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[CGData] LLD for MachO (#90166)
It reads raw CG data encoded in the custom section (__llvm_outline) in object files and merges them into the indexed codegen data file specified by `-codegen-data-generate-path={path}`. This depends on #90074. This is a patch for https://discourse.llvm.org/t/rfc-enhanced-machine-outliner-part-2-thinlto-nolto/78753.
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‎lld/MachO/Config.h

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@@ -210,6 +210,7 @@ struct Configuration {
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std::vector<SectionAlign> sectionAlignments;
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std::vector<SegmentProtection> segmentProtections;
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bool ltoDebugPassManager = false;
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llvm::StringRef codegenDataGeneratePath;
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bool csProfileGenerate = false;
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llvm::StringRef csProfilePath;
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bool pgoWarnMismatch;

‎lld/MachO/Driver.cpp

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@@ -36,6 +36,7 @@
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#include "llvm/ADT/StringRef.h"
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#include "llvm/BinaryFormat/MachO.h"
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#include "llvm/BinaryFormat/Magic.h"
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#include "llvm/CGData/CodeGenDataWriter.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/LTO/LTO.h"
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#include "llvm/Object/Archive.h"
@@ -1322,6 +1323,37 @@ static void gatherInputSections() {
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}
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}
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static void codegenDataGenerate() {
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TimeTraceScope timeScope("Generating codegen data");
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OutlinedHashTreeRecord globalOutlineRecord;
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for (ConcatInputSection *isec : inputSections)
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if (isec->getSegName() == segment_names::data &&
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isec->getName() == section_names::outlinedHashTree) {
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// Read outlined hash tree from each section.
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OutlinedHashTreeRecord localOutlineRecord;
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auto *data = isec->data.data();
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localOutlineRecord.deserialize(data);
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// Merge it to the global hash tree.
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globalOutlineRecord.merge(localOutlineRecord);
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}
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CodeGenDataWriter Writer;
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if (!globalOutlineRecord.empty())
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Writer.addRecord(globalOutlineRecord);
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std::error_code EC;
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auto fileName = config->codegenDataGeneratePath;
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assert(!fileName.empty());
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raw_fd_ostream Output(fileName, EC, sys::fs::OF_None);
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if (EC)
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error("fail to create " + fileName + ": " + EC.message());
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if (auto E = Writer.write(Output))
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error("fail to write CGData: " + toString(std::move(E)));
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}
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static void foldIdenticalLiterals() {
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TimeTraceScope timeScope("Fold identical literals");
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// We always create a cStringSection, regardless of whether dedupLiterals is
@@ -1759,6 +1791,8 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
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config->ignoreAutoLinkOptions.insert(arg->getValue());
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config->strictAutoLink = args.hasArg(OPT_strict_auto_link);
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config->ltoDebugPassManager = args.hasArg(OPT_lto_debug_pass_manager);
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config->codegenDataGeneratePath =
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args.getLastArgValue(OPT_codegen_data_generate_path);
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config->csProfileGenerate = args.hasArg(OPT_cs_profile_generate);
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config->csProfilePath = args.getLastArgValue(OPT_cs_profile_path);
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config->pgoWarnMismatch =
@@ -2103,6 +2137,10 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
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}
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gatherInputSections();
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if (!config->codegenDataGeneratePath.empty())
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codegenDataGenerate();
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if (config->callGraphProfileSort)
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priorityBuilder.extractCallGraphProfile();
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‎lld/MachO/InputSection.h

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@@ -354,6 +354,7 @@ constexpr const char objcMethname[] = "__objc_methname";
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constexpr const char objcNonLazyCatList[] = "__objc_nlcatlist";
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constexpr const char objcNonLazyClassList[] = "__objc_nlclslist";
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constexpr const char objcProtoList[] = "__objc_protolist";
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constexpr const char outlinedHashTree[] = "__llvm_outline";
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constexpr const char pageZero[] = "__pagezero";
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constexpr const char pointers[] = "__pointers";
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constexpr const char rebase[] = "__rebase";

‎lld/MachO/Options.td

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@@ -162,6 +162,10 @@ def no_objc_category_merging : Flag<["-"], "no_objc_category_merging">,
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Group<grp_lld>;
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def lto_debug_pass_manager: Flag<["--"], "lto-debug-pass-manager">,
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HelpText<"Debug new pass manager">, Group<grp_lld>;
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def codegen_data_generate_path : Separate<["--"], "codegen-data-generate-path">, Group<grp_lld>;
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def codegen_data_generate_path_eq : Joined<["--"], "codegen-data-generate-path=">,
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Alias<!cast<Separate>(codegen_data_generate_path)>, MetaVarName<"<cgdata>">,
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HelpText<"Write the CG data to the specified path <cgdata>.">, Group<grp_lld>;
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def cs_profile_generate: Flag<["--"], "cs-profile-generate">,
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HelpText<"Perform context sensitive PGO instrumentation">, Group<grp_lld>;
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def cs_profile_path: Joined<["--"], "cs-profile-path=">,

‎lld/test/CMakeLists.txt

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@@ -48,6 +48,7 @@ if (NOT LLD_BUILT_STANDALONE)
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llvm-ar
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llvm-as
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llvm-bcanalyzer
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llvm-cgdata
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llvm-config
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llvm-cvtres
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llvm-dis

‎lld/test/MachO/cgdata-generate.s

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# UNSUPPORTED: system-windows
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# REQUIRES: aarch64
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# RUN: rm -rf %t; split-file %s %t
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# Synthesize raw cgdata without the header (24 byte) from the indexed cgdata.
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# RUN: llvm-cgdata --convert --format binary %t/raw-1.cgtext -o %t/raw-1.cgdata
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# RUN: od -t x1 -j 24 -An %t/raw-1.cgdata | tr -d '\n\r\t' | sed 's/ \+/ /g; s/^ *//; s/ *$//; s/ /,0x/g; s/^/0x/' > %t/raw-1-bytes.txt
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# RUN: sed "s/<RAW_BYTES>/$(cat %t/raw-1-bytes.txt)/g" %t/merge-template.s > %t/merge-1.s
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# RUN: llvm-cgdata --convert --format binary %t/raw-2.cgtext -o %t/raw-2.cgdata
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# RUN: od -t x1 -j 24 -An %t/raw-2.cgdata | tr -d '\n\r\t' | sed 's/ \+/ /g; s/^ *//; s/ *$//; s/ /,0x/g; s/^/0x/' > %t/raw-2-bytes.txt
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# RUN: sed "s/<RAW_BYTES>/$(cat %t/raw-2-bytes.txt)/g" %t/merge-template.s > %t/merge-2.s
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# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/merge-1.s -o %t/merge-1.o
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# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/merge-2.s -o %t/merge-2.o
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# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/main.s -o %t/main.o
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# This checks if the codegen data from the linker is identical to the merged codegen data
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# from each object file, which is obtained using the llvm-cgdata tool.
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# RUN: %no-arg-lld -dylib -arch arm64 -platform_version ios 14.0 15.0 -o %t/out \
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# RUN: %t/merge-1.o %t/merge-2.o %t/main.o --codegen-data-generate-path=%t/out-cgdata
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# RUN: llvm-cgdata --merge %t/merge-1.o %t/merge-2.o %t/main.o -o %t/merge-cgdata
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# RUN: diff %t/out-cgdata %t/merge-cgdata
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# Merge order doesn't matter. `main.o` is dropped due to missing __llvm_outline.
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# RUN: llvm-cgdata --merge %t/merge-2.o %t/merge-1.o -o %t/merge-cgdata-shuffle
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# RUN: diff %t/out-cgdata %t/merge-cgdata-shuffle
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# We can also generate the merged codegen data from the executable that is not dead-stripped.
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# RUN: llvm-objdump -h %t/out| FileCheck %s
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# CHECK: __llvm_outline
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# RUN: llvm-cgdata --merge %t/out -o %t/merge-cgdata-exe
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# RUN: diff %t/merge-cgdata-exe %t/merge-cgdata
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# Dead-strip will remove __llvm_outline sections from the final executable.
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# But the codeden data is still correctly produced from the linker.
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# RUN: %no-arg-lld -dylib -arch arm64 -platform_version ios 14.0 15.0 -o %t/out-strip \
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# RUN: %t/merge-1.o %t/merge-2.o %t/main.o -dead_strip --codegen-data-generate-path=%t/out-cgdata-strip
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# RUN: llvm-cgdata --merge %t/merge-1.o %t/merge-2.o %t/main.o -o %t/merge-cgdata-strip
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# RUN: diff %t/out-cgdata-strip %t/merge-cgdata-strip
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# RUN: diff %t/out-cgdata-strip %t/merge-cgdata
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# Ensure no __llvm_outline section remains in the executable.
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# RUN: llvm-objdump -h %t/out-strip | FileCheck %s --check-prefix=STRIP
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# STRIP-NOT: __llvm_outline
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#--- raw-1.cgtext
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:outlined_hash_tree
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0:
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Hash: 0x0
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Terminals: 0
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SuccessorIds: [ 1 ]
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1:
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Hash: 0x1
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Terminals: 0
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SuccessorIds: [ 2 ]
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2:
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Hash: 0x2
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Terminals: 4
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SuccessorIds: [ ]
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...
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#--- raw-2.cgtext
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:outlined_hash_tree
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0:
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Hash: 0x0
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Terminals: 0
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SuccessorIds: [ 1 ]
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1:
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Hash: 0x1
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Terminals: 0
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SuccessorIds: [ 2 ]
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2:
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Hash: 0x3
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Terminals: 5
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SuccessorIds: [ ]
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...
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#--- merge-template.s
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.section __DATA,__llvm_outline
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_data:
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.byte <RAW_BYTES>
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#--- main.s
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.globl _main
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.text
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_main:
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ret

‎lld/test/lit.cfg.py

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@@ -40,6 +40,7 @@
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tool_patterns = [
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"llc",
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"llvm-as",
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"llvm-cgdata",
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"llvm-mc",
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"llvm-nm",
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"llvm-objdump",

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