On Thu, 25 Jan 2018, Richard Biener wrote:
--- gcc/match.pd (revision 257047)
+++ gcc/match.pd (working copy)
@@ -1939,6 +1939,37 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(minus (convert (view_convert:stype @1))
(convert (view_convert:stype @2)))))))
+/* (A * C) +- (B * C) -> (A+-B) * C and (A * C) +- A -> A * (C+-1).
+ Modeled after fold_plusminus_mult_expr. */
+(if (!TYPE_SATURATING (type)
+ && (!FLOAT_TYPE_P (type) || flag_associative_math))
+ (for plusminus (plus minus)
+ (simplify
+ (plusminus (mult:s @0 @1) (mult:cs @0 @2))
No :c on the first mult, so we don't actually handle A*C+B*C?
--
Marc Glisse