https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125124
Bug ID: 125124
Summary: [17 Regression] ICE on ffmpeg-8.1 GIMPLE pass: vect in
vect_bb_slp_scalar_cost, at tree-vect-slp.cc:9455
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
Target Milestone: ---
Noticed ICE on gcc-master from r17-241-gfff26a966b9f68 (did not bisect) when
building `ffmpeg-8.1`. `cvise` extracted this sample:
// $ cat rv60dsp.c.c
char ff_rv60_idct16x16_add_dst_1, ff_rv60_idct16x16_add___trans_tmp_1;
short ff_rv60_idct16x16_add_tmp[56];
void ff_rv60_idct16x16_add() {
for (int y; y; y++) {
int tmp00 = 31 * ff_rv60_idct16x16_add_tmp[y * 16] -
7 * ff_rv60_idct16x16_add_tmp[y * 16 + 1] -
6 * ff_rv60_idct16x16_add_tmp[y * 16 + 10] -
20 * ff_rv60_idct16x16_add_tmp[y * 16 + 4],
tmp02 = 20 * ff_rv60_idct16x16_add_tmp[y * 16] -
6 * ff_rv60_idct16x16_add_tmp[y * 16 + 1] +
7 * ff_rv60_idct16x16_add_tmp[y * 16 + 10] +
31 * ff_rv60_idct16x16_add_tmp[y * 16 + 4];
ff_rv60_idct16x16_add_dst_1 = (tmp00 >> 7) + (tmp02 >> 7);
{
if (ff_rv60_idct16x16_add_dst_1)
ff_rv60_idct16x16_add___trans_tmp_1 = ff_rv60_idct16x16_add_dst_1;
}
ff_rv60_idct16x16_add_dst_1 = ff_rv60_idct16x16_add___trans_tmp_1;
}
}
$ gcc/xgcc -Bgcc -c rv60dsp.c.c -O2 -fno-strict-overflow -Wall
rv60dsp.c.c: In function ‘ff_rv60_idct16x16_add’:
rv60dsp.c.c:4:15: warning: ‘y’ is used uninitialized [-Wuninitialized]
4 | for (int y; y; y++) {
| ^
rv60dsp.c.c:4:12: note: ‘y’ was declared here
4 | for (int y; y; y++) {
| ^
during GIMPLE pass: vect
rv60dsp.c.c:3:6: internal compiler error: in vect_bb_slp_scalar_cost, at
tree-vect-slp.cc:9455
3 | void ff_rv60_idct16x16_add() {
| ^~~~~~~~~~~~~~~~~~~~~
0x26ba780 diagnostics::context::diagnostic_impl(rich_location*,
diagnostics::metadata const*, diagnostics::option_id, char const*,
__va_list_tag (*) [1], diagnostics::kind)
???:0
0x26ac96c internal_error(char const*, ...)
???:0
0x26b7cb7 fancy_abort(char const*, int, char const*)
???:0
0x146e9d6 vect_bb_vectorization_profitable_p(_bb_vec_info*, vec<_slp_instance*,
va_heap, vl_ptr>, loop*)
???:0
0x147899e vect_slp_bbs(vec<basic_block_def*, va_heap, vl_ptr> const&, loop*)
???:0
0x1479c41 vect_slp_if_converted_bb(basic_block_def*, loop*)
???:0
0x148c7c4 try_vectorize_loop(hash_table<simduid_to_vf, false, xcallocator>*&,
unsigned int*, loop*, function*)
???:0
0x148cbf8 (anonymous namespace)::pass_vectorize::execute(function*)
???:0
$ gcc/xgcc -Bgcc -v
Reading specs from gcc/specs
COLLECT_GCC=gcc/xgcc
COLLECT_LTO_WRAPPER=gcc/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/slyfox/dev/git/gcc/configure --disable-multilib
--disable-bootstrap --disable-lto --disable-libsanitizer --enable-languages=c
CFLAGS='-O1 -g0' CXXFLAGS='-O1 -g0' LDFLAGS='-O1 -g0'
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 17.0.0 20260501 (experimental) (GCC)
