> On Thu, Nov 14, 2024 at 11:59 AM Eikansh Gupta
> <quic_eikag...@quicinc.com> wrote:
> >
> > This patch simplify `(trunc)copysign ((extend)x, CST)` to `copysign
> > (x, -1.0/1.0)` depending on the sign of CST. Previously, it was simplified
> > to
> `copysign (x, CST)`.
> > It can be optimized as the sign of the CST matters, not the value.
> >
> > The patch also simplify `(trunc)abs (extend x)` to `abs (x)`.
>
> Please do not mix two different changes.
The second change is needed because at match.pd:1198, copysign(x, +ve CST) is
converted to abs(x).
>
> > PR tree-optimization/112472
> >
> > gcc/ChangeLog:
> >
> > * match.pd ((trunc)copysign ((extend)x, -CST) --> copysign (x,
> > -1.0)):
> New pattern.
> > ((trunc)abs (extend x) --> abs (x)): New pattern.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.dg/tree-ssa/pr112472.c: New test.
> >
> > Signed-off-by: Eikansh Gupta <quic_eikag...@quicinc.com>
> > ---
> > gcc/match.pd | 25 +++++++++++++++++++-----
> > gcc/testsuite/gcc.dg/tree-ssa/pr112472.c | 22 +++++++++++++++++++++
> > 2 files changed, 42 insertions(+), 5 deletions(-) create mode 100644
> > gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd index
> > 00988241348..5b930beb418 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -8854,19 +8854,34 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> > type, OPTIMIZE_FOR_BOTH))
> > (tos @0))))
> >
> > -/* Simplify (trunc)copysign ((extend)x, (extend)y) to copysignf (x, y),
> > - x,y is float value, similar for _Float16/double. */
> > +/* Simplify (trunc)copysign ((extend)x, (extend)y) to copysignf (x, y) and
> > + simplify (trunc)copysign ((extend)x, CST) to copysign (x, -1.0/1.0).
> > + x,y is float value, similar for _Float16/double. */
> > (for copysigns (COPYSIGN_ALL)
> > (simplify
> > - (convert (copysigns (convert@2 @0) (convert @1)))
> > + (convert (copysigns (convert@2 @0) (convert2? @1)))
>
> You want to capture convert2? with @3
>
> > (if (optimize
> > && !HONOR_SNANS (@2)
> > && types_match (type, TREE_TYPE (@0))
> > - && types_match (type, TREE_TYPE (@1))
> > && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (@2))
> > && direct_internal_fn_supported_p (IFN_COPYSIGN,
> > type, OPTIMIZE_FOR_BOTH))
> > - (IFN_COPYSIGN @0 @1))))
> > + (if (TREE_CODE (@1) == REAL_CST)
>
> and check TREE_CODE (@3) == REAL_CST, we might not always fold a
> conversion of a FP constant.
A basic question here. When do we not fold this type of conversion?
> > + (if (REAL_VALUE_NEGATIVE (TREE_REAL_CST (@1)))
> > + (IFN_COPYSIGN @0 { build_minus_one_cst (type); })
> > + (IFN_COPYSIGN @0 { build_one_cst (type); }))
Should I remove the above line as copysign(x, +ve CST) is converted to abs(x)?
> > + (if (types_match (type, TREE_TYPE (@1)))
> > + (IFN_COPYSIGN @0 @1))))))
> > +
> > +/* (trunc)abs (extend x) --> abs (x)
> > + x is a float value */
> > +(simplify
> > + (convert (abs (convert@1 @0)))
> > + (if (optimize
> > + && !HONOR_SNANS (@1)
> > + && types_match (type, TREE_TYPE (@0))
> > + && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (@1)))
> > + (abs @0)))
>
> This one is OK, but I don't see a testcase? Please split it out to a
> separate patch
> and add one.
The second testcase is for this change. I will split it into separate patch.
>
> Richard.
Regards,
Eikansh
