[r16-2374 Regression] FAIL: gcc.target/i386/asm-hard-reg-2.c (test for errors, line 32) on Linux/x86_64

On Linux/x86_64,

a51c146ebce41b5e4326b222f2d9e04bb22d276f is the first bad commit
commit a51c146ebce41b5e4326b222f2d9e04bb22d276f
Author: Stefan Schulze Frielinghaus <[email protected]>
Date:   Mon Jul 21 13:05:26 2025 +0200

    Hard register constraints

caused

FAIL: gcc.dg/asm-hard-reg-1.c scan-assembler-times foo\t%ecx 2
FAIL: gcc.dg/asm-hard-reg-1.c scan-assembler-times foo\t%rcx 2
FAIL: gcc.dg/asm-hard-reg-2.c (test for excess errors)
FAIL: gcc.dg/asm-hard-reg-4.c (test for excess errors)
FAIL: gcc.dg/asm-hard-reg-5.c (test for excess errors)
FAIL: gcc.dg/asm-hard-reg-6.c scan-assembler-times bar\t%ebx,\\(%rsi\\) 1
FAIL: gcc.dg/asm-hard-reg-6.c scan-assembler-times foo\t%eax,%rcx 1
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 15)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 16)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 19)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 20)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 21)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 22)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 25)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 26)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 29)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 30)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 31)
FAIL: gcc.target/i386/asm-hard-reg-2.c  (test for errors, line 32)

with GCC configured with

../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r16-2374/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=gcc.dg/asm-hard-reg-1.c --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-1.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-2.c --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-2.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-4.c --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-4.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-5.c --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-5.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-6.c --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/asm-hard-reg-6.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/asm-hard-reg-2.c --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/asm-hard-reg-2.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.)