[lld] r239005 - COFF: /include'd symbols must be preserved.
Peter Collingbourne
peter at pcc.me.uk
Wed Jun 3 22:21:54 PDT 2015
In any case, it looks like the internalizer already has code to prevent
internalization of dllexported symbols (see the shouldInternalize function
in lib/Transforms/IPO/Internalize.cpp).
Peter
On Wed, Jun 03, 2015 at 09:10:27PM -0700, Rui Ueyama wrote:
> It doesn't support DLL yet.
>
> On Wed, Jun 3, 2015 at 8:40 PM, David Majnemer <david.majnemer at gmail.com>
> wrote:
>
> > Do you already do the same for exported symbols?
> >
> >
> > On Wednesday, June 3, 2015, Rui Ueyama <ruiu at google.com> wrote:
> >
> >> Author: ruiu
> >> Date: Wed Jun 3 21:12:16 2015
> >> New Revision: 239005
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=239005&view=rev
> >> Log:
> >> COFF: /include'd symbols must be preserved.
> >>
> >> Not only entry point symbol but also symbols specified by /include
> >> option must be preserved, as they will never be dead-stripped.
> >>
> >> http://reviews.llvm.org/D10220
> >>
> >> Modified:
> >> lld/trunk/COFF/Config.h
> >> lld/trunk/COFF/Driver.cpp
> >> lld/trunk/COFF/SymbolTable.cpp
> >> lld/trunk/COFF/Writer.cpp
> >> lld/trunk/COFF/Writer.h
> >> lld/trunk/test/COFF/lto.ll
> >>
> >> Modified: lld/trunk/COFF/Config.h
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Config.h?rev=239005&r1=239004&r2=239005&view=diff
> >>
> >> ==============================================================================
> >> --- lld/trunk/COFF/Config.h (original)
> >> +++ lld/trunk/COFF/Config.h Wed Jun 3 21:12:16 2015
> >> @@ -27,7 +27,10 @@ public:
> >> llvm::COFF::MachineTypes MachineType =
> >> llvm::COFF::IMAGE_FILE_MACHINE_AMD64;
> >> bool Verbose = false;
> >> WindowsSubsystem Subsystem = llvm::COFF::IMAGE_SUBSYSTEM_UNKNOWN;
> >> - std::string EntryName;
> >> + StringRef EntryName;
> >> +
> >> + // Symbols in this set are considered as live by the garbage collector.
> >> + std::set<StringRef> GCRoots;
> >>
> >> std::set<StringRef> NoDefaultLibs;
> >> bool NoDefaultLibAll = false;
> >>
> >> Modified: lld/trunk/COFF/Driver.cpp
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Driver.cpp?rev=239005&r1=239004&r2=239005&view=diff
> >>
> >> ==============================================================================
> >> --- lld/trunk/COFF/Driver.cpp (original)
> >> +++ lld/trunk/COFF/Driver.cpp Wed Jun 3 21:12:16 2015
> >> @@ -312,8 +312,11 @@ bool LinkerDriver::link(int Argc, const
> >>
> >> // Add undefined symbols given via the command line.
> >> // (/include is equivalent to Unix linker's -u option.)
> >> - for (auto *Arg : Args->filtered(OPT_incl))
> >> - Symtab.addUndefined(Arg->getValue());
> >> + for (auto *Arg : Args->filtered(OPT_incl)) {
> >> + StringRef Sym = Arg->getValue();
> >> + Symtab.addUndefined(Sym);
> >> + Config->GCRoots.insert(Sym);
> >> + }
> >>
> >> // Parse all input files and put all symbols to the symbol table.
> >> // The symbol table will take care of name resolution.
> >> @@ -362,11 +365,14 @@ bool LinkerDriver::link(int Argc, const
> >> }
> >> Config->EntryName = EntryOrErr.get();
> >> }
> >> + Config->GCRoots.insert(Config->EntryName);
> >>
> >> // Make sure we have resolved all symbols.
> >> if (Symtab.reportRemainingUndefines())
> >> return false;
> >>
> >> + // Do LTO by compiling bitcode input files to a native COFF file
> >> + // then link that file.
> >> if (auto EC = Symtab.addCombinedLTOObject()) {
> >> llvm::errs() << EC.message() << "\n";
> >> return false;
> >>
> >> Modified: lld/trunk/COFF/SymbolTable.cpp
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/SymbolTable.cpp?rev=239005&r1=239004&r2=239005&view=diff
> >>
> >> ==============================================================================
> >> --- lld/trunk/COFF/SymbolTable.cpp (original)
> >> +++ lld/trunk/COFF/SymbolTable.cpp Wed Jun 3 21:12:16 2015
> >> @@ -227,20 +227,17 @@ std::error_code SymbolTable::addCombined
> >> 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);
> >> + CG.addMustPreserveSymbol(S->getName());
> >>
> >> - // 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());
> >> + // Likewise for other symbols that must be preserved.
> >> + for (StringRef Name : Config->GCRoots)
> >> + if (isa<DefinedBitcode>(Symtab[Name]->Body))
> >> + CG.addMustPreserveSymbol(Name);
> >>
> >> CG.setModule(BitcodeFiles[0]->releaseModule());
> >> for (unsigned I = 1, E = BitcodeFiles.size(); I != E; ++I)
> >>
> >> Modified: lld/trunk/COFF/Writer.cpp
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.cpp?rev=239005&r1=239004&r2=239005&view=diff
> >>
> >> ==============================================================================
> >> --- lld/trunk/COFF/Writer.cpp (original)
> >> +++ lld/trunk/COFF/Writer.cpp Wed Jun 3 21:12:16 2015
> >> @@ -87,8 +87,8 @@ void OutputSection::writeHeader(uint8_t
> >> }
> >>
> >> void Writer::markLive() {
> >> - Entry = cast<Defined>(Symtab->find(Config->EntryName));
> >> - Entry->markLive();
> >> + for (StringRef Name : Config->GCRoots)
> >> + cast<Defined>(Symtab->find(Name))->markLive();
> >> for (Chunk *C : Symtab->getChunks())
> >> if (C->isRoot())
> >> C->markLive();
> >> @@ -291,6 +291,7 @@ void Writer::writeHeader() {
> >> PE->Subsystem = Config->Subsystem;
> >> PE->SizeOfImage = SizeOfImage;
> >> PE->SizeOfHeaders = SizeOfHeaders;
> >> + Defined *Entry = cast<Defined>(Symtab->find(Config->EntryName));
> >> PE->AddressOfEntryPoint = Entry->getRVA();
> >> PE->SizeOfStackReserve = Config->StackReserve;
> >> PE->SizeOfStackCommit = Config->StackCommit;
> >>
> >> Modified: lld/trunk/COFF/Writer.h
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.h?rev=239005&r1=239004&r2=239005&view=diff
> >>
> >> ==============================================================================
> >> --- lld/trunk/COFF/Writer.h (original)
> >> +++ lld/trunk/COFF/Writer.h Wed Jun 3 21:12:16 2015
> >> @@ -98,7 +98,6 @@ private:
> >> uint32_t ImportDirectoryTableSize = 0;
> >> uint32_t ImportAddressTableSize = 0;
> >>
> >> - Defined *Entry;
> >> uint64_t FileSize;
> >> uint64_t SizeOfImage;
> >> uint64_t SizeOfHeaders;
> >>
> >> Modified: lld/trunk/test/COFF/lto.ll
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/lto.ll?rev=239005&r1=239004&r2=239005&view=diff
> >>
> >> ==============================================================================
> >> --- lld/trunk/test/COFF/lto.ll (original)
> >> +++ lld/trunk/test/COFF/lto.ll Wed Jun 3 21:12:16 2015
> >> @@ -8,10 +8,10 @@
> >> ; 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: lld -flavor link2 /out:%T/main.exe /entry:main /include:f2
> >> /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: lld -flavor link2 /out:%T/main.exe /entry:main /include:f2
> >> /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
> >>
> >> @@ -34,6 +34,21 @@
> >> ; TEXT-11-NEXT: .text:
> >> ; TEXT-11-NEXT: xorl %eax, %eax
> >> ; TEXT-11-NEXT: retq
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: int3
> >> +; TEXT-11-NEXT: movl $2, %eax
> >> +; TEXT-11-NEXT: retq
> >>
> >> ; HEADERS-01: AddressOfEntryPoint: 0x1000
> >> ; TEXT-01: Disassembly of section .text:
> >> @@ -79,3 +94,13 @@ define i32 @main() {
> >> }
> >>
> >> declare void @foo()
> >> +
> >> +$f1 = comdat any
> >> +define i32 @f1() comdat($f1) {
> >> + ret i32 1
> >> +}
> >> +
> >> +$f2 = comdat any
> >> +define i32 @f2() comdat($f2) {
> >> + ret i32 2
> >> +}
> >>
> >>
> >> _______________________________________________
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> >> llvm-commits at cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >>
> >
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--
Peter
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