[Bug middle-end/100536] ICE: in expand_call with large union (1GB) argument

["k.even-mendoza at imperial dot ac.uk" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100536

Karine EM <k.even-mendoza at imperial dot ac.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |k.even-mendoza at imperial dot ac.
                   |                            |uk

--- Comment #5 from Karine EM <k.even-mendoza at imperial dot ac.uk> ---
With GCC-11 and GCC-10, the compiler does not crash but returns: "confused by
earlier errors, bailing out" and ends gracefully. But with GCC-12, I got a
similar crash, with a flat array, a bit over 1GB:

     1  struct a {
     2    char arr[1100000000];
     3  } b[1];
     4  void c(struct a e) {
     5    if (__builtin_memcmp(e.arr, b, 6))
     6      __builtin_abort();
     7  }
     8  int main() {
     9    struct a d;
    10    d.arr;
    11    c(d);
    12    return 0;
    13  }

However, the compiler does recognize the huge stack and gives: "sorry,
unimplemented: passing too large argument on stack", but still crash. If there
is already an error printed, what is the problem to terminate the compilation
gracefully as GCC-11 and GCC-10 used to do?



==========
With GCC-11 and GCC-10 (at least for this case):
gcc-10 -O2 2c8efdb591d9739d4434f1c216106706c62bd78f_v2.c
2c8efdb591d9739d4434f1c216106706c62bd78f_v2.c: In function ‘main’:
2c8efdb591d9739d4434f1c216106706c62bd78f_v2.c:11:3: sorry, unimplemented:
passing too large argument on stack
   11 |   c(d);
      |   ^~~~
2c8efdb591d9739d4434f1c216106706c62bd78f_v2.c:11: confused by earlier errors,
bailing out

==========
With GCC-12 ((GCC) 12.0.0 20211216 (experimental)), this is the trace:
2c8efdb591d9739d4434f1c216106706c62bd78f.c:11:3: sorry, unimplemented: passing
too large argument on stack
   11 |   c(d);
      |   ^~~~
during RTL pass: expand
2c8efdb591d9739d4434f1c216106706c62bd78f.c:11:3: internal compiler error: in
expand_call, at calls.c:3905
0x6cced7 expand_call(tree_node*, rtx_def*, int)
        .././../gcc-source/gcc/calls.c:3905
0xb43a3f expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
expand_modifier, rtx_def**, bool)
        .././../gcc-source/gcc/expr.c:11536
0xa14b41 expand_expr
        .././../gcc-source/gcc/expr.h:301
0xa14b41 expand_call_stmt
        .././../gcc-source/gcc/cfgexpand.c:2831
0xa14b41 expand_gimple_stmt_1
        .././../gcc-source/gcc/cfgexpand.c:3864
0xa14b41 expand_gimple_stmt
        .././../gcc-source/gcc/cfgexpand.c:4028
0xa1a67e expand_gimple_basic_block
        .././../gcc-source/gcc/cfgexpand.c:6069
0xa1c527 execute
        .././../gcc-source/gcc/cfgexpand.c:6795
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