bolt/deps/llvm-18.1.8/clang/lib/CodeGen/Targets/RISCV.cpp
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//===- RISCV.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
//
//===----------------------------------------------------------------------===//
#include "ABIInfoImpl.h"
#include "TargetInfo.h"
using namespace clang;
using namespace clang::CodeGen;
//===----------------------------------------------------------------------===//
// RISC-V ABI Implementation
//===----------------------------------------------------------------------===//
namespace {
class RISCVABIInfo : public DefaultABIInfo {
private:
// Size of the integer ('x') registers in bits.
unsigned XLen;
// Size of the floating point ('f') registers in bits. Note that the target
// ISA might have a wider FLen than the selected ABI (e.g. an RV32IF target
// with soft float ABI has FLen==0).
unsigned FLen;
const int NumArgGPRs;
const int NumArgFPRs;
const bool EABI;
bool detectFPCCEligibleStructHelper(QualType Ty, CharUnits CurOff,
llvm::Type *&Field1Ty,
CharUnits &Field1Off,
llvm::Type *&Field2Ty,
CharUnits &Field2Off) const;
public:
RISCVABIInfo(CodeGen::CodeGenTypes &CGT, unsigned XLen, unsigned FLen,
bool EABI)
: DefaultABIInfo(CGT), XLen(XLen), FLen(FLen), NumArgGPRs(EABI ? 6 : 8),
NumArgFPRs(FLen != 0 ? 8 : 0), EABI(EABI) {}
// DefaultABIInfo's classifyReturnType and classifyArgumentType are
// non-virtual, but computeInfo is virtual, so we overload it.
void computeInfo(CGFunctionInfo &FI) const override;
ABIArgInfo classifyArgumentType(QualType Ty, bool IsFixed, int &ArgGPRsLeft,
int &ArgFPRsLeft) const;
ABIArgInfo classifyReturnType(QualType RetTy) const;
Address EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
QualType Ty) const override;
ABIArgInfo extendType(QualType Ty) const;
bool detectFPCCEligibleStruct(QualType Ty, llvm::Type *&Field1Ty,
CharUnits &Field1Off, llvm::Type *&Field2Ty,
CharUnits &Field2Off, int &NeededArgGPRs,
int &NeededArgFPRs) const;
ABIArgInfo coerceAndExpandFPCCEligibleStruct(llvm::Type *Field1Ty,
CharUnits Field1Off,
llvm::Type *Field2Ty,
CharUnits Field2Off) const;
ABIArgInfo coerceVLSVector(QualType Ty) const;
};
} // end anonymous namespace
void RISCVABIInfo::computeInfo(CGFunctionInfo &FI) const {
QualType RetTy = FI.getReturnType();
if (!getCXXABI().classifyReturnType(FI))
FI.getReturnInfo() = classifyReturnType(RetTy);
// IsRetIndirect is true if classifyArgumentType indicated the value should
// be passed indirect, or if the type size is a scalar greater than 2*XLen
// and not a complex type with elements <= FLen. e.g. fp128 is passed direct
// in LLVM IR, relying on the backend lowering code to rewrite the argument
// list and pass indirectly on RV32.
bool IsRetIndirect = FI.getReturnInfo().getKind() == ABIArgInfo::Indirect;
if (!IsRetIndirect && RetTy->isScalarType() &&
getContext().getTypeSize(RetTy) > (2 * XLen)) {
if (RetTy->isComplexType() && FLen) {
QualType EltTy = RetTy->castAs<ComplexType>()->getElementType();
IsRetIndirect = getContext().getTypeSize(EltTy) > FLen;
} else {
// This is a normal scalar > 2*XLen, such as fp128 on RV32.
IsRetIndirect = true;
}
}
int ArgGPRsLeft = IsRetIndirect ? NumArgGPRs - 1 : NumArgGPRs;
int ArgFPRsLeft = NumArgFPRs;
int NumFixedArgs = FI.getNumRequiredArgs();
int ArgNum = 0;
for (auto &ArgInfo : FI.arguments()) {
bool IsFixed = ArgNum < NumFixedArgs;
ArgInfo.info =
classifyArgumentType(ArgInfo.type, IsFixed, ArgGPRsLeft, ArgFPRsLeft);
ArgNum++;
}
}
// Returns true if the struct is a potential candidate for the floating point
// calling convention. If this function returns true, the caller is
// responsible for checking that if there is only a single field then that
// field is a float.
bool RISCVABIInfo::detectFPCCEligibleStructHelper(QualType Ty, CharUnits CurOff,
llvm::Type *&Field1Ty,
CharUnits &Field1Off,
llvm::Type *&Field2Ty,
CharUnits &Field2Off) const {
bool IsInt = Ty->isIntegralOrEnumerationType();
bool IsFloat = Ty->isRealFloatingType();
if (IsInt || IsFloat) {
uint64_t Size = getContext().getTypeSize(Ty);
if (IsInt && Size > XLen)
return false;
// Can't be eligible if larger than the FP registers. Handling of half
// precision values has been specified in the ABI, so don't block those.
if (IsFloat && Size > FLen)
return false;
// Can't be eligible if an integer type was already found (int+int pairs
// are not eligible).
if (IsInt && Field1Ty && Field1Ty->isIntegerTy())
return false;
if (!Field1Ty) {
Field1Ty = CGT.ConvertType(Ty);
Field1Off = CurOff;
return true;
}
if (!Field2Ty) {
Field2Ty = CGT.ConvertType(Ty);
Field2Off = CurOff;
return true;
}
return false;
}
if (auto CTy = Ty->getAs<ComplexType>()) {
if (Field1Ty)
return false;
QualType EltTy = CTy->getElementType();
if (getContext().getTypeSize(EltTy) > FLen)
return false;
Field1Ty = CGT.ConvertType(EltTy);
Field1Off = CurOff;
Field2Ty = Field1Ty;
Field2Off = Field1Off + getContext().getTypeSizeInChars(EltTy);
return true;
}
if (const ConstantArrayType *ATy = getContext().getAsConstantArrayType(Ty)) {
uint64_t ArraySize = ATy->getSize().getZExtValue();
QualType EltTy = ATy->getElementType();
// Non-zero-length arrays of empty records make the struct ineligible for
// the FP calling convention in C++.
if (const auto *RTy = EltTy->getAs<RecordType>()) {
if (ArraySize != 0 && isa<CXXRecordDecl>(RTy->getDecl()) &&
isEmptyRecord(getContext(), EltTy, true, true))
return false;
}
CharUnits EltSize = getContext().getTypeSizeInChars(EltTy);
for (uint64_t i = 0; i < ArraySize; ++i) {
bool Ret = detectFPCCEligibleStructHelper(EltTy, CurOff, Field1Ty,
Field1Off, Field2Ty, Field2Off);
if (!Ret)
return false;
CurOff += EltSize;
}
return true;
}
if (const auto *RTy = Ty->getAs<RecordType>()) {
// Structures with either a non-trivial destructor or a non-trivial
// copy constructor are not eligible for the FP calling convention.
if (getRecordArgABI(Ty, CGT.getCXXABI()))
return false;
if (isEmptyRecord(getContext(), Ty, true, true))
return true;
const RecordDecl *RD = RTy->getDecl();
// Unions aren't eligible unless they're empty (which is caught above).
if (RD->isUnion())
return false;
const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
// If this is a C++ record, check the bases first.
if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
for (const CXXBaseSpecifier &B : CXXRD->bases()) {
const auto *BDecl =
cast<CXXRecordDecl>(B.getType()->castAs<RecordType>()->getDecl());
CharUnits BaseOff = Layout.getBaseClassOffset(BDecl);
bool Ret = detectFPCCEligibleStructHelper(B.getType(), CurOff + BaseOff,
Field1Ty, Field1Off, Field2Ty,
Field2Off);
if (!Ret)
return false;
}
}
int ZeroWidthBitFieldCount = 0;
for (const FieldDecl *FD : RD->fields()) {
uint64_t FieldOffInBits = Layout.getFieldOffset(FD->getFieldIndex());
QualType QTy = FD->getType();
if (FD->isBitField()) {
unsigned BitWidth = FD->getBitWidthValue(getContext());
// Allow a bitfield with a type greater than XLen as long as the
// bitwidth is XLen or less.
if (getContext().getTypeSize(QTy) > XLen && BitWidth <= XLen)
QTy = getContext().getIntTypeForBitwidth(XLen, false);
if (BitWidth == 0) {
ZeroWidthBitFieldCount++;
continue;
}
}
bool Ret = detectFPCCEligibleStructHelper(
QTy, CurOff + getContext().toCharUnitsFromBits(FieldOffInBits),
Field1Ty, Field1Off, Field2Ty, Field2Off);
if (!Ret)
return false;
// As a quirk of the ABI, zero-width bitfields aren't ignored for fp+fp
// or int+fp structs, but are ignored for a struct with an fp field and
// any number of zero-width bitfields.
if (Field2Ty && ZeroWidthBitFieldCount > 0)
return false;
}
return Field1Ty != nullptr;
}
return false;
}
// Determine if a struct is eligible for passing according to the floating
// point calling convention (i.e., when flattened it contains a single fp
// value, fp+fp, or int+fp of appropriate size). If so, NeededArgFPRs and
// NeededArgGPRs are incremented appropriately.
bool RISCVABIInfo::detectFPCCEligibleStruct(QualType Ty, llvm::Type *&Field1Ty,
CharUnits &Field1Off,
llvm::Type *&Field2Ty,
CharUnits &Field2Off,
int &NeededArgGPRs,
int &NeededArgFPRs) const {
Field1Ty = nullptr;
Field2Ty = nullptr;
NeededArgGPRs = 0;
NeededArgFPRs = 0;
bool IsCandidate = detectFPCCEligibleStructHelper(
Ty, CharUnits::Zero(), Field1Ty, Field1Off, Field2Ty, Field2Off);
if (!Field1Ty)
return false;
// Not really a candidate if we have a single int but no float.
if (Field1Ty && !Field2Ty && !Field1Ty->isFloatingPointTy())
return false;
if (!IsCandidate)
return false;
if (Field1Ty && Field1Ty->isFloatingPointTy())
NeededArgFPRs++;
else if (Field1Ty)
NeededArgGPRs++;
if (Field2Ty && Field2Ty->isFloatingPointTy())
NeededArgFPRs++;
else if (Field2Ty)
NeededArgGPRs++;
return true;
}
// Call getCoerceAndExpand for the two-element flattened struct described by
// Field1Ty, Field1Off, Field2Ty, Field2Off. This method will create an
// appropriate coerceToType and unpaddedCoerceToType.
ABIArgInfo RISCVABIInfo::coerceAndExpandFPCCEligibleStruct(
llvm::Type *Field1Ty, CharUnits Field1Off, llvm::Type *Field2Ty,
CharUnits Field2Off) const {
SmallVector<llvm::Type *, 3> CoerceElts;
SmallVector<llvm::Type *, 2> UnpaddedCoerceElts;
if (!Field1Off.isZero())
CoerceElts.push_back(llvm::ArrayType::get(
llvm::Type::getInt8Ty(getVMContext()), Field1Off.getQuantity()));
CoerceElts.push_back(Field1Ty);
UnpaddedCoerceElts.push_back(Field1Ty);
if (!Field2Ty) {
return ABIArgInfo::getCoerceAndExpand(
llvm::StructType::get(getVMContext(), CoerceElts, !Field1Off.isZero()),
UnpaddedCoerceElts[0]);
}
CharUnits Field2Align =
CharUnits::fromQuantity(getDataLayout().getABITypeAlign(Field2Ty));
CharUnits Field1End = Field1Off +
CharUnits::fromQuantity(getDataLayout().getTypeStoreSize(Field1Ty));
CharUnits Field2OffNoPadNoPack = Field1End.alignTo(Field2Align);
CharUnits Padding = CharUnits::Zero();
if (Field2Off > Field2OffNoPadNoPack)
Padding = Field2Off - Field2OffNoPadNoPack;
else if (Field2Off != Field2Align && Field2Off > Field1End)
Padding = Field2Off - Field1End;
bool IsPacked = !Field2Off.isMultipleOf(Field2Align);
if (!Padding.isZero())
CoerceElts.push_back(llvm::ArrayType::get(
llvm::Type::getInt8Ty(getVMContext()), Padding.getQuantity()));
CoerceElts.push_back(Field2Ty);
UnpaddedCoerceElts.push_back(Field2Ty);
auto CoerceToType =
llvm::StructType::get(getVMContext(), CoerceElts, IsPacked);
auto UnpaddedCoerceToType =
llvm::StructType::get(getVMContext(), UnpaddedCoerceElts, IsPacked);
return ABIArgInfo::getCoerceAndExpand(CoerceToType, UnpaddedCoerceToType);
}
// Fixed-length RVV vectors are represented as scalable vectors in function
// args/return and must be coerced from fixed vectors.
ABIArgInfo RISCVABIInfo::coerceVLSVector(QualType Ty) const {
assert(Ty->isVectorType() && "expected vector type!");
const auto *VT = Ty->castAs<VectorType>();
assert(VT->getElementType()->isBuiltinType() && "expected builtin type!");
auto VScale =
getContext().getTargetInfo().getVScaleRange(getContext().getLangOpts());
unsigned NumElts = VT->getNumElements();
llvm::Type *EltType;
if (VT->getVectorKind() == VectorKind::RVVFixedLengthMask) {
NumElts *= 8;
EltType = llvm::Type::getInt1Ty(getVMContext());
} else {
assert(VT->getVectorKind() == VectorKind::RVVFixedLengthData &&
"Unexpected vector kind");
EltType = CGT.ConvertType(VT->getElementType());
}
// The MinNumElts is simplified from equation:
// NumElts / VScale =
// (EltSize * NumElts / (VScale * RVVBitsPerBlock))
// * (RVVBitsPerBlock / EltSize)
llvm::ScalableVectorType *ResType =
llvm::ScalableVectorType::get(EltType, NumElts / VScale->first);
return ABIArgInfo::getDirect(ResType);
}
ABIArgInfo RISCVABIInfo::classifyArgumentType(QualType Ty, bool IsFixed,
int &ArgGPRsLeft,
int &ArgFPRsLeft) const {
assert(ArgGPRsLeft <= NumArgGPRs && "Arg GPR tracking underflow");
Ty = useFirstFieldIfTransparentUnion(Ty);
// Structures with either a non-trivial destructor or a non-trivial
// copy constructor are always passed indirectly.
if (CGCXXABI::RecordArgABI RAA = getRecordArgABI(Ty, getCXXABI())) {
if (ArgGPRsLeft)
ArgGPRsLeft -= 1;
return getNaturalAlignIndirect(Ty, /*ByVal=*/RAA ==
CGCXXABI::RAA_DirectInMemory);
}
// Ignore empty structs/unions.
if (isEmptyRecord(getContext(), Ty, true))
return ABIArgInfo::getIgnore();
uint64_t Size = getContext().getTypeSize(Ty);
// Pass floating point values via FPRs if possible.
if (IsFixed && Ty->isFloatingType() && !Ty->isComplexType() &&
FLen >= Size && ArgFPRsLeft) {
ArgFPRsLeft--;
return ABIArgInfo::getDirect();
}
// Complex types for the hard float ABI must be passed direct rather than
// using CoerceAndExpand.
if (IsFixed && Ty->isComplexType() && FLen && ArgFPRsLeft >= 2) {
QualType EltTy = Ty->castAs<ComplexType>()->getElementType();
if (getContext().getTypeSize(EltTy) <= FLen) {
ArgFPRsLeft -= 2;
return ABIArgInfo::getDirect();
}
}
if (IsFixed && FLen && Ty->isStructureOrClassType()) {
llvm::Type *Field1Ty = nullptr;
llvm::Type *Field2Ty = nullptr;
CharUnits Field1Off = CharUnits::Zero();
CharUnits Field2Off = CharUnits::Zero();
int NeededArgGPRs = 0;
int NeededArgFPRs = 0;
bool IsCandidate =
detectFPCCEligibleStruct(Ty, Field1Ty, Field1Off, Field2Ty, Field2Off,
NeededArgGPRs, NeededArgFPRs);
if (IsCandidate && NeededArgGPRs <= ArgGPRsLeft &&
NeededArgFPRs <= ArgFPRsLeft) {
ArgGPRsLeft -= NeededArgGPRs;
ArgFPRsLeft -= NeededArgFPRs;
return coerceAndExpandFPCCEligibleStruct(Field1Ty, Field1Off, Field2Ty,
Field2Off);
}
}
uint64_t NeededAlign = getContext().getTypeAlign(Ty);
// Determine the number of GPRs needed to pass the current argument
// according to the ABI. 2*XLen-aligned varargs are passed in "aligned"
// register pairs, so may consume 3 registers.
// TODO: To be compatible with GCC's behaviors, we don't align registers
// currently if we are using ILP32E calling convention. This behavior may be
// changed when RV32E/ILP32E is ratified.
int NeededArgGPRs = 1;
if (!IsFixed && NeededAlign == 2 * XLen)
NeededArgGPRs = 2 + (EABI && XLen == 32 ? 0 : (ArgGPRsLeft % 2));
else if (Size > XLen && Size <= 2 * XLen)
NeededArgGPRs = 2;
if (NeededArgGPRs > ArgGPRsLeft) {
NeededArgGPRs = ArgGPRsLeft;
}
ArgGPRsLeft -= NeededArgGPRs;
if (!isAggregateTypeForABI(Ty) && !Ty->isVectorType()) {
// Treat an enum type as its underlying type.
if (const EnumType *EnumTy = Ty->getAs<EnumType>())
Ty = EnumTy->getDecl()->getIntegerType();
// All integral types are promoted to XLen width
if (Size < XLen && Ty->isIntegralOrEnumerationType()) {
return extendType(Ty);
}
if (const auto *EIT = Ty->getAs<BitIntType>()) {
if (EIT->getNumBits() < XLen)
return extendType(Ty);
if (EIT->getNumBits() > 128 ||
(!getContext().getTargetInfo().hasInt128Type() &&
EIT->getNumBits() > 64))
return getNaturalAlignIndirect(Ty, /*ByVal=*/false);
}
return ABIArgInfo::getDirect();
}
if (const VectorType *VT = Ty->getAs<VectorType>())
if (VT->getVectorKind() == VectorKind::RVVFixedLengthData ||
VT->getVectorKind() == VectorKind::RVVFixedLengthMask)
return coerceVLSVector(Ty);
// Aggregates which are <= 2*XLen will be passed in registers if possible,
// so coerce to integers.
if (Size <= 2 * XLen) {
unsigned Alignment = getContext().getTypeAlign(Ty);
// Use a single XLen int if possible, 2*XLen if 2*XLen alignment is
// required, and a 2-element XLen array if only XLen alignment is required.
if (Size <= XLen) {
return ABIArgInfo::getDirect(
llvm::IntegerType::get(getVMContext(), XLen));
} else if (Alignment == 2 * XLen) {
return ABIArgInfo::getDirect(
llvm::IntegerType::get(getVMContext(), 2 * XLen));
} else {
return ABIArgInfo::getDirect(llvm::ArrayType::get(
llvm::IntegerType::get(getVMContext(), XLen), 2));
}
}
return getNaturalAlignIndirect(Ty, /*ByVal=*/false);
}
ABIArgInfo RISCVABIInfo::classifyReturnType(QualType RetTy) const {
if (RetTy->isVoidType())
return ABIArgInfo::getIgnore();
int ArgGPRsLeft = 2;
int ArgFPRsLeft = FLen ? 2 : 0;
// The rules for return and argument types are the same, so defer to
// classifyArgumentType.
return classifyArgumentType(RetTy, /*IsFixed=*/true, ArgGPRsLeft,
ArgFPRsLeft);
}
Address RISCVABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
QualType Ty) const {
CharUnits SlotSize = CharUnits::fromQuantity(XLen / 8);
// Empty records are ignored for parameter passing purposes.
if (isEmptyRecord(getContext(), Ty, true)) {
return Address(CGF.Builder.CreateLoad(VAListAddr),
CGF.ConvertTypeForMem(Ty), SlotSize);
}
auto TInfo = getContext().getTypeInfoInChars(Ty);
// TODO: To be compatible with GCC's behaviors, we force arguments with
// 2×XLEN-bit alignment and size at most 2×XLEN bits like `long long`,
// `unsigned long long` and `double` to have 4-byte alignment. This
// behavior may be changed when RV32E/ILP32E is ratified.
if (EABI && XLen == 32)
TInfo.Align = std::min(TInfo.Align, CharUnits::fromQuantity(4));
// Arguments bigger than 2*Xlen bytes are passed indirectly.
bool IsIndirect = TInfo.Width > 2 * SlotSize;
return emitVoidPtrVAArg(CGF, VAListAddr, Ty, IsIndirect, TInfo,
SlotSize, /*AllowHigherAlign=*/true);
}
ABIArgInfo RISCVABIInfo::extendType(QualType Ty) const {
int TySize = getContext().getTypeSize(Ty);
// RV64 ABI requires unsigned 32 bit integers to be sign extended.
if (XLen == 64 && Ty->isUnsignedIntegerOrEnumerationType() && TySize == 32)
return ABIArgInfo::getSignExtend(Ty);
return ABIArgInfo::getExtend(Ty);
}
namespace {
class RISCVTargetCodeGenInfo : public TargetCodeGenInfo {
public:
RISCVTargetCodeGenInfo(CodeGen::CodeGenTypes &CGT, unsigned XLen,
unsigned FLen, bool EABI)
: TargetCodeGenInfo(
std::make_unique<RISCVABIInfo>(CGT, XLen, FLen, EABI)) {}
void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
CodeGen::CodeGenModule &CGM) const override {
const auto *FD = dyn_cast_or_null<FunctionDecl>(D);
if (!FD) return;
const auto *Attr = FD->getAttr<RISCVInterruptAttr>();
if (!Attr)
return;
const char *Kind;
switch (Attr->getInterrupt()) {
case RISCVInterruptAttr::supervisor: Kind = "supervisor"; break;
case RISCVInterruptAttr::machine: Kind = "machine"; break;
}
auto *Fn = cast<llvm::Function>(GV);
Fn->addFnAttr("interrupt", Kind);
}
};
} // namespace
std::unique_ptr<TargetCodeGenInfo>
CodeGen::createRISCVTargetCodeGenInfo(CodeGenModule &CGM, unsigned XLen,
unsigned FLen, bool EABI) {
return std::make_unique<RISCVTargetCodeGenInfo>(CGM.getTypes(), XLen, FLen,
EABI);
}