[Bug tree-optimization/118487] New: [15 Regression] ICE tree check: expected vector_cst, have ssa_name in vector_cst_encoded_nelts, at tree.h:4683 since r15-5563-g1c4d39ada33d36

[mjires at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118487

            Bug ID: 118487
           Summary: [15 Regression] ICE tree check: expected vector_cst,
                    have ssa_name in vector_cst_encoded_nelts, at
                    tree.h:4683 since r15-5563-g1c4d39ada33d36
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mjires at gcc dot gnu.org
                CC: cmuellner at gcc dot gnu.org
  Target Milestone: ---

Compiling reduced testcase gcc.dg/tree-ssa/vector-11.c results in ICE since
r15-5563-g1c4d39ada33d36.

$ cat vector-11.c
typedef int vec __attribute__((vector_size(16)));
vec f1_p_v_in, f1_sel00, f1_sel11, f1_sel, f1_v_out_2;
void f1() {
  vec v_1, v_2, v_x, v_y;
  v_1 = __builtin_shuffle(f1_p_v_in, f1_sel00);
  v_2 = __builtin_shuffle(f1_p_v_in, f1_sel11);
  v_x = v_2 - v_1;
  v_y = v_1 + v_2;
  f1_v_out_2 = __builtin_shuffle(v_y, v_x, f1_sel);
}


$ gcc vector-11.c -Ofast
during GIMPLE pass: forwprop
vector-11.c: In function ‘f1’:
vector-11.c:3:6: internal compiler error: tree check: expected vector_cst, have
ssa_name in vector_cst_encoded_nelts, at tree.h:4720
    3 | void f1() {
      |      ^~
0x36ef415 internal_error(char const*, ...)
        /home/mjires/git/GCC/master/gcc/diagnostic-global-context.cc:517
0x1cd0691 tree_check_failed(tree_node const*, char const*, int, char const*,
...)
        /home/mjires/git/GCC/master/gcc/tree.cc:9044
0xe66065 tree_check(tree_node const*, char const*, int, char const*, tree_code)
        /home/mjires/git/GCC/master/gcc/tree.h:3975
0xea5f28 vector_cst_encoded_nelts(tree_node const*)
        /home/mjires/git/GCC/master/gcc/tree.h:4720
0x1cd7a8a vector_cst_elt(tree_node const*, unsigned int)
        /home/mjires/git/GCC/master/gcc/tree.cc:10419
0x1a51b5a recognise_vec_perm_simplify_seq
        /home/mjires/git/GCC/master/gcc/tree-ssa-forwprop.cc:3632
0x1a55930 execute
        /home/mjires/git/GCC/master/gcc/tree-ssa-forwprop.cc:4553
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.


$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/mjires/built/master/libexec/gcc/x86_64-pc-linux-gnu/15.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/mjires/git/GCC/master/configure
--prefix=/home/mjires/built/master --disable-bootstrap
--enable-languages=c,c++,fortran,lto --disable-multilib --disable-libsanitizer
--enable-checking
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 15.0.1 20250115 (experimental) (GCC)