https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89518
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2019-02-27
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
We do not have a (a / b) * b + (a % b) simplification rule. The following adds
one:
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 269242)
+++ gcc/match.pd (working copy)
@@ -2729,6 +2729,13 @@ (define_operator_list COND_TERNARY
(mult (convert1? (exact_div @0 @@1)) (convert2? @1))
(convert @0))
+/* Simplify (A / B) * B + (A % B) -> A. */
+(for div (trunc_div ceil_div floor_div round_div)
+ mod (trunc_mod ceil_mod floor_mod round_mod)
+ (simplify
+ (plus:c (mult:c (div @0 @1) @1) (mod @0 @1))
+ @0))
+
/* ((X /[ex] A) +- B) * A --> X +- A * B. */
(for op (plus minus)
(simplify
