[llvm] b497665 - Reland D64327 [MC][ELF] Allow STT_SECTION referencing SHF_MERGE on REL targets
Vitaly Buka via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 5 04:04:42 PDT 2020
It fails CFI tests
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/28828
On Sun, 2 Aug 2020 at 18:06, Fangrui Song via llvm-commits <
llvm-commits at lists.llvm.org> wrote:
>
> Author: Fangrui Song
> Date: 2020-08-02T18:05:17-07:00
> New Revision: b497665d98ad5026b1d3d67d5793a28fefe27bea
>
> URL:
> https://github.com/llvm/llvm-project/commit/b497665d98ad5026b1d3d67d5793a28fefe27bea
> DIFF:
> https://github.com/llvm/llvm-project/commit/b497665d98ad5026b1d3d67d5793a28fefe27bea.diff
>
> LOG: Reland D64327 [MC][ELF] Allow STT_SECTION referencing SHF_MERGE on
> REL targets
>
> This drops a GNU gold workaround and reverts the revert commit rL366708.
>
> Before binutils 2.34, gold -O2 and above did not correctly handle
> R_386_GOTOFF to
> SHF_MERGE|SHF_STRINGS sections:
> https://sourceware.org/bugzilla/show_bug.cgi?id=16794
>
> >From the original review:
>
> ... it reduced the size of a big ARM-32 debug image by 33%. It contained
> ~68M
> of relocations symbols out of total ~71M symbols (96% of symbols table
> was
> generated for relocations with symbol).
>
> -Wl,-O2 (and -Wl,-O3) is so rare that we should just lower the
> optimization level for LLVM_LINKER_IS_GOLD rather than pessimizing all
> users.
>
> Added:
>
>
> Modified:
> llvm/cmake/modules/AddLLVM.cmake
> llvm/lib/MC/ELFObjectWriter.cpp
> llvm/test/MC/ELF/basic-elf-32.s
> llvm/test/MC/ELF/compression.s
> llvm/test/MC/ELF/relocation-386.s
> llvm/test/MC/Mips/elf-relsym.s
> llvm/test/MC/Mips/xgot.s
>
> Removed:
>
>
>
>
> ################################################################################
> diff --git a/llvm/cmake/modules/AddLLVM.cmake
> b/llvm/cmake/modules/AddLLVM.cmake
> index 333167bfb6b0..a25f3e87af61 100644
> --- a/llvm/cmake/modules/AddLLVM.cmake
> +++ b/llvm/cmake/modules/AddLLVM.cmake
> @@ -222,8 +222,13 @@ function(add_link_opts target_name)
> # Pass -O3 to the linker. This enabled
> diff erent optimizations on
> diff erent
> # linkers.
> if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin|SunOS|AIX" OR WIN32))
> - set_property(TARGET ${target_name} APPEND_STRING PROPERTY
> - LINK_FLAGS " -Wl,-O3")
> + # Before binutils 2.34, gold -O2 and above did not correctly handle
> R_386_GOTOFF to
> + # SHF_MERGE|SHF_STRINGS sections:
> https://sourceware.org/bugzilla/show_bug.cgi?id=16794
> + if(LLVM_LINKER_IS_GOLD)
> + set_property(TARGET ${target_name} APPEND_STRING PROPERTY
> LINK_FLAGS " -Wl,-O1")
> + else()
> + set_property(TARGET ${target_name} APPEND_STRING PROPERTY
> LINK_FLAGS " -Wl,-O3")
> + endif()
> endif()
>
> if(LLVM_LINKER_IS_GOLD)
>
> diff --git a/llvm/lib/MC/ELFObjectWriter.cpp
> b/llvm/lib/MC/ELFObjectWriter.cpp
> index 1ca9d0fe1e18..5a5692c0cb63 100644
> --- a/llvm/lib/MC/ELFObjectWriter.cpp
> +++ b/llvm/lib/MC/ELFObjectWriter.cpp
> @@ -1389,11 +1389,6 @@ bool
> ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm,
> if (Flags & ELF::SHF_MERGE) {
> if (C != 0)
> return true;
> -
> - // It looks like gold has a bug (http://sourceware.org/PR16794)
> and can
> - // only handle section relocations to mergeable sections if using
> RELA.
> - if (!hasRelocationAddend())
> - return true;
> }
>
> // Most TLS relocations use a got, so they need the symbol. Even
> those that
>
> diff --git a/llvm/test/MC/ELF/basic-elf-32.s
> b/llvm/test/MC/ELF/basic-elf-32.s
> index effc363d1c6c..1a923106036a 100644
> --- a/llvm/test/MC/ELF/basic-elf-32.s
> +++ b/llvm/test/MC/ELF/basic-elf-32.s
> @@ -46,9 +46,9 @@ main: # @main
>
> // CHECK: Relocations [
> // CHECK: Section {{.*}} .rel.text {
> -// CHECK: 0x6 R_386_32 .L.str1
> +// CHECK: 0x6 R_386_32 .rodata.str1.1 0x0
> // CHECK: 0xB R_386_PC32 puts
> -// CHECK: 0x12 R_386_32 .L.str2
> +// CHECK: 0x12 R_386_32 .rodata.str1.1 0x0
> // CHECK: 0x17 R_386_PC32 puts
> // CHECK: }
> // CHECK: ]
>
> diff --git a/llvm/test/MC/ELF/compression.s
> b/llvm/test/MC/ELF/compression.s
> index 93a77b3fcbdb..9bc5c0ecc699 100644
> --- a/llvm/test/MC/ELF/compression.s
> +++ b/llvm/test/MC/ELF/compression.s
> @@ -38,7 +38,7 @@
>
> // In x86 32 bit named symbols are used for temporary symbols in merge
> // sections, so make sure we handle symbols inside compressed sections
> -// 386-SYMBOLS-GNU: Name: .Linfo_string0
> +// 386-SYMBOLS-GNU: Name: .zdebug_str
> // 386-SYMBOLS-GNU-NOT: }
> // 386-SYMBOLS-GNU: Section: .zdebug_str
>
> @@ -73,7 +73,7 @@
> // ZLIB-STYLE-FLAGS32-NEXT: AddressAlignment: 4
> // ZLIB-STYLE-FLAGS64-NEXT: AddressAlignment: 8
>
> -// 386-SYMBOLS-ZLIB: Name: .Linfo_string0
> +// 386-SYMBOLS-ZLIB: Name: .debug_str
> // 386-SYMBOLS-ZLIB-NOT: }
> // 386-SYMBOLS-ZLIB: Section: .debug_str
>
>
> diff --git a/llvm/test/MC/ELF/relocation-386.s
> b/llvm/test/MC/ELF/relocation-386.s
> index 4273750a4192..b9bf9b6a00c1 100644
> --- a/llvm/test/MC/ELF/relocation-386.s
> +++ b/llvm/test/MC/ELF/relocation-386.s
> @@ -8,7 +8,7 @@
> // I386: Format: elf32-i386
> // CHECK: Relocations [
> // CHECK-NEXT: Section {{.*}} .rel.text {
> -// CHECK-NEXT: 0x2 R_386_GOTOFF .Lfoo 0x0
> +// CHECK-NEXT: 0x2 R_386_GOTOFF .rodata.str1.16 0x0
> // CHECK-NEXT: 0x{{[^ ]+}} R_386_PLT32 bar2 0x0
> // CHECK-NEXT: 0x{{[^ ]+}} R_386_GOTPC _GLOBAL_OFFSET_TABLE_ 0x0
> // Relocation 3 (bar3 at GOTOFF) is done with symbol 7 (bss)
>
> diff --git a/llvm/test/MC/Mips/elf-relsym.s
> b/llvm/test/MC/Mips/elf-relsym.s
> index b8c2f89e82e6..d19b4e3c4820 100644
> --- a/llvm/test/MC/Mips/elf-relsym.s
> +++ b/llvm/test/MC/Mips/elf-relsym.s
> @@ -4,16 +4,10 @@
>
> // CHECK: Symbols [
> // CHECK: Symbol {
> -// CHECK: Name: $.str
> +// CHECK: Name: .rodata.cst8
> // CHECK: }
> // CHECK: Symbol {
> -// CHECK: Name: $.str1
> -// CHECK: }
> -// CHECK: Symbol {
> -// CHECK: Name: $CPI0_0
> -// CHECK: }
> -// CHECK: Symbol {
> -// CHECK: Name: $CPI0_1
> +// CHECK: Name: .rodata.str1.1
> // CHECK: }
> // CHECK: ]
>
>
> diff --git a/llvm/test/MC/Mips/xgot.s b/llvm/test/MC/Mips/xgot.s
> index 100d25e67223..76490f0dec93 100644
> --- a/llvm/test/MC/Mips/xgot.s
> +++ b/llvm/test/MC/Mips/xgot.s
> @@ -10,8 +10,8 @@
> // CHECK: 0x1C R_MIPS_GOT_LO16 ext_1
> // CHECK: 0x24 R_MIPS_CALL_HI16 printf
> // CHECK: 0x30 R_MIPS_CALL_LO16 printf
> -// CHECK: 0x2C R_MIPS_GOT16 $.str
> -// CHECK: 0x38 R_MIPS_LO16 $.str
> +// CHECK: 0x2C R_MIPS_GOT16 .rodata.str1.1 0x0
> +// CHECK: 0x38 R_MIPS_LO16 .rodata.str1.1 0x0
> // CHECK: ]
>
> .text
>
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200805/1aa39480/attachment.html>
More information about the llvm-commits
mailing list