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Re: [PATCH 00/13] Removal of SDB debug info support
- From: Jeff Law <law at redhat dot com>
- To: Richard Biener <richard dot guenther at gmail dot com>, Jim Wilson <wilson at tuliptree dot org>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 26 Oct 2017 06:57:56 -0600
- Subject: Re: [PATCH 00/13] Removal of SDB debug info support
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On 10/26/2017 03:33 AM, Richard Biener wrote:
> 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?
I didn't see anything I would consider controversial in the series. I'd
echo Richi's comment about potentially keeping the flag as ignored.
jeff