[lld] r325316 - Fix an issue that weak bit is dropped when there's a lazy object symbol.

[Rafael Avila de Espindola via llvm-commits]

Thanks!

It is easy to forget to update the --start-lib case when the .a handling
changes. I wonder if they could share more code.

Thanks,
Rafael

Rui Ueyama via llvm-commits <llvm-commits at lists.llvm.org> writes:

> Author: ruiu
> Date: Thu Feb 15 20:27:46 2018
> New Revision: 325316
>
> URL: http://llvm.org/viewvc/llvm-project?rev=325316&view=rev
> Log:
> Fix an issue that weak bit is dropped when there's a lazy object symbol.
>
> Previously, we accidentally dropped STB_WEAK bit from an undefined symbol
> if there is a lazy object symbol with the same name. That caused a
> compatibility issue with GNU gold.
>
> Added:
>     lld/trunk/test/ELF/weak-undef-lib.s
> Modified:
>     lld/trunk/ELF/SymbolTable.cpp
>
> Modified: lld/trunk/ELF/SymbolTable.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=325316&r1=325315&r2=325316&view=diff
> ==============================================================================
> --- lld/trunk/ELF/SymbolTable.cpp (original)
> +++ lld/trunk/ELF/SymbolTable.cpp Thu Feb 15 20:27:46 2018
> @@ -568,9 +568,12 @@ void SymbolTable::addLazyObject(StringRe
>      return;
>  
>    // See comment for addLazyArchive above.
> -  if (S->isWeak())
> +  if (S->isWeak()) {
>      replaceSymbol<LazyObject>(S, Obj, Name, S->Type);
> -  else if (InputFile *F = Obj.fetch())
> +    S->Binding = STB_WEAK;
> +    return;
> +  }
> +  if (InputFile *F = Obj.fetch())
>      addFile<ELFT>(F);
>  }
>  
>
> Added: lld/trunk/test/ELF/weak-undef-lib.s
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/weak-undef-lib.s?rev=325316&view=auto
> ==============================================================================
> --- lld/trunk/test/ELF/weak-undef-lib.s (added)
> +++ lld/trunk/test/ELF/weak-undef-lib.s Thu Feb 15 20:27:46 2018
> @@ -0,0 +1,19 @@
> +# REQUIRES: x86
> +# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t1.o
> +# RUN: echo -e '.globl foo\nfoo: ret' | \
> +# RUN:   llvm-mc -filetype=obj -triple=x86_64-pc-linux - -o %t2.o
> +
> +# RUN: ld.lld -shared -o %t.so %t1.o --start-lib %t2.o
> +# RUN: llvm-readobj -dyn-symbols %t.so | FileCheck %s
> +
> +# CHECK:      Name: foo
> +# CHECK-NEXT: Value: 0x0
> +# CHECK-NEXT: Size: 0
> +# CHECK-NEXT: Binding: Weak
> +# CHECK-NEXT: Type: None
> +# CHECK-NEXT: Other: 0
> +# CHECK-NEXT: Section: Undefined
> +
> +.weak foo
> +.data
> +.quad foo
>
>
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