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e0c7f081f1
PR #117514 refactored BPSectionOrderer to be used by the ELF port but introduced some inefficiency: * BPSectionBase/BPSymbol are wrappers around a single pointer. The numbers of sections and symbols could be huge, and the extra allocations are memory inefficient. * Reconstructing the returned DenseMap (since BPSectionBase != InputSectin) is wasteful. This patch refactors BPSectionOrderer with Curiously Recurring Template Pattern and eliminates the inefficiency. In addition, `symbolToSectionIdxs` is removed and `rootSymbolToSectionIdxs` building is moved to lld/MachO: while getting sections for symbols is cheap in Mach-O, it is awkward and inefficient in the ELF port. While here, add a file-level comment and replace some `StringMap<*>` (which copies strings) with `DenseMap<CachedHashStringRef, *>`. Pull Request: https://github.com/llvm/llvm-project/pull/124482
36 lines
1.3 KiB
C++
36 lines
1.3 KiB
C++
//===- BPSectionOrderer.h -------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// This file uses Balanced Partitioning to order sections to improve startup
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/// time and compressed size.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLD_MACHO_BPSECTION_ORDERER_H
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#define LLD_MACHO_BPSECTION_ORDERER_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/StringRef.h"
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namespace lld::macho {
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class InputSection;
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/// Run Balanced Partitioning to find the optimal function and data order to
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/// improve startup time and compressed size.
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///
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/// It is important that .subsections_via_symbols is used to ensure functions
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/// and data are in their own sections and thus can be reordered.
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llvm::DenseMap<const InputSection *, int>
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runBalancedPartitioning(llvm::StringRef profilePath,
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bool forFunctionCompression, bool forDataCompression,
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bool compressionSortStartupFunctions, bool verbose);
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} // namespace lld::macho
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#endif
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