[libunwind] r292723 - X86: swap EBP, ESP on !APPLE

[Saleem Abdulrasool via cfe-commits]

I think that this is safe enough and does make libunwind work on x86 Linux,
so lets go for it.

On Thu, Jan 26, 2017 at 10:10 AM, Hans Wennborg <hans at chromium.org> wrote:

> Michał suggested on the PR that this should be merged to the release
> branch.
>
> Saleem, what do you think?
>
> On Sat, Jan 21, 2017 at 8:22 AM, Saleem Abdulrasool via cfe-commits
> <cfe-commits at lists.llvm.org> wrote:
> > Author: compnerd
> > Date: Sat Jan 21 10:22:59 2017
> > New Revision: 292723
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=292723&view=rev
> > Log:
> > X86: swap EBP, ESP on !APPLE
> >
> > Restore the `libunwind.h` enumeration values back to the inverted
> > values.  This diverges from the DWARF definition of the register values.
> > However, this allows our header to be compatible with other unwind
> > implementations (e.g. HP, GNU Savannah, GCC).
> >
> > The register IDs are only swapped in the header and need to be unswapped
> > when accessing the unwind register file.  The flipped EBP and ESP only
> > applies on non-Apple x86 targets.
> >
> > When optimizations were enabled, EBP and ESP would no longer be
> > equivalent.  As a result, the incorrect access on Linux would manifest
> > as a failure to unwind the stack.  We can now unwind the stack with and
> > without FPO on Linux x86.
> >
> > Resolves PR30879!
> >
> > Modified:
> >     libunwind/trunk/include/libunwind.h
> >     libunwind/trunk/src/Registers.hpp
> >
> > Modified: libunwind/trunk/include/libunwind.h
> > URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/
> include/libunwind.h?rev=292723&r1=292722&r2=292723&view=diff
> > ============================================================
> ==================
> > --- libunwind/trunk/include/libunwind.h (original)
> > +++ libunwind/trunk/include/libunwind.h Sat Jan 21 10:22:59 2017
> > @@ -165,13 +165,8 @@ enum {
> >    UNW_X86_ECX = 1,
> >    UNW_X86_EDX = 2,
> >    UNW_X86_EBX = 3,
> > -#if defined(__CloudABI__) || defined(__FreeBSD__)
> > -  UNW_X86_ESP = 4,
> > -  UNW_X86_EBP = 5,
> > -#else
> >    UNW_X86_EBP = 4,
> >    UNW_X86_ESP = 5,
> > -#endif
> >    UNW_X86_ESI = 6,
> >    UNW_X86_EDI = 7
> >  };
> >
> > Modified: libunwind/trunk/src/Registers.hpp
> > URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/
> Registers.hpp?rev=292723&r1=292722&r2=292723&view=diff
> > ============================================================
> ==================
> > --- libunwind/trunk/src/Registers.hpp (original)
> > +++ libunwind/trunk/src/Registers.hpp Sat Jan 21 10:22:59 2017
> > @@ -122,9 +122,17 @@ inline uint32_t Registers_x86::getRegist
> >      return _registers.__edx;
> >    case UNW_X86_EBX:
> >      return _registers.__ebx;
> > +#if !defined(__APPLE__)
> > +  case UNW_X86_ESP:
> > +#else
> >    case UNW_X86_EBP:
> > +#endif
> >      return _registers.__ebp;
> > +#if !defined(__APPLE__)
> > +  case UNW_X86_EBP:
> > +#else
> >    case UNW_X86_ESP:
> > +#endif
> >      return _registers.__esp;
> >    case UNW_X86_ESI:
> >      return _registers.__esi;
> > @@ -154,10 +162,18 @@ inline void Registers_x86::setRegister(i
> >    case UNW_X86_EBX:
> >      _registers.__ebx = value;
> >      return;
> > +#if !defined(__APPLE__)
> > +  case UNW_X86_ESP:
> > +#else
> >    case UNW_X86_EBP:
> > +#endif
> >      _registers.__ebp = value;
> >      return;
> > +#if !defined(__APPLE__)
> > +  case UNW_X86_EBP:
> > +#else
> >    case UNW_X86_ESP:
> > +#endif
> >      _registers.__esp = value;
> >      return;
> >    case UNW_X86_ESI:
> >
> >
> > _______________________________________________
> > cfe-commits mailing list
> > cfe-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>



-- 
Saleem Abdulrasool
compnerd (at) compnerd (dot) org
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