[lld] r238777 - COFF: Initial implementation of link-time optimization.
Peter Collingbourne
peter at pcc.me.uk
Mon Jun 1 13:10:11 PDT 2015
Author: pcc
Date: Mon Jun 1 15:10:10 2015
New Revision: 238777
URL: http://llvm.org/viewvc/llvm-project?rev=238777&view=rev
Log:
COFF: Initial implementation of link-time optimization.
This implementation is known to work in very simple cases (see new test case).
Differential Revision: http://reviews.llvm.org/D10115
Added:
lld/trunk/test/COFF/Inputs/lto-dep.ll
lld/trunk/test/COFF/lto.ll
Modified:
lld/trunk/COFF/CMakeLists.txt
lld/trunk/COFF/Driver.cpp
lld/trunk/COFF/InputFiles.cpp
lld/trunk/COFF/InputFiles.h
lld/trunk/COFF/SymbolTable.cpp
lld/trunk/COFF/SymbolTable.h
lld/trunk/COFF/Symbols.cpp
lld/trunk/COFF/Symbols.h
lld/trunk/test/CMakeLists.txt
lld/trunk/test/lit.cfg
Modified: lld/trunk/COFF/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/CMakeLists.txt?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/CMakeLists.txt (original)
+++ lld/trunk/COFF/CMakeLists.txt Mon Jun 1 15:10:10 2015
@@ -10,6 +10,14 @@ add_llvm_library(lldCOFF
SymbolTable.cpp
Symbols.cpp
Writer.cpp
+
+ LINK_COMPONENTS
+ ${LLVM_TARGETS_TO_BUILD}
+ Core
+ LTO
+ MC
+ MCDisassembler
+ Support
)
add_dependencies(lldCOFF COFFOptionsTableGen)
Modified: lld/trunk/COFF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Driver.cpp?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/Driver.cpp (original)
+++ lld/trunk/COFF/Driver.cpp Mon Jun 1 15:10:10 2015
@@ -23,6 +23,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
+#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/raw_ostream.h"
#include <memory>
@@ -75,6 +76,8 @@ ErrorOr<std::unique_ptr<InputFile>> Link
file_magic Magic = identify_magic(MBRef.getBuffer());
if (Magic == file_magic::archive)
return std::unique_ptr<InputFile>(new ArchiveFile(MBRef));
+ if (Magic == file_magic::bitcode)
+ return std::unique_ptr<InputFile>(new BitcodeFile(Path));
return std::unique_ptr<InputFile>(new ObjectFile(MBRef));
}
@@ -191,6 +194,14 @@ std::vector<StringRef> LinkerDriver::get
}
bool LinkerDriver::link(int Argc, const char *Argv[]) {
+ // Needed for LTO.
+ llvm::InitializeAllTargetInfos();
+ llvm::InitializeAllTargets();
+ llvm::InitializeAllTargetMCs();
+ llvm::InitializeAllAsmParsers();
+ llvm::InitializeAllAsmPrinters();
+ llvm::InitializeAllDisassemblers();
+
// Parse command line options.
auto ArgsOrErr = parseArgs(Argc, Argv);
if (auto EC = ArgsOrErr.getError()) {
@@ -356,6 +367,11 @@ bool LinkerDriver::link(int Argc, const
if (Symtab.reportRemainingUndefines())
return false;
+ if (auto EC = Symtab.addCombinedLTOObject()) {
+ llvm::errs() << EC.message() << "\n";
+ return false;
+ }
+
// /include option takes precedence over garbage collection.
for (auto *Arg : Args->filtered(OPT_incl))
Symtab.find(Arg->getValue())->markLive();
Modified: lld/trunk/COFF/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/InputFiles.cpp?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/InputFiles.cpp (original)
+++ lld/trunk/COFF/InputFiles.cpp Mon Jun 1 15:10:10 2015
@@ -12,6 +12,7 @@
#include "InputFiles.h"
#include "Writer.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/LTO/LTOModule.h"
#include "llvm/Object/COFF.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Debug.h"
@@ -239,5 +240,32 @@ std::error_code ImportFile::parse() {
return std::error_code();
}
+std::error_code BitcodeFile::parse() {
+ std::string Err;
+ if (!Filename.empty()) {
+ M.reset(LTOModule::createFromFile(Filename.c_str(), llvm::TargetOptions(),
+ Err));
+ } else {
+ M.reset(LTOModule::createFromBuffer(MBRef.getBufferStart(),
+ MBRef.getBufferSize(),
+ llvm::TargetOptions(), Err));
+ }
+ if (!Err.empty()) {
+ llvm::errs() << Err << '\n';
+ return make_error_code(LLDError::BrokenFile);
+ }
+
+ for (unsigned I = 0, E = M->getSymbolCount(); I != E; ++I) {
+ StringRef SymName = M->getSymbolName(I);
+ if ((M->getSymbolAttributes(I) & LTO_SYMBOL_DEFINITION_MASK) ==
+ LTO_SYMBOL_DEFINITION_UNDEFINED) {
+ SymbolBodies.push_back(new (Alloc) Undefined(SymName));
+ } else {
+ SymbolBodies.push_back(new (Alloc) DefinedBitcode(SymName));
+ }
+ }
+
+ return std::error_code();
+}
} // namespace coff
} // namespace lld
Modified: lld/trunk/COFF/InputFiles.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/InputFiles.h?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/InputFiles.h (original)
+++ lld/trunk/COFF/InputFiles.h Mon Jun 1 15:10:10 2015
@@ -15,6 +15,7 @@
#include "Symbols.h"
#include "lld/Core/LLVM.h"
#include "llvm/ADT/ArrayRef.h"
+#include "llvm/LTO/LTOModule.h"
#include "llvm/Object/Archive.h"
#include "llvm/Object/COFF.h"
#include <memory>
@@ -24,13 +25,14 @@
namespace lld {
namespace coff {
+using llvm::LTOModule;
using llvm::object::Archive;
using llvm::object::COFFObjectFile;
// The root class of input files.
class InputFile {
public:
- enum Kind { ArchiveKind, ObjectKind, ImportKind };
+ enum Kind { ArchiveKind, ObjectKind, ImportKind, BitcodeKind };
Kind kind() const { return FileKind; }
virtual ~InputFile() {}
@@ -157,6 +159,28 @@ private:
StringAllocator StringAlloc;
};
+// Used for LTO.
+class BitcodeFile : public InputFile {
+public:
+ explicit BitcodeFile(StringRef S) : InputFile(BitcodeKind), Filename(S) {}
+ explicit BitcodeFile(MemoryBufferRef M) : InputFile(BitcodeKind), MBRef(M) {}
+ static bool classof(const InputFile *F) { return F->kind() == BitcodeKind; }
+ StringRef getName() override { return Filename; }
+ std::vector<SymbolBody *> &getSymbols() override { return SymbolBodies; }
+
+ LTOModule *getModule() const { return M.get(); }
+ LTOModule *releaseModule() { return M.release(); }
+
+private:
+ std::error_code parse() override;
+
+ std::string Filename;
+ MemoryBufferRef MBRef;
+ std::vector<SymbolBody *> SymbolBodies;
+ llvm::BumpPtrAllocator Alloc;
+ std::unique_ptr<LTOModule> M;
+};
+
} // namespace coff
} // namespace lld
Modified: lld/trunk/COFF/SymbolTable.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/SymbolTable.cpp?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/SymbolTable.cpp (original)
+++ lld/trunk/COFF/SymbolTable.cpp Mon Jun 1 15:10:10 2015
@@ -12,6 +12,7 @@
#include "Error.h"
#include "SymbolTable.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/LTO/LTOCodeGenerator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
@@ -34,6 +35,8 @@ std::error_code SymbolTable::addFile(std
return addObject(P);
if (auto *P = dyn_cast<ArchiveFile>(FileP))
return addArchive(P);
+ if (auto *P = dyn_cast<BitcodeFile>(FileP))
+ return addBitcode(P);
return addImport(cast<ImportFile>(FileP));
}
@@ -65,6 +68,17 @@ std::error_code SymbolTable::addArchive(
return std::error_code();
}
+std::error_code SymbolTable::addBitcode(BitcodeFile *File) {
+ BitcodeFiles.emplace_back(File);
+ for (SymbolBody *Body : File->getSymbols())
+ if (Body->isExternal())
+ if (auto EC = resolve(Body))
+ return EC;
+
+ // TODO: Handle linker directives.
+ return std::error_code();
+}
+
std::error_code SymbolTable::addImport(ImportFile *File) {
ImportFiles.emplace_back(File);
for (SymbolBody *Body : File->getSymbols())
@@ -213,5 +227,68 @@ void SymbolTable::dump() {
}
}
+std::error_code SymbolTable::addCombinedLTOObject() {
+ if (BitcodeFiles.empty())
+ return std::error_code();
+
+ llvm::LTOCodeGenerator CG;
+ std::set<DefinedBitcode *> PreservedBitcodeSymbols;
+
+ // All symbols referenced by non-bitcode objects must be preserved.
+ for (std::unique_ptr<ObjectFile> &File : ObjectFiles)
+ for (SymbolBody *Body : File->getSymbols())
+ if (auto *S = dyn_cast<DefinedBitcode>(Body->getReplacement()))
+ PreservedBitcodeSymbols.insert(S);
+
+ // Likewise for the linker-generated reference to the entry point.
+ if (auto *S = dyn_cast<DefinedBitcode>(Symtab[Config->EntryName]->Body))
+ PreservedBitcodeSymbols.insert(S);
+
+ for (DefinedBitcode *S : PreservedBitcodeSymbols)
+ CG.addMustPreserveSymbol(S->getName());
+
+ CG.setModule(BitcodeFiles[0]->releaseModule());
+ for (unsigned I = 1, E = BitcodeFiles.size(); I != E; ++I)
+ CG.addModule(BitcodeFiles[I]->getModule());
+
+ std::string ErrMsg;
+ LTOObjectFile = CG.compile(false, false, false, ErrMsg);
+ if (!LTOObjectFile) {
+ llvm::errs() << ErrMsg << '\n';
+ return make_error_code(LLDError::BrokenFile);
+ }
+
+ // Create an object file and add it to the symbol table by replacing any
+ // DefinedBitcode symbols with the definitions in the object file.
+ auto Obj = new ObjectFile(LTOObjectFile->getMemBufferRef());
+ ObjectFiles.emplace_back(Obj);
+ if (auto EC = Obj->parse())
+ return EC;
+ for (SymbolBody *Body : Obj->getSymbols()) {
+ if (!Body->isExternal())
+ continue;
+
+ // Find an existing Symbol. We should not see any new symbols at this point.
+ StringRef Name = Body->getName();
+ Symbol *Sym = Symtab[Name];
+ if (!Sym) {
+ llvm::errs() << "LTO: unexpected new symbol: " << Name << '\n';
+ return make_error_code(LLDError::BrokenFile);
+ }
+ Body->setBackref(Sym);
+
+ if (isa<DefinedBitcode>(Sym->Body)) {
+ // The symbol should now be defined.
+ if (!isa<Defined>(Body)) {
+ llvm::errs() << "LTO: undefined symbol: " << Name << '\n';
+ return make_error_code(LLDError::BrokenFile);
+ }
+ Sym->Body = Body;
+ }
+ }
+
+ return std::error_code();
+}
+
} // namespace coff
} // namespace lld
Modified: lld/trunk/COFF/SymbolTable.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/SymbolTable.h?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/SymbolTable.h (original)
+++ lld/trunk/COFF/SymbolTable.h Mon Jun 1 15:10:10 2015
@@ -58,6 +58,11 @@ public:
// Dump contents of the symbol table to stderr.
void dump();
+ // Build a COFF object representing the combined contents of BitcodeFiles
+ // and add it to the symbol table. Called after all files are added and
+ // before the writer writes results to a file.
+ std::error_code addCombinedLTOObject();
+
// The writer needs to handle DLL import libraries specially in
// order to create the import descriptor table.
std::vector<std::unique_ptr<ImportFile>> ImportFiles;
@@ -75,6 +80,7 @@ private:
std::error_code addObject(ObjectFile *File);
std::error_code addArchive(ArchiveFile *File);
std::error_code addImport(ImportFile *File);
+ std::error_code addBitcode(BitcodeFile *File);
std::error_code resolve(SymbolBody *Body);
std::error_code addMemberFile(Lazy *Body);
@@ -82,7 +88,9 @@ private:
std::unordered_map<StringRef, Symbol *> Symtab;
std::vector<std::unique_ptr<ArchiveFile>> ArchiveFiles;
+ std::vector<std::unique_ptr<BitcodeFile>> BitcodeFiles;
std::vector<std::unique_ptr<SymbolBody>> OwningSymbols;
+ std::unique_ptr<MemoryBuffer> LTOObjectFile;
llvm::BumpPtrAllocator Alloc;
};
Modified: lld/trunk/COFF/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Symbols.cpp?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/Symbols.cpp (original)
+++ lld/trunk/COFF/Symbols.cpp Mon Jun 1 15:10:10 2015
@@ -81,6 +81,8 @@ ErrorOr<std::unique_ptr<InputFile>> Lazy
return std::unique_ptr<InputFile>(nullptr);
file_magic Magic = identify_magic(MBRef.getBuffer());
+ if (Magic == file_magic::bitcode)
+ return std::unique_ptr<InputFile>(new BitcodeFile(MBRef));
if (Magic == file_magic::coff_import_library)
return std::unique_ptr<InputFile>(new ImportFile(MBRef));
Modified: lld/trunk/COFF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Symbols.h?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/COFF/Symbols.h (original)
+++ lld/trunk/COFF/Symbols.h Mon Jun 1 15:10:10 2015
@@ -48,6 +48,7 @@ public:
DefinedAbsoluteKind,
DefinedImportDataKind,
DefinedImportThunkKind,
+ DefinedBitcodeKind,
DefinedLast,
UndefinedKind,
LazyKind,
@@ -251,6 +252,18 @@ private:
ImportThunkChunk Data;
};
+class DefinedBitcode : public Defined {
+public:
+ DefinedBitcode(StringRef Name) : Defined(DefinedBitcodeKind, Name) {}
+
+ static bool classof(const SymbolBody *S) {
+ return S->kind() == DefinedBitcodeKind;
+ }
+
+ uint64_t getRVA() override { llvm_unreachable("bitcode reached writer"); }
+ uint64_t getFileOff() override { llvm_unreachable("bitcode reached writer"); }
+};
+
} // namespace coff
} // namespace lld
Modified: lld/trunk/test/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/CMakeLists.txt?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/test/CMakeLists.txt (original)
+++ lld/trunk/test/CMakeLists.txt Mon Jun 1 15:10:10 2015
@@ -20,7 +20,7 @@ configure_lit_site_cfg(
)
set(LLD_TEST_DEPS
- FileCheck not llvm-ar llvm-nm
+ FileCheck not llvm-ar llvm-as llvm-nm llc
lld llvm-config llvm-objdump llvm-readobj yaml2obj obj2yaml
linker-script-test macho-dump llvm-mc llvm-nm
)
Added: lld/trunk/test/COFF/Inputs/lto-dep.ll
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/Inputs/lto-dep.ll?rev=238777&view=auto
==============================================================================
--- lld/trunk/test/COFF/Inputs/lto-dep.ll (added)
+++ lld/trunk/test/COFF/Inputs/lto-dep.ll Mon Jun 1 15:10:10 2015
@@ -0,0 +1,6 @@
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+define void @foo() {
+ ret void
+}
Added: lld/trunk/test/COFF/lto.ll
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/lto.ll?rev=238777&view=auto
==============================================================================
--- lld/trunk/test/COFF/lto.ll (added)
+++ lld/trunk/test/COFF/lto.ll Mon Jun 1 15:10:10 2015
@@ -0,0 +1,81 @@
+; RUN: llvm-as -o %T/main.lto.obj %s
+; RUN: llvm-as -o %T/foo.lto.obj %S/Inputs/lto-dep.ll
+; RUN: rm -f %T/foo.lto.lib
+; RUN: llvm-ar cru %T/foo.lto.lib %T/foo.lto.obj
+
+; RUN: llc -filetype=obj -o %T/main.obj %s
+; RUN: llc -filetype=obj -o %T/foo.obj %S/Inputs/lto-dep.ll
+; RUN: rm -f %T/foo.lib
+; RUN: llvm-ar cru %T/foo.lib %T/foo.obj
+
+; RUN: lld -flavor link2 /out:%T/main.exe /entry:main /subsystem:console %T/main.lto.obj %T/foo.lto.obj
+; RUN: llvm-readobj -file-headers %T/main.exe | FileCheck -check-prefix=HEADERS-11 %s
+; RUN: llvm-objdump -d %T/main.exe | FileCheck -check-prefix=TEXT-11 %s
+; RUN: lld -flavor link2 /out:%T/main.exe /entry:main /subsystem:console %T/main.lto.obj %T/foo.lto.lib
+; RUN: llvm-readobj -file-headers %T/main.exe | FileCheck -check-prefix=HEADERS-11 %s
+; RUN: llvm-objdump -d %T/main.exe | FileCheck -check-prefix=TEXT-11 %s
+
+; RUN: lld -flavor link2 /out:%T/main.exe /entry:main /subsystem:console %T/main.obj %T/foo.lto.obj
+; RUN: llvm-readobj -file-headers %T/main.exe | FileCheck -check-prefix=HEADERS-01 %s
+; RUN: llvm-objdump -d %T/main.exe | FileCheck -check-prefix=TEXT-01 %s
+; RUN: lld -flavor link2 /out:%T/main.exe /entry:main /subsystem:console %T/main.obj %T/foo.lto.lib
+; RUN: llvm-readobj -file-headers %T/main.exe | FileCheck -check-prefix=HEADERS-01 %s
+; RUN: llvm-objdump -d %T/main.exe | FileCheck -check-prefix=TEXT-01 %s
+
+; RUN: lld -flavor link2 /out:%T/main.exe /entry:main /subsystem:console %T/main.lto.obj %T/foo.obj
+; RUN: llvm-readobj -file-headers %T/main.exe | FileCheck -check-prefix=HEADERS-10 %s
+; RUN: llvm-objdump -d %T/main.exe | FileCheck -check-prefix=TEXT-10 %s
+; RUN: lld -flavor link2 /out:%T/main.exe /entry:main /subsystem:console %T/main.lto.obj %T/foo.lib
+; RUN: llvm-readobj -file-headers %T/main.exe | FileCheck -check-prefix=HEADERS-10 %s
+; RUN: llvm-objdump -d %T/main.exe | FileCheck -check-prefix=TEXT-10 %s
+
+; HEADERS-11: AddressOfEntryPoint: 0x1000
+; TEXT-11: Disassembly of section .text:
+; TEXT-11-NEXT: .text:
+; TEXT-11-NEXT: xorl %eax, %eax
+; TEXT-11-NEXT: retq
+
+; HEADERS-01: AddressOfEntryPoint: 0x1000
+; TEXT-01: Disassembly of section .text:
+; TEXT-01-NEXT: .text:
+; TEXT-01-NEXT: subq $40, %rsp
+; TEXT-01-NEXT: callq 7
+; TEXT-01-NEXT: xorl %eax, %eax
+; TEXT-01-NEXT: addq $40, %rsp
+; TEXT-01-NEXT: retq
+; TEXT-01-NEXT: retq
+
+; HEADERS-10: AddressOfEntryPoint: 0x1010
+; TEXT-10: Disassembly of section .text:
+; TEXT-10-NEXT: .text:
+; TEXT-10-NEXT: retq
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: int3
+; TEXT-10-NEXT: subq $40, %rsp
+; TEXT-10-NEXT: callq -25
+; TEXT-10-NEXT: xorl %eax, %eax
+; TEXT-10-NEXT: addq $40, %rsp
+; TEXT-10-NEXT: retq
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+define i32 @main() {
+ call void @foo()
+ ret i32 0
+}
+
+declare void @foo()
Modified: lld/trunk/test/lit.cfg
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/lit.cfg?rev=238777&r1=238776&r2=238777&view=diff
==============================================================================
--- lld/trunk/test/lit.cfg (original)
+++ lld/trunk/test/lit.cfg Mon Jun 1 15:10:10 2015
@@ -33,7 +33,7 @@ else:
config.test_format = lit.formats.ShTest(execute_external)
# suffixes: A list of file extensions to treat as test files.
-config.suffixes = ['.objtxt', '.test']
+config.suffixes = ['.ll', '.objtxt', '.test']
# excludes: A list of directories to exclude from the testsuite. The 'Inputs'
# subdirectories contain auxiliary inputs for various tests in their parent
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