[r15-2196 Regression] FAIL: c-c++-common/dfp/convert-bfp-6.c -std=gnu++98 execution test on Linux/x86_64

[haochen.jiang]

On Linux/x86_64,

88d16194d0c8a6bdc2896c8944bfbf3e6038c9d2 is the first bad commit
commit 88d16194d0c8a6bdc2896c8944bfbf3e6038c9d2
Author: Jeff Law <j...@ventanamicro.com>
Date:   Mon Jul 22 08:45:10 2024 -0600

    [NFC][PR rtl-optimization/115877] Avoid setting irrelevant bit groups as 
live in ext-dce

caused

FAIL: c-c++-common/dfp/convert-bfp-10.c execution test
FAIL: c-c++-common/dfp/convert-bfp-10.c  -std=c++14 execution test
FAIL: c-c++-common/dfp/convert-bfp-10.c  -std=c++17 execution test
FAIL: c-c++-common/dfp/convert-bfp-10.c  -std=c++20 execution test
FAIL: c-c++-common/dfp/convert-bfp-10.c  -std=c++98 execution test
FAIL: c-c++-common/dfp/convert-bfp-6.c execution test
FAIL: c-c++-common/dfp/convert-bfp-6.c  -std=gnu++14 execution test
FAIL: c-c++-common/dfp/convert-bfp-6.c  -std=gnu++17 execution test
FAIL: c-c++-common/dfp/convert-bfp-6.c  -std=gnu++20 execution test
FAIL: c-c++-common/dfp/convert-bfp-6.c  -std=gnu++98 execution test

with GCC configured with

../../gcc/configure 
--prefix=/export/users/haochenj/src/gcc-bisect/master/master/r15-2196/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="dfp.exp=c-c++-common/dfp/convert-bfp-10.c 
--target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check 
RUNTESTFLAGS="dfp.exp=c-c++-common/dfp/convert-bfp-10.c 
--target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check 
RUNTESTFLAGS="dfp.exp=c-c++-common/dfp/convert-bfp-6.c 
--target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check 
RUNTESTFLAGS="dfp.exp=c-c++-common/dfp/convert-bfp-6.c 
--target_board='unix{-m32\ -march=cascadelake}'"

(Please do not reply to this email, for question about this report, contact me 
at haochen dot jiang at intel.com.)
(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.)