[PATCH] D116995: [gold] Ignore bitcode from sections inside object files

[Tom Stellard via Phabricator via llvm-commits]

tstellar updated this revision to Diff 399097.
tstellar added a comment.

Add test case.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D116995/new/

https://reviews.llvm.org/D116995

Files:
  llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
  llvm/test/tools/gold/X86/Inputs/bcsection.s
  llvm/test/tools/gold/X86/bcsection.ll
  llvm/tools/gold/gold-plugin.cpp


Index: llvm/tools/gold/gold-plugin.cpp
===================================================================
--- llvm/tools/gold/gold-plugin.cpp
+++ llvm/tools/gold/gold-plugin.cpp
@@ -540,6 +540,14 @@
     BufferRef = Buffer->getMemBufferRef();
   }
 
+  // Only use bitcode files for LTO.  InputFile::create() will load bitcode
+  // from special sections within a binary object, this bitcode is typically
+  // generated by -fembed-bitcode and is not meant for LTO use.
+  if (identify_magic(BufferRef.getBuffer()) != file_magic::bitcode) {
+    *claimed = 0;
+    return LDPS_OK;
+  }
+
   *claimed = 1;
 
   Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
Index: llvm/test/tools/gold/X86/bcsection.ll
===================================================================
--- llvm/test/tools/gold/X86/bcsection.ll
+++ llvm/test/tools/gold/X86/bcsection.ll
@@ -2,16 +2,29 @@
 ; RUN: llvm-as -o %t/bcsection.bc %s
 
 ; RUN: llvm-mc -I=%t -filetype=obj -triple=x86_64-unknown-unknown -o %t/bcsection.bco %p/Inputs/bcsection.s
-; RUN: llvm-nm --no-llvm-bc %t/bcsection.bco 2>&1 | FileCheck %s -check-prefix=NO-SYMBOLS
-; NO-SYMBOLS: no symbols
+; RUN: llc -filetype=obj -mtriple=x86_64-unknown-unknown -o %t/bcsection-lib.o %p/Inputs/bcsection-lib.ll
 
-; RUN: %gold -r -o %t/bcsection.o -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext %t/bcsection.bco
-; RUN: llvm-nm --no-llvm-bc %t/bcsection.o | FileCheck %s
+; RUN: %gold -shared --no-undefined -o %t/bcsection.so -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext %t/bcsection.bco %t/bcsection-lib.o
+
+; This test checks that the gold plugin does not attempt to use the bitcode
+; in the .llvmbc section for LTO.  bcsection-lib.o calls a function that is
+; present the symbol table of bcsection.bco, but not included in the embedded
+; bitcode.  If the linker were to use the bitcode, then the symbols in the
+; symbol table of bcsection.bco will be ignored and the link will fail.
+;
+; bcsection.bco:
+;  .text:
+;    elf_func
+;  .llvmbc:
+;    bitcode_func
+;
+; bcsection-lib.o:
+;   calls elf_func()
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-unknown"
 
 ; CHECK: main
-define i32 @main() {
+define i32 @bitcode_func() {
   ret i32 0
 }
Index: llvm/test/tools/gold/X86/Inputs/bcsection.s
===================================================================
--- llvm/test/tools/gold/X86/Inputs/bcsection.s
+++ llvm/test/tools/gold/X86/Inputs/bcsection.s
@@ -1,2 +1,7 @@
+.global elf_func
+
+elf_func:
+   ret
+
 .section .llvmbc
 .incbin "bcsection.bc"
Index: llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
===================================================================
--- /dev/null
+++ llvm/test/tools/gold/X86/Inputs/bcsection-lib.ll
@@ -0,0 +1,6 @@
+declare void @elf_func()
+
+define i32 @lib_func() {
+  call void @elf_func()
+  ret i32 0
+}


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