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de2dbe57ed
In derivatives of loops, no longer allocate boxes for indirect case payloads. Instead, use a custom pullback context in the runtime which contains a bump-pointer allocator. When a function contains a differentiated loop, the closure context is a `Builtin.NativeObject`, which contains a `swift::AutoDiffLinearMapContext` and a tail-allocated top-level linear map struct (which represents the linear map struct that was previously directly partial-applied into the pullback). In branching trace enums, the payloads of previously indirect cases will be allocated by `swift::AutoDiffLinearMapContext::allocate` and stored as a `Builtin.RawPointer`.
73 lines
2.1 KiB
C++
73 lines
2.1 KiB
C++
//===--- AutoDiffSupport.cpp ----------------------------------*- C++ -*---===//
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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) 2019 - 2020 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 "AutoDiffSupport.h"
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#include "swift/ABI/Metadata.h"
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#include "swift/Runtime/HeapObject.h"
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using namespace swift;
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using namespace llvm;
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SWIFT_CC(swift)
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static void destroyLinearMapContext(SWIFT_CONTEXT HeapObject *obj) {
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free(obj);
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}
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/// Heap metadata for a linear map context.
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static FullMetadata<HeapMetadata> linearMapContextHeapMetadata = {
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{
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{
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&destroyLinearMapContext
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},
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{
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/*value witness table*/ nullptr
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}
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},
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{
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MetadataKind::Opaque
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}
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};
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AutoDiffLinearMapContext::AutoDiffLinearMapContext()
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: HeapObject(&linearMapContextHeapMetadata) {
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}
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void *AutoDiffLinearMapContext::projectTopLevelSubcontext() const {
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auto offset = alignTo(
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sizeof(AutoDiffLinearMapContext), alignof(AutoDiffLinearMapContext));
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return const_cast<uint8_t *>(
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reinterpret_cast<const uint8_t *>(this) + offset);
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}
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void *AutoDiffLinearMapContext::allocate(size_t size) {
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return allocator.Allocate(size, alignof(AutoDiffLinearMapContext));
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}
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AutoDiffLinearMapContext *swift::swift_autoDiffCreateLinearMapContext(
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size_t topLevelLinearMapStructSize) {
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auto allocationSize = alignTo(
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sizeof(AutoDiffLinearMapContext), alignof(AutoDiffLinearMapContext))
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+ topLevelLinearMapStructSize;
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auto *buffer = (AutoDiffLinearMapContext *)malloc(allocationSize);
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return new (buffer) AutoDiffLinearMapContext;
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}
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void *swift::swift_autoDiffProjectTopLevelSubcontext(
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AutoDiffLinearMapContext *allocator) {
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return allocator->projectTopLevelSubcontext();
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}
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void *swift::swift_autoDiffAllocateSubcontext(
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AutoDiffLinearMapContext *allocator, size_t size) {
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return allocator->allocate(size);
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}
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