r360403 - Change -gz and -Wa, --compress-debug-sections to use gABI compression (SHF_COMPRESSED)

[Fāng-ruì Sòng via cfe-commits]

It's fine :) The problem may be that users with older pre-2.26 binutils may
have older GNU as as well. Their GNU as may not recognize
--compress-debug-sections=zlib.

On Wed, May 15, 2019 at 3:39 AM Eric Christopher <echristo at gmail.com> wrote:

> Hi Ray,
>
> I've temporarily reverted this here:
>
> echristo at jhereg ~/s/llvm-project> git llvm push
> Pushing 1 commit:
>   fda79815a33 Temporarily revert "Change -gz and
> -Wa,--compress-debug-sections to use gABI compression
> (SHF_COMPRESSED)"
> Sending        cfe/trunk/docs/ReleaseNotes.rst
> Sending        cfe/trunk/lib/Frontend/CompilerInvocation.cpp
> Sending        cfe/trunk/tools/driver/cc1as_main.cpp
> Transmitting file data ...done
> Committing transaction...
> Committed revision 360703.
> Committed fda79815a33 to svn.
>
> From my message:
>
>     This affects users of older (pre 2.26) binutils in such a way that
> they can't necessarily
>     work around it as it doesn't support the compress option on the
> command line. Reverting
>     to unblock them and we can revisit whether to make this change now
> or fix how we want
>     to express the option.
>
> I'm not sure what we want to do here, but wanted to unblock people in
> the meantime. What do you think?
>
> Thanks!
>
> -eric
>
>
> On Thu, May 9, 2019 at 7:05 PM Fangrui Song via cfe-commits
> <cfe-commits at lists.llvm.org> wrote:
> >
> > Author: maskray
> > Date: Thu May  9 19:08:21 2019
> > New Revision: 360403
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=360403&view=rev
> > Log:
> > Change -gz and -Wa,--compress-debug-sections to use gABI compression
> (SHF_COMPRESSED)
> >
> > Since July 15, 2015 (binutils-gdb commit
> > 19a7fe52ae3d0971e67a134bcb1648899e21ae1c, included in 2.26), gas
> > --compress-debug-sections=zlib (gcc -gz) means zlib-gabi:
> > SHF_COMPRESSED. Before that it meant zlib-gnu (.zdebug).
> >
> > clang's -gz was introduced in rC306115 (Jun 2017) to indicate zlib-gnu.
> It
> > is 2019 now and it is not unreasonable to assume users of the new
> > feature to have new linkers (ld.bfd/gold >= 2.26, lld >= rLLD273661).
> >
> > Change clang's default accordingly to improve standard conformance.
> > zlib-gnu becomes out of fashion and gets poorer toolchain support.
> > Its mangled names confuse tools and are more likely to cause problems.
> >
> > Reviewed By: compnerd
> >
> > Differential Revision: https://reviews.llvm.org/D61689
> >
> > Modified:
> >     cfe/trunk/docs/ReleaseNotes.rst
> >     cfe/trunk/lib/Frontend/CompilerInvocation.cpp
> >     cfe/trunk/tools/driver/cc1as_main.cpp
> >
> > Modified: cfe/trunk/docs/ReleaseNotes.rst
> > URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/ReleaseNotes.rst?rev=360403&r1=360402&r2=360403&view=diff
> >
> ==============================================================================
> > --- cfe/trunk/docs/ReleaseNotes.rst (original)
> > +++ cfe/trunk/docs/ReleaseNotes.rst Thu May  9 19:08:21 2019
> > @@ -77,7 +77,10 @@ Modified Compiler Flags
> >
> >  - `clang -dumpversion` now returns the version of Clang itself.
> >
> > -- ...
> > +- On ELF, ``-gz`` now defaults to ``-gz=zlib``. It produces
> ``SHF_COMPRESSED``
> > +  style compression of debug information. GNU binutils 2.26 or newer,
> or lld is
> > +  required to link produced object files. Use ``-gz=zlib-gnu`` to get
> the old
> > +  behavior.
> >
> >  New Pragmas in Clang
> >  --------------------
> >
> > Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=360403&r1=360402&r2=360403&view=diff
> >
> ==============================================================================
> > --- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original)
> > +++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Thu May  9 19:08:21
> 2019
> > @@ -1052,8 +1052,7 @@ static bool ParseCodeGenArgs(CodeGenOpti
> >    if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections,
> >                                       OPT_compress_debug_sections_EQ)) {
> >      if (A->getOption().getID() == OPT_compress_debug_sections) {
> > -      // TODO: be more clever about the compression type auto-detection
> > -      Opts.setCompressDebugSections(llvm::DebugCompressionType::GNU);
> > +      Opts.setCompressDebugSections(llvm::DebugCompressionType::Z);
> >      } else {
> >        auto DCT =
> llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
> >                       .Case("none", llvm::DebugCompressionType::None)
> >
> > Modified: cfe/trunk/tools/driver/cc1as_main.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/tools/driver/cc1as_main.cpp?rev=360403&r1=360402&r2=360403&view=diff
> >
> ==============================================================================
> > --- cfe/trunk/tools/driver/cc1as_main.cpp (original)
> > +++ cfe/trunk/tools/driver/cc1as_main.cpp Thu May  9 19:08:21 2019
> > @@ -221,8 +221,7 @@ bool AssemblerInvocation::CreateFromArgs
> >    if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections,
> >                                       OPT_compress_debug_sections_EQ)) {
> >      if (A->getOption().getID() == OPT_compress_debug_sections) {
> > -      // TODO: be more clever about the compression type auto-detection
> > -      Opts.CompressDebugSections = llvm::DebugCompressionType::GNU;
> > +      Opts.CompressDebugSections = llvm::DebugCompressionType::Z;
> >      } else {
> >        Opts.CompressDebugSections =
> >            llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
> >
> >
> > _______________________________________________
> > cfe-commits mailing list
> > cfe-commits at lists.llvm.org
> > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>


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