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Re: genmatch infinite loop during bootstrap on AIX
- From: David Edelsohn <dje dot gcc at gmail dot com>
- To: Richard Biener <richard dot guenther at gmail dot com>
- Cc: Richard Biener <rguenther at suse dot de>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 29 Oct 2014 13:13:14 -0400
- Subject: Re: genmatch infinite loop during bootstrap on AIX
- Authentication-results: sourceware.org; auth=none
- References: <CAGWvnykRi9tjw4VPpArRaDYYMZvwxjvYt_oqDGMhjmataTLKJA at mail dot gmail dot com> <alpine dot LSU dot 2 dot 11 dot 1410291315100 dot 19560 at zhemvz dot fhfr dot qr> <CAGWvnymbzrTHtYQ4qEPUVgg7n41Y509nKMi9E-U910xVC7u-bw at mail dot gmail dot com> <CAFiYyc1e=trZ4GEObvO_eCenc=1yPzNj+UMu1_CdL9aC9x5wcQ at mail dot gmail dot com>
On Wed, Oct 29, 2014 at 9:24 AM, Richard Biener
> Because only genmatch calls functions from libstdc++. Btw, why
> would genmatch miscompile an empty function or the call to it?
I tried bootstrapping with libstdc++ built without the AIX ld "-G"
flag and that is succeeding.
"-G" produces a shared object for use with SVR4-style runtime linking,
so this version of libstdc++ no longer allows runtime function
interposition, e.g., operator new, although it is not used frequently.
Something about the GCC-produced tail calls is interacting badly with
Note that this makes GCC bootstrap on AIX very fragile at the moment
because it depends on how libstdc++ was built in previous releases. I
can bootstrap with GCC 4.6.3 and 4.8.1 but not with 4.7.3, 4.8.0, nor
4.9.0. A problematic libstdc++ from earlier releases causes genmatch
to loop in stage 1.