Re: [r17-603 Regression] FAIL: g++.dg/opt/shrink-wrapping-vector-1.C -std=gnu++98 scan-rtl-dump pro_and_epilogue "Performing shrink-wrapping" on Linux/x86_64

On Tue, May 19, 2026 at 10:09 PM Haochen Jiang <[email protected]> wrote:
>
> On Linux/x86_64,
>
> acfdad706d8acca6c4ed6ef3b63c2e02f1c47881 is the first bad commit
> commit acfdad706d8acca6c4ed6ef3b63c2e02f1c47881
> Author: Nathan Myers <[email protected]>
> Date:   Fri Apr 3 23:55:39 2026 -0400
>
>     libstdc++: Use allocate_at_least in vector, string (P0401) [PR118030]
>
> caused
>
> FAIL: g++.dg/opt/shrink-wrapping-vector-1.C  -std=gnu++98  scan-rtl-dump pro_and_epilogue "Performing shrink-wrapping"

I filed https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125400 for the
missed optimization which is causing the missed shrink wrapping.
If I can figure out how to xfail it for C++98 only I will unless
someone beats me to it. Note It fails on all the specified targets in
the testcase as it is generic issue.

Thanks,
Andrea

>
> with GCC configured with
>
> ../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r17-603/usr --enable-clocale=gnu --with-system-zlib --with-demangler-in-ld --with-fpmath=sse --enable-languages=c,c++,fortran --enable-cet --without-isl --enable-libmpx x86_64-linux --disable-bootstrap
>
> To reproduce:
>
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=g++.dg/opt/shrink-wrapping-vector-1.C --target_board='unix{-m64}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=g++.dg/opt/shrink-wrapping-vector-1.C --target_board='unix{-m64\ -march=cascadelake}'"
>
> (Please directly reply to this email for question about this report.)
> (If you met problems with cascadelake related, disabling AVX512F in command line might save that.)
> (However, please make sure that there is no potential problems with AVX512.)