gimple.cc: Adjust gimple_call_builtin_p and gimple_call_combined_fn [PR105150]

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.