Hi Richard,
Thanks for your comments and tips. fold_binary_op_with_conditional_arg performs
the reverse transformation to this patch in certain situations:
/* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
... */
static tree
fold_binary_op_with_conditional_arg (location_t loc,
...
/* This transformation is only worthwhile if we don't have to wrap ARG
in a SAVE_EXPR and the operation can be simplified without recursing
on at least one of the branches once its pushed inside the COND_EXPR. */
if (!TREE_CONSTANT (arg)
&& (TREE_SIDE_EFFECTS (arg) ...)
return NULL_TREE;
...
For instance, this causes infinite recursion in
gcc.dg/vect/fast-math-vect-call-2 because ARG is a float literal.
Regards,
Yuliang
-----Original Message-----
From: Richard Biener <richard.guent...@gmail.com>
Sent: 20 September 2019 13:02
To: Yuliang Wang <yuliang.w...@arm.com>
Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>; Richard Sandiford
<richard.sandif...@arm.com>
Subject: Re: [PATCH] Reduction of conditional operations for vectorization
On Fri, Sep 20, 2019 at 10:09 AM Yuliang Wang <yuliang.w...@arm.com> wrote:
>
> Hi,
>
> ifcvt transforms the following conditional operation reduction pattern:
>
> if ( condition )
> a = a OP b;
> else
> a = a OP c;
>
> Into:
>
> a_1 = a OP b;
> a_2 = a OP c;
> a = condition ? a_1 : a_2;
>
> Where OP is one of { plus minus mult min max and ior eor }.
>
> This patch further optimizes the above to:
>
> a_0 = condition ? b : c;
> a = a OP a_0;
>
> Which enables vectorization on AArch64.
> Also supported are permutations of the above operand ordering subject to
> commutativity of OP.
>
> Added new tests. Built and regression tested on aarch64-none-elf and
> aarch64-linux-gnu.
@@ -3206,7 +3206,41 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* !A ? B : C -> A ? C : B. */
(simplify
(cnd (logical_inverted_value truth_valued_p@0) @1 @2)
- (cnd @0 @2 @1)))
+ (cnd @0 @2 @1))
+
+ /* !A ? B : C -> A ? C : B. */
+ (simplify
+ (cnd (logical_inverted_value truth_valued_p@0) @1 @2) (cnd @0 @2
+ @1))
+
looks like you duplicate the above pattern. Should have raised a warning in
the genmatch run.
The patch header shows you are not working against trunk?
+ (for op (plus minus mult
+ min max
+ bit_and bit_ior bit_xor)
+ (simplify
+ (cnd @0 (op @1 @2) (op @1 @3))
+ (op @1 (cnd @0 @2 @3)))
+ (simplify
+ (cnd @0 (op @1 @2) (op @3 @2))
+ (op (cnd @0 @1 @3) @2))
+ (if (op != MINUS_EXPR)
+ (simplify
+ (cnd @0 (op @1 @2) (op @3 @1))
+ (op @1 (cnd @0 @2 @3)))
+ (simplify
+ (cnd @0 (op @2 @1) (op @1 @3))
+ (op @1 (cnd @0 @2 @3)))))
if you would have dropped minus handling this simplifies to
(for op (...)
(simpify
(cnd @0 (op:c @1 @2) (op:c @1 @3))
(op @1 (cnd @0 @2 @3)))
you can then add minus special-cases if they are important
(simplify
(cnd @0 (minus @1 @2) (minus @1 @3))
...
(simplify
(cnd @0 (minus @2 @1) (minus @3 @1))
I think that's clearer.
+ /* Hack: generic-match causes infinite recursion
+ by reverting this transformation when
+ i) -fno-trapping-math is enabled, and
+ ii) the common operand does not need to be wrapped in a SAVE_EXPR.
+ */
What's the specific transform that causes this? Yes, there are some left in
fold-const.c.
Thanks,
Richard.
> Best Regards,
> Yuliang Wang
>
>
> gcc/ChangeLog:
>
> 2019-09-19 Yuliang Wang <yuliang.w...@arm.com>
>
> * match.pd (for cnd (cond vec_cond)): New match statements for the
> above patterns.
> * doc/sourcebuild.texi (vect_condred_si): Document new target
> selector.
>
> gcc/testsuite/ChangeLog:
>
> 2019-09-19 Yuliang Wang <yuliang.w...@arm.com>
>
> * gcc.target/aarch64/sve2/condred_1.c: New test.
> * gcc.dg/vect/vect-condred-1.c: As above.
> * gcc.dg/vect/vect-condred-2.c: As above.
> * gcc.dg/vect/vect-condred-3.c: As above.
> * gcc.dg/vect/vect-condred-4.c: As above.
> * gcc.dg/vect/vect-condred-5.c: As above.
> * gcc.dg/vect/vect-condred-6.c: As above.
> * gcc.dg/vect/vect-condred-7.c: As above.
> * gcc.dg/vect/vect-condred-8.c: As above.
> * lib/target-supports.exp (check_effective_target_vect_condred_si):
> Return true for AArch64 without SVE.
