https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123517
--- Comment #6 from Sam James <sjames at gcc dot gnu.org> ---
If I revert r16-6651, I get:
```
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/build/./gcc/xgcc
-B/var/tmp/portage/sys-devel/gcc-16.0.9999/work/build/./gcc/
-B/usr/x86_64-pc-linux-gnu/bin/ -B/usr/x86_64-pc-linux-gnu/lib
/ -isystem /usr/x86_64-pc-linux-gnu/include -isystem
/usr/x86_64-pc-linux-gnu/sys-include -fno-checking -g -O2 -O3 -march=native
-fno-semantic-interposition -mtls-dialect=gnu2 -fdiagno
stics-color=always -Wa,-O2 -Wa,-mtune=znver4 -ggdb3 -pipe
-Werror=strict-aliasing -Werror=lto-type-mismatch -Werror=odr
-fdiagnostics-color=always -fdiagnostics-urls=never --param=ggc-mi
n-expand=150 -ggdb3 -O2 -g -O2 -O3 -march=native -fno-semantic-interposition
-mtls-dialect=gnu2 -fdiagnostics-color=always -Wa,-O2 -Wa,-mtune=znver4 -ggdb3
-pipe -Werror=strict-aliasing
-Werror=lto-type-mismatch -Werror=odr -fdiagnostics-color=always
-fdiagnostics-urls=never --param=ggc-min-expand=150 -ggdb3 -DIN_GCC -W -Wall
-Wno-error=narrowing -Wwrite-strings -Wca
st-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition
-isystem ./include -fpic -mlong-double-80 -DUSE_ELF_SYMVER -fcf-protection
-mshstk -g -DIN_LIBGCC2 -fbuilding-li
bgcc -fno-stack-protector -fno-stack-clash-protection -fpic -mlong-double-80
-DUSE_ELF_SYMVER -fcf-protection -mshstk -I. -I. -I../.././gcc
-I/var/tmp/portage/sys-devel/gcc-16.0.9999/wo
rk/gcc-16.0.9999/libgcc
-I/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/.
-I/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/../gcc
-I/var/tmp/port
age/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/../include
-I/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/config/i386
-I/var/tmp/portage/sys-devel/gcc-16.0.99
99/work/gcc-16.0.9999/libgcc/config/libbid -DENABLE_DECIMAL_BID_FORMAT
-DHAVE_CC_TLS -DUSE_TLS -o _paritydi2.o -MT _paritydi2.o -MD -MP -MF
_paritydi2.dep -DL_paritydi2 -c /var/tmp/por
tage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/libgcc2.c
-fvisibility=hidden -DHIDE_EXPORTS
during GIMPLE pass: slp
In file included from
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/libgcc2.c:56:
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/libgcc2.c:
In function ‘__parityti2’:
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/libgcc2.h:216:25:
internal compiler error: Segmentation fault
216 | #define __NDW(a,b) __ ## a ## ti ## b
| ^~
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/libgcc2.h:342:25:
note: in expansion of macro ‘__NDW’
342 | #define __parityDI2 __NDW(parity,2)
| ^~~~~
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/libgcc/libgcc2.c:897:1:
note: in expansion of macro ‘__parityDI2’
897 | __parityDI2 (UDWtype x)
| ^~~~~~~~~~~
0x5586579bda03 internal_error(char const*, ...)
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/diagnostic-global-context.cc:787
0x558655ea028a crash_signal
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/toplev.cc:325
0x5586562d47da vec<tree_node*, va_heap, vl_embed>::operator[](unsigned int)
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/vec.h:911
0x5586562d47da vec<tree_node*, va_heap, vl_ptr>::operator[](unsigned int)
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/vec.h:1610
0x5586562d47da vectorize_slp_instance_root_stmt(vec_info*, _slp_tree*,
_slp_instance*)
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/tree-vect-slp.cc:12209
0x5586562ff345 vect_schedule_slp(vec_info*, vec<_slp_instance*, va_heap,
vl_ptr> const&)
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/tree-vect-slp.cc:12495
0x558656302284 vect_slp_region
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/tree-vect-slp.cc:10423
0x55865630446b vect_slp_bbs
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/tree-vect-slp.cc:10535
0x558656304b15 vect_slp_function(function*)
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/tree-vect-slp.cc:10657
0x5586563124b5 execute
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/gcc/tree-vectorizer.cc:1571
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://bugs.gentoo.org/> for instructions.
make[3]: *** [Makefile:517: _paritydi2.o] Error 1
```
