[r17-915 Regression] FAIL: gcc.target/i386/sse2-psubw-2.c scan-assembler-times [ \t]psubw[ \t] 2 on Linux/x86_64

On Linux/x86_64,

84e5bd1e7dbdd106956ed0f5d8ddee7bf7b3be7c is the first bad commit
commit 84e5bd1e7dbdd106956ed0f5d8ddee7bf7b3be7c
Author: Roger Sayle <[email protected]>
Date:   Thu May 28 20:46:04 2026 +0100

    x86 SSE: Improve vector increment/decrement on x86.

caused

FAIL: gcc.target/i386/sse2-paddb-2.c scan-assembler-times [ \t]paddb[ \t] 2
FAIL: gcc.target/i386/sse2-paddd-2.c scan-assembler-times [ \t]paddd[ \t] 2
FAIL: gcc.target/i386/sse2-paddw-2.c scan-assembler-times [ \t]paddw[ \t] 2
FAIL: gcc.target/i386/sse2-psubb-2.c scan-assembler-times [ \t]psubb[ \t] 2
FAIL: gcc.target/i386/sse2-psubd-2.c scan-assembler-times [ \t]psubd[ \t] 2
FAIL: gcc.target/i386/sse2-psubw-2.c scan-assembler-times [ \t]psubw[ \t] 2

with GCC configured with

../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r17-915/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="i386.exp=gcc.target/i386/sse2-paddb-2.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-paddb-2.c --target_board='unix{-m64\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-paddd-2.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-paddd-2.c --target_board='unix{-m64\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-paddw-2.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-paddw-2.c --target_board='unix{-m64\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-psubb-2.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-psubb-2.c --target_board='unix{-m64\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-psubd-2.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-psubd-2.c --target_board='unix{-m64\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-psubw-2.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/sse2-psubw-2.c --target_board='unix{-m64\ -march=cascadelake}'"

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(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.)