On September 4, 2016 12:33:02 PM GMT+02:00, Tom de Vries
<tom_devr...@mentor.com> wrote:
>On 04/09/16 08:12, Richard Biener wrote:
>> On September 3, 2016 5:23:35 PM GMT+02:00, Tom de Vries
><tom_devr...@mentor.com> wrote:
>>> >Hi,
>>> >
>>> >this patch fixes a c++ ICE, a p1 6/7 regression.
>>> >
>>> >
>>> >Consider test.C:
>>> >...
>>> >void bar (__builtin_va_list &);
>>> >
>>> >struct c
>>> >{
>>> > operator const __builtin_va_list &();
>>> > operator __builtin_va_list &();
>>> >};
>>> >
>>> >void
>>> >foo (void) {
>>> > struct c c1;
>>> >
>>> > bar (c1);
>>> >}
>>> >...
>>> >
>>> >The compiler ICEs as follows:
>>> >...
>>> >test.C: In function ‘void foo()’:
>>> >test.C:13:10: internal compiler error: canonical types differ for
>>> >identical types __va_list_tag [1] and __va_list_tag [1]
>>> > bar (c1);
>>> > ^
>>> >comptypes(tree_node*, tree_node*, int)
>>> > src/gcc/cp/typeck.c:1430
>>> >reference_related_p(tree_node*, tree_node*)
>>> > src/gcc/cp/call.c:1415
>>> >reference_binding
>>> > src/gcc/cp/call.c:1559
>>> >implicit_conversion
>>> > src/gcc/cp/call.c:1805
>>> >build_user_type_conversion_1
>>> > src/gcc/cp/call.c:3776
>>> >reference_binding
>>> > src/gcc/cp/call.c:1664
>>> >implicit_conversion
>>> > src/gcc/cp/call.c:1805
>>> >add_function_candidate
>>> > src/gcc/cp/call.c:2141
>>> >add_candidates
>>> > src/gcc/cp/call.c:5394
>>> >perform_overload_resolution
>>> > src/gcc/cp/call.c:4066
>>> >build_new_function_call(tree_node*, vec<tree_node*, va_gc,
>vl_embed>**,
>>> > bool, int)
>>> > src/gcc/cp/call.c:4143
>>> >finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**,
>bool,
>>> > bool, int)
>>> > src/gcc/cp/semantics.c:2440
>>> >...
>>> >
>>> >The regression is caused by the commit for PR70955, that adds a
>>> >"sysv_abi va_list" attribute to the struct in the va_list type
>(which
>>> >is
>>> >an array of one of struct).
>>> >
>>> >The ICE in comptypes happens as follows: we're comparing two
>versions
>>> >of
>>> >va_list type (with identical array element type), each with the
>>> >canonical type set to themselves. Since the types are considered
>>> >identical, they're supposed to have identical canonical types,
>which is
>
>> Did you figure out why they are not assigned the same canonical type?
>
>When constructing the first type in ix86_build_builtin_va_list_64, it's
>
>cached.
>
>When constructing the second type in build_array_type_1 (with call
>stack: grokdeclarator -> cp_build_qualified_type_real ->
>build_cplus_array_type -> build_cplus_array_type -> build_array_type ->
>
>build_array_type_1), we call type_hash_canon.
>
>But the cached type has name __builtin_sysv_va_list, and the new type
>has no name, so we hit the clause 'TYPE_NAME (a->type) != TYPE_NAME
>(b->type)' in type_cache_hasher::equal.
>
>Consequently, TYPE_CANONICAL for the new type remain set to self.
But how did it then work before the patch causing this?
Richard.
>Thanks,
>- Tom
