build/build-clang/llvmorg-15-init-16512-g4b1e3d193706.patch

   1 From 8482662676a4b6ef79a718c8c09943cb15241664 Mon Sep 17 00:00:00 2001
   2 From: Tom Stellard <tstellar@redhat.com>
   3 Date: Tue, 21 Jun 2022 22:22:11 -0700
   4 Subject: [PATCH] [gold] Ignore bitcode from sections inside object files
   5
   6 -fembed-bitcode will put bitcode into special sections within object
   7 files, but this is not meant to be used by LTO, so the gold plugin
   8 should ignore it.
   9
  10 https://github.com/llvm/llvm-project/issues/47216
  11
  12 Reviewed By: tejohnson, MaskRay
  13
  14 Differential Revision: https://reviews.llvm.org/D116995
  15 ---
  16  llvm/docs/BitCodeFormat.rst                   |  3 ++-
  17  llvm/docs/GoldPlugin.rst                      |  4 ++++
  18  .../tools/gold/X86/Inputs/bcsection-lib.ll    |  6 +++++
  19  llvm/test/tools/gold/X86/Inputs/bcsection.s   |  5 ++++
  20  llvm/test/tools/gold/X86/bcsection.ll         | 23 +++++++++++++++----
  21  llvm/tools/gold/gold-plugin.cpp               |  8 +++++++
  22  6 files changed, 43 insertions(+), 6 deletions(-)
  23  create mode 100644 llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
  24
  25 diff --git a/llvm/docs/BitCodeFormat.rst b/llvm/docs/BitCodeFormat.rst
  26 index 8e81a7daa459..df1f6915d7d5 100644
  27 --- a/llvm/docs/BitCodeFormat.rst
  28 +++ b/llvm/docs/BitCodeFormat.rst
  29 @@ -475,7 +475,8 @@ formats.  This wrapper format is useful for accommodating LTO in compilation
  30  pipelines where intermediate objects must be native object files which contain
  31  metadata in other sections.
  32
  33 -Not all tools support this format.
  34 +Not all tools support this format.  For example, lld and the gold plugin will
  35 +ignore these sections when linking object files.
  36
  37  .. _encoding of LLVM IR:
  38
  39 diff --git a/llvm/docs/GoldPlugin.rst b/llvm/docs/GoldPlugin.rst
  40 index ce310bc2cf3c..07d2fc203eba 100644
  41 --- a/llvm/docs/GoldPlugin.rst
  42 +++ b/llvm/docs/GoldPlugin.rst
  43 @@ -17,6 +17,10 @@ and above also supports LTO via plugins.  However, usage of the LLVM
  44  gold plugin with ld.bfd is not tested and therefore not officially
  45  supported or recommended.
  46
  47 +As of LLVM 15, the gold plugin will ignore bitcode from the ``.llvmbc``
  48 +section inside of ELF object files.  However, LTO with bitcode files
  49 +is still supported.
  50 +
  51  .. _`gold linker`: http://sourceware.org/binutils
  52  .. _`GCC LTO`: http://gcc.gnu.org/wiki/LinkTimeOptimization
  53  .. _`gold plugin interface`: http://gcc.gnu.org/wiki/whopr/driver
  54 diff --git a/llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll b/llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
  55 new file mode 100644
  56 index 000000000000..ef3557c19cdc
  57 --- /dev/null
  58 +++ b/llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
  59 @@ -0,0 +1,6 @@
  60 +declare void @elf_func()
  61 +
  62 +define i32 @lib_func() {
  63 +  call void @elf_func()
  64 +  ret i32 0
  65 +}
  66 diff --git a/llvm/test/tools/gold/X86/Inputs/bcsection.s b/llvm/test/tools/gold/X86/Inputs/bcsection.s
  67 index ede1e5c532dd..c523612563b4 100644
  68 --- a/llvm/test/tools/gold/X86/Inputs/bcsection.s
  69 +++ b/llvm/test/tools/gold/X86/Inputs/bcsection.s
  70 @@ -1,2 +1,7 @@
  71 +.global elf_func
  72 +
  73 +elf_func:
  74 +   ret
  75 +
  76  .section .llvmbc
  77  .incbin "bcsection.bc"
  78 diff --git a/llvm/test/tools/gold/X86/bcsection.ll b/llvm/test/tools/gold/X86/bcsection.ll
  79 index 6d3481f8f966..09882d83fe91 100644
  80 --- a/llvm/test/tools/gold/X86/bcsection.ll
  81 +++ b/llvm/test/tools/gold/X86/bcsection.ll
  82 @@ -2,16 +2,29 @@
  83  ; RUN: llvm-as -o %t/bcsection.bc %s
  84
  85  ; RUN: llvm-mc -I=%t -filetype=obj -triple=x86_64-unknown-unknown -o %t/bcsection.bco %p/Inputs/bcsection.s
  86 -; RUN: llvm-nm --no-llvm-bc %t/bcsection.bco 2>&1 | FileCheck %s -check-prefix=NO-SYMBOLS
  87 -; NO-SYMBOLS: no symbols
  88 +; RUN: llc -filetype=obj -mtriple=x86_64-unknown-unknown -o %t/bcsection-lib.o %p/Inputs/bcsection-lib.ll
  89
  90 -; RUN: %gold -r -o %t/bcsection.o -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext %t/bcsection.bco
  91 -; RUN: llvm-nm --no-llvm-bc %t/bcsection.o | FileCheck %s
  92 +; RUN: %gold -shared --no-undefined -o %t/bcsection.so -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext %t/bcsection.bco %t/bcsection-lib.o
  93 +
  94 +; This test checks that the gold plugin does not attempt to use the bitcode
  95 +; in the .llvmbc section for LTO.  bcsection-lib.o calls a function that is
  96 +; present the symbol table of bcsection.bco, but not included in the embedded
  97 +; bitcode.  If the linker were to use the bitcode, then the symbols in the
  98 +; symbol table of bcsection.bco will be ignored and the link will fail.
  99 +;
 100 +; bcsection.bco:
 101 +;  .text:
 102 +;    elf_func
 103 +;  .llvmbc:
 104 +;    bitcode_func
 105 +;
 106 +; bcsection-lib.o:
 107 +;   calls elf_func()
 108
 109  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 110  target triple = "x86_64-unknown-unknown"
 111
 112  ; CHECK: main
 113 -define i32 @main() {
 114 +define i32 @bitcode_func() {
 115    ret i32 0
 116  }
 117 diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
 118 index 180c181368e3..294c7a3d6178 100644
 119 --- a/llvm/tools/gold/gold-plugin.cpp
 120 +++ b/llvm/tools/gold/gold-plugin.cpp
 121 @@ -540,6 +540,14 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
 122      BufferRef = Buffer->getMemBufferRef();
 123    }
 124
 125 +  // Only use bitcode files for LTO.  InputFile::create() will load bitcode
 126 +  // from the .llvmbc section within a binary object, this bitcode is typically
 127 +  // generated by -fembed-bitcode and is not to be used by LLVMgold.so for LTO.
 128 +  if (identify_magic(BufferRef.getBuffer()) != file_magic::bitcode) {
 129 +    *claimed = 0;
 130 +    return LDPS_OK;
 131 +  }
 132 +
 133    *claimed = 1;
 134
 135    Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
 136 --
 137 2.37.1.1.g659da70093
 138