Re: Whats wrong with this pattern?

[Bill Currie <bcurrie at tssc dot co dot nz>]

Jan Hubicka wrote:
> So if I write subreg aware HImode mult pattern first, it ought to match it,
> not match the non-subreg version that appears in the file later.
> (when insn have the subregs)
> The pattern itself seems to be correct, because once I disable the later (mulhi)
> pattern, everything works smoothly.

What about putting more stringent conditions in?  Worked well for me on
the i860 (gotta get round to releasing the patchess...).  eg:

+(define_insn ""
+  [(set (match_operand 0 "reg_or_load_operand" "=r,r,f,f,r,f,o,m,m")
+       (match_operand 1 "reg_or_load_operand"  "r,f,r,f,m,m,r,f,m"))]
+  "((GET_MODE (operands[0]) == SImode && GET_MODE (operands[1]) ==
SImode)
+    || (GET_MODE (operands[0]) == PSImode && GET_MODE (operands[1]) ==
PSImode)
+    || (GET_MODE (operands[0]) == SFmode && GET_MODE (operands[1]) ==
SFmode))"
+  "@
+   shl %?r0,%1,%0
+   fxfr %1,%0
+   ixfr %1,%0
+   fmov.ss %1,%0
+   ld.l %1,%0
+   fld.l %1,%0
+   st.l %1,%0
+   fst.l %1,%0
+   #")

> ALso when I reverse order of patterns (HImode multiply goes first and
> disable the subreged patterns by condition "0", HImode multiply pattern
> never match.) So it looks like recog always try only the later of the patterns!
> Why?

I just had another look at your posted insn, and I think I know what's
wrong (ie why it won't match nicely):  the clobber.

(define_insn "umulqihi3"
  [(set (match_operand:HI 0 "register_operand" "=a")
        (mult:HI (zero_extend:HI (match_operand:QI 1 "register_operand"
"%0"))
                 (zero_extend:HI (match_operand:QI 2
"nonimmediate_operand" "qm"))))
   (clobber (reg:CC 17))]

AIUI, a (set (x) (mult (y) (z))) will never match this unless it also
has a clobber in it.  Should this not be defined as a define_expand and
then match against an unnamed insn? ie

(define_expand "umulqihi3"
  [(set (match_operand:HI 0 "register_operand" "=a")
        (mult:HI (zero_extend:HI (match_operand:QI 1 "register_operand"
"%0"))
                 (zero_extend:HI (match_operand:QI 2
"nonimmediate_operand" "qm"))))
   (clobber (reg:CC 17))]

define_insn ""
   (set (match_operand:HI 0 "register_operand" "=a")
        (mult:HI (zero_extend:HI (match_operand:QI 1 "register_operand"
"%0"))
                 (zero_extend:HI (match_operand:QI 2
"nonimmediate_operand" "qm"))))]

I *think* this will work better, though I could be missing something.

HTH (or at least provides some ideas)
Bill
-- 
Leave others their otherness