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gold-plugin: Implement parallel LTO code generation using llvm::splitCodeGen. 

Parallelism can be enabled using a new plugin option, jobs=N, where N is
the number of code generation threads.

Differential Revision: http://reviews.llvm.org/D12308

llvm-svn: 246584
This commit is contained in:
Peter Collingbourne 2015-09-01 20:40:22 +00:00
parent 5b3942f54a
commit 87202a4aac
2 changed files with 69 additions and 34 deletions
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22
llvm/test/tools/gold/X86/parallel.ll Normal file
View File

@ -0,0 +1,22 @@
; RUN: llvm-as -o %t.bc %s
; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so -u foo -u bar -plugin-opt jobs=2 -plugin-opt save-temps -o %t %t.bc
; RUN: llvm-nm %t.o0 | FileCheck --check-prefix=CHECK0 %s
; RUN: llvm-nm %t.o1 | FileCheck --check-prefix=CHECK1 %s
target triple = "x86_64-unknown-linux-gnu"
; CHECK0-NOT: bar
; CHECK0: T foo
; CHECK0-NOT: bar
define void @foo() {
call void @bar()
ret void
}
; CHECK1-NOT: foo
; CHECK1: T bar
; CHECK1-NOT: foo
define void @bar() {
call void @foo()
ret void
}

81
llvm/tools/gold/gold-plugin.cpp
View File

@ -20,6 +20,7 @@
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/CodeGen/ParallelCG.h"
#include "llvm/IR/AutoUpgrade.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DiagnosticInfo.h"
@ -92,6 +93,7 @@ namespace options {
static bool generate_api_file = false;
static OutputType TheOutputType = OT_NORMAL;
static unsigned OptLevel = 2;
static unsigned Parallelism = 1;
static std::string obj_path;
static std::string extra_library_path;
static std::string triple;
@ -127,8 +129,11 @@ namespace options {
TheOutputType = OT_DISABLE;
} else if (opt.size() == 2 && opt[0] == 'O') {
if (opt[1] < '0' || opt[1] > '3')
report_fatal_error("Optimization level must be between 0 and 3");
message(LDPL_FATAL, "Optimization level must be between 0 and 3");
OptLevel = opt[1] - '0';
} else if (opt.startswith("jobs=")) {
if (StringRef(opt_ + 5).getAsInteger(10, Parallelism))
message(LDPL_FATAL, "Invalid parallelism level: %s", opt_ + 5);
} else {
// Save this option to pass to the code generator.
// ParseCommandLineOptions() expects argv[0] to be program name. Lazily
@ -742,8 +747,8 @@ static void saveBCFile(StringRef Path, Module &M) {
WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ true);
}
static void codegen(Module &M) {
const std::string &TripleStr = M.getTargetTriple();
static void codegen(std::unique_ptr<Module> M) {
const std::string &TripleStr = M->getTargetTriple();
Triple TheTriple(TripleStr);
std::string ErrMsg;
@ -779,12 +784,10 @@ static void codegen(Module &M) {
TripleStr, options::mcpu, Features.getString(), Options, RelocationModel,
CodeModel::Default, CGOptLevel));
runLTOPasses(M, *TM);
runLTOPasses(*M, *TM);
if (options::TheOutputType == options::OT_SAVE_TEMPS)
saveBCFile(output_name + ".opt.bc", M);
legacy::PassManager CodeGenPasses;
saveBCFile(output_name + ".opt.bc", *M);
SmallString<128> Filename;
if (!options::obj_path.empty())
@ -792,37 +795,47 @@ static void codegen(Module &M) {
else if (options::TheOutputType == options::OT_SAVE_TEMPS)
Filename = output_name + ".o";
int FD;
std::vector<SmallString<128>> Filenames(options::Parallelism);
bool TempOutFile = Filename.empty();
if (TempOutFile) {
std::error_code EC =
sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filename);
if (EC)
message(LDPL_FATAL, "Could not create temporary file: %s",
EC.message().c_str());
} else {
std::error_code EC =
sys::fs::openFileForWrite(Filename.c_str(), FD, sys::fs::F_None);
if (EC)
message(LDPL_FATAL, "Could not open file: %s", EC.message().c_str());
}
{
raw_fd_ostream OS(FD, true);
// Open a file descriptor for each backend thread. This is done in a block
// so that the output file descriptors are closed before gold opens them.
std::list<llvm::raw_fd_ostream> OSs;
std::vector<llvm::raw_pwrite_stream *> OSPtrs(options::Parallelism);
for (unsigned I = 0; I != options::Parallelism; ++I) {
int FD;
if (TempOutFile) {
std::error_code EC =
sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filenames[I]);
if (EC)
message(LDPL_FATAL, "Could not create temporary file: %s",
EC.message().c_str());
} else {
Filenames[I] = Filename;
if (options::Parallelism != 1)
Filenames[I] += utostr(I);
std::error_code EC =
sys::fs::openFileForWrite(Filenames[I], FD, sys::fs::F_None);
if (EC)
message(LDPL_FATAL, "Could not open file: %s", EC.message().c_str());
}
OSs.emplace_back(FD, true);
OSPtrs[I] = &OSs.back();
}
if (TM->addPassesToEmitFile(CodeGenPasses, OS,
TargetMachine::CGFT_ObjectFile))
message(LDPL_FATAL, "Failed to setup codegen");
CodeGenPasses.run(M);
// Run backend threads.
splitCodeGen(std::move(M), OSPtrs, options::mcpu, Features.getString(),
Options, RelocationModel, CodeModel::Default, CGOptLevel);
}
if (add_input_file(Filename.c_str()) != LDPS_OK)
message(LDPL_FATAL,
"Unable to add .o file to the link. File left behind in: %s",
Filename.c_str());
if (TempOutFile)
Cleanup.push_back(Filename.c_str());
for (auto &Filename : Filenames) {
if (add_input_file(Filename.c_str()) != LDPS_OK)
message(LDPL_FATAL,
"Unable to add .o file to the link. File left behind in: %s",
Filename.c_str());
if (TempOutFile)
Cleanup.push_back(Filename.c_str());
}
}
/// gold informs us that all symbols have been read. At this point, we use
@ -889,7 +902,7 @@ static ld_plugin_status allSymbolsReadHook(raw_fd_ostream *ApiFile) {
return LDPS_OK;
}
codegen(*L.getModule());
codegen(std::move(Combined));
if (!options::extra_library_path.empty() &&
set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK)