[lld] r301282 - Export __progname even if a -dynamic-list is given.

[Galina Kistanova via llvm-commits]

Hello Rui,

This commit broke test on one of our builders:

http://lab.llvm.org:8011/builders/lld-x86_64-win7/builds/7606

Failing Tests (1):
    lld :: ELF/progname.s

Please have a look at this?

Thanks

Galina

On Mon, Apr 24, 2017 at 5:15 PM, Rui Ueyama via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: ruiu
> Date: Mon Apr 24 19:15:48 2017
> New Revision: 301282
>
> URL: http://llvm.org/viewvc/llvm-project?rev=301282&view=rev
> Log:
> Export __progname even if a -dynamic-list is given.
>
> BSD's __progname symbol is defined in crt1.o and linked against main
> executables. The libc expects that main executables export __progname
> symbol via .dynsym sections. In order to handle this case, we scan
> undefined symbols in DSOs and exported them by setting Sym->ExportDynamic
> to true.
>
> But it turned out that setting that variable is not enough to make sure
> that symbols are exported in all use cases. If a -dynamic-list option is
> given, all symbols not explicitly mentioned in a version script are
> hidden by default. That hides __progname symbol. This patch fixes the
> issue.
>
> Fixes https://bugs.llvm.org/show_bug.cgi?id=32703
>
> Modified:
>     lld/trunk/ELF/SymbolTable.cpp
>     lld/trunk/test/ELF/progname.s
>
> Modified: lld/trunk/ELF/SymbolTable.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/
> SymbolTable.cpp?rev=301282&r1=301281&r2=301282&view=diff
> ============================================================
> ==================
> --- lld/trunk/ELF/SymbolTable.cpp (original)
> +++ lld/trunk/ELF/SymbolTable.cpp Mon Apr 24 19:15:48 2017
> @@ -548,11 +548,20 @@ template <class ELFT> void SymbolTable<E
>  // shared libraries can find them.
>  // Except this, we ignore undefined symbols in DSOs.
>  template <class ELFT> void SymbolTable<ELFT>::scanShlibUndefined() {
> -  for (SharedFile<ELFT> *File : SharedFiles)
> -    for (StringRef U : File->getUndefinedSymbols())
> -      if (SymbolBody *Sym = find(U))
> -        if (Sym->isDefined())
> -          Sym->symbol()->ExportDynamic = true;
> +  for (SharedFile<ELFT> *File : SharedFiles) {
> +    for (StringRef U : File->getUndefinedSymbols()) {
> +      SymbolBody *Sym = find(U);
> +      if (!Sym || !Sym->isDefined())
> +        continue;
> +      Sym->symbol()->ExportDynamic = true;
> +
> +      // If -dynamic-list is given, the default version is set to
> +      // VER_NDX_LOCAL, which prevents a symbol to be exported via
> .dynsym.
> +      // Set to VER_NDX_GLOBAL so the symbol will be handled as if it were
> +      // specified by -dynamic-list.
> +      Sym->symbol()->VersionId = VER_NDX_GLOBAL;
> +    }
> +  }
>  }
>
>  // Initialize DemangledSyms with a map from demangled symbols to symbol
>
> Modified: lld/trunk/test/ELF/progname.s
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/
> progname.s?rev=301282&r1=301281&r2=301282&view=diff
> ============================================================
> ==================
> --- lld/trunk/test/ELF/progname.s (original)
> +++ lld/trunk/test/ELF/progname.s Mon Apr 24 19:15:48 2017
> @@ -12,6 +12,10 @@
>  // RUN: ld.lld -o %t %t.o %t.so
>  // RUN: llvm-readobj -dyn-symbols %t | FileCheck %s
>
> +// RUN: echo "{_start;};" > %t.dynlist
> +// RUN: ld.lld -dynamic-list %t.dynlist -o %t %t.o %t.so
> +// RUN: llvm-readobj -dyn-symbols %t | FileCheck %s
> +
>  // CHECK:      Name:     __progname@
>  // CHECK-NEXT: Value:    0x201000
>  // CHECK-NEXT: Size:     0
>
>
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