gimple.cc: Adjust gimple_call_builtin_p and gimple_call_combined_fn [PR105150]

On Tue, Apr 05, 2022 at 11:28:53AM +0200, Richard Biener wrote:
> > In GIMPLE, we call:
> >   && gimple_builtin_call_types_compatible_p (stmt, fndecl)
> > but that is insufficient, that verifies whether the arguments passed to
> > GIMPLE_CALL match the fndecl argument types.  But that fndecl may very well
> > be the user declaration, so doesn't have to match exactly the builtin
> > as predeclared by builtins.def etc. (though, there is the cotcha that say
> > for FILE * we just use void * etc.).  So e.g. in tree-ssa-strlen.cc
> > we use additional:
> >   tree callee = gimple_call_fndecl (stmt);
> >   tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (callee));
> >   if (decl
> >       && decl != callee
> >       && !gimple_builtin_call_types_compatible_p (stmt, decl))
> >     return false;
>
> Yeah, I think we should use that (and only that) function decl
> in get_call_combined_fn and gimple_call_combined_fn until the
> frontend stops slapping wrong BUILT_IN_* on random decls.

So, as a preparation step, this patch adjusts gimple_call_builtin_p
and gimple_call_combined_fn so that they check argument types against
the builtin_decl_explicit TYPE_ARG_TYPES rather than against the
actual used fndecl.

2022-04-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/105150
	* gimple.cc (gimple_call_builtin_p, gimple_call_combined_fn):
	For BUILT_IN_NORMAL calls, call gimple_builtin_call_types_compatible_p
	preferrably on builtin_decl_explicit decl rather than fndecl.
	* tree-ssa-strlen.cc (valid_builtin_call): Don't call
	gimple_builtin_call_types_compatible_p here.

gcc/gimple.cc

@@ -2841,7 +2841,12 @@ gimple_call_builtin_p (const gimple *stmt)
   if (is_gimple_call (stmt)
       && (fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
       && DECL_BUILT_IN_CLASS (fndecl) != NOT_BUILT_IN)
-    return gimple_builtin_call_types_compatible_p (stmt, fndecl);
+    {
+      if (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
+	if (tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (fndecl)))
+	  fndecl = decl;
+      return gimple_builtin_call_types_compatible_p (stmt, fndecl);
+    }
   return false;
 }
 
@@ -2854,7 +2859,12 @@ gimple_call_builtin_p (const gimple *stmt, enum built_in_class klass)
   if (is_gimple_call (stmt)
       && (fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
       && DECL_BUILT_IN_CLASS (fndecl) == klass)
-    return gimple_builtin_call_types_compatible_p (stmt, fndecl);
+    {
+      if (klass == BUILT_IN_NORMAL)
+	if (tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (fndecl)))
+	  fndecl = decl;
+      return gimple_builtin_call_types_compatible_p (stmt, fndecl);
+    }
   return false;
 }
 
@@ -2867,7 +2877,11 @@ gimple_call_builtin_p (const gimple *stmt, enum built_in_function code)
   if (is_gimple_call (stmt)
       && (fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
       && fndecl_built_in_p (fndecl, code))
-    return gimple_builtin_call_types_compatible_p (stmt, fndecl);
+    {
+      if (tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (fndecl)))
+	fndecl = decl;
+      return gimple_builtin_call_types_compatible_p (stmt, fndecl);
+    }
   return false;
 }
 
@@ -2884,10 +2898,14 @@ gimple_call_combined_fn (const gimple *stmt)
 	return as_combined_fn (gimple_call_internal_fn (call));
 
       tree fndecl = gimple_call_fndecl (stmt);
-      if (fndecl
-	  && fndecl_built_in_p (fndecl, BUILT_IN_NORMAL)
-	  && gimple_builtin_call_types_compatible_p (stmt, fndecl))
-	return as_combined_fn (DECL_FUNCTION_CODE (fndecl));
+      if (fndecl && fndecl_built_in_p (fndecl, BUILT_IN_NORMAL))
+	{
+	  tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (fndecl));
+	  if (!decl)
+	    decl = fndecl;
+	  if (gimple_builtin_call_types_compatible_p (stmt, decl))
+	    return as_combined_fn (DECL_FUNCTION_CODE (fndecl));
+	}
     }
   return CFN_LAST;
 }

gcc/tree-ssa-strlen.cc

@@ -1736,12 +1736,6 @@ valid_builtin_call (gimple *stmt)
     return false;
 
   tree callee = gimple_call_fndecl (stmt);
-  tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (callee));
-  if (decl
-      && decl != callee
-      && !gimple_builtin_call_types_compatible_p (stmt, decl))
-    return false;
-
   switch (DECL_FUNCTION_CODE (callee))
     {
     case BUILT_IN_MEMCMP: