[lld] r235357 - [GNU/ELF] Add support for -X/--discard-locals.
Aaron Ballman
aaron at aaronballman.com
Fri Apr 24 07:40:39 PDT 2015
This commit is still causing failures on Windows. Can you please fix or revert?
Thanks!
~Aaron
On Thu, Apr 23, 2015 at 11:11 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
> On Mon, Apr 20, 2015 at 6:52 PM, Davide Italiano <davide at freebsd.org> wrote:
>> Author: davide
>> Date: Mon Apr 20 17:52:56 2015
>> New Revision: 235357
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=235357&view=rev
>> Log:
>> [GNU/ELF] Add support for -X/--discard-locals.
>>
>> There's (almost) never need to keep .L symbols around for production
>> builds. In fact, the FreeBSD kernel explicitly specify -X beacuse the
>> size impact (and the subsequent performance impact) might be significant,
>> because we keep symbols in memory.
>> I was tempted to make this the default, but I haven't (yet).
>>
>> PR: 23232
>>
>> Added:
>> lld/trunk/test/elf/discard-locals.test
>> Modified:
>> lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h
>> lld/trunk/lib/Driver/GnuLdDriver.cpp
>> lld/trunk/lib/Driver/GnuLdOptions.td
>> lld/trunk/lib/ReaderWriter/ELF/SectionChunks.cpp
>>
>> Modified: lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h?rev=235357&r1=235356&r2=235357&view=diff
>> ==============================================================================
>> --- lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h (original)
>> +++ lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h Mon Apr 20 17:52:56 2015
>> @@ -314,6 +314,10 @@ public:
>> bool discardLocals() const { return _discardLocals; }
>> void setDiscardLocals(bool d) { _discardLocals = d; }
>>
>> + /// \brief Discard temprorary local symbols.
>> + bool discardTempLocals() const { return _discardTempLocals; }
>> + void setDiscardTempLocals(bool d) { _discardTempLocals = d; }
>> +
>> /// \brief Strip symbols.
>> bool stripSymbols() const { return _stripSymbols; }
>> void setStripSymbols(bool strip) { _stripSymbols = strip; }
>> @@ -370,6 +374,7 @@ protected:
>> bool _noAllowDynamicLibraries = false;
>> bool _mergeRODataToTextSegment = true;
>> bool _demangle = true;
>> + bool _discardTempLocals = false;
>> bool _discardLocals = false;
>> bool _stripSymbols = false;
>> bool _alignSegments = true;
>>
>> Modified: lld/trunk/lib/Driver/GnuLdDriver.cpp
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/Driver/GnuLdDriver.cpp?rev=235357&r1=235356&r2=235357&view=diff
>> ==============================================================================
>> --- lld/trunk/lib/Driver/GnuLdDriver.cpp (original)
>> +++ lld/trunk/lib/Driver/GnuLdDriver.cpp Mon Apr 20 17:52:56 2015
>> @@ -478,6 +478,9 @@ bool GnuLdDriver::parse(int argc, const
>> if (parsedArgs->hasArg(OPT_discard_loc))
>> ctx->setDiscardLocals(true);
>>
>> + if (parsedArgs->hasArg(OPT_discard_temp_loc))
>> + ctx->setDiscardTempLocals(true);
>> +
>> if (parsedArgs->hasArg(OPT_strip_all))
>> ctx->setStripSymbols(true);
>>
>>
>> Modified: lld/trunk/lib/Driver/GnuLdOptions.td
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/Driver/GnuLdOptions.td?rev=235357&r1=235356&r2=235357&view=diff
>> ==============================================================================
>> --- lld/trunk/lib/Driver/GnuLdOptions.td (original)
>> +++ lld/trunk/lib/Driver/GnuLdOptions.td Mon Apr 20 17:52:56 2015
>> @@ -260,6 +260,11 @@ def discard_loc : Flag<["--"], "discard-
>> Group<grp_symbolopts>;
>> def alias_discard_loc: Flag<["-"], "x">,
>> Alias<discard_loc>;
>> +def discard_temp_loc : Flag<["--"], "discard-locals">,
>> + HelpText<"Discard temporary local symbols">,
>> + Group<grp_symbolopts>;
>> +def alias_discard_temp_loc : Flag<["-"], "X">,
>> + Alias<discard_temp_loc>;
>> def no_demangle : Flag<["--"], "no-demangle">,
>> HelpText<"Dont demangle C++ symbols">,
>> Group<grp_symbolopts>;
>>
>> Modified: lld/trunk/lib/ReaderWriter/ELF/SectionChunks.cpp
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/ELF/SectionChunks.cpp?rev=235357&r1=235356&r2=235357&view=diff
>> ==============================================================================
>> --- lld/trunk/lib/ReaderWriter/ELF/SectionChunks.cpp (original)
>> +++ lld/trunk/lib/ReaderWriter/ELF/SectionChunks.cpp Mon Apr 20 17:52:56 2015
>> @@ -489,6 +489,11 @@ void SymbolTable<ELFT>::addSymbol(const
>> if (this->_ctx.discardLocals() && symbol.getBinding() == llvm::ELF::STB_LOCAL)
>> return;
>>
>> + // Temporary locals are all the symbols which name starts with .L.
>> + // This is defined by the ELF standard.
>> + if (this->_ctx.discardTempLocals() && atom->name().startswith(".L"))
>> + return;
>> +
>> _symbolTable.push_back(SymbolEntry(atom, symbol, atomLayout));
>> this->_fsize += sizeof(Elf_Sym);
>> if (this->_flags & SHF_ALLOC)
>>
>> Added: lld/trunk/test/elf/discard-locals.test
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf/discard-locals.test?rev=235357&view=auto
>> ==============================================================================
>> --- lld/trunk/test/elf/discard-locals.test (added)
>> +++ lld/trunk/test/elf/discard-locals.test Mon Apr 20 17:52:56 2015
>> @@ -0,0 +1,66 @@
>> +# Test that -X/--discard-locals works.
>> +#
>> +#RUN: yaml2obj -format=elf %s -o=%t.o
>> +#RUN: lld -flavor gnu %t.o -shared -X -o %t1
>> +#RUN: llvm-objdump -t %t1 | FileCheck %s
>> +
>> +#CHECK-NOT: 0000000000400121 l .rodata 00000000 .Lsym8
>> +
>> +---
>> +FileHeader:
>> + Class: ELFCLASS64
>> + Data: ELFDATA2LSB
>> + OSABI: ELFOSABI_FREEBSD
>> + Type: ET_REL
>> + Machine: EM_X86_64
>> +Sections:
>> + - Name: .text
>> + Type: SHT_PROGBITS
>> + Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
>> + AddressAlign: 0x0000000000000004
>> + Content: 00000000F20F100D00000000C3
>> + - Name: .data
>> + Type: SHT_PROGBITS
>> + Flags: [ SHF_WRITE, SHF_ALLOC ]
>> + AddressAlign: 0x0000000000000004
>> + Content: ''
>> + - Name: .bss
>> + Type: SHT_NOBITS
>> + Flags: [ SHF_WRITE, SHF_ALLOC ]
>> + AddressAlign: 0x0000000000000004
>> + Content: ''
>> + - Name: .rodata.str1.1
>> + Type: SHT_PROGBITS
>> + Flags: [ SHF_ALLOC, SHF_MERGE, SHF_STRINGS ]
>> + AddressAlign: 0x0000000000000001
>> + Content: ''
>> + - Name: .rela.text
>> + Type: SHT_RELA
>> + Link: .symtab
>> + AddressAlign: 0x0000000000000008
>> + Info: .text
>> + Relocations:
>> + - Offset: 0x0000000000000008
>> + Symbol: .Lsym8
>> + Type: R_X86_64_PC32
>> + Addend: -4
>> +Symbols:
>> + Local:
>> + - Name: .Lsym8
>> + Section: .rodata.str1.1
>> + - Name: test
>> + Section: .text
>> + Value: 0x000000000000000C
>> + - Name: .text
>> + Type: STT_SECTION
>> + Section: .text
>> + - Name: .data
>> + Type: STT_SECTION
>> + Section: .data
>> + - Name: .bss
>> + Type: STT_SECTION
>> + Section: .bss
>> + - Name: .rodata.str1.1
>> + Type: STT_SECTION
>> + Section: .rodata.str1.1
>> +...
>
> This test is failing for me on Windows, with:
>
>>lit E:\llvm\llvm\tools\lld\test\elf\discard-locals.test
> -- Testing: 1 tests, 1 threads --
> FAIL: lld :: elf/discard-locals.test (1 of 1)
> ******************** TEST 'lld :: elf/discard-locals.test' FAILED
> ********************
> Script:
> --
> yaml2obj -format=elf
> E:\llvm\llvm\tools\lld\test\elf\discard-locals.test
> -o=E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp.o
> lld -flavor gnu
> E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp.o
> -shared -X -o E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp1
> llvm-objdump -t
> E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp1 |
> FileCheck E:\llvm\llvm\tools\lld\test\elf\discard-locals.test
> --
> Exit Code: 1
>
> Command Output (stdout):
> --
> Command 0: "yaml2obj" "-format=elf"
> "E:\llvm\llvm\tools\lld\test\elf\discard-locals.test"
> "-o=E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp.o"
> Command 0 Result: 0
> Command 0 Output:
>
>
> Command 0 Stderr:
>
>
> Command 1: "lld" "-flavor" "gnu"
> "E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp.o"
> "-shared" "-X" "-o"
> "E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp1"
> Command 1 Result: 1
> Command 1 Output:
>
>
> Command 1 Stderr:
> Cannot open E:\llvm\2013\tools\lld\test\elf\Output\discard-locals.test.tmp.o:
> incompatible machine type
>
>
>
>
> --
>
> ********************
> Testing Time: 0.04s
> ********************
> Failing Tests (1):
> lld :: elf/discard-locals.test
>
> Unexpected Failures: 1
>
> ~Aaron
>
>>
>>
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