PATCH: fix think-o in genrecog.c

[Sandra Loosemore]

I've been experimenting with a patch that adds a new define_peephole2 
for MIPS.  It was blowing up with a segfault in insn-recog.c while 
building libstdc++, and looking at the generated code for my new pattern 
there was clearly a bad offset being passed to peep2_next_insn.  I 
tracked it down to a regression from r174305, Richard's patch to add a 
new data structure to keep track of positions in genrecog.c.  Looks like 
a think-o in the code that accounts for filtering out match_scratch and 
match_dup in the input pattern; and for added fun, the caching of 
position chains was making it produce incorrect code for a 
define_peephole2 that doesn't even involve those things.  :-P  (In fact, 
it's the existing "Same as above, except LO is the initial target of the 
macc" pattern in mips.md that was initially being mis-counted.)

Is this patch OK to check in?  I tested it by diffing the generated 
insn-recog.c for a mips-sde-elf build against one I got using a 
pre-r174305 genrecog.c.

-Sandra

2011-07-18  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* genrecog.c (make_insn_sequence): Correct position numbering
	when filtering out match_scratch and match_dup.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: genrecog.patch
Type: text/x-patch
Size: 487 bytes
Desc: not available
URL: <http://gcc.gnu.org/pipermail/gcc-patches/attachments/20110719/fe769763/attachment.bin>