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//===- WebAssembly.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;
//===----------------------------------------------------------------------===//
// WebAssembly ABI Implementation
//
// This is a very simple ABI that relies a lot on DefaultABIInfo.
//===----------------------------------------------------------------------===//
class WebAssemblyABIInfo final : public ABIInfo {
DefaultABIInfo defaultInfo;
WebAssemblyABIKind Kind;
public:
explicit WebAssemblyABIInfo(CodeGen::CodeGenTypes &CGT,
WebAssemblyABIKind Kind)
: ABIInfo(CGT), defaultInfo(CGT), Kind(Kind) {}
private:
ABIArgInfo classifyReturnType(QualType RetTy) const;
ABIArgInfo classifyArgumentType(QualType Ty) const;
// DefaultABIInfo's classifyReturnType and classifyArgumentType are
// non-virtual, but computeInfo and EmitVAArg are virtual, so we
// overload them.
void computeInfo(CGFunctionInfo &FI) const override {
if (!getCXXABI().classifyReturnType(FI))
FI.getReturnInfo() = classifyReturnType(FI.getReturnType());
for (auto &Arg : FI.arguments())
Arg.info = classifyArgumentType(Arg.type);
}
RValue EmitVAArg(CodeGenFunction &CGF, Address VAListAddr, QualType Ty,
AggValueSlot Slot) const override;
};
class WebAssemblyTargetCodeGenInfo final : public TargetCodeGenInfo {
public:
explicit WebAssemblyTargetCodeGenInfo(CodeGen::CodeGenTypes &CGT,
WebAssemblyABIKind K)
: TargetCodeGenInfo(std::make_unique<WebAssemblyABIInfo>(CGT, K)) {
SwiftInfo =
std::make_unique<SwiftABIInfo>(CGT, /*SwiftErrorInRegister=*/false);
}
void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
CodeGen::CodeGenModule &CGM) const override {
TargetCodeGenInfo::setTargetAttributes(D, GV, CGM);
if (const auto *FD = dyn_cast_or_null<FunctionDecl>(D)) {
if (const auto *Attr = FD->getAttr<WebAssemblyImportModuleAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);
llvm::AttrBuilder B(GV->getContext());
B.addAttribute("wasm-import-module", Attr->getImportModule());
Fn->addFnAttrs(B);
}
if (const auto *Attr = FD->getAttr<WebAssemblyImportNameAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);
llvm::AttrBuilder B(GV->getContext());
B.addAttribute("wasm-import-name", Attr->getImportName());
Fn->addFnAttrs(B);
}
if (const auto *Attr = FD->getAttr<WebAssemblyExportNameAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);
llvm::AttrBuilder B(GV->getContext());
B.addAttribute("wasm-export-name", Attr->getExportName());
Fn->addFnAttrs(B);
}
}
if (auto *FD = dyn_cast_or_null<FunctionDecl>(D)) {
llvm::Function *Fn = cast<llvm::Function>(GV);
if (!FD->doesThisDeclarationHaveABody() && !FD->hasPrototype())
Fn->addFnAttr("no-prototype");
}
}
/// Return the WebAssembly externref reference type.
virtual llvm::Type *getWasmExternrefReferenceType() const override {
return llvm::Type::getWasm_ExternrefTy(getABIInfo().getVMContext());
}
/// Return the WebAssembly funcref reference type.
virtual llvm::Type *getWasmFuncrefReferenceType() const override {
return llvm::Type::getWasm_FuncrefTy(getABIInfo().getVMContext());
}
};
/// Classify argument of given type \p Ty.
ABIArgInfo WebAssemblyABIInfo::classifyArgumentType(QualType Ty) const {
Ty = useFirstFieldIfTransparentUnion(Ty);
if (isAggregateTypeForABI(Ty)) {
// Records with non-trivial destructors/copy-constructors should not be
// passed by value.
if (auto RAA = getRecordArgABI(Ty, getCXXABI()))
return getNaturalAlignIndirect(Ty, RAA == CGCXXABI::RAA_DirectInMemory);
// Ignore empty structs/unions.
if (isEmptyRecord(getContext(), Ty, true))
return ABIArgInfo::getIgnore();
// Lower single-element structs to just pass a regular value. TODO: We
// could do reasonable-size multiple-element structs too, using getExpand(),
// though watch out for things like bitfields.
if (const Type *SeltTy = isSingleElementStruct(Ty, getContext()))
return ABIArgInfo::getDirect(CGT.ConvertType(QualType(SeltTy, 0)));
// For the experimental multivalue ABI, fully expand all other aggregates
if (Kind == WebAssemblyABIKind::ExperimentalMV) {
const RecordType *RT = Ty->getAs<RecordType>();
assert(RT);
bool HasBitField = false;
for (auto *Field : RT->getDecl()->fields()) {
if (Field->isBitField()) {
HasBitField = true;
break;
}
}
if (!HasBitField)
return ABIArgInfo::getExpand();
}
}
// Otherwise just do the default thing.
return defaultInfo.classifyArgumentType(Ty);
}
ABIArgInfo WebAssemblyABIInfo::classifyReturnType(QualType RetTy) const {
if (isAggregateTypeForABI(RetTy)) {
// Records with non-trivial destructors/copy-constructors should not be
// returned by value.
if (!getRecordArgABI(RetTy, getCXXABI())) {
// Ignore empty structs/unions.
if (isEmptyRecord(getContext(), RetTy, true))
return ABIArgInfo::getIgnore();
// Lower single-element structs to just return a regular value. TODO: We
// could do reasonable-size multiple-element structs too, using
// ABIArgInfo::getDirect().
if (const Type *SeltTy = isSingleElementStruct(RetTy, getContext()))
return ABIArgInfo::getDirect(CGT.ConvertType(QualType(SeltTy, 0)));
// For the experimental multivalue ABI, return all other aggregates
if (Kind == WebAssemblyABIKind::ExperimentalMV)
return ABIArgInfo::getDirect();
}
}
// Otherwise just do the default thing.
return defaultInfo.classifyReturnType(RetTy);
}
RValue WebAssemblyABIInfo::EmitVAArg(CodeGenFunction &CGF, Address VAListAddr,
QualType Ty, AggValueSlot Slot) const {
bool IsIndirect = isAggregateTypeForABI(Ty) &&
!isEmptyRecord(getContext(), Ty, true) &&
!isSingleElementStruct(Ty, getContext());
return emitVoidPtrVAArg(CGF, VAListAddr, Ty, IsIndirect,
getContext().getTypeInfoInChars(Ty),
CharUnits::fromQuantity(4),
/*AllowHigherAlign=*/true, Slot);
}
std::unique_ptr<TargetCodeGenInfo>
CodeGen::createWebAssemblyTargetCodeGenInfo(CodeGenModule &CGM,
WebAssemblyABIKind K) {
return std::make_unique<WebAssemblyTargetCodeGenInfo>(CGM.getTypes(), K);
}
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