[Bug tree-optimization/95581] [11 Regression] ICE in gimple_call_arg, at gimple.h:3260 since r11-959-gb825a22890740f341eae566af27e18e528cd29a7

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95581

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
gimple_call_arg(stmt, 2) asserts for this GIMPLE_CALL statement:

  vect__5.6_24 = __builtin_altivec_mask_for_load (vectp_a.5_8);

The call is made with just one argument but the type of the function is
actually

 <function_type 0x7ffff789a0a8
    type <vector_type 0x7ffff787b0a8 __vector signed char
        type <integer_type 0x7ffff77b22a0 signed char public QI
            size <integer_cst 0x7ffff77b40c0 constant 8>
            unit-size <integer_cst 0x7ffff77b40d8 constant 1>
            align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff77b22a0 precision:8 min <integer_cst 0x7ffff77b4078 -128> max
<integer_cst 0x7ffff77b40a8 127>>
        V16QI
        size <integer_cst 0x7ffff77b4018 constant 128>
        unit-size <integer_cst 0x7ffff77b4030 constant 16>
        align:128 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff787b000 nunits:16>
    SI
    size <integer_cst 0x7ffff77b4210 type <integer_type 0x7ffff77b20a8
bitsizetype> constant 32>
    unit-size <integer_cst 0x7ffff77b4228 type <integer_type 0x7ffff77b2000
sizetype> constant 4>
    align:32 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff789a888
    arg-types <tree_list 0x7ffff789b0f0
        value <integer_type 0x7ffff77b2738 long int public DI
            size <integer_cst 0x7ffff77a1fc0 constant 64>
            unit-size <integer_cst 0x7ffff77a1fd8 constant 8>
            align:64 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff77b2738 precision:64 min <integer_cst 0x7ffff77b4258
-9223372036854775808> max <integer_cst 0x7ffff77b4270 9223372036854775807>
            pointer_to_this <pointer_type 0x7ffff77c1dc8>>
        chain <tree_list 0x7ffff789b118 value <pointer_type 0x7ffff77ba150>
            chain <tree_list 0x7ffff77af0a0 value <void_type 0x7ffff77b2f18
void>>>>
    pointer_to_this <pointer_type 0x7ffff794be70>>

I couldn't found the function documented in the manual or exercised by the test
suite but I see it created in gcc/config/rs6000/rs6000-call.c:

  decl = add_builtin_function ("__builtin_altivec_mask_for_load",
                               v16qi_ftype_long_pcvoid,
                               ALTIVEC_BUILTIN_MASK_FOR_LOAD,
                               BUILT_IN_MD, NULL, NULL_TREE);

Is it okay to call it with fewer arguments than its type indicates?