[llvm-commits] [lld] r172553 - in /lld/trunk: lib/ReaderWriter/ELF/ReaderELF.cpp test/elf/check.objtxt

[Nick Kledzik]

But you do want content for weak symbols that are C++ out-of-line copies.  
I thought it was just weak aliases that needed this (or at least the use of
weak aliases in the runtime sample you had).

-Nick

On Jan 15, 2013, at 1:13 PM, Michael J. Spencer wrote:
> Author: mspencer
> Date: Tue Jan 15 15:13:02 2013
> New Revision: 172553
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=172553&view=rev
> Log:
> [ELF] Never allocate content to weak symbols as they may be merged away.
> 
> This is done by creating a new non-weak anonymous symbol and creating
> an atom with content for that symbol. This is added after the weak symbol
> so that they have the same address.
> 
> Modified:
>    lld/trunk/lib/ReaderWriter/ELF/ReaderELF.cpp
>    lld/trunk/test/elf/check.objtxt
> 
> Modified: lld/trunk/lib/ReaderWriter/ELF/ReaderELF.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/ELF/ReaderELF.cpp?rev=172553&r1=172552&r2=172553&view=diff
> ==============================================================================
> --- lld/trunk/lib/ReaderWriter/ELF/ReaderELF.cpp (original)
> +++ lld/trunk/lib/ReaderWriter/ELF/ReaderELF.cpp Tue Jan 15 15:13:02 2013
> @@ -215,6 +215,22 @@
>                                    : (*(si + 1))->st_value - (*si)->st_value;
>         }
> 
> +
> +        // Don't allocate content to a weak symbol, as they may be merged away.
> +        // Create an anonymous atom to hold the data.
> +        ELFDefinedAtom<ELFT> *anonAtom = nullptr;
> +        if ((*si)->getBinding() == llvm::ELF::STB_WEAK && contentSize != 0) {
> +          // Create a new non-weak ELF symbol.
> +          auto sym = new (_readerStorage.Allocate<Elf_Sym>()) Elf_Sym;
> +          *sym = **si;
> +          sym->setBinding(llvm::ELF::STB_GLOBAL);
> +          anonAtom = createDefinedAtomAndAssignRelocations(
> +            "", sectionName, sym, i.first,
> +            ArrayRef<uint8_t>(
> +              (uint8_t *)sectionContents.data() + (*si)->st_value, contentSize));
> +          contentSize = 0;
> +        }
> +
>         ArrayRef<uint8_t> symbolData = ArrayRef<uint8_t>(
>           (uint8_t *)sectionContents.data() + (*si)->st_value, contentSize);
> 
> @@ -223,6 +239,8 @@
> 
>         _definedAtoms._atoms.push_back(newAtom);
>         _symbolToAtomMapping.insert(std::make_pair((*si), newAtom));
> +        if (anonAtom)
> +          _definedAtoms._atoms.push_back(anonAtom);
>       }
>     }
> 
> 
> Modified: lld/trunk/test/elf/check.objtxt
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf/check.objtxt?rev=172553&r1=172552&r2=172553&view=diff
> ==============================================================================
> --- lld/trunk/test/elf/check.objtxt (original)
> +++ lld/trunk/test/elf/check.objtxt Tue Jan 15 15:13:02 2013
> @@ -13,9 +13,9 @@
> 
> ELF-i386:    - name:              weak_func
> ELF-i386:      scope:             global
> -ELF-i386:      content:           [ 55, 89, E5, 83, EC, 18, C7, 04, 24, 0E, 00, 00, 
> -ELF-i386:                           00, E8, FC, FF, FF, FF, C9, C3 ]
> ELF-i386:      merge:             as-weak
> +ELF-i386:      content:           [ 55, 89, E5, 83, EC, 18, C7, 04, 24, 0E, 00, 00,
> +ELF-i386:                           00, E8, FC, FF, FF, FF, C9, C3 ]
> 
> ELF-i386:    - name:              hidden_func
> ELF-i386:      scope:             hidden
> @@ -65,9 +65,9 @@
> 
> ELF-hexagon:    - name:              weak_func
> ELF-hexagon:      scope:             global
> -ELF-hexagon:      content:           [ 00, C0, 9D, A0, 00, 40, 00, 00, 00, C0, 00, 78, 
> -ELF-hexagon:                           00, C0, 00, 5A, 1E, C0, 1E, 96 ]
> ELF-hexagon:      merge:             as-weak
> +ELF-hexagon:      content:           [ 00, C0, 9D, A0, 00, 40, 00, 00, 00, C0, 00, 78,
> +ELF-hexagon:                           00, C0, 00, 5A, 1E, C0, 1E, 96 ]
> 
> ELF-hexagon:    - name:              hidden_func
> ELF-hexagon:      scope:             hidden
> 
> 
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