[Bug tree-optimization/106457] array_at_struct_end_p returns TRUE for a two-dimension array which is not inside any structure

["qinzhao at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106457

--- Comment #7 from qinzhao at gcc dot gnu.org ---
another testing case failed with the current "array_at_struct_end_p":
gcc/testsuite/gcc.target/aarch64/vadd_reduc-2.c
  1 /* { dg-do compile } */
  2 /* { dg-additional-options "-O3 -std=c99" } */
  3 /* { dg-final { check-function-bodies "**" "" "" } } */
  4 
  5 #include <stdint.h>
  6 
  7 #pragma GCC target "+nosve"
  8 
  9 /*
 10 **test:
 11 **      ...
 12 **      addv    s0, v0.4s
 13 **      fmov    w0, s0
 14 **      and     w1, w0, 65535
 15 **      add     w0, w1, w0, lsr 16
 16 **      lsr     w0, w0, 1
 17 **      ret
 18 */
 19 int test (uint8_t *p, uint32_t t[1][1], int n) {
 20 
 21   int sum = 0;
 22   uint32_t a0;
 23   for (int i = 0; i < 4; i++, p++)
 24     t[i][0] = p[0];
 25 
 26   for (int i = 0; i < 4; i++) {
 27     {
 28       int t0 = t[0][i] + t[0][i];
 29       a0 = t0;
 30     };
 31     sum += a0;
 32   }
 33   return (((uint16_t)sum) + ((uint32_t)sum >> 16)) >> 1;
 34 }

in the above, at line 24, the array_ref t[i][0] was identified as "true" by the
current array_at_struct_end_p:
Breakpoint 1, array_at_struct_end_p (ref=0xfffff57a2990) at
../../latest_gcc/gcc/tree.cc:12690
12690     if (TREE_CODE (ref) == ARRAY_REF
(gdb) call debug_tree(ref)
 <array_ref 0xfffff57a2990
    type <integer_type 0xfffff599e310 uint32_t sizes-gimplified public unsigned
SI
        size <integer_cst 0xfffff56c1050 constant 32>
        unit-size <integer_cst 0xfffff56c1068 constant 4>
        align:32 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0xfffff57d0690 precision:32 min <integer_cst 0xfffff56c1080 0> max <integer_cst
0xfffff56c1038 4294967295> context <translation_unit_decl 0xfffff5a00ca8 t.c>>

    arg:0 <mem_ref 0xfffff59f8390
        type <array_type 0xfffff5a70dc8 type <integer_type 0xfffff599e310
uint32_t>
            SI size <integer_cst 0xfffff56c1050 32> unit-size <integer_cst
0xfffff56c1068 4>
            align:32 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0xfffff5a70e70 domain <integer_type 0xfffff5a70d20>
            pointer_to_this <pointer_type 0xfffff5a71110>>

        arg:0 <ssa_name 0xfffff5761908 type <pointer_type 0xfffff5a71110>
            visited
            def_stmt _4 = t_27(D) + _3;
            version:4
            ptr-info 0xfffff56c84c0>
        arg:1 <integer_cst 0xfffff56c8328 constant 0>
        t.c:24:6 start: t.c:24:5 finish: t.c:24:8>
    arg:1 <integer_cst 0xfffff56c11a0 type <integer_type 0xfffff57d05e8 int>
constant 0>
    t.c:24:9 start: t.c:24:5 finish: t.c:24:11>
...(gdb) n
12774     if (ref
(gdb) n
12806     return true;
(gdb) 

Looks like that the current array_at_struct_end_p cannot handle multi-dimension
array reference correctly.