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comparison lld/MachO/LTO.cpp @ 207:2e18cbf3894f

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LLVM12
author Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date Tue, 08 Jun 2021 06:07:14 +0900
parents
children 5f17cb93ff66
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173:0572611fdcc8 207:2e18cbf3894f
1 //===- LTO.cpp ------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "LTO.h"
10 #include "Config.h"
11 #include "Driver.h"
12 #include "InputFiles.h"
13 #include "Symbols.h"
14 #include "Target.h"
15
16 #include "lld/Common/ErrorHandler.h"
17 #include "lld/Common/Strings.h"
18 #include "lld/Common/TargetOptionsCommandFlags.h"
19 #include "llvm/LTO/LTO.h"
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/Path.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include "llvm/Transforms/ObjCARC.h"
24
25 using namespace lld;
26 using namespace lld::macho;
27 using namespace llvm;
28 using namespace llvm::MachO;
29 using namespace llvm::sys;
30
31 static lto::Config createConfig() {
32 lto::Config c;
33 c.Options = initTargetOptionsFromCodeGenFlags();
34 c.CodeModel = getCodeModelFromCMModel();
35 c.CPU = getCPUStr();
36 c.MAttrs = getMAttrs();
37 c.UseNewPM = config->ltoNewPassManager;
38 c.PreCodeGenPassesHook = [](legacy::PassManager &pm) {
39 pm.add(createObjCARCContractPass());
40 };
41 c.TimeTraceEnabled = config->timeTraceEnabled;
42 c.TimeTraceGranularity = config->timeTraceGranularity;
43 if (config->saveTemps)
44 checkError(c.addSaveTemps(config->outputFile.str() + ".",
45 /*UseInputModulePath=*/true));
46 return c;
47 }
48
49 BitcodeCompiler::BitcodeCompiler() {
50 lto::ThinBackend backend = lto::createInProcessThinBackend(
51 heavyweight_hardware_concurrency(config->thinLTOJobs));
52 ltoObj = std::make_unique<lto::LTO>(createConfig(), backend);
53 }
54
55 void BitcodeCompiler::add(BitcodeFile &f) {
56 ArrayRef<lto::InputFile::Symbol> objSyms = f.obj->symbols();
57 std::vector<lto::SymbolResolution> resols;
58 resols.reserve(objSyms.size());
59
60 // Provide a resolution to the LTO API for each symbol.
61 auto symIt = f.symbols.begin();
62 for (const lto::InputFile::Symbol &objSym : objSyms) {
63 resols.emplace_back();
64 lto::SymbolResolution &r = resols.back();
65 Symbol *sym = *symIt++;
66
67 // Ideally we shouldn't check for SF_Undefined but currently IRObjectFile
68 // reports two symbols for module ASM defined. Without this check, lld
69 // flags an undefined in IR with a definition in ASM as prevailing.
70 // Once IRObjectFile is fixed to report only one symbol this hack can
71 // be removed.
72 r.Prevailing = !objSym.isUndefined() && sym->getFile() == &f;
73
74 // FIXME: What about other output types? And we can probably be less
75 // restrictive with -flat_namespace, but it's an infrequent use case.
76 r.VisibleToRegularObj = config->outputType != MH_EXECUTE ||
77 config->namespaceKind == NamespaceKind::flat ||
78 sym->isUsedInRegularObj;
79
80 // Un-define the symbol so that we don't get duplicate symbol errors when we
81 // load the ObjFile emitted by LTO compilation.
82 if (r.Prevailing)
83 replaceSymbol<Undefined>(sym, sym->getName(), sym->getFile(),
84 RefState::Strong);
85
86 // TODO: set the other resolution configs properly
87 }
88 checkError(ltoObj->add(std::move(f.obj), resols));
89 }
90
91 // Merge all the bitcode files we have seen, codegen the result
92 // and return the resulting ObjectFile(s).
93 std::vector<ObjFile *> BitcodeCompiler::compile() {
94 unsigned maxTasks = ltoObj->getMaxTasks();
95 buf.resize(maxTasks);
96
97 checkError(ltoObj->run([&](size_t task) {
98 return std::make_unique<lto::NativeObjectStream>(
99 std::make_unique<raw_svector_ostream>(buf[task]));
100 }));
101
102 if (config->saveTemps) {
103 if (!buf[0].empty())
104 saveBuffer(buf[0], config->outputFile + ".lto.o");
105 for (unsigned i = 1; i != maxTasks; ++i)
106 saveBuffer(buf[i], config->outputFile + Twine(i) + ".lto.o");
107 }
108
109 if (!config->ltoObjPath.empty())
110 fs::create_directories(config->ltoObjPath);
111
112 std::vector<ObjFile *> ret;
113 for (unsigned i = 0; i != maxTasks; ++i) {
114 if (buf[i].empty())
115 continue;
116 SmallString<261> filePath("/tmp/lto.tmp");
117 uint32_t modTime = 0;
118 if (!config->ltoObjPath.empty()) {
119 filePath = config->ltoObjPath;
120 path::append(filePath, Twine(i) + "." +
121 getArchitectureName(config->arch()) +
122 ".lto.o");
123 saveBuffer(buf[i], filePath);
124 modTime = getModTime(filePath);
125 }
126 ret.push_back(make<ObjFile>(
127 MemoryBufferRef(buf[i], saver.save(filePath.str())), modTime, ""));
128 }
129
130 return ret;
131 }