[llvm] r203082 - DebugInfo: Tag units as having been indexed in GNU pubnames by using a DW_AT_GNU_pubnames of DW_FORM_flag(_present) rather than sec_offsets to the pubnames/types sections

[Eric Christopher]

Cool.

Thanks! :)

-eric

On Wed, Mar 5, 2014 at 9:47 PM, David Blaikie <dblaikie at gmail.com> wrote:
> Author: dblaikie
> Date: Wed Mar  5 23:47:39 2014
> New Revision: 203082
>
> URL: http://llvm.org/viewvc/llvm-project?rev=203082&view=rev
> Log:
> DebugInfo: Tag units as having been indexed in GNU pubnames by using a DW_AT_GNU_pubnames of DW_FORM_flag(_present) rather than sec_offsets to the pubnames/types sections
>
> This is consistent with GDB ToT and reduces the number of relocations in
> (type and compile) units, substantially reducing relocations and debug
> size in fission + type units builds.
>
> Modified:
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>     llvm/trunk/test/DebugInfo/X86/gnu-public-names-empty.ll
>     llvm/trunk/test/DebugInfo/X86/gnu-public-names.ll
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=203082&r1=203081&r2=203082&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Mar  5 23:47:39 2014
> @@ -733,13 +733,7 @@ void DwarfDebug::addGnuPubAttributes(Dwa
>    if (!GenerateGnuPubSections)
>      return;
>
> -  addSectionLabel(Asm, U, D, dwarf::DW_AT_GNU_pubnames,
> -                  Asm->GetTempSymbol("gnu_pubnames", U->getUniqueID()),
> -                  DwarfGnuPubNamesSectionSym);
> -
> -  addSectionLabel(Asm, U, D, dwarf::DW_AT_GNU_pubtypes,
> -                  Asm->GetTempSymbol("gnu_pubtypes", U->getUniqueID()),
> -                  DwarfGnuPubTypesSectionSym);
> +  U->addFlag(D, dwarf::DW_AT_GNU_pubnames);
>  }
>
>  // Create new DwarfCompileUnit for the given metadata node with tag
>
> Modified: llvm/trunk/test/DebugInfo/X86/gnu-public-names-empty.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/gnu-public-names-empty.ll?rev=203082&r1=203081&r2=203082&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/gnu-public-names-empty.ll (original)
> +++ llvm/trunk/test/DebugInfo/X86/gnu-public-names-empty.ll Wed Mar  5 23:47:39 2014
> @@ -6,8 +6,8 @@
>
>  ; Check that the attributes in the compile unit both point to a correct
>  ; location, even when nothing is exported.
> -; CHECK: DW_AT_GNU_pubnames [DW_FORM_sec_offset]   (0x00000000)
> -; CHECK: DW_AT_GNU_pubtypes [DW_FORM_sec_offset]   (0x00000000)
> +; CHECK: DW_AT_GNU_pubnames [DW_FORM_flag_present]   (true)
> +; CHECK-NOT: DW_AT_GNU_pubtypes [
>
>  !llvm.dbg.cu = !{!0}
>  !llvm.module.flags = !{!3, !4}
>
> Modified: llvm/trunk/test/DebugInfo/X86/gnu-public-names.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/gnu-public-names.ll?rev=203082&r1=203081&r2=203082&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/gnu-public-names.ll (original)
> +++ llvm/trunk/test/DebugInfo/X86/gnu-public-names.ll Wed Mar  5 23:47:39 2014
> @@ -47,8 +47,8 @@
>
>  ; CHECK: .debug_info contents:
>  ; CHECK: Compile Unit: length = [[UNIT_SIZE:[0-9a-f]+]]
> -; CHECK: DW_AT_GNU_pubnames [DW_FORM_sec_offset]   (0x00000000)
> -; CHECK: DW_AT_GNU_pubtypes [DW_FORM_sec_offset]   (0x00000000)
> +; CHECK: DW_AT_GNU_pubnames [DW_FORM_flag_present]   (true)
> +; CHECK-NOT: DW_AT_GNU_pubtypes [
>
>  ; CHECK: [[C:[0-9a-f]+]]: DW_TAG_structure_type
>  ; CHECK-NEXT: DW_AT_name {{.*}} "C"
> @@ -127,8 +127,8 @@
>
>  ; DWARF3: .debug_info contents:
>  ; DWARF3: Compile Unit: length = [[UNIT_SIZE:[0-9a-f]+]]
> -; DWARF3: DW_AT_GNU_pubnames [DW_FORM_data4]   (0x00000000)
> -; DWARF3: DW_AT_GNU_pubtypes [DW_FORM_data4]   (0x00000000)
> +; DWARF3: DW_AT_GNU_pubnames [DW_FORM_flag]   (0x01)
> +; DWARF3-NOT: DW_AT_GNU_pubtypes [
>
>  ; DWARF3: [[C:[0-9a-f]+]]: DW_TAG_structure_type
>  ; DWARF3-NEXT: DW_AT_name {{.*}} "C"
>
>
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