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df7ebcd9e8
an owner attached. Use this to implement [byref(heap)]. Force locals to the heap if they've been referenced in a way that requires this. Swift SVN r1265
81 lines
2.7 KiB
C++
81 lines
2.7 KiB
C++
//===--- StructLayout.cpp - Layout of structures -------------------------===//
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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 algorithms for laying out structures.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Target/TargetData.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/DerivedTypes.h"
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#include "IRGenModule.h"
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#include "GenType.h"
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#include "StructLayout.h"
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using namespace swift;
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using namespace irgen;
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/// Perform structure layout on the given types.
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StructLayout::StructLayout(IRGenModule &IGM, LayoutKind layoutKind,
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LayoutStrategy strategy,
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llvm::ArrayRef<const TypeInfo *> types) {
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// For now, we actually only have one algorithm, and it's not
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// exactly optimal.
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Size storageSize(0);
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Alignment storageAlign(1);
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llvm::SmallVector<llvm::Type*, 8> storageTypes;
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// FIXME: heap header.
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for (const TypeInfo *type : types) {
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// The struct alignment is the max of the alignment of the fields.
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storageAlign = std::max(storageAlign, type->StorageAlignment);
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// If the current tuple size isn't a multiple of the field's
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// required alignment, we need padding.
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if (Size offsetFromAlignment = storageSize % type->StorageAlignment) {
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unsigned paddingRequired
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= type->StorageAlignment.getValue() - offsetFromAlignment.getValue();
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// We don't actually need to uglify the IR unless the natural
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// alignment of the IR type for the field isn't good enough.
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Alignment fieldIRAlignment(
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IGM.TargetData.getABITypeAlignment(type->StorageType));
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assert(fieldIRAlignment <= type->StorageAlignment);
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if (fieldIRAlignment != type->StorageAlignment) {
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storageTypes.push_back(llvm::ArrayType::get(IGM.Int8Ty,
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paddingRequired));
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}
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// Regardless, the storage size goes up.
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storageSize += Size(paddingRequired);
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}
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ElementLayout element = { storageSize, (unsigned) storageTypes.size() };
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Elements.push_back(element);
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storageTypes.push_back(type->getStorageType());
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storageSize += type->StorageSize;
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}
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Align = storageAlign;
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TotalSize = storageSize;
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if (storageTypes.empty()) {
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Ty = IGM.Int8Ty;
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} else {
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Ty = llvm::StructType::get(IGM.getLLVMContext(), storageTypes);
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}
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}
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