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llvm-project/llvm/lib/CodeGen/GlobalISel/InlineAsmLowering.cpp

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//===-- lib/CodeGen/GlobalISel/InlineAsmLowering.cpp ----------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements the lowering from LLVM IR inline asm to MIR INLINEASM
///
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/InlineAsmLowering.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#define DEBUG_TYPE "inline-asm-lowering"
using namespace llvm;
void InlineAsmLowering::anchor() {}
namespace {
/// GISelAsmOperandInfo - This contains information for each constraint that we
/// are lowering.
class GISelAsmOperandInfo : public TargetLowering::AsmOperandInfo {
public:
/// Regs - If this is a register or register class operand, this
/// contains the set of assigned registers corresponding to the operand.
SmallVector<Register, 1> Regs;
explicit GISelAsmOperandInfo(const TargetLowering::AsmOperandInfo &Info)
: TargetLowering::AsmOperandInfo(Info) {}
};
using GISelAsmOperandInfoVector = SmallVector<GISelAsmOperandInfo, 16>;
class ExtraFlags {
unsigned Flags = 0;
public:
explicit ExtraFlags(const CallBase &CB) {
const InlineAsm *IA = cast<InlineAsm>(CB.getCalledOperand());
if (IA->hasSideEffects())
Flags |= InlineAsm::Extra_HasSideEffects;
if (IA->isAlignStack())
Flags |= InlineAsm::Extra_IsAlignStack;
if (CB.isConvergent())
Flags |= InlineAsm::Extra_IsConvergent;
Flags |= IA->getDialect() * InlineAsm::Extra_AsmDialect;
}
void update(const TargetLowering::AsmOperandInfo &OpInfo) {
// Ideally, we would only check against memory constraints. However, the
// meaning of an Other constraint can be target-specific and we can't easily
// reason about it. Therefore, be conservative and set MayLoad/MayStore
// for Other constraints as well.
if (OpInfo.ConstraintType == TargetLowering::C_Memory ||
OpInfo.ConstraintType == TargetLowering::C_Other) {
if (OpInfo.Type == InlineAsm::isInput)
Flags |= InlineAsm::Extra_MayLoad;
else if (OpInfo.Type == InlineAsm::isOutput)
Flags |= InlineAsm::Extra_MayStore;
else if (OpInfo.Type == InlineAsm::isClobber)
Flags |= (InlineAsm::Extra_MayLoad | InlineAsm::Extra_MayStore);
}
}
unsigned get() const { return Flags; }
};
} // namespace
/// Assign virtual/physical registers for the specified register operand.
static void getRegistersForValue(MachineFunction &MF,
MachineIRBuilder &MIRBuilder,
GISelAsmOperandInfo &OpInfo,
GISelAsmOperandInfo &RefOpInfo) {
const TargetLowering &TLI = *MF.getSubtarget().getTargetLowering();
const TargetRegisterInfo &TRI = *MF.getSubtarget().getRegisterInfo();
// No work to do for memory operations.
if (OpInfo.ConstraintType == TargetLowering::C_Memory)
return;
// If this is a constraint for a single physreg, or a constraint for a
// register class, find it.
Register AssignedReg;
const TargetRegisterClass *RC;
std::tie(AssignedReg, RC) = TLI.getRegForInlineAsmConstraint(
&TRI, RefOpInfo.ConstraintCode, RefOpInfo.ConstraintVT);
// RC is unset only on failure. Return immediately.
if (!RC)
return;
// No need to allocate a matching input constraint since the constraint it's
// matching to has already been allocated.
if (OpInfo.isMatchingInputConstraint())
return;
// Initialize NumRegs.
unsigned NumRegs = 1;
if (OpInfo.ConstraintVT != MVT::Other)
NumRegs =
TLI.getNumRegisters(MF.getFunction().getContext(), OpInfo.ConstraintVT);
// If this is a constraint for a specific physical register, but the type of
// the operand requires more than one register to be passed, we allocate the
// required amount of physical registers, starting from the selected physical
// register.
// For this, first retrieve a register iterator for the given register class
TargetRegisterClass::iterator I = RC->begin();
MachineRegisterInfo &RegInfo = MF.getRegInfo();
// Advance the iterator to the assigned register (if set)
if (AssignedReg) {
for (; *I != AssignedReg; ++I)
assert(I != RC->end() && "AssignedReg should be a member of provided RC");
}
// Finally, assign the registers. If the AssignedReg isn't set, create virtual
// registers with the provided register class
for (; NumRegs; --NumRegs, ++I) {
assert(I != RC->end() && "Ran out of registers to allocate!");
Register R = AssignedReg ? Register(*I) : RegInfo.createVirtualRegister(RC);
OpInfo.Regs.push_back(R);
}
}
/// Return an integer indicating how general CT is.
static unsigned getConstraintGenerality(TargetLowering::ConstraintType CT) {
switch (CT) {
case TargetLowering::C_Immediate:
case TargetLowering::C_Other:
case TargetLowering::C_Unknown:
return 0;
case TargetLowering::C_Register:
return 1;
case TargetLowering::C_RegisterClass:
return 2;
case TargetLowering::C_Memory:
return 3;
}
llvm_unreachable("Invalid constraint type");
}
static void chooseConstraint(TargetLowering::AsmOperandInfo &OpInfo,
const TargetLowering *TLI) {
assert(OpInfo.Codes.size() > 1 && "Doesn't have multiple constraint options");
unsigned BestIdx = 0;
TargetLowering::ConstraintType BestType = TargetLowering::C_Unknown;
int BestGenerality = -1;
// Loop over the options, keeping track of the most general one.
for (unsigned i = 0, e = OpInfo.Codes.size(); i != e; ++i) {
TargetLowering::ConstraintType CType =
TLI->getConstraintType(OpInfo.Codes[i]);
// Indirect 'other' or 'immediate' constraints are not allowed.
if (OpInfo.isIndirect && !(CType == TargetLowering::C_Memory ||
CType == TargetLowering::C_Register ||
CType == TargetLowering::C_RegisterClass))
continue;
// If this is an 'other' or 'immediate' constraint, see if the operand is
// valid for it. For example, on X86 we might have an 'rI' constraint. If
// the operand is an integer in the range [0..31] we want to use I (saving a
// load of a register), otherwise we must use 'r'.
if (CType == TargetLowering::C_Other ||
CType == TargetLowering::C_Immediate) {
assert(OpInfo.Codes[i].size() == 1 &&
"Unhandled multi-letter 'other' constraint");
// FIXME: prefer immediate constraints if the target allows it
}
// Things with matching constraints can only be registers, per gcc
// documentation. This mainly affects "g" constraints.
if (CType == TargetLowering::C_Memory && OpInfo.hasMatchingInput())
continue;
// This constraint letter is more general than the previous one, use it.
int Generality = getConstraintGenerality(CType);
if (Generality > BestGenerality) {
BestType = CType;
BestIdx = i;
BestGenerality = Generality;
}
}
OpInfo.ConstraintCode = OpInfo.Codes[BestIdx];
OpInfo.ConstraintType = BestType;
}
static void computeConstraintToUse(const TargetLowering *TLI,
TargetLowering::AsmOperandInfo &OpInfo) {
assert(!OpInfo.Codes.empty() && "Must have at least one constraint");
// Single-letter constraints ('r') are very common.
if (OpInfo.Codes.size() == 1) {
OpInfo.ConstraintCode = OpInfo.Codes[0];
OpInfo.ConstraintType = TLI->getConstraintType(OpInfo.ConstraintCode);
} else {
chooseConstraint(OpInfo, TLI);
}
// 'X' matches anything.
if (OpInfo.ConstraintCode == "X" && OpInfo.CallOperandVal) {
// Labels and constants are handled elsewhere ('X' is the only thing
// that matches labels). For Functions, the type here is the type of
// the result, which is not what we want to look at; leave them alone.
Value *Val = OpInfo.CallOperandVal;
if (isa<BasicBlock>(Val) || isa<ConstantInt>(Val) || isa<Function>(Val))
return;
// Otherwise, try to resolve it to something we know about by looking at
// the actual operand type.
if (const char *Repl = TLI->LowerXConstraint(OpInfo.ConstraintVT)) {
OpInfo.ConstraintCode = Repl;
OpInfo.ConstraintType = TLI->getConstraintType(OpInfo.ConstraintCode);
}
}
}
static unsigned getNumOpRegs(const MachineInstr &I, unsigned OpIdx) {
unsigned Flag = I.getOperand(OpIdx).getImm();
return InlineAsm::getNumOperandRegisters(Flag);
}
static bool buildAnyextOrCopy(Register Dst, Register Src,
MachineIRBuilder &MIRBuilder) {
const TargetRegisterInfo *TRI =
MIRBuilder.getMF().getSubtarget().getRegisterInfo();
MachineRegisterInfo *MRI = MIRBuilder.getMRI();
auto SrcTy = MRI->getType(Src);
if (!SrcTy.isValid()) {
LLVM_DEBUG(dbgs() << "Source type for copy is not valid\n");
return false;
}
unsigned SrcSize = TRI->getRegSizeInBits(Src, *MRI);
unsigned DstSize = TRI->getRegSizeInBits(Dst, *MRI);
if (DstSize < SrcSize) {
LLVM_DEBUG(dbgs() << "Input can't fit in destination reg class\n");
return false;
}
// Attempt to anyext small scalar sources.
if (DstSize > SrcSize) {
if (!SrcTy.isScalar()) {
LLVM_DEBUG(dbgs() << "Can't extend non-scalar input to size of"
"destination register class\n");
return false;
}
Src = MIRBuilder.buildAnyExt(LLT::scalar(DstSize), Src).getReg(0);
}
MIRBuilder.buildCopy(Dst, Src);
return true;
}
bool InlineAsmLowering::lowerInlineAsm(
MachineIRBuilder &MIRBuilder, const CallBase &Call,
std::function<ArrayRef<Register>(const Value &Val)> GetOrCreateVRegs)
const {
const InlineAsm *IA = cast<InlineAsm>(Call.getCalledOperand());
/// ConstraintOperands - Information about all of the constraints.
GISelAsmOperandInfoVector ConstraintOperands;
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
const DataLayout &DL = F.getParent()->getDataLayout();
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
MachineRegisterInfo *MRI = MIRBuilder.getMRI();
TargetLowering::AsmOperandInfoVector TargetConstraints =
TLI->ParseConstraints(DL, TRI, Call);
ExtraFlags ExtraInfo(Call);
unsigned ArgNo = 0; // ArgNo - The argument of the CallInst.
unsigned ResNo = 0; // ResNo - The result number of the next output.
for (auto &T : TargetConstraints) {
ConstraintOperands.push_back(GISelAsmOperandInfo(T));
GISelAsmOperandInfo &OpInfo = ConstraintOperands.back();
// Compute the value type for each operand.
if (OpInfo.Type == InlineAsm::isInput ||
(OpInfo.Type == InlineAsm::isOutput && OpInfo.isIndirect)) {
OpInfo.CallOperandVal = const_cast<Value *>(Call.getArgOperand(ArgNo++));
if (isa<BasicBlock>(OpInfo.CallOperandVal)) {
LLVM_DEBUG(dbgs() << "Basic block input operands not supported yet\n");
return false;
}
Type *OpTy = OpInfo.CallOperandVal->getType();
// If this is an indirect operand, the operand is a pointer to the
// accessed type.
if (OpInfo.isIndirect) {
PointerType *PtrTy = dyn_cast<PointerType>(OpTy);
if (!PtrTy)
report_fatal_error("Indirect operand for inline asm not a pointer!");
OpTy = PtrTy->getElementType();
}
// FIXME: Support aggregate input operands
if (!OpTy->isSingleValueType()) {
LLVM_DEBUG(
dbgs() << "Aggregate input operands are not supported yet\n");
return false;
}
OpInfo.ConstraintVT = TLI->getValueType(DL, OpTy, true).getSimpleVT();
} else if (OpInfo.Type == InlineAsm::isOutput && !OpInfo.isIndirect) {
assert(!Call.getType()->isVoidTy() && "Bad inline asm!");
if (StructType *STy = dyn_cast<StructType>(Call.getType())) {
OpInfo.ConstraintVT =
TLI->getSimpleValueType(DL, STy->getElementType(ResNo));
} else {
assert(ResNo == 0 && "Asm only has one result!");
OpInfo.ConstraintVT = TLI->getSimpleValueType(DL, Call.getType());
}
++ResNo;
} else {
OpInfo.ConstraintVT = MVT::Other;
}
// Compute the constraint code and ConstraintType to use.
computeConstraintToUse(TLI, OpInfo);
// The selected constraint type might expose new sideeffects
ExtraInfo.update(OpInfo);
}
// At this point, all operand types are decided.
// Create the MachineInstr, but don't insert it yet since input
// operands still need to insert instructions before this one
auto Inst = MIRBuilder.buildInstrNoInsert(TargetOpcode::INLINEASM)
.addExternalSymbol(IA->getAsmString().c_str())
.addImm(ExtraInfo.get());
// Starting from this operand: flag followed by register(s) will be added as
// operands to Inst for each constraint. Used for matching input constraints.
unsigned StartIdx = Inst->getNumOperands();
// Collects the output operands for later processing
GISelAsmOperandInfoVector OutputOperands;
for (auto &OpInfo : ConstraintOperands) {
GISelAsmOperandInfo &RefOpInfo =
OpInfo.isMatchingInputConstraint()
? ConstraintOperands[OpInfo.getMatchedOperand()]
: OpInfo;
// Assign registers for register operands
getRegistersForValue(MF, MIRBuilder, OpInfo, RefOpInfo);
switch (OpInfo.Type) {
case InlineAsm::isOutput:
if (OpInfo.ConstraintType == TargetLowering::C_Memory) {
unsigned ConstraintID =
TLI->getInlineAsmMemConstraint(OpInfo.ConstraintCode);
assert(ConstraintID != InlineAsm::Constraint_Unknown &&
"Failed to convert memory constraint code to constraint id.");
// Add information to the INLINEASM instruction to know about this
// output.
unsigned OpFlags = InlineAsm::getFlagWord(InlineAsm::Kind_Mem, 1);
OpFlags = InlineAsm::getFlagWordForMem(OpFlags, ConstraintID);
Inst.addImm(OpFlags);
ArrayRef<Register> SourceRegs =
GetOrCreateVRegs(*OpInfo.CallOperandVal);
assert(
SourceRegs.size() == 1 &&
"Expected the memory output to fit into a single virtual register");
Inst.addReg(SourceRegs[0]);
} else {
// Otherwise, this outputs to a register (directly for C_Register /
// C_RegisterClass. Find a register that we can use.
assert(OpInfo.ConstraintType == TargetLowering::C_Register ||
OpInfo.ConstraintType == TargetLowering::C_RegisterClass);
if (OpInfo.Regs.empty()) {
LLVM_DEBUG(dbgs()
<< "Couldn't allocate output register for constraint\n");
return false;
}
// Add information to the INLINEASM instruction to know that this
// register is set.
unsigned Flag = InlineAsm::getFlagWord(
OpInfo.isEarlyClobber ? InlineAsm::Kind_RegDefEarlyClobber
: InlineAsm::Kind_RegDef,
OpInfo.Regs.size());
if (OpInfo.Regs.front().isVirtual()) {
// Put the register class of the virtual registers in the flag word.
// That way, later passes can recompute register class constraints for
// inline assembly as well as normal instructions. Don't do this for
// tied operands that can use the regclass information from the def.
const TargetRegisterClass *RC = MRI->getRegClass(OpInfo.Regs.front());
Flag = InlineAsm::getFlagWordForRegClass(Flag, RC->getID());
}
Inst.addImm(Flag);
for (Register Reg : OpInfo.Regs) {
Inst.addReg(Reg,
RegState::Define | getImplRegState(Reg.isPhysical()) |
(OpInfo.isEarlyClobber ? RegState::EarlyClobber : 0));
}
// Remember this output operand for later processing
OutputOperands.push_back(OpInfo);
}
break;
case InlineAsm::isInput: {
if (OpInfo.isMatchingInputConstraint()) {
unsigned DefIdx = OpInfo.getMatchedOperand();
// Find operand with register def that corresponds to DefIdx.
unsigned InstFlagIdx = StartIdx;
for (unsigned i = 0; i < DefIdx; ++i)
InstFlagIdx += getNumOpRegs(*Inst, InstFlagIdx) + 1;
assert(getNumOpRegs(*Inst, InstFlagIdx) == 1 && "Wrong flag");
unsigned MatchedOperandFlag = Inst->getOperand(InstFlagIdx).getImm();
if (InlineAsm::isMemKind(MatchedOperandFlag)) {
LLVM_DEBUG(dbgs() << "Matching input constraint to mem operand not "
"supported. This should be target specific.\n");
return false;
}
if (!InlineAsm::isRegDefKind(MatchedOperandFlag) &&
!InlineAsm::isRegDefEarlyClobberKind(MatchedOperandFlag)) {
LLVM_DEBUG(dbgs() << "Unknown matching constraint\n");
return false;
}
// We want to tie input to register in next operand.
unsigned DefRegIdx = InstFlagIdx + 1;
Register Def = Inst->getOperand(DefRegIdx).getReg();
ArrayRef<Register> SrcRegs = GetOrCreateVRegs(*OpInfo.CallOperandVal);
assert(SrcRegs.size() == 1 && "Single register is expected here");
// When Def is physreg: use given input.
Register In = SrcRegs[0];
// When Def is vreg: copy input to new vreg with same reg class as Def.
if (Def.isVirtual()) {
In = MRI->createVirtualRegister(MRI->getRegClass(Def));
if (!buildAnyextOrCopy(In, SrcRegs[0], MIRBuilder))
return false;
}
// Add Flag and input register operand (In) to Inst. Tie In to Def.
unsigned UseFlag = InlineAsm::getFlagWord(InlineAsm::Kind_RegUse, 1);
unsigned Flag = InlineAsm::getFlagWordForMatchingOp(UseFlag, DefIdx);
Inst.addImm(Flag);
Inst.addReg(In);
Inst->tieOperands(DefRegIdx, Inst->getNumOperands() - 1);
break;
}
if (OpInfo.ConstraintType == TargetLowering::C_Other &&
OpInfo.isIndirect) {
LLVM_DEBUG(dbgs() << "Indirect input operands with unknown constraint "
"not supported yet\n");
return false;
}
if (OpInfo.ConstraintType == TargetLowering::C_Immediate ||
OpInfo.ConstraintType == TargetLowering::C_Other) {
std::vector<MachineOperand> Ops;
if (!lowerAsmOperandForConstraint(OpInfo.CallOperandVal,
OpInfo.ConstraintCode, Ops,
MIRBuilder)) {
LLVM_DEBUG(dbgs() << "Don't support constraint: "
<< OpInfo.ConstraintCode << " yet\n");
return false;
}
assert(Ops.size() > 0 &&
"Expected constraint to be lowered to at least one operand");
// Add information to the INLINEASM node to know about this input.
unsigned OpFlags =
InlineAsm::getFlagWord(InlineAsm::Kind_Imm, Ops.size());
Inst.addImm(OpFlags);
Inst.add(Ops);
break;
}
if (OpInfo.ConstraintType == TargetLowering::C_Memory) {
if (!OpInfo.isIndirect) {
LLVM_DEBUG(dbgs()
<< "Cannot indirectify memory input operands yet\n");
return false;
}
assert(OpInfo.isIndirect && "Operand must be indirect to be a mem!");
unsigned ConstraintID =
TLI->getInlineAsmMemConstraint(OpInfo.ConstraintCode);
unsigned OpFlags = InlineAsm::getFlagWord(InlineAsm::Kind_Mem, 1);
OpFlags = InlineAsm::getFlagWordForMem(OpFlags, ConstraintID);
Inst.addImm(OpFlags);
ArrayRef<Register> SourceRegs =
GetOrCreateVRegs(*OpInfo.CallOperandVal);
assert(
SourceRegs.size() == 1 &&
"Expected the memory input to fit into a single virtual register");
Inst.addReg(SourceRegs[0]);
break;
}
assert((OpInfo.ConstraintType == TargetLowering::C_RegisterClass ||
OpInfo.ConstraintType == TargetLowering::C_Register) &&
"Unknown constraint type!");
if (OpInfo.isIndirect) {
LLVM_DEBUG(dbgs() << "Can't handle indirect register inputs yet "
"for constraint '"
<< OpInfo.ConstraintCode << "'\n");
return false;
}
// Copy the input into the appropriate registers.
if (OpInfo.Regs.empty()) {
LLVM_DEBUG(
dbgs()
<< "Couldn't allocate input register for register constraint\n");
return false;
}
unsigned NumRegs = OpInfo.Regs.size();
ArrayRef<Register> SourceRegs = GetOrCreateVRegs(*OpInfo.CallOperandVal);
assert(NumRegs == SourceRegs.size() &&
"Expected the number of input registers to match the number of "
"source registers");
if (NumRegs > 1) {
LLVM_DEBUG(dbgs() << "Input operands with multiple input registers are "
"not supported yet\n");
return false;
}
unsigned Flag = InlineAsm::getFlagWord(InlineAsm::Kind_RegUse, NumRegs);
if (OpInfo.Regs.front().isVirtual()) {
// Put the register class of the virtual registers in the flag word.
const TargetRegisterClass *RC = MRI->getRegClass(OpInfo.Regs.front());
Flag = InlineAsm::getFlagWordForRegClass(Flag, RC->getID());
}
Inst.addImm(Flag);
if (!buildAnyextOrCopy(OpInfo.Regs[0], SourceRegs[0], MIRBuilder))
return false;
Inst.addReg(OpInfo.Regs[0]);
break;
}
case InlineAsm::isClobber: {
unsigned NumRegs = OpInfo.Regs.size();
if (NumRegs > 0) {
unsigned Flag =
InlineAsm::getFlagWord(InlineAsm::Kind_Clobber, NumRegs);
Inst.addImm(Flag);
for (Register Reg : OpInfo.Regs) {
Inst.addReg(Reg, RegState::Define | RegState::EarlyClobber |
getImplRegState(Reg.isPhysical()));
}
}
break;
}
}
}
if (const MDNode *SrcLoc = Call.getMetadata("srcloc"))
Inst.addMetadata(SrcLoc);
// All inputs are handled, insert the instruction now
MIRBuilder.insertInstr(Inst);
// Finally, copy the output operands into the output registers
ArrayRef<Register> ResRegs = GetOrCreateVRegs(Call);
if (ResRegs.size() != OutputOperands.size()) {
LLVM_DEBUG(dbgs() << "Expected the number of output registers to match the "
"number of destination registers\n");
return false;
}
for (unsigned int i = 0, e = ResRegs.size(); i < e; i++) {
GISelAsmOperandInfo &OpInfo = OutputOperands[i];
if (OpInfo.Regs.empty())
continue;
switch (OpInfo.ConstraintType) {
case TargetLowering::C_Register:
case TargetLowering::C_RegisterClass: {
if (OpInfo.Regs.size() > 1) {
LLVM_DEBUG(dbgs() << "Output operands with multiple defining "
"registers are not supported yet\n");
return false;
}
Register SrcReg = OpInfo.Regs[0];
unsigned SrcSize = TRI->getRegSizeInBits(SrcReg, *MRI);
if (MRI->getType(ResRegs[i]).getSizeInBits() < SrcSize) {
// First copy the non-typed virtual register into a generic virtual
// register
Register Tmp1Reg =
MRI->createGenericVirtualRegister(LLT::scalar(SrcSize));
MIRBuilder.buildCopy(Tmp1Reg, SrcReg);
// Need to truncate the result of the register
MIRBuilder.buildTrunc(ResRegs[i], Tmp1Reg);
} else {
MIRBuilder.buildCopy(ResRegs[i], SrcReg);
}
break;
}
case TargetLowering::C_Immediate:
case TargetLowering::C_Other:
LLVM_DEBUG(
dbgs() << "Cannot lower target specific output constraints yet\n");
return false;
case TargetLowering::C_Memory:
break; // Already handled.
case TargetLowering::C_Unknown:
LLVM_DEBUG(dbgs() << "Unexpected unknown constraint\n");
return false;
}
}
return true;
}
bool InlineAsmLowering::lowerAsmOperandForConstraint(
Value *Val, StringRef Constraint, std::vector<MachineOperand> &Ops,
MachineIRBuilder &MIRBuilder) const {
if (Constraint.size() > 1)
return false;
char ConstraintLetter = Constraint[0];
switch (ConstraintLetter) {
default:
return false;
case 'i': // Simple Integer or Relocatable Constant
case 'n': // immediate integer with a known value.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
assert(CI->getBitWidth() <= 64 &&
"expected immediate to fit into 64-bits");
// Boolean constants should be zero-extended, others are sign-extended
bool IsBool = CI->getBitWidth() == 1;
int64_t ExtVal = IsBool ? CI->getZExtValue() : CI->getSExtValue();
Ops.push_back(MachineOperand::CreateImm(ExtVal));
return true;
}
return false;
}
}
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