[gcc r12-7792] rs6000: Skip overload instances with NULL fntype [PR104967]

[Kewen Lin <linkw@gcc.gnu.org>]

https://gcc.gnu.org/g:497bde3ab92b2c292f78672db341bbb7cc1bcf1f

commit r12-7792-g497bde3ab92b2c292f78672db341bbb7cc1bcf1f
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Wed Mar 23 20:46:06 2022 -0500

    rs6000: Skip overload instances with NULL fntype [PR104967]
    
    For some overload built-in function instance, if it requires
    a data type which isn't defined on the target, its fntype
    would be initialized as NULL.  This patch is to consider
    this possibility in function find_instance, as shown in
    PR104967.
    
            PR target/104967
    
    gcc/ChangeLog:
    
            * config/rs6000/rs6000-c.cc (find_instance): Skip instances with null
            function types.

Diff:
---
 gcc/config/rs6000/rs6000-c.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gcc/config/rs6000/rs6000-c.cc b/gcc/config/rs6000/rs6000-c.cc
index 2f0f4fe337d..84bb98f94fb 100644
--- a/gcc/config/rs6000/rs6000-c.cc
+++ b/gcc/config/rs6000/rs6000-c.cc
@@ -1686,6 +1686,10 @@ find_instance (bool *unsupported_builtin, ovlddata **instance,
 
   ovlddata *inst = *instance;
   gcc_assert (inst != NULL);
+  /* It is possible for an instance to require a data type that isn't
+     defined on this target, in which case inst->fntype will be NULL.  */
+  if (!inst->fntype)
+    return error_mark_node;
   tree fntype = rs6000_builtin_info[inst->bifid].fntype;
   tree parmtype0 = TREE_VALUE (TYPE_ARG_TYPES (fntype));
   tree parmtype1 = TREE_VALUE (TREE_CHAIN (TYPE_ARG_TYPES (fntype)));