Don't include subst attributes in "@" md helpers

In a later patch, I need to add "@" to a pattern that uses subst
attributes.  This combination is problematic for two reasons:

(1) define_substs are applied and filtered at a later stage than the
    handling of "@" patterns, so that the handling of "@" patterns
    doesn't know which subst variants are valid and which will later be
    dropped.  Just adding a "@" therefore triggers a build error due to
    references to non-existent patterns.

(2) Currently, the code will treat a single "@" pattern as contributing
    to a single set of overloaded functions.  These overloaded functions
    will have an integer argument for every subst attribute.  For example,
    the vczle and vczbe in:

      "@aarch64_rev<REVERSE:rev_op><mode><vczle><vczbe>"

    are subst attributes, and so currently we'd try to generate a
    single set of overloads that take four arguments: one for rev_op,
    one for the mode, one for vczle, and one for vczbe.  The gen_*
    and maybe_gen_* functions will also have one rtx argument for
    each operand in the original pattern.

    This model doesn't really make sense for define_substs, since
    define_substs are allowed to add extra operands to an instruction.
    The number of rtx operands to the generators would then be
    incorrect.

I think a more sensible way of handling define_substs would be to
apply them first (and thus expand things like <vczle> and <vczbe>
above) and then apply "@".  However, that's a relatively invasive
change and not suitable for stage 3.

This patch instead skips over subst attributes and restricts "@"
overload handling to the cases where no define_subst is applied.
I looked through all uses of "@" names in target code and there
seemed to be only one current use of "@" with define_substs,
in x86 vector code.  The current behaviour seemed to be unwanted there,
and the x86 code was having to work around it.

gcc/
	* read-rtl.cc (md_reader::handle_overloaded_name): Don't add
	arguments for uses of subst attributes.
	(apply_iterators): Only add instructions to an overloaded helper
	if they use the default subst iterator values.
	* doc/md.texi: Update documentation accordingly.
	* config/i386/i386-expand.cc (expand_vec_perm_broadcast_1): Update
	accordingly.

0 files changed, 0 insertions, 0 deletions