Re: [ABSU_EXPR] Add some of the missing patterns in match,pd

[Marc Glisse <marc dot glisse at inria dot fr>]

(why is there no mention of ABSU_EXPR in doc/* ?)

--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -571,10 +571,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    (copysigns (op @0) @1)
    (copysigns @0 @1))))

-/* abs(x)*abs(x) -> x*x.  Should be valid for all types.  */
-(simplify
- (mult (abs@1 @0) @1)
- (mult @0 @0))
+/* abs(x)*abs(x) -> x*x.  Should be valid for all types.
+   also for absu(x)*absu(x) -> x*x.  */
+(for op (abs absu)
+ (simplify
+  (mult (op@1 @0) @1)
+  (mult @0 @0)))

1) the types are wrong, it should be (convert (mult @0 @0)), or maybe 
view_convert if vectors also use absu.
2) this is only valid with -fwrapv (TYPE_OVERFLOW_WRAPS(TREE_TYPE(@0))), 
otherwise you are possibly replacing a multiplication on unsigned with a 
multiplication on signed that may overflow. So maybe it is actually 
supposed to be
(mult (convert @0) (convert @0))

 /* cos(copysign(x, y)) -> cos(x).  Similarly for cosh.  */
 (for coss (COS COSH)
@@ -1013,15 +1015,24 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
       && tree_nop_conversion_p (type, TREE_TYPE (@2)))
   (bit_xor (convert @1) (convert @2))))

-(simplify
- (abs (abs@1 @0))
- @1)
-(simplify
- (abs (negate @0))
- (abs @0))
-(simplify
- (abs tree_expr_nonnegative_p@0)
- @0)
+/* Convert abs (abs (X)) into abs (X).
+   also absu (absu (X)) into absu (X).  */
+(for op (abs absu)
+ (simplify
+  (op (op@1 @0))
+  @1))

You cannot have (absu (absu @0)) since absu takes a signed integer and 
returns an unsigned one. (absu (abs @0)) may indeed be equivalent to 
(convert (abs @0)). Possibly (op (convert (absu @0))) could also be 
simplified if convert is a NOP.

+/* Convert abs[u] (-X) -> abs[u] (X).  */
+(for op (abs absu)
+ (simplify
+  (op (negate @0))
+  (op @0)))
+
+/* Convert abs[u] (X)  where X is nonnegative -> (X).  */
+(for op (abs absu)
+ (simplify
+  (op tree_expr_nonnegative_p@0)
+  @0))

Missing convert again.

Where are the testcases?

> Bootstrap and regression testing on x86_64-linux-gnu. Is this OK if no 
> regressions.

Does it mean you have run the tests or intend to run them in the future? 
It is confusing.

--
Marc Glisse