i386: Make most MD builtins nothrow, leaf [PR112962]

i386: Make most MD builtins nothrow, leaf [PR112962]

The following patch makes most of x86 MD builtins nothrow,leaf
(like most middle-end builtins are).  For -fnon-call-exceptions it
doesn't nothrow, better might be to still add it if the builtins
don't read or write memory and can't raise floating point exceptions,
but we don't have such information readily available, so the patch
uses just !flag_non_call_exceptions for now.
Not sure if we shouldn't have some exceptions for the leaf attribute,
e.g. wonder about EMMS/FEMMS and the various xsave/xrstor etc. builtins,
pedantically none of those builtins do anything that leaf functions
are forbidden to do (having callbacks, calling functions from current TU,
longjump into the current TU), but sometimes non-leaf is also used on
really complex functions to prevent some unwanted optimizations.
That said, haven't run into any problems as is with the patch.

2023-12-20  Jakub Jelinek  <jakub@redhat.com>

	PR target/112962
	* config/i386/i386-builtins.cc (ix86_builtins): Increase by one
	element.
	(def_builtin): If not -fnon-call-exceptions, set TREE_NOTHROW on
	the builtin FUNCTION_DECL.  Add leaf attribute to DECL_ATTRIBUTES.
	(ix86_add_new_builtins): Likewise.