Richard Sandiford <richard.sandif...@arm.com> writes:
> Marc Glisse <marc.gli...@inria.fr> writes:
>> On Thu, 15 Oct 2015, Richard Sandiford wrote:
>>
>>> This patch makes sure that, for every simplification that uses
>>> fold_strip_sign_ops, there are associated match.pd rules for the
>>> leaf sign ops, i.e. abs, negate and copysign. A follow-on patch
>>> will add a pass to handle more complex cases.
>>>
>>> Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi.
>>> OK to install?
>>>
>>> Thanks,
>>> Richard
>>>
>>>
>>> gcc/
>>> * match.pd: Add rules to simplify ccos, ccosh, hypot, copysign
>>> and x*x in cases where the operands are sign ops. Extend these
>>> rules to handle copysign as a sign op (including for cos, cosh
>>> and pow, which already treated negate and abs as sign ops).
>>>
>>> diff --git a/gcc/match.pd b/gcc/match.pd
>>> index 83c48cd..4331df6 100644
>>> --- a/gcc/match.pd
>>> +++ b/gcc/match.pd
>>> @@ -61,6 +61,12 @@ along with GCC; see the file COPYING3. If not see
>>> (define_operator_list TAN BUILT_IN_TANF BUILT_IN_TAN BUILT_IN_TANL)
>>> (define_operator_list COSH BUILT_IN_COSHF BUILT_IN_COSH BUILT_IN_COSHL)
>>> (define_operator_list CEXPI BUILT_IN_CEXPIF BUILT_IN_CEXPI BUILT_IN_CEXPIL)
>>> +(define_operator_list CCOS BUILT_IN_CCOSF BUILT_IN_CCOS BUILT_IN_CCOSL)
>>> +(define_operator_list CCOSH BUILT_IN_CCOSHF BUILT_IN_CCOSH BUILT_IN_CCOSHL)
>>> +(define_operator_list HYPOT BUILT_IN_HYPOTF BUILT_IN_HYPOT BUILT_IN_HYPOTL)
>>> +(define_operator_list COPYSIGN BUILT_IN_COPYSIGNF
>>> + BUILT_IN_COPYSIGN
>>> + BUILT_IN_COPYSIGNL)
>>>
>>> /* Simplifications of operations with one constant operand and
>>> simplifications to constants or single values. */
>>> @@ -321,7 +327,69 @@ along with GCC; see the file COPYING3. If not see
>>> (pows (op @0) REAL_CST@1)
>>> (with { HOST_WIDE_INT n; }
>>> (if (real_isinteger (&TREE_REAL_CST (@1), &n) && (n & 1) == 0)
>>> - (pows @0 @1))))))
>>> + (pows @0 @1)))))
>>> + /* Strip negate and abs from both operands of hypot. */
>>> + (for hypots (HYPOT)
>>> + (simplify
>>> + (hypots (op @0) @1)
>>> + (hypots @0 @1))
>>> + (simplify
>>> + (hypots @0 (op @1))
>>> + (hypots @0 @1)))
>>
>> Out of curiosity, would hypots:c have worked? (it is probably not worth
>> gratuitously swapping the operands to save 3 lines though)
>
> Yeah, I think I'd prefer to keep it like it is if that's OK.
>
>>> + /* copysign(-x, y) and copysign(abs(x), y) -> copysign(x, y). */
>>> + (for copysigns (COPYSIGN)
>>> + (simplify
>>> + (copysigns (op @0) @1)
>>> + (copysigns @0 @1)))
>>> + /* -x*-x and abs(x)*abs(x) -> x*x. Should be valid for all types. */
>>> + (simplify
>>> + (mult (op @0) (op @1))
>>> + (mult @0 @0)))
>>
>> Typo @1 -> @0 ?
>
> Argh! Thanks for catching that. Wonder how many proof-reads that
> escaped :-(
>
>> This will partially duplicate Naveen's patch "Move some bit and binary
>> optimizations in simplify and match".
>
> OK. Should I just limit it to the abs case?
>
>>> +/* copysign(x,y)*copysign(x,y) -> x*x. */
>>> +(for copysigns (COPYSIGN)
>>> + (simplify
>>> + (mult (copysigns @0 @1) (copysigns @0 @1))
>>
>> (mult (copysigns@2 @0 @1) @2)
>> ? Or is there some reason not to rely on CSE? (I don't think copysign has
>> any errno issue)
>
> No, simply didn't know about that trick. I'll use it for the
> (mult (op @0) (op @0)) case as well.
Here's the updated patch. I've kept the (mult (negate@1 @0) @1)
pattern for now, but can limit it to abs as necessary when
Naveen's patch goes in.
Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi.
Thanks,
Richard
