsigned)ARMRI::RegPairEven)
// Even register.
return getRegisterPairEven(Reg, MF);
return 0;
}
void
ARMBaseRegisterInfo::UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
MachineFunction &MF) const {
MachineRegisterInfo *MRI = &MF.getRegInfo();
std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(Reg);
if ((Hint.first == (unsigned)ARMRI::RegPairOdd ||
Hint.first == (unsigned)ARMRI::RegPairEven) &&
TargetRegisterInfo::isVirtualRegister(Hint.second)) {
// If 'Reg' is one of the even / odd register pair and it's now changed
// (e.g. coalesced) into a different register. The other register of the
// pair allocation hint must be updated to reflect the relationship
// change.
unsigned OtherReg = Hint.second;
Hint = MRI->getRegAllocationHint(OtherReg);
if (Hint.second == Reg)
// Make sure the pair has not already divorced.
MRI->setRegAllocationHint(OtherReg, Hint.first, NewReg);
}
}
bool
ARMBaseRegisterInfo::avoidWriteAfterWrite(const TargetRegisterClass *RC) const {
// CortexA9 has a Write-after-write hazard for NEON registers.
if (!STI.isCortexA9())
return false;
switch (RC->getID()) {
case ARM::DPRRegClassID:
case ARM::DPR_8RegClassID:
case ARM::DPR_VFP2RegClassID:
case ARM::QPRRegClassID:
case ARM::QPR_8RegClassID:
case ARM::QPR_VFP2RegClassID:
case ARM::SPRRegClassID:
case ARM::SPR_8RegClassID:
// Avoid reusing S, D, and Q registers.
// Don't increase register pressure for QQ and QQQQ.
return true;
default:
return false;
}
}
bool ARMBaseRegisterInfo::hasBasePointer(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
if (!EnableBasePointer)
return false;
if (needsStackRealignment(MF) && MFI->hasVarSizedObjects())
return true;
// Thumb has trouble with negative offsets from the FP. Thumb2 has a limited
// negative range for ldr/str (255), and thumb1 is positive offsets only.
// It's going to be better to use the SP or Base Pointer instead. When there
// are variable sized objects, we can't reference off of the SP, so we
// reserve a Base Pointer.
if (AFI->isThumbFunction() && MFI->hasVarSizedObjects()) {
// Conservatively estimate whether the negative offset from the frame
// pointer will be sufficient to reach. If a function has a smallish
// frame, it's less likely to have lots of spills and callee saved
// space, so it's all more likely to be within range of the frame pointer.
// If it's wrong, the scavenger will still enable access to work, it just
// won't be optimal.
if (AFI->isThumb2Function() && MFI->getLocalFrameSize() < 128)
return false;
return true;
}
return false;
}
bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
// We can't realign the stack if:
// 1. Dynamic stack realignment is explicitly disabled,
// 2. This is a Thumb1 function (it's not useful, so we don't bother), or
// 3. There are VLAs in the function and the base pointer is disabled.
return (MF.getTarget().Options.RealignStack && !AFI->isThumb1OnlyFunction() &&
(!MFI->hasVarSizedObjects() || EnableBasePointer));
}
bool ARMBaseRegisterInfo::
needsStackRealignment(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const Function *F = MF.getFunction();
unsigned StackAlign = MF.getTarget().getFrameLowering()->getStackAlignment();
bool requiresRealignment = ((MFI->getLocalFrameMaxAlign() > StackAlign) ||
F->hasFnAttr(Attribute::StackAlignment));
return requiresRealignment && canRealignStack(MF);
}
bool ARMBaseRegisterInfo::
cannotEliminateFrame(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
if (MF.getTarget().Options.DisableFramePointerElim(MF) && MFI->adjustsStack())
return true;
return MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken()
|| needsStackRealignment(MF);
}
unsigned
ARMBaseRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
if (TFI->hasFP(MF))
return FramePtr;
return ARM::SP;
}
unsigned ARMBaseRegisterInfo::getEHExceptionRegister() const {
llvm_unreachable("What is the exception register");
return 0;
}
unsigned ARMBaseRegisterInfo::getEHHandlerRegister() const {
llvm_unreachable("What is the exception handler register");
return 0;
}
unsigned ARMBaseRegisterInfo::getRegisterPairEven(unsigned Reg,
const MachineFunction &MF) const {
switch (Reg) {
default: break;
// Return 0 if either register of the pair is a special register.
// So no R12, etc.
case ARM::R1: return ARM::R0;
case ARM::R3: return ARM::R2;
case ARM::R5: return ARM::R4;
case ARM::R7:
return (isReservedReg(MF, ARM::R7) || isReservedReg(MF, ARM::R6))
? 0 : ARM::R6;
case ARM::R9: return isReservedReg(MF, ARM::R9) ? 0 :ARM::R8;
case ARM::R11: return isReservedReg(MF, ARM::R11) ? 0 : ARM::R10;
case ARM::S1: return ARM::S0;
case ARM::S3: return ARM::S2;
case ARM::S5: return ARM::S4;
case ARM::S7: return ARM::S6;
case ARM::S9: return ARM::S8;
case ARM::S11: return ARM::S10;
case ARM::S13: return ARM::S12;
case ARM::S15: return ARM::S14;
case ARM::S17: return ARM::S16;
case ARM::S19: return ARM::S18;
case ARM::S21: return ARM::S20;
case ARM::S23: return ARM::S22;
case ARM::S25: return ARM::S24;
case ARM::S27: return ARM::S26;
case ARM::S29: return ARM::S28;
case ARM::S31: return ARM::S30;
case ARM::D1: return ARM::D0;
case ARM::D3: return ARM::D2;
case ARM::D5: return ARM::D4;
case ARM::D7: return ARM::D6;
case ARM::D9: return ARM::D8;
case ARM::D11: return ARM::D10;
case ARM::D13: return ARM::D12;
case ARM::D15: return ARM::D14;
case ARM::D17: return ARM::D16;
case ARM::D19: return ARM::D18;
case ARM::D21: return ARM::D20;
case ARM::D23: return ARM::D22;
case ARM::D25: return ARM::D24;
case ARM::D27: return ARM::D26;
case ARM::D29: return ARM::D28;
case ARM::D31: return ARM::D30;
}
return 0;
}
unsigned ARMBaseRegisterInfo::getRegisterPairOdd(unsigned Reg,
const MachineFunction &MF) const {
switch (Reg) {
default: break;
// Return 0 if either register of the pair is a special register.
// So no R12, etc.
case ARM::R0: return ARM::R1;
case ARM::R2: return ARM::R3;
case ARM::R4: return ARM::R5;
case ARM::R6:
return (isReservedReg(MF, ARM::R7) || isReservedReg(MF, ARM::R6))
? 0 : ARM::R7;
case ARM::R8: return isReservedReg(MF, ARM::R9) ? 0 :ARM::R9;
case ARM::R10: return isReservedReg(MF, ARM::R11) ? 0 : ARM::R11;
case ARM::S0: return ARM::S1;
case ARM::S2: return ARM::S3;
case ARM::S4: return ARM::S5;
case ARM::S6: return ARM::S7;
case ARM::S8: return ARM::S9;
case ARM::S10: return ARM::S11;
case ARM::S12: return ARM::S13;
case ARM::S14: return ARM::S15;
case ARM::S16: return ARM::S17;
case ARM::S18: return ARM::S19;
case ARM::S20: return ARM::S21;
case ARM::S22: return ARM::S23;
case ARM::S24: return ARM::S25;
case ARM::S26: return ARM::S27;
case ARM::S28: return ARM::S29;
case ARM::S30: return ARM::S31;
case ARM::D0: return ARM::D1;
case ARM::D2: return ARM::D3;
case ARM::D4: return ARM::D5;
case ARM::D6: return ARM::D7;
case ARM::D8: return ARM::D9;
case ARM::D10: return ARM::D11;
case ARM::D12: return ARM::D13;
case ARM::D14: return ARM::D15;
case ARM::D16: return ARM::D17;
case ARM::D18: return ARM::D19;
case ARM::D20: return ARM::D21;
case ARM::D22: return ARM::D23;
case ARM::D24: return ARM::D25;
case ARM::D26: return ARM::D27;
case ARM::D28: return ARM::D29;
case ARM::D30: return ARM::D31;
}
return 0;
}
/// emitLoadConstPool - Emits a load from constpool to materialize the
/// specified immediate.
void ARMBaseRegisterInfo::
emitLoadConstPool(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
DebugLoc dl,
unsigned DestReg, unsigned SubIdx, int Val,
ARMCC::CondCodes Pred,
unsigned PredReg, unsigned MIFlags) const {
MachineFunction &MF = *MBB.getParent();
MachineConstantPool *ConstantPool = MF.getConstantPool();
const Constant *C =
ConstantInt::get(Type::getInt32Ty(MF.getFunction()->getContext()), Val);
unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
BuildMI(MBB, MBBI, dl, TII.get(ARM::LDRcp))
.addReg(DestReg, getDefRegState(true), SubIdx)
.addConstantPoolIndex(Idx)
.addImm(0).addImm(Pred).addReg(PredReg)
.setMIFlags(MIFlags);
}
bool ARMBaseRegisterInfo::
requiresRegisterScavenging(const MachineFunction &MF) const {
return true;
}
bool ARMBaseRegisterInfo::
requiresFrameIndexScavenging(const MachineFunction &MF) const {
return true;
}
bool ARMBaseRegisterInfo::
requiresVirtualBaseRegisters(const MachineFunction &MF) const {
return EnableLocalStackAlloc;
}
static void
emitSPUpdate(bool isARM,
MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
DebugLoc dl, const ARMBaseInstrInfo &TII,
int NumBytes,
ARMCC::CondCodes Pred = ARMCC::AL, unsigned PredReg = 0) {
if (isARM)
emitARMRegPlusImmediate(MBB, MBBI, dl, ARM::SP, ARM::SP, NumBytes,
Pred, PredReg, TII);
else
emitT2RegPlusImmediate(MBB, MBBI, dl, ARM::SP, ARM::SP, NumBytes,
Pred, PredReg, TII);
}
void ARMBaseRegisterInfo::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
if (!TFI->hasReservedCallFrame(MF)) {
// If we have alloca, convert as follows:
// ADJCALLSTACKDOWN -> sub, sp, sp, amount
// ADJCALLSTACKUP -> add, sp, sp, amount
MachineInstr *Old = I;
DebugLoc dl = Old->getDebugLoc();
unsigned Amount = Old->getOperand(0).getImm();
if (Amount != 0) {
// We need to keep the stack aligned properly. To do this, we round the
// amount of space needed for the outgoing arguments up to the next
// alignment boundary.
unsigned Align = TFI->getStackAlignment();
Amount = (Amount+Align-1)/Align*Align;
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
assert(!AFI->isThumb1OnlyFunction() &&
"This eliminateCallFramePseudoInstr does not support Thumb1!");
bool isARM = !AFI->isThumbFunction();
// Replace the pseudo instruction with a new instruction...
unsigned Opc = Old->getOpcode();
int PIdx = Old->findFirstPredOperandIdx();
ARMCC::CondCodes Pred = (PIdx == -1)
? ARMCC::AL : (ARMCC::CondCodes)Old->getOperand(PIdx).getImm();
if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
// Note: PredReg is operand 2 for ADJCALLSTACKDOWN.
unsigned PredReg = Old->getOperand(2).getReg();
emitSPUpdate(isARM, MBB, I, dl, TII, -Amount, Pred, PredReg);
} else {
// Note: PredReg is operand 3 for ADJCALLSTACKUP.
unsigned PredReg = Old->getOperand(3).getReg();
assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
emitSPUpdate(isARM, MBB, I, dl, TII, Amount, Pred, PredReg);
}
}
}
MBB.erase(I);
}
int64_t ARMBaseRegisterInfo::
getFrameIndexInstrOffset(const MachineInstr *MI, int Idx) const {
const MCInstrDesc &Desc = MI->getDesc();
unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
int64_t InstrOffs = 0;;
int Scale = 1;
unsigned ImmIdx = 0;
switch (AddrMode) {
case ARMII::AddrModeT2_i8:
case ARMII::AddrModeT2_i12:
case ARMII::AddrMode_i12:
InstrOffs = MI->getOperand(Idx+1).getImm();
Scale = 1;
break;
case ARMII::AddrMode5: {
// VFP address mode.
const MachineOperand &OffOp = MI->getOperand(Idx+1);
InstrOffs = ARM_AM::getAM5Offset(OffOp.getImm());
if (ARM_AM::getAM5Op(OffOp.getImm()) == ARM_AM::sub)
InstrOffs = -InstrOffs;
Scale = 4;
break;
}
case ARMII::AddrMode2: {
ImmIdx = Idx+2;
InstrOffs = ARM_AM::getAM2Offset(MI->getOperand(ImmIdx).getImm());
if (ARM_AM::getAM2Op(MI->getOperand(ImmIdx).getImm()) == ARM_AM::sub)
InstrOffs = -InstrOffs;
break;
}
case ARMII::AddrMode3: {
ImmIdx = Idx+2;
InstrOffs = ARM_AM::getAM3Offset(MI->getOperand(ImmIdx).getImm());
if (ARM_AM::getAM3Op(MI->getOperand(ImmIdx).getImm()) == ARM_AM::sub)
InstrOffs = -InstrOffs;
break;
}
case ARMII::AddrModeT1_s: {
ImmIdx = Idx+1;
InstrOffs = MI->getOperand(ImmIdx).getImm();
Scale = 4;
break;
}
default:
llvm_unreachable("Unsupported addressing mode!");
break;
}
return InstrOffs * Scale;
}
/// needsFrameBaseReg - Returns true if the instruction's frame index
/// reference would be better served by a base register other than FP
/// or SP. Used by LocalStackFrameAllocation to determine which frame index
/// references it should create new base registers for.
bool ARMBaseRegisterInfo::
needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const {
for (unsigned i = 0; !MI->getOperand(i).isFI(); ++i) {
assert(i < MI->getNumOperands() &&"Instr doesn't have FrameIndex operand!");
}
// It's the load/store FI references that cause issues, as it can be difficult
// to materialize the offset if it won't fit in the literal field. Estimate
// based on the size of the local frame and some conservative assumptions
// about the rest of the stack frame (note, this is pre-regalloc, so
// we don't know everything for certain yet) whether this offset is likely
// to be out of range of the immediate. Return true if so.
// We only generate virtual base registers for loads and stores, so
// return false for everything else.
unsigned Opc = MI->getOpcode();
switch (Opc) {
case ARM::LDRi12: case ARM::LDRH: case ARM::LDRBi12:
case ARM::STRi12: case ARM::STRH: case ARM::STRBi12:
case ARM::t2LDRi12: case ARM::t2LDRi8:
case ARM::t2STRi12: case ARM::t2STRi8:
case ARM::VLDRS: case ARM::VLDRD:
case ARM::VSTRS: case ARM::VSTRD:
case ARM::tSTRspi: case ARM::tLDRspi:
if (ForceAllBaseRegAlloc)
return true;
break;
default:
return false;
}
// Without a virtual base register, if the function has variable sized
// objects, all fixed-size local references will be via the frame pointer,
// Approximate the offset and see if it's legal for the instruction.
// Note that the incoming offset is based on the SP value at function entry,
// so it'll be negative.
MachineFunction &MF = *MI->getParent()->getParent();
const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
MachineFrameInfo *MFI = MF.getFrameInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
// Estimate an offset from the frame pointer.
// Conservatively assume all callee-saved registers get pushed. R4-R6
// will be earlier than the FP, so we ignore those.
// R7, LR
int64_t FPOffset = Offset - 8;
// ARM and Thumb2 functions also need to consider R8-R11 and D8-D15
if (!AFI->isThumbFunction() || !AFI->isThumb1OnlyFunction())
FPOffset -= 80;
// Estimate an offset from the stack pointer.
// The incoming offset is relating to the SP at the start of the function,
// but when we access the local it'll be relative to the SP after local
// allocation, so adjust our SP-relative offset by that allocation size.
Offset = -Offset;
Offset += MFI->getLocalFrameSize();
// Assume that we'll have at least some spill slots allocated.
// FIXME: This is a total SWAG number. We should run some statistics
// and pick a real one.
Offset += 128; // 128 bytes of spill slots
// If there is a frame pointer, try using it.
// The FP is only available if there is no dynamic realignment. We
// don't know for sure yet whether we'll need that, so we guess based
// on whether there are any local variables that would trigger it.
unsigned StackAlign = TFI->getStackAlignment();
if (TFI->hasFP(MF) &&
!((MFI->getLocalFrameMaxAlign() > StackAlign) && canRealignStack(MF))) {
if (isFrameOffsetLegal(MI, FPOffset))
return false;
}
// If we can reference via the stack pointer, try that.
// FIXME: This (and the code that resolves the references) can be improved
// to only disallow SP relative references in the live range of
// the VLA(s). In practice, it's unclear how much difference that
// would make, but it may be worth doing.
if (!MFI->hasVarSizedObjects() && isFrameOffsetLegal(MI, Offset))
return false;
// The offset likely isn't legal, we want to allocate a virtual base register.
return true;
}
/// materializeFrameBaseRegister - Insert defining instruction(s) for BaseReg to
/// be a pointer to FrameIdx at the beginning of the basic block.
void ARMBaseRegisterInfo::
materializeFrameBaseRegister(MachineBasicBlock *MBB,
unsigned BaseReg, int FrameIdx,
int64_t Offset) const {
ARMFunctionInfo *AFI = MBB->getParent()->getInfo<ARMFunctionInfo>();
unsigned ADDriOpc = !AFI->isThumbFunction() ? ARM::ADDri :
(AFI->isThumb1OnlyFunction() ? ARM::tADDrSPi : ARM::t2ADDri);
MachineBasicBlock::iterator Ins = MBB->begin();
DebugLoc DL; // Defaults to "unknown"
if (Ins != MBB->end())
DL = Ins->getDebugLoc();
const MCInstrDesc &MCID = TII.get(ADDriOpc);
MachineRegisterInfo &MRI = MBB->getParent()->getRegInfo();
MRI.constrainRegClass(BaseReg, TII.getRegClass(MCID, 0, this));
MachineInstrBuilder MIB = AddDefaultPred(BuildMI(*MBB, Ins, DL, MCID, BaseReg)
.addFrameIndex(FrameIdx).addImm(Offset));
if (!AFI->isThumb1OnlyFunction())
AddDefaultCC(MIB);
}
void
ARMBaseRegisterInfo::resolveFrameIndex(MachineBasicBlock::iterator I,
unsigned BaseReg, int64_t Offset) const {
MachineInstr &MI = *I;
MachineBasicBlock &MBB = *MI.getParent();
MachineFunction &MF = *MBB.getParent();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
int Off = Offset; // ARM doesn't need the general 64-bit offsets
unsigned i = 0;
assert(!AFI->isThumb1OnlyFunction() &&
"This resolveFrameIndex does not support Thumb1!");
while (!MI.getOperand(i).isFI()) {
++i;
assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
}
bool Done = false;
if (!AFI->isThumbFunction())
Done = rewriteARMFrameIndex(MI, i, BaseReg, Off, TII);
else {
assert(AFI->isThumb2Function());
Done = rewriteT2FrameIndex(MI, i, BaseReg, Off, TII);
}
assert (Done && "Unable to resolve frame index!");
(void)Done;
}
bool ARMBaseRegisterInfo::isFrameOffsetLegal(const MachineInstr *MI,
int64_t Offset) const {
const MCInstrDesc &Desc = MI->getDesc();
unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
unsigned i = 0;
while (!MI->getOperand(i).isFI()) {
++i;
assert(i < MI->getNumOperands() &&"Instr doesn't have FrameIndex operand!");
}
// AddrMode4 and AddrMode6 cannot handle any offset.
if (AddrMode == ARMII::AddrMode4 || AddrMode == ARMII::AddrMode6)
return Offset == 0;
unsigned NumBits = 0;
unsigned Scale = 1;
bool isSigned = true;
switch (AddrMode) {
case ARMII::AddrModeT2_i8:
case ARMII::AddrModeT2_i12:
// i8 supports only negative, and i12 supports only positive, so
// based on Offset sign, consider the appropriate instruction
Scale = 1;
if (Offset < 0) {
NumBits = 8;
Offset = -Offset;
} else {
NumBits = 12;
}
break;
case ARMII::AddrMode5:
// VFP address mode.
NumBits = 8;
Scale = 4;
break;
case ARMII::AddrMode_i12:
case ARMII::AddrMode2:
NumBits = 12;
break;
case ARMII::AddrMode3:
NumBits = 8;
break;
case ARMII::AddrModeT1_s:
NumBits = 5;
Scale = 4;
isSigned = false;
break;
default:
llvm_unreachable("Unsupported addressing mode!");
break;
}
Offset += getFrameIndexInstrOffset(MI, i);
// Make sure the offset is encodable for instructions that scale the
// immediate.
if ((Offset & (Scale-1)) != 0)
return false;
if (isSigned && Offset < 0)
Offset = -Offset;
unsigned Mask = (1 << NumBits) - 1;
if ((unsigned)Offset <= Mask * Scale)
return true;
return false;
}
void
ARMBaseRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
int SPAdj, RegScavenger *RS) const {
unsigned i = 0;
MachineInstr &MI = *II;
MachineBasicBlock &MBB = *MI.getParent();
MachineFunction &MF = *MBB.getParent();
const ARMFrameLowering *TFI =
static_cast<const ARMFrameLowering*>(MF.getTarget().getFrameLowering());
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
assert(!AFI->isThumb1OnlyFunction() &&
"This eliminateFrameIndex does not support Thumb1!");
while (!MI.getOperand(i).isFI()) {
++i;
assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
}
int FrameIndex = MI.getOperand(i).getIndex();
unsigned FrameReg;
int Offset = TFI->ResolveFrameIndexReference(MF, FrameIndex, FrameReg, SPAdj);
// Special handling of dbg_value instructions.
if (MI.isDebugValue()) {
MI.getOperand(i). ChangeToRegister(FrameReg, false /*isDef*/);
MI.getOperand(i+1).ChangeToImmediate(Offset);
return;
}
// Modify MI as necessary to handle as much of 'Offset' as possible
bool Done = false;
if (!AFI->isThumbFunction())
Done = rewriteARMFrameIndex(MI, i, FrameReg, Offset, TII);
else {
assert(AFI->isThumb2Function());
Done = rewriteT2FrameIndex(MI, i, FrameReg, Offset, TII);
}
if (Done)
return;
// If we get here, the immediate doesn't fit into the instruction. We folded
// as much as possible above, handle the rest, providing a register that is
// SP+LargeImm.
assert((Offset ||
(MI.getDesc().TSFlags & ARMII::AddrModeMask) == ARMII::AddrMode4 ||
(MI.getDesc().TSFlags & ARMII::AddrModeMask) == ARMII::AddrMode6) &&
"This code isn't needed if offset already handled!");
unsigned ScratchReg = 0;
int PIdx = MI.findFirstPredOperandIdx();
ARMCC::CondCodes Pred = (PIdx == -1)
? ARMCC::AL : (ARMCC::CondCodes)MI.getOperand(PIdx).getImm();
unsigned PredReg = (PIdx == -1) ? 0 : MI.getOperand(PIdx+1).getReg();
if (Offset == 0)
// Must be addrmode4/6.
MI.getOperand(i).ChangeToRegister(FrameReg, false, false, false);
else {
ScratchReg = MF.getRegInfo().createVirtualRegister(ARM::GPRRegisterClass);
if (!AFI->isThumbFunction())
emitARMRegPlusImmediate(MBB, II, MI.getDebugLoc(), ScratchReg, FrameReg,
Offset, Pred, PredReg, TII);
else {
assert(AFI->isThumb2Function());
emitT2RegPlusImmediate(MBB, II, MI.getDebugLoc(), ScratchReg, FrameReg,
Offset, Pred, PredReg, TII);
}
// Update the original instruction to use the scratch register.
MI.getOperand(i).ChangeToRegister(ScratchReg, false, false, true);
}
}
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