[Bug tree-optimization/126988] New: ICE on valid code at -O{2,3} with "-fno-vect-cost-model -fno-tree-sra" on x86_64-linux-gnu: in check_loop_closed_ssa_def, at tree-ssa-loop-manip.cc:664

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126988

            Bug ID: 126988
           Summary: ICE on valid code at -O{2,3} with
                    "-fno-vect-cost-model -fno-tree-sra" on
                    x86_64-linux-gnu: in check_loop_closed_ssa_def, at
                    tree-ssa-loop-manip.cc:664
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/bxq78c5be

Note:
- fails: trunk
- works: 16.2 and earlier

[641] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/home/suz/suz-local/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/17.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++,lto --disable-werror
--disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 17.0.0 20260820 (experimental) [master r17-1628-gd1c12591336] (GCC) 
[642] % 
[642] % gcctk -O2 -c -fno-vect-cost-model -fno-tree-sra small.c
during GIMPLE pass: slp
small.c: In function ‘u’:
small.c:16:6: internal compiler error: in check_loop_closed_ssa_def, at
tree-ssa-loop-manip.cc:664
   16 | void u() {
      |      ^
0x28040bb internal_error(char const*, ...)
        ../../gcc-trunk/gcc/diagnostic-global-context.cc:787
0xa31bd3 fancy_abort(char const*, int, char const*)
        ../../gcc-trunk/gcc/diagnostics/context.cc:1813
0x8f9e02 check_loop_closed_ssa_def
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:664
0x13c4807 check_loop_closed_ssa_bb
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:689
0x13c4c96 verify_loop_closed_ssa(bool, loop*)
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:714
0x13c4c96 verify_loop_closed_ssa(bool, loop*)
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:698
0x10c9ca9 execute_function_todo
        ../../gcc-trunk/gcc/passes.cc:2118
0x10ca3ae execute_todo
        ../../gcc-trunk/gcc/passes.cc:2152
/local/home/suz/suz-local/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/17.0.0/cc1
-quiet -I /usr/local/include -I /local/suz-local/software/local/include
-imultiarch x86_64-linux-gnu -iprefix
/local/home/suz/suz-local/software/local/gcc-trunk/bin/../lib/gcc/x86_64-pc-linux-gnu/17.0.0/
small.c -quiet -dumpbase small.c -dumpbase-ext .c -mtune=generic -march=x86-64
-O2 -fvect-cost-model=unlimited -fno-tree-sra -o /tmp/ccqqnGwq.s
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.
[643] % 
[643] % cat small.c
extern void t(int);
typedef struct {
  char a;
  char b;
  char c;
  char d;
  char e;
  char f;
  char g;
  char h;
} i;
char j, k, l, n;
short m, p, r;
float o;
int q, s;
void u() {
  i v, a;
ab:
  n = q ? 0 : 3;
  if (l)
    goto ac;
  a.a = a.b = a.c = -v.c;
  a.d = -v.d;
ad:
  v.a = v.b = v.c = a.c;
  v.d = a.d;
  v.e++;
  v.f = v.g = v.h = a.h + 1;
  while (j)
    ;
  if (s)
    goto ab;
  a.e = 0;
  if (m)
    goto ad;
ac:
  p = o ?: 5;
  if (l) {
    v.a = a.a - 1;
    v.b = a.b - 1;
    v.c = a.c - 1;
    v.d = a.d - 1;
    v.e = a.e - 1;
    v.g = v.h = (a.h - 1) & (p - (unsigned)k) >> k;
  }
  a.a = v.a - 1;
  a.b = v.b - 1;
  a.c = v.c + v.c - 1;
  a.d = v.d + v.d - 1;
  a.e = v.e + v.e - 1;
  r = n ? 0 : v.f >> v.g;
  t(v.h);
  t((long)a.a >> a.b);
  t((long)a.c >> a.d);
  t((long)a.e >> 56);
}