Re: [PATCH 00/13] Removal of SDB debug info support

[Richard Biener <richard dot guenther at gmail dot com>]

On Wed, Oct 25, 2017 at 11:24 PM, Jim Wilson <wilson@tuliptree.org> wrote:
> We have no targets that emit SDB debug info by default.  We dropped all
> of the SVR3 Unix and embedded COFF targets a while ago.  The only
> targets that are still able to emit SDB debug info are cygwin, mingw,
> and msdosdjgpp.
>
> I tried a cygwin build with sources modified to emit SDB by default, to
> see if the support was still usable.  I ran into multiple problems.
>  There is no SDB support for IMPORTED_DECL which was added in 2008.  -
> freorder-functions and -freorder-blocks-and-partition did not work and
> had to be disabled.  I hit a cgraph assert because sdbout.c uses
> assemble_name on types, which fails if there is a function and type
> with the same name.  This also causes types to be added to the debug
> info with prepended underscores which is wrong.  I then ran into a
> problem with the i386_pe_declare_function_type call from
> i386_pe_file_end and gave up because I didn't see an easy workaround.
>
> It seems clear that the SDB support is no longer usable, and probably
> hasn't been for a while.  This support should just be removed.
>
> SDB is both a debug info format and an old Unix debugger.  There were
> some references to the debugger that I left in, changing to past tense,
> as the comments are useful history to explain why the code was written
> the was it was.  Otherwise, I tried to eliminate all references to sdb
> as a debug info format.
>
> This patch series was tested with a C only cross compiler build for all
> modified embedded targets, a default languages build for power aix,
> i686 cygwin, and x86_64 linux.  I also did gdb testsuite runs for
> cygwin and linux.  There were no regressions.
>
> As a debug info maintainer, I can self approve some of this stuff,
> would be would be good to get a review from one of the other global
> reviewers, and/or target maintainers.

You have my approval for this.  Can you add a blurb to gcc-8/changes.html,
like "support for emitting SDB debug info has been removed" in the caveats
section?

Thanks,
Richard.

> Jim
>