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b74f42602a
This further trims dependencies to LLVMSupport by introducing the equivalent `SWIFT_USED` macro.
82 lines
2.9 KiB
C++
82 lines
2.9 KiB
C++
//===--- ExistentialContainer.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 - 2018 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 https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include "swift/Runtime/ExistentialContainer.h"
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#include "swift/Runtime/HeapObject.h"
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using namespace swift;
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//===----------------------------------------------------------------------===//
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// OpaqueExistentialContainer Implementation
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//===----------------------------------------------------------------------===//
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template <>
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bool OpaqueExistentialContainer::isValueInline() const {
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return Type->getValueWitnesses()->isValueInline();
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}
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template <>
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const OpaqueValue *OpaqueExistentialContainer::projectValue() const {
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auto *vwt = Type->getValueWitnesses();
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if (vwt->isValueInline())
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return reinterpret_cast<const OpaqueValue *>(&Buffer);
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// Compute the byte offset of the object in the box.
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unsigned alignMask = vwt->getAlignmentMask();
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unsigned byteOffset = (sizeof(HeapObject) + alignMask) & ~alignMask;
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auto *bytePtr = reinterpret_cast<const char *>(
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*reinterpret_cast<HeapObject *const *const>(&Buffer));
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return reinterpret_cast<const OpaqueValue *>(bytePtr + byteOffset);
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}
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template <>
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void OpaqueExistentialContainer::deinit() {
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auto *vwt = Type->getValueWitnesses();
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if (vwt->isValueInline()) {
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return;
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}
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unsigned alignMask = vwt->getAlignmentMask();
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unsigned size = vwt->size;
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swift_deallocObject(*reinterpret_cast<HeapObject **>(&Buffer), size,
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alignMask);
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}
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#ifndef NDEBUG
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// *NOTE* This routine performs unused memory reads on purpose to try to catch
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// use-after-frees in conjunction with ASAN or Guard Malloc.
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template <> SWIFT_USED void OpaqueExistentialContainer::verify() const {
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// We do not actually care about value. We just want to see if the
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// memory is valid or not. So convert to a uint8_t and try to
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// memcpy into firstByte. We use volatile to just ensure that this
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// does not get dead code eliminated.
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uint8_t firstByte;
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memcpy(&firstByte, projectValue(), 1);
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volatile uint8_t firstVolatileByte = firstByte;
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(void)firstVolatileByte;
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}
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/// Dump information about this specific container and its contents.
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template <> SWIFT_USED void OpaqueExistentialContainer::dump() const {
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// Quickly verify to make sure we are well formed.
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verify();
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printf("TargetOpaqueExistentialContainer.\n");
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printf("Metadata Pointer: %p.\n", Type);
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printf("Value Pointer: %p.\n", projectValue());
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printf("Is Value Stored Inline: %s.\n", isValueInline() ? "true" : "false");
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}
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#endif
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