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c3d1f0d661
Start out with pointer spare bits, heap object alignment, null page size, and ObjC reserved bits, and provide static values for X86-64 and for a worst-case generic platform. Swift SVN r7833
81 lines
3.0 KiB
C++
81 lines
3.0 KiB
C++
//===--- SwiftTargetInfo.cpp --------------------------------------------*-===//
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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 defines the SwiftTargetInfo abstract base class. This class
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// provides an interface to target-dependent attributes of interest to Swift.
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//
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//===----------------------------------------------------------------------===//
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#include "SwiftTargetInfo.h"
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#include "IRGenModule.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/IR/DataLayout.h"
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#include "swift/IRGen/Options.h"
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using namespace swift;
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using namespace irgen;
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/// Creates a generic SwiftTargetInfo with conservative values that should
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/// be valid for any platform absent more specific information.
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static SwiftTargetInfo getGenericSwiftTargetInfo(IRGenModule &IGM) {
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auto pointerSize = IGM.DataLayout.getPointerSizeInBits();
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// Assume no spare bits in pointers.
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llvm::BitVector pointerSpareBits(pointerSize, false);
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// Assume all bit patterns are reserved by the ObjC runtime.
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llvm::BitVector objcReservedBits(pointerSize, true);
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// Assume no special alignment of heap objects.
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Alignment heapObjectAlignment(1);
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// Assume only zero is an invalid pointer.
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uint64_t leastValidPointerValue = 1;
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return SwiftTargetInfo(std::move(pointerSpareBits),
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std::move(objcReservedBits),
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heapObjectAlignment,
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leastValidPointerValue);
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}
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/// Creates SwiftTargetInfo for X86-64 platforms.
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static SwiftTargetInfo getX86_64SwiftTargetInfo(IRGenModule &IGM) {
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// User space only uses the low 47 bits of a pointer.
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// FIXME: In kernel mode, the highest bit is occupied.
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llvm::BitVector pointerSpareBits(47, false);
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pointerSpareBits.resize(64, true);
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// Objective-C reserves the lowest and highest bits for tagged pointers.
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llvm::BitVector objcReservedBits(64, false);
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objcReservedBits[0] = true;
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objcReservedBits[63] = true;
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// Heap objects are 16-byte-aligned.
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Alignment heapObjectAlignment(16);
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// The null 4K page is always unmapped.
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// FIXME: Are additional null pages always unmapped on some platforms?
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uint64_t leastValidPointerValue = 4096;
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return SwiftTargetInfo(std::move(pointerSpareBits),
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std::move(objcReservedBits),
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heapObjectAlignment,
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leastValidPointerValue);
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}
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SwiftTargetInfo SwiftTargetInfo::get(IRGenModule &IGM) {
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llvm::Triple triple(IGM.Opts.Triple);
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switch (triple.getArch()) {
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case llvm::Triple::x86_64:
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return getX86_64SwiftTargetInfo(IGM);
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default:
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return getGenericSwiftTargetInfo(IGM);
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}
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} |