f6b6e72143
We have been creating many ConcatInputSections with identical values due
to .subsections_via_symbols. This diff factors out the identical values
into a Shared struct, to reduce memory consumption and make copying
cheaper.
I also changed `callSiteCount` from a uint32_t to a 31-bit field to save an
extra word.
All in all, this takes InputSection from 120 to 72 bytes (and
ConcatInputSection from 160 to 112 bytes), i.e. 30% size reduction in
ConcatInputSection.
Numbers for linking chromium_framework on my 3.2 GHz 16-Core Intel Xeon W:
N Min Max Median Avg Stddev
x 20 4.14 4.24 4.18 4.183 0.027548999
+ 20 4.04 4.11 4.075 4.0775 0.018027756
Difference at 95.0% confidence
-0.1055 +/- 0.0149005
-2.52211% +/- 0.356215%
(Student's t, pooled s = 0.0232803)
Reviewed By: #lld-macho, thakis
Differential Revision: https://reviews.llvm.org/D105305
44 lines
1.5 KiB
C++
44 lines
1.5 KiB
C++
//===- DWARF.cpp ----------------------------------------------------------===//
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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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#include "Dwarf.h"
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#include "InputFiles.h"
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#include "InputSection.h"
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#include "OutputSegment.h"
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#include <memory>
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using namespace lld;
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using namespace lld::macho;
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using namespace llvm;
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std::unique_ptr<DwarfObject> DwarfObject::create(ObjFile *obj) {
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auto dObj = std::make_unique<DwarfObject>();
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bool hasDwarfInfo = false;
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// LLD only needs to extract the source file path from the debug info, so we
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// initialize DwarfObject with just the sections necessary to get that path.
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// The debugger will locate the debug info via the object file paths that we
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// emit in our STABS symbols, so we don't need to process & emit them
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// ourselves.
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for (const InputSection *isec : obj->debugSections) {
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if (StringRef *s =
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StringSwitch<StringRef *>(isec->getName())
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.Case(section_names::debugInfo, &dObj->infoSection.Data)
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.Case(section_names::debugAbbrev, &dObj->abbrevSection)
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.Case(section_names::debugStr, &dObj->strSection)
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.Default(nullptr)) {
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*s = toStringRef(isec->data);
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hasDwarfInfo = true;
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}
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}
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if (hasDwarfInfo)
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return dObj;
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return nullptr;
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}
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