Re: [PR 79905] ICE with vector_type

[Nathan Sidwell <nathan at acm dot org>]

On 04/04/2017 09:00 AM, Richard Biener wrote:

> tree
> add_builtin_type (const char *name, tree type)
> {
>   tree   id = get_identifier (name);
>   tree decl = build_decl (BUILTINS_LOCATION, TYPE_DECL, id, type);
>   return lang_hooks.decls.pushdecl (decl);
> }
>
> this seems to miss setting TYPE_NAME (type) = decl - oh, that may be
> what set_underlying_type does via the langhook.

Correct, via the langhook.  I wonder if the smacking of the 
incoming-type's TYPE_NAME is so that the global tree node references the 
now-named builtin type.  If we were to make a clone here, (things like) 
VS4SI_type_node would remain an unnamed type.  And I guess debug would 
be unhappy?

> At this point I'd rather restrict fiddling in this fragile area in
> rs6000.c only ;)

me too.

> Does removing the TYPE_NAME setting fix things?

no,  those TYPE_NAME assignments are redundant -- set_underlying_type 
has already initialized it.

The attached PoC fixes 79905 (no idea what ppc test it might break)

nathan

--
Nathan Sidwell

Index: config/rs6000/rs6000.c
===================================================================
--- config/rs6000/rs6000.c	(revision 246647)
+++ config/rs6000/rs6000.c	(working copy)
@@ -17459,9 +17459,23 @@ rs6000_init_builtins (void)
   tdecl = add_builtin_type ("__vector unsigned int", unsigned_V4SI_type_node);
   TYPE_NAME (unsigned_V4SI_type_node) = tdecl;
 
-  tdecl = add_builtin_type ("__vector signed int", V4SI_type_node);
-  TYPE_NAME (V4SI_type_node) = tdecl;
+  { // Ugly POC hack
+    TYPE_NAME (V4SI_type_node) = error_mark_node; // placeholder
+    tdecl = add_builtin_type ("__vector signed int", V4SI_type_node);
+    TYPE_NAME (V4SI_type_node) = NULL_TREE; // restore
 
+    // Ew, change the underlying type
+    DECL_ORIGINAL_TYPE (tdecl) = V4SI_type_node;
+    tree clone = build_variant_type_copy (V4SI_type_node);
+    TYPE_STUB_DECL (clone) = TYPE_STUB_DECL (V4SI_type_node);
+    TYPE_NAME (clone) = tdecl;
+
+    TREE_USED (clone) = 1;
+    TREE_TYPE (tdecl) = clone;
+
+    V4SI_type_node = TREE_TYPE (tdecl);
+  }
+  
   tdecl = add_builtin_type ("__vector __bool int", bool_V4SI_type_node);
   TYPE_NAME (bool_V4SI_type_node) = tdecl;