mirror of
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9b38c4b5db
When doing struct layout for fixed-layout structs or tuples, combine the spare bit masks of their elements to form the spare bit mask of the aggregate, treating padding between elements as spare bits as well.
For now, disable using these spare bits to form extra inhabitants for structs and tuples; we would need additional runtime work to expose these extra inhabitants for correct generic runtime behavior. This puts us in a weird situation where 'enum { case A(Struct), B, C }' spills a bit but 'enum { case A(Struct), B(Struct), C }' doesn't, but the work to make the former happen isn't immediately critical for String optimization.
Swift SVN r12165
477 lines
18 KiB
C++
477 lines
18 KiB
C++
//===--- GenStruct.cpp - Swift IR Generation For 'struct' Types -----------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements IR generation for struct types.
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//
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//===----------------------------------------------------------------------===//
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#include "GenStruct.h"
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#include "swift/AST/Types.h"
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#include "swift/AST/Decl.h"
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#include "swift/AST/IRGenOptions.h"
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#include "swift/AST/Pattern.h"
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#include "swift/Basic/Optional.h"
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#include "swift/SIL/SILModule.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Function.h"
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#include "GenMeta.h"
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#include "GenSequential.h"
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#include "GenType.h"
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#include "IRGenFunction.h"
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#include "IRGenModule.h"
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#include "Linking.h"
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#include "IndirectTypeInfo.h"
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#include "NonFixedTypeInfo.h"
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#include "StructMetadataLayout.h"
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using namespace swift;
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using namespace irgen;
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namespace {
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class StructFieldInfo : public SequentialField<StructFieldInfo> {
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public:
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StructFieldInfo(VarDecl *field, const TypeInfo &type)
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: SequentialField(type), Field(field) {}
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/// The field.
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VarDecl * const Field;
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StringRef getFieldName() const {
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return Field->getName().str();
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}
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CanType getType(IRGenModule &IGM, CanType T) const {
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return T->getTypeOfMember(IGM.SILMod->getSwiftModule(),
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Field, nullptr)
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->getCanonicalType();
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}
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};
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/// A common base class for structs.
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template <class Impl, class Base>
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class StructTypeInfoBase :
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public SequentialTypeInfo<Impl, Base, StructFieldInfo> {
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typedef SequentialTypeInfo<Impl, Base, StructFieldInfo> super;
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protected:
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template <class... As>
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StructTypeInfoBase(As &&...args) : super(std::forward<As>(args)...) {}
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using super::asImpl;
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public:
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const StructFieldInfo &getFieldInfo(VarDecl *field) const {
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// FIXME: cache the physical field index in the VarDecl.
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for (auto &fieldInfo : asImpl().getFields()) {
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if (fieldInfo.Field == field)
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return fieldInfo;
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}
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llvm_unreachable("field not in struct?");
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}
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/// Given a full struct explosion, project out a single field.
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void projectFieldFromExplosion(IRGenFunction &IGF,
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Explosion &in,
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VarDecl *field,
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Explosion &out) const {
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assert(in.getKind() == out.getKind());
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auto &fieldInfo = getFieldInfo(field);
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// If the field requires no storage, there's nothing to do.
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if (fieldInfo.isEmpty())
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return;
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// Otherwise, project from the base.
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auto fieldRange = fieldInfo.getProjectionRange(out.getKind());
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auto elements = in.getRange(fieldRange.first, fieldRange.second);
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out.add(elements);
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}
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/// Given the address of a tuple, project out the address of a
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/// single element.
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Address projectFieldAddress(IRGenFunction &IGF,
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Address addr,
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CanType T,
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VarDecl *field) const {
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const StructFieldInfo &fieldInfo = getFieldInfo(field);
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if (fieldInfo.isEmpty())
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return fieldInfo.getTypeInfo().getUndefAddress();
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auto offsets = asImpl().getNonFixedOffsets(IGF, T);
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return fieldInfo.projectAddress(IGF, addr, offsets);
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}
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/// Return the constant offset of a field as a SizeTy, or nullptr if the
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/// field is not at a fixed offset.
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llvm::Constant *getConstantFieldOffset(IRGenModule &IGM,
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VarDecl *field) const {
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const StructFieldInfo &fieldInfo = getFieldInfo(field);
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if (fieldInfo.getKind() == ElementLayout::Kind::Fixed) {
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return llvm::ConstantInt::get(IGM.SizeTy,
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fieldInfo.getFixedByteOffset().getValue());
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}
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return nullptr;
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}
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};
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/// A type implementation for loadable struct types.
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class LoadableStructTypeInfo
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: public StructTypeInfoBase<LoadableStructTypeInfo, LoadableTypeInfo> {
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public:
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// FIXME: Spare bits between struct members.
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LoadableStructTypeInfo(unsigned numFields, llvm::Type *T, Size size,
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llvm::BitVector spareBits,
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Alignment align, IsPOD_t isPOD)
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: StructTypeInfoBase(numFields, T, size, std::move(spareBits),
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align, isPOD)
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{}
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bool isIndirectArgument(ExplosionKind kind) const override { return false; }
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void initializeFromParams(IRGenFunction &IGF, Explosion ¶ms,
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Address addr, CanType T) const override {
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LoadableStructTypeInfo::initialize(IGF, params, addr);
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}
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Nothing_t getNonFixedOffsets(IRGenFunction &IGF, CanType T) const {
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return Nothing;
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}
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Nothing_t getNonFixedOffsets(IRGenFunction &IGF) const {
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return Nothing;
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}
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// FIXME: Suppress use of extra inhabitants for single-payload enum layout
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// until we're ready to handle the runtime logic for exporting extra
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// inhabitants through generic structs.
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bool mayHaveExtraInhabitants(IRGenModule&) const override { return false; }
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unsigned getFixedExtraInhabitantCount(IRGenModule&) const override {
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return 0;
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}
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};
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/// A type implementation for non-loadable but fixed-size struct types.
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class FixedStructTypeInfo
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: public StructTypeInfoBase<FixedStructTypeInfo,
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IndirectTypeInfo<FixedStructTypeInfo,
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FixedTypeInfo>> {
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public:
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// FIXME: Spare bits between struct members.
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FixedStructTypeInfo(unsigned numFields, llvm::Type *T, Size size,
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llvm::BitVector spareBits,
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Alignment align, IsPOD_t isPOD)
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: StructTypeInfoBase(numFields, T, size, std::move(spareBits), align,
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isPOD)
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{}
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Nothing_t getNonFixedOffsets(IRGenFunction &IGF, CanType T) const {
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return Nothing;
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}
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Nothing_t getNonFixedOffsets(IRGenFunction &IGF) const { return Nothing; }
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// FIXME: Suppress use of extra inhabitants for single-payload enum layout
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// until we're ready to handle the runtime logic for exporting extra
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// inhabitants through generic structs.
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bool mayHaveExtraInhabitants(IRGenModule&) const override { return false; }
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unsigned getFixedExtraInhabitantCount(IRGenModule&) const override {
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return 0;
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}
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};
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/// Find the beginning of the field offset vector in a struct's metadata.
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static Address
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emitAddressOfFieldOffsetVector(IRGenFunction &IGF,
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StructDecl *S,
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llvm::Value *metadata) {
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struct GetStartOfFieldOffsets
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: StructMetadataScanner<GetStartOfFieldOffsets>
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{
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GetStartOfFieldOffsets(IRGenModule &IGM, StructDecl *target)
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: StructMetadataScanner(IGM, target) {}
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unsigned StartOfFieldOffsets = ~0U;
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void noteAddressPoint() {
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assert(StartOfFieldOffsets == ~0U
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&& "found field offsets before address point?");
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NextIndex = 0;
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}
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void noteStartOfFieldOffsets() { StartOfFieldOffsets = NextIndex; }
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};
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// Find where the field offsets begin.
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GetStartOfFieldOffsets scanner(IGF.IGM, S);
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scanner.layout();
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assert(scanner.StartOfFieldOffsets != ~0U
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&& "did not find start of field offsets?!");
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unsigned StartOfFieldOffsets = scanner.StartOfFieldOffsets;
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// Find that offset into the metadata.
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llvm::Value *fieldVector
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= IGF.Builder.CreateBitCast(metadata, IGF.IGM.SizeTy->getPointerTo());
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return IGF.Builder.CreateConstArrayGEP(
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Address(fieldVector, IGF.IGM.getPointerAlignment()),
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StartOfFieldOffsets,
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IGF.IGM.getPointerSize());
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}
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/// Accessor for the non-fixed offsets of a struct type.
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class StructNonFixedOffsets : public NonFixedOffsetsImpl {
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CanType TheStruct;
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public:
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StructNonFixedOffsets(CanType type) : TheStruct(type) {
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assert(TheStruct->getStructOrBoundGenericStruct());
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}
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llvm::Value *getOffsetForIndex(IRGenFunction &IGF, unsigned index) {
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// Get the field offset vector from the struct metadata.
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llvm::Value *metadata = IGF.emitTypeMetadataRef(TheStruct);
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Address fieldVector = emitAddressOfFieldOffsetVector(IGF,
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TheStruct->getStructOrBoundGenericStruct(),
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metadata);
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// Grab the indexed offset.
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fieldVector = IGF.Builder.CreateConstArrayGEP(fieldVector, index,
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IGF.IGM.getPointerSize());
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return IGF.Builder.CreateLoad(fieldVector);
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}
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};
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/// A type implementation for non-fixed struct types.
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class NonFixedStructTypeInfo
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: public StructTypeInfoBase<NonFixedStructTypeInfo,
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WitnessSizedTypeInfo<NonFixedStructTypeInfo>>
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{
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public:
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NonFixedStructTypeInfo(unsigned numFields, llvm::Type *T,
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Alignment align, IsPOD_t isPOD)
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: StructTypeInfoBase(numFields, T, align, isPOD) {
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}
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// We have an indirect schema.
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void getSchema(ExplosionSchema &s) const override {
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s.add(ExplosionSchema::Element::forAggregate(getStorageType(),
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getBestKnownAlignment()));
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}
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StructNonFixedOffsets
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getNonFixedOffsets(IRGenFunction &IGF, CanType T) const {
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return StructNonFixedOffsets(T);
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}
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void initializeMetadata(IRGenFunction &IGF,
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llvm::Value *metadata,
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llvm::Value *vwtable,
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CanType T) const override {
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// Get the field offset vector.
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llvm::Value *fieldVector = emitAddressOfFieldOffsetVector(IGF,
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T->getStructOrBoundGenericStruct(),
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metadata).getAddress();
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// Collect the stored properties of the type.
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llvm::SmallVector<VarDecl*, 4> storedProperties;
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for (auto prop : T->getStructOrBoundGenericStruct()
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->getStoredProperties()) {
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storedProperties.push_back(prop);
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}
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// Fill out an array with the field type metadata records.
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Address fields = IGF.createAlloca(
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llvm::ArrayType::get(IGF.IGM.TypeMetadataPtrTy,
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storedProperties.size()),
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IGF.IGM.getPointerAlignment(), "structFields");
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fields = IGF.Builder.CreateBitCast(fields,
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IGF.IGM.TypeMetadataPtrTy->getPointerTo());
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unsigned index = 0;
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for (auto prop : storedProperties) {
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llvm::Value *metadata = IGF.emitTypeMetadataRef(
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prop->getType()->getCanonicalType());
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Address field = IGF.Builder.CreateConstArrayGEP(fields, index,
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IGF.IGM.getPointerSize());
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IGF.Builder.CreateStore(metadata, field);
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++index;
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}
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// Ask the runtime to lay out the struct.
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auto numFields = llvm::ConstantInt::get(IGF.IGM.SizeTy,
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storedProperties.size());
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IGF.Builder.CreateCall4(IGF.IGM.getInitStructMetadataUniversalFn(),
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numFields, fields.getAddress(),
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fieldVector, vwtable);
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}
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};
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class StructTypeBuilder :
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public SequentialTypeBuilder<StructTypeBuilder, StructFieldInfo, VarDecl*> {
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llvm::StructType *StructTy;
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CanType TheStruct;
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public:
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StructTypeBuilder(IRGenModule &IGM, llvm::StructType *structTy,
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CanType type) :
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SequentialTypeBuilder(IGM), StructTy(structTy), TheStruct(type) {
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}
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LoadableStructTypeInfo *createLoadable(ArrayRef<StructFieldInfo> fields,
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const StructLayout &layout) {
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return create<LoadableStructTypeInfo>(fields, layout.getType(),
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layout.getSize(),
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layout.getSpareBits(),
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layout.getAlignment(),
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layout.isKnownPOD());
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}
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FixedStructTypeInfo *createFixed(ArrayRef<StructFieldInfo> fields,
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const StructLayout &layout) {
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return create<FixedStructTypeInfo>(fields, layout.getType(),
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layout.getSize(),
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layout.getSpareBits(),
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layout.getAlignment(),
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layout.isKnownPOD());
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}
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NonFixedStructTypeInfo *createNonFixed(ArrayRef<StructFieldInfo> fields,
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const StructLayout &layout) {
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return create<NonFixedStructTypeInfo>(fields, layout.getType(),
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layout.getAlignment(),
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layout.isKnownPOD());
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}
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StructFieldInfo getFieldInfo(unsigned index,
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VarDecl *field, const TypeInfo &fieldTI) {
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return StructFieldInfo(field, fieldTI);
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}
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SILType getType(VarDecl *field) {
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assert(field->getDeclContext() == TheStruct->getAnyNominal());
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auto silType = SILType::getPrimitiveAddressType(TheStruct);
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return silType.getFieldType(field, *IGM.SILMod);
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}
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StructLayout performLayout(ArrayRef<const TypeInfo *> fieldTypes) {
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return StructLayout(IGM, LayoutKind::NonHeapObject,
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LayoutStrategy::Optimal, fieldTypes, StructTy);
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}
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};
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} // end anonymous namespace.
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/// A convenient macro for delegating an operation to all of the
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/// various struct implementations.
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#define FOR_STRUCT_IMPL(IGF, type, op, ...) do { \
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auto &structTI = IGF.getTypeInfo(type); \
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if (isa<LoadableStructTypeInfo>(structTI)) { \
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return structTI.as<LoadableStructTypeInfo>().op(IGF, __VA_ARGS__); \
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} else if (isa<FixedTypeInfo>(structTI)) { \
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return structTI.as<FixedStructTypeInfo>().op(IGF, __VA_ARGS__); \
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} else { \
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return structTI.as<NonFixedStructTypeInfo>().op(IGF, __VA_ARGS__); \
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} \
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} while(0)
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Address irgen::projectPhysicalStructMemberAddress(IRGenFunction &IGF,
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Address base,
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SILType baseType,
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VarDecl *field) {
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FOR_STRUCT_IMPL(IGF, baseType, projectFieldAddress, base,
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baseType.getSwiftRValueType(), field);
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}
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void irgen::projectPhysicalStructMemberFromExplosion(IRGenFunction &IGF,
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SILType baseType,
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Explosion &base,
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VarDecl *field,
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Explosion &out) {
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FOR_STRUCT_IMPL(IGF, baseType, projectFieldFromExplosion, base, field, out);
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}
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llvm::Constant *irgen::emitPhysicalStructMemberFixedOffset(IRGenModule &IGM,
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SILType baseType,
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VarDecl *field) {
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FOR_STRUCT_IMPL(IGM, baseType, getConstantFieldOffset, field);
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}
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/// emitStructDecl - Emit all the declarations associated with this struct type.
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void IRGenModule::emitStructDecl(StructDecl *st) {
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emitStructMetadata(*this, st);
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// FIXME: This is mostly copy-paste from emitExtension;
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// figure out how to refactor!
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for (Decl *member : st->getMembers()) {
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switch (member->getKind()) {
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case DeclKind::Import:
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case DeclKind::TopLevelCode:
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case DeclKind::Protocol:
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case DeclKind::Extension:
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case DeclKind::Destructor:
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case DeclKind::EnumCase:
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case DeclKind::EnumElement:
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case DeclKind::InfixOperator:
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case DeclKind::PrefixOperator:
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case DeclKind::PostfixOperator:
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llvm_unreachable("decl not allowed in struct!");
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// We can have meaningful initializers for variables, but
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// we can't handle them yet. For the moment, just ignore them.
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case DeclKind::PatternBinding:
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continue;
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case DeclKind::Subscript:
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// Getter/setter will be handled separately.
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continue;
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case DeclKind::TypeAlias:
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case DeclKind::AssociatedType:
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case DeclKind::GenericTypeParam:
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continue;
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case DeclKind::Enum:
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emitEnumDecl(cast<EnumDecl>(member));
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continue;
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case DeclKind::Struct:
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emitStructDecl(cast<StructDecl>(member));
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continue;
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case DeclKind::Class:
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emitClassDecl(cast<ClassDecl>(member));
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continue;
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case DeclKind::Var:
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if (cast<VarDecl>(member)->isComputed())
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// Getter/setter will be handled separately.
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continue;
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// FIXME: Will need an implementation here for resilience
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continue;
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case DeclKind::Func:
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emitLocalDecls(cast<FuncDecl>(member));
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continue;
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case DeclKind::Constructor:
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emitLocalDecls(cast<ConstructorDecl>(member));
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continue;
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}
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llvm_unreachable("bad extension member kind");
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}
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}
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#include "llvm/Support/raw_ostream.h"
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const TypeInfo *TypeConverter::convertStructType(TypeBase *key, CanType type,
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StructDecl *D) {
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// Collect all the fields from the type.
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SmallVector<VarDecl*, 8> fields;
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for (VarDecl *VD : D->getStoredProperties())
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fields.push_back(VD);
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// Create the struct type.
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auto ty = IGM.createNominalType(D);
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// Register a forward declaration before we look at any of the child types.
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addForwardDecl(key, ty);
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// Build the type.
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StructTypeBuilder builder(IGM, ty, type);
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return builder.layout(fields);
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}
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