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llvm-project/llvm/lib/Target/Mips/MipsInstrInfo.cpp

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//===- MipsInstrInfo.cpp - Mips Instruction 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 Mips implementation of the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "MipsInstrInfo.h"
#include "MCTargetDesc/MipsBaseInfo.h"
#include "MCTargetDesc/MipsMCTargetDesc.h"
#include "MipsSubtarget.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/Target/TargetMachine.h"
#include <cassert>
using namespace llvm;
#define GET_INSTRINFO_CTOR_DTOR
#include "MipsGenInstrInfo.inc"
// Pin the vtable to this file.
void MipsInstrInfo::anchor() {}
MipsInstrInfo::MipsInstrInfo(const MipsSubtarget &STI, unsigned UncondBr)
: MipsGenInstrInfo(Mips::ADJCALLSTACKDOWN, Mips::ADJCALLSTACKUP),
Subtarget(STI), UncondBrOpc(UncondBr) {}
const MipsInstrInfo *MipsInstrInfo::create(MipsSubtarget &STI) {
if (STI.inMips16Mode())
return createMips16InstrInfo(STI);
return createMipsSEInstrInfo(STI);
}
bool MipsInstrInfo::isZeroImm(const MachineOperand &op) const {
return op.isImm() && op.getImm() == 0;
}
/// insertNoop - If data hazard condition is found insert the target nop
/// instruction.
// FIXME: This appears to be dead code.
void MipsInstrInfo::
insertNoop(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI) const
{
DebugLoc DL;
BuildMI(MBB, MI, DL, get(Mips::NOP));
}
MachineMemOperand *
MipsInstrInfo::GetMemOperand(MachineBasicBlock &MBB, int FI,
MachineMemOperand::Flags Flags) const {
MachineFunction &MF = *MBB.getParent();
MachineFrameInfo &MFI = MF.getFrameInfo();
unsigned Align = MFI.getObjectAlignment(FI);
return MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(MF, FI),
Flags, MFI.getObjectSize(FI), Align);
}
//===----------------------------------------------------------------------===//
// Branch Analysis
//===----------------------------------------------------------------------===//
void MipsInstrInfo::AnalyzeCondBr(const MachineInstr *Inst, unsigned Opc,
MachineBasicBlock *&BB,
SmallVectorImpl<MachineOperand> &Cond) const {
assert(getAnalyzableBrOpc(Opc) && "Not an analyzable branch");
int NumOp = Inst->getNumExplicitOperands();
// for both int and fp branches, the last explicit operand is the
// MBB.
BB = Inst->getOperand(NumOp-1).getMBB();
Cond.push_back(MachineOperand::CreateImm(Opc));
for (int i = 0; i < NumOp-1; i++)
Cond.push_back(Inst->getOperand(i));
}
bool MipsInstrInfo::analyzeBranch(MachineBasicBlock &MBB,
MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify) const {
SmallVector<MachineInstr*, 2> BranchInstrs;
BranchType BT = analyzeBranch(MBB, TBB, FBB, Cond, AllowModify, BranchInstrs);
return (BT == BT_None) || (BT == BT_Indirect);
}
void MipsInstrInfo::BuildCondBr(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
const DebugLoc &DL,
ArrayRef<MachineOperand> Cond) const {
unsigned Opc = Cond[0].getImm();
const MCInstrDesc &MCID = get(Opc);
MachineInstrBuilder MIB = BuildMI(&MBB, DL, MCID);
for (unsigned i = 1; i < Cond.size(); ++i) {
assert((Cond[i].isImm() || Cond[i].isReg()) &&
"Cannot copy operand for conditional branch!");
MIB.add(Cond[i]);
}
MIB.addMBB(TBB);
}
unsigned MipsInstrInfo::insertBranch(MachineBasicBlock &MBB,
MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
ArrayRef<MachineOperand> Cond,
const DebugLoc &DL,
int *BytesAdded) const {
// Shouldn't be a fall through.
assert(TBB && "insertBranch must not be told to insert a fallthrough");
assert(!BytesAdded && "code size not handled");
// # of condition operands:
// Unconditional branches: 0
// Floating point branches: 1 (opc)
// Int BranchZero: 2 (opc, reg)
// Int Branch: 3 (opc, reg0, reg1)
assert((Cond.size() <= 3) &&
"# of Mips branch conditions must be <= 3!");
// Two-way Conditional branch.
if (FBB) {
BuildCondBr(MBB, TBB, DL, Cond);
BuildMI(&MBB, DL, get(UncondBrOpc)).addMBB(FBB);
return 2;
}
// One way branch.
// Unconditional branch.
if (Cond.empty())
BuildMI(&MBB, DL, get(UncondBrOpc)).addMBB(TBB);
else // Conditional branch.
BuildCondBr(MBB, TBB, DL, Cond);
return 1;
}
unsigned MipsInstrInfo::removeBranch(MachineBasicBlock &MBB,
int *BytesRemoved) const {
assert(!BytesRemoved && "code size not handled");
MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
unsigned removed = 0;
// Up to 2 branches are removed.
// Note that indirect branches are not removed.
while (I != REnd && removed < 2) {
// Skip past debug instructions.
if (I->isDebugValue()) {
++I;
continue;
}
if (!getAnalyzableBrOpc(I->getOpcode()))
break;
// Remove the branch.
I->eraseFromParent();
I = MBB.rbegin();
++removed;
}
return removed;
}
/// reverseBranchCondition - Return the inverse opcode of the
/// specified Branch instruction.
bool MipsInstrInfo::reverseBranchCondition(
SmallVectorImpl<MachineOperand> &Cond) const {
assert( (Cond.size() && Cond.size() <= 3) &&
"Invalid Mips branch condition!");
Cond[0].setImm(getOppositeBranchOpc(Cond[0].getImm()));
return false;
}
MipsInstrInfo::BranchType MipsInstrInfo::analyzeBranch(
MachineBasicBlock &MBB, MachineBasicBlock *&TBB, MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond, bool AllowModify,
SmallVectorImpl<MachineInstr *> &BranchInstrs) const {
MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
// Skip all the debug instructions.
while (I != REnd && I->isDebugValue())
++I;
if (I == REnd || !isUnpredicatedTerminator(*I)) {
// This block ends with no branches (it just falls through to its succ).
// Leave TBB/FBB null.
TBB = FBB = nullptr;
return BT_NoBranch;
}
MachineInstr *LastInst = &*I;
unsigned LastOpc = LastInst->getOpcode();
BranchInstrs.push_back(LastInst);
// Not an analyzable branch (e.g., indirect jump).
if (!getAnalyzableBrOpc(LastOpc))
return LastInst->isIndirectBranch() ? BT_Indirect : BT_None;
// Get the second to last instruction in the block.
unsigned SecondLastOpc = 0;
MachineInstr *SecondLastInst = nullptr;
// Skip past any debug instruction to see if the second last actual
// is a branch.
++I;
while (I != REnd && I->isDebugValue())
++I;
if (I != REnd) {
SecondLastInst = &*I;
SecondLastOpc = getAnalyzableBrOpc(SecondLastInst->getOpcode());
// Not an analyzable branch (must be an indirect jump).
if (isUnpredicatedTerminator(*SecondLastInst) && !SecondLastOpc)
return BT_None;
}
// If there is only one terminator instruction, process it.
if (!SecondLastOpc) {
// Unconditional branch.
if (LastInst->isUnconditionalBranch()) {
TBB = LastInst->getOperand(0).getMBB();
return BT_Uncond;
}
// Conditional branch
AnalyzeCondBr(LastInst, LastOpc, TBB, Cond);
return BT_Cond;
}
// If we reached here, there are two branches.
// If there are three terminators, we don't know what sort of block this is.
if (++I != REnd && isUnpredicatedTerminator(*I))
return BT_None;
BranchInstrs.insert(BranchInstrs.begin(), SecondLastInst);
// If second to last instruction is an unconditional branch,
// analyze it and remove the last instruction.
if (SecondLastInst->isUnconditionalBranch()) {
// Return if the last instruction cannot be removed.
if (!AllowModify)
return BT_None;
TBB = SecondLastInst->getOperand(0).getMBB();
LastInst->eraseFromParent();
BranchInstrs.pop_back();
return BT_Uncond;
}
// Conditional branch followed by an unconditional branch.
// The last one must be unconditional.
if (!LastInst->isUnconditionalBranch())
return BT_None;
AnalyzeCondBr(SecondLastInst, SecondLastOpc, TBB, Cond);
FBB = LastInst->getOperand(0).getMBB();
return BT_CondUncond;
}
/// Return the corresponding compact (no delay slot) form of a branch.
unsigned MipsInstrInfo::getEquivalentCompactForm(
const MachineBasicBlock::iterator I) const {
unsigned Opcode = I->getOpcode();
bool canUseShortMicroMipsCTI = false;
if (Subtarget.inMicroMipsMode()) {
switch (Opcode) {
case Mips::BNE:
case Mips::BNE_MM:
case Mips::BEQ:
case Mips::BEQ_MM:
// microMIPS has NE,EQ branches that do not have delay slots provided one
// of the operands is zero.
if (I->getOperand(1).getReg() == Subtarget.getABI().GetZeroReg())
canUseShortMicroMipsCTI = true;
break;
// For microMIPS the PseudoReturn and PseudoIndirectBranch are always
// expanded to JR_MM, so they can be replaced with JRC16_MM.
case Mips::JR:
case Mips::PseudoReturn:
case Mips::PseudoIndirectBranch:
case Mips::TAILCALLREG:
canUseShortMicroMipsCTI = true;
break;
}
}
// MIPSR6 forbids both operands being the zero register.
if (Subtarget.hasMips32r6() && (I->getNumOperands() > 1) &&
(I->getOperand(0).isReg() &&
(I->getOperand(0).getReg() == Mips::ZERO ||
I->getOperand(0).getReg() == Mips::ZERO_64)) &&
(I->getOperand(1).isReg() &&
(I->getOperand(1).getReg() == Mips::ZERO ||
I->getOperand(1).getReg() == Mips::ZERO_64)))
return 0;
if (Subtarget.hasMips32r6() || canUseShortMicroMipsCTI) {
switch (Opcode) {
case Mips::B:
return Mips::BC;
case Mips::BAL:
return Mips::BALC;
case Mips::BEQ:
case Mips::BEQ_MM:
if (canUseShortMicroMipsCTI)
return Mips::BEQZC_MM;
else if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BEQC;
case Mips::BNE:
case Mips::BNE_MM:
if (canUseShortMicroMipsCTI)
return Mips::BNEZC_MM;
else if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BNEC;
case Mips::BGE:
if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BGEC;
case Mips::BGEU:
if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BGEUC;
case Mips::BGEZ:
return Mips::BGEZC;
case Mips::BGTZ:
return Mips::BGTZC;
case Mips::BLEZ:
return Mips::BLEZC;
case Mips::BLT:
if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BLTC;
case Mips::BLTU:
if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BLTUC;
case Mips::BLTZ:
return Mips::BLTZC;
case Mips::BEQ64:
if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BEQC64;
case Mips::BNE64:
if (I->getOperand(0).getReg() == I->getOperand(1).getReg())
return 0;
return Mips::BNEC64;
case Mips::BGTZ64:
return Mips::BGTZC64;
case Mips::BGEZ64:
return Mips::BGEZC64;
case Mips::BLTZ64:
return Mips::BLTZC64;
case Mips::BLEZ64:
return Mips::BLEZC64;
// For MIPSR6, the instruction 'jic' can be used for these cases. Some
// tools will accept 'jrc reg' as an alias for 'jic 0, $reg'.
case Mips::JR:
case Mips::PseudoReturn:
case Mips::PseudoIndirectBranch:
case Mips::TAILCALLREG:
if (canUseShortMicroMipsCTI)
return Mips::JRC16_MM;
return Mips::JIC;
case Mips::JALRPseudo:
return Mips::JIALC;
case Mips::JR64:
case Mips::PseudoReturn64:
case Mips::PseudoIndirectBranch64:
case Mips::TAILCALLREG64:
return Mips::JIC64;
case Mips::JALR64Pseudo:
return Mips::JIALC64;
default:
return 0;
}
}
return 0;
}
/// Predicate for distingushing between control transfer instructions and all
/// other instructions for handling forbidden slots. Consider inline assembly
/// as unsafe as well.
bool MipsInstrInfo::SafeInForbiddenSlot(const MachineInstr &MI) const {
if (MI.isInlineAsm())
return false;
return (MI.getDesc().TSFlags & MipsII::IsCTI) == 0;
}
/// Predicate for distingushing instructions that have forbidden slots.
bool MipsInstrInfo::HasForbiddenSlot(const MachineInstr &MI) const {
return (MI.getDesc().TSFlags & MipsII::HasForbiddenSlot) != 0;
}
/// Return the number of bytes of code the specified instruction may be.
unsigned MipsInstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
switch (MI.getOpcode()) {
default:
return MI.getDesc().getSize();
case TargetOpcode::INLINEASM: { // Inline Asm: Variable size.
const MachineFunction *MF = MI.getParent()->getParent();
const char *AsmStr = MI.getOperand(0).getSymbolName();
return getInlineAsmLength(AsmStr, *MF->getTarget().getMCAsmInfo());
}
case Mips::CONSTPOOL_ENTRY:
// If this machine instr is a constant pool entry, its size is recorded as
// operand #2.
return MI.getOperand(2).getImm();
}
}
MachineInstrBuilder
MipsInstrInfo::genInstrWithNewOpc(unsigned NewOpc,
MachineBasicBlock::iterator I) const {
MachineInstrBuilder MIB;
// Certain branches have two forms: e.g beq $1, $zero, dest vs beqz $1, dest
// Pick the zero form of the branch for readable assembly and for greater
// branch distance in non-microMIPS mode.
// Additional MIPSR6 does not permit the use of register $zero for compact
// branches.
// FIXME: Certain atomic sequences on mips64 generate 32bit references to
// Mips::ZERO, which is incorrect. This test should be updated to use
// Subtarget.getABI().GetZeroReg() when those atomic sequences and others
// are fixed.
int ZeroOperandPosition = -1;
bool BranchWithZeroOperand = false;
if (I->isBranch() && !I->isPseudo()) {
auto TRI = I->getParent()->getParent()->getSubtarget().getRegisterInfo();
ZeroOperandPosition = I->findRegisterUseOperandIdx(Mips::ZERO, false, TRI);
BranchWithZeroOperand = ZeroOperandPosition != -1;
}
if (BranchWithZeroOperand) {
switch (NewOpc) {
case Mips::BEQC:
NewOpc = Mips::BEQZC;
break;
case Mips::BNEC:
NewOpc = Mips::BNEZC;
break;
case Mips::BGEC:
NewOpc = Mips::BGEZC;
break;
case Mips::BLTC:
NewOpc = Mips::BLTZC;
break;
case Mips::BEQC64:
NewOpc = Mips::BEQZC64;
break;
case Mips::BNEC64:
NewOpc = Mips::BNEZC64;
break;
}
}
MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), get(NewOpc));
// For MIPSR6 JI*C requires an immediate 0 as an operand, JIALC(64) an
// immediate 0 as an operand and requires the removal of it's %ra<imp-def>
// implicit operand as copying the implicit operations of the instructio we're
// looking at will give us the correct flags.
if (NewOpc == Mips::JIC || NewOpc == Mips::JIALC || NewOpc == Mips::JIC64 ||
NewOpc == Mips::JIALC64) {
if (NewOpc == Mips::JIALC || NewOpc == Mips::JIALC64)
MIB->RemoveOperand(0);
for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
MIB.add(I->getOperand(J));
}
MIB.addImm(0);
} else {
for (unsigned J = 0, E = I->getDesc().getNumOperands(); J < E; ++J) {
if (BranchWithZeroOperand && (unsigned)ZeroOperandPosition == J)
continue;
MIB.add(I->getOperand(J));
}
}
MIB.copyImplicitOps(*I);
MIB.setMemRefs(I->memoperands_begin(), I->memoperands_end());
return MIB;
}
bool MipsInstrInfo::findCommutedOpIndices(MachineInstr &MI, unsigned &SrcOpIdx1,
unsigned &SrcOpIdx2) const {
assert(!MI.isBundle() &&
"TargetInstrInfo::findCommutedOpIndices() can't handle bundles");
const MCInstrDesc &MCID = MI.getDesc();
if (!MCID.isCommutable())
return false;
switch (MI.getOpcode()) {
case Mips::DPADD_U_H:
case Mips::DPADD_U_W:
case Mips::DPADD_U_D:
case Mips::DPADD_S_H:
case Mips::DPADD_S_W:
case Mips::DPADD_S_D:
// The first operand is both input and output, so it should not commute
if (!fixCommutedOpIndices(SrcOpIdx1, SrcOpIdx2, 2, 3))
return false;
if (!MI.getOperand(SrcOpIdx1).isReg() || !MI.getOperand(SrcOpIdx2).isReg())
return false;
return true;
}
return TargetInstrInfo::findCommutedOpIndices(MI, SrcOpIdx1, SrcOpIdx2);
}
// ins, ext, dext*, dins have the following constraints:
// 0 <= pos < X
// 0 < size <= X
// 0 < pos+size <= x
//
// dinsm and dinsm have the following contraints:
// 0 <= pos < X
// 0 <= size <= X
// 0 < pos+size <= x
static bool verifyInsExtInstruction(const MachineInstr &MI, StringRef &ErrInfo,
const int64_t PosLow, const int64_t PosHigh,
const int64_t SizeLow,
const int64_t SizeHigh,
const int64_t BothLow,
const int64_t BothHigh) {
MachineOperand MOPos = MI.getOperand(2);
if (!MOPos.isImm()) {
ErrInfo = "Position is not an immediate!";
return false;
}
int64_t Pos = MOPos.getImm();
if (!((PosLow <= Pos) && (Pos < PosHigh))) {
ErrInfo = "Position operand is out of range!";
return false;
}
MachineOperand MOSize = MI.getOperand(3);
if (!MOSize.isImm()) {
ErrInfo = "Size operand is not an immediate!";
return false;
}
int64_t Size = MOSize.getImm();
if (!((SizeLow < Size) && (Size <= SizeHigh))) {
ErrInfo = "Size operand is out of range!";
return false;
}
if (!((BothLow < (Pos + Size)) && ((Pos + Size) <= BothHigh))) {
ErrInfo = "Position + Size is out of range!";
return false;
}
return true;
}
// Perform target specific instruction verification.
bool MipsInstrInfo::verifyInstruction(const MachineInstr &MI,
StringRef &ErrInfo) const {
// Verify that ins and ext instructions are well formed.
switch (MI.getOpcode()) {
case Mips::EXT:
case Mips::EXT_MM:
case Mips::INS:
case Mips::INS_MM:
case Mips::DINS:
case Mips::DINS_MM64R6:
return verifyInsExtInstruction(MI, ErrInfo, 0, 32, 0, 32, 0, 32);
case Mips::DINSM:
case Mips::DINSM_MM64R6:
// The ISA spec has a subtle difference here in that it says:
// 2 <= size <= 64 for 'dinsm', so we change the bounds so that it
// is in line with the rest of instructions.
return verifyInsExtInstruction(MI, ErrInfo, 0, 32, 1, 64, 32, 64);
case Mips::DINSU:
case Mips::DINSU_MM64R6:
// The ISA spec has a subtle difference here in that it says:
// 2 <= size <= 64 for 'dinsm', so we change the bounds so that it
// is in line with the rest of instructions.
return verifyInsExtInstruction(MI, ErrInfo, 32, 64, 1, 32, 32, 64);
case Mips::DEXT:
case Mips::DEXT_MM64R6:
return verifyInsExtInstruction(MI, ErrInfo, 0, 32, 0, 32, 0, 63);
case Mips::DEXTM:
case Mips::DEXTM_MM64R6:
return verifyInsExtInstruction(MI, ErrInfo, 0, 32, 32, 64, 32, 64);
case Mips::DEXTU:
case Mips::DEXTU_MM64R6:
return verifyInsExtInstruction(MI, ErrInfo, 32, 64, 0, 32, 32, 64);
default:
return true;
}
return true;
}
std::pair<unsigned, unsigned>
MipsInstrInfo::decomposeMachineOperandsTargetFlags(unsigned TF) const {
return std::make_pair(TF, 0u);
}
ArrayRef<std::pair<unsigned, const char*>>
MipsInstrInfo::getSerializableDirectMachineOperandTargetFlags() const {
using namespace MipsII;
static const std::pair<unsigned, const char*> Flags[] = {
{MO_GOT, "mips-got"},
{MO_GOT_CALL, "mips-got-call"},
{MO_GPREL, "mips-gprel"},
{MO_ABS_HI, "mips-abs-hi"},
{MO_ABS_LO, "mips-abs-lo"},
{MO_TLSGD, "mips-tlsgd"},
{MO_TLSLDM, "mips-tlsldm"},
{MO_DTPREL_HI, "mips-dtprel-hi"},
{MO_DTPREL_LO, "mips-dtprel-lo"},
{MO_GOTTPREL, "mips-gottprel"},
{MO_TPREL_HI, "mips-tprel-hi"},
{MO_TPREL_LO, "mips-tprel-lo"},
{MO_GPOFF_HI, "mips-gpoff-hi"},
{MO_GPOFF_LO, "mips-gpoff-lo"},
{MO_GOT_DISP, "mips-got-disp"},
{MO_GOT_PAGE, "mips-got-page"},
{MO_GOT_OFST, "mips-got-ofst"},
{MO_HIGHER, "mips-higher"},
{MO_HIGHEST, "mips-highest"},
{MO_GOT_HI16, "mips-got-hi16"},
{MO_GOT_LO16, "mips-got-lo16"},
{MO_CALL_HI16, "mips-call-hi16"},
{MO_CALL_LO16, "mips-call-lo16"}
};
return makeArrayRef(Flags);
}
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