[PING] INSN attribute to enable/disable alternatives

[Andreas Krebbel]

Hi,

these 3 patches introduce a new special attribute to be used in INSN
definitions in order to enable or disable certain INSN alternatives.
I think this comes in quite handy when enhancing a back end with new
instructions.

Other GCC developers have already agreed that this is a useful
feature.  What's left is to check the implementation.  So could please
someone have a look at it?

The first of the patches shows how that features might be used by a
back end to significantly reduce duplicated patterns for different CPU
types.  This patch only addresses the most obvious cases.

I've verified that the patches still work with current GCC.

[PATCH 1/3] S/390: New `enabled' insn attribute
http://gcc.gnu.org/ml/gcc-patches/2007-08/msg01908.html

[PATCH 2/3] reload,recog: New `enabled' insn attribute
http://gcc.gnu.org/ml/gcc-patches/2007-08/msg01909.html

[PATCH 3/3] genattr: New `enabled' insn attribute
http://gcc.gnu.org/ml/gcc-patches/2007-08/msg01910.html

OK for mainline?

Bye,

-Andreas-