[Bug tree-optimization/98960] Failure to optimize accumulate loop to mul

rguenth at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Thu Feb 4 07:55:27 GMT 2021


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98960

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-02-04

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Final value replacement has

(set_scalar_evolution
  instantiated_below = 5
  (scalar = sum_7)
  (scalar_evolution = {0, +, {1, +, 1}_1}_1))
)
(chrec_apply 
  (varying_loop = 1 
) 
  (chrec = {0, +, {1, +, 1}_1}_1)
  (x = (unsigned int) max_value_4(D) + 4294967295)
  (res = scev_not_known))
not replacing:
  sum_1 = PHI <sum_7(3)>

because it doesn't know this (IIRC there's a duplicate bug where I tried some
things to handle this).


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