[Xtensa] add IRA support

[Bob Wilson]

I've committed this patch to use IRA for the Xtensa port.  I had to revert a 
change that I made earlier this year: I had added a secondary reload based on 
the mode instead of the register class.  That put IRA's copy_cost() function 
into an infinite recursion.  I suspect my patch was a bad idea to begin with, 
but I need to find the original testcase that exposed the problem before I can 
remember what was going on.  In any case, it was an obscure problem so I'm just 
going to revert the patch for now.  I ran the testsuite for an xtensa-elf target 
with two different Xtensa processor configurations to verify that this works.

2008-08-29  Bob Wilson  <bob.wilson@acm.org>

	* config/xtensa/xtensa.c (xtensa_secondary_reload_class): Revert
	change from 2008-04-03.
	* config/xtensa/xtensa.h (IRA_COVER_CLASSES): Define.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: gcc-ira.patch
Type: text/x-diff
Size: 998 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/gcc-patches/attachments/20080831/7218924f/attachment.bin>