RE: the rtl expression does not match in define_peephole

["Dave Korn" <dave dot korn at artimi dot com>]

Dong Phuong wrote on 30 September 2008 17:32:

> But when I define peepholes to reduce it, there's
> nothing change. When I look at the  rtl expression, I
> see that there something beetween the instruction ADD
> and CMP :
> 
> (insn 18 16 19 0x0 (set (reg/v:HI 22)
>         (plus:HI (reg/v:HI 22)
>             (const_int 1 [0x1]))) -1 (nil) -----> ADD
>     (nil))
> 
> (note 19 18 20 NOTE_INSN_LOOP_CONT)  -----> st that I
>                                       don't understand

  This is documented in the manual (which you really ought to read) alongside
all the other note types:

http://gcc.gnu.org/onlinedocs/gccint/Insns.html#index-NOTE_005fINSN_005fLOOP_0
05fCONT-2615

> (code_label 20 19 22 5 "" [0 uses])
> 
> (insn 22 20 23 0x0 (set (cc0)
>         (compare (reg/v:HI 22)
>             (const_int 4 [0x4]))) -1 (nil) ------> CMP
>     (nil))
> 
> 
> so does that strange expressions prevent my peepholes
> from running ?

  Yes.

> And in my case, what do I have to do ?

  Nothing.  That's not a valid match, because there's a label in-between the
two instructions; they can't possibly be combined into one single instruction
if there's a branch target in between them.

    cheers,
      DaveK
-- 
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