On Mon, 5 Nov 2018 at 19:22, Ramana Radhakrishnan
<ramana.radhakrish...@arm.com> wrote:
>
> On 26/10/2018 06:04, Prathamesh Kulkarni wrote:
> > Hi,
> > This is a rebased version of patch that adds a pattern to neon.md for
> > implementing division with multiplication by reciprocal using
> > vrecpe/vrecps with -funsafe-math-optimizations excluding -Os.
> > The newly added test-cases are not vectorized on armeb target with
> > -O2. I posted the analysis for that here:
> > https://gcc.gnu.org/ml/gcc-patches/2016-05/msg01765.html
> >
> > Briefly, the difference between little and big-endian vectorizer is in
> > arm_builtin_support_vector_misalignment() which calls
> > default_builtin_support_vector_misalignment() for big-endian case, and
> > that returns false because
> > movmisalign_optab does not exist for V2SF mode. This isn't observed
> > with -O3 because loop peeling for alignment gets enabled.
> >
> > It seems that the test cases in patch appear unsupported on armeb,
> > after r221677 thus this patch requires no changes to
> > target-supports.exp to adjust for armeb (unlike last time which
> > stalled the patch).
> >
> > Bootstrap+tested on arm-linux-gnueabihf.
> > Cross-tested on arm*-*-* variants.
> > OK for trunk ?
> >
> > Thanks,
> > Prathamesh
> >
> >
> > tcwg-319-3.txt
> >
> > 2018-10-26 Prathamesh Kulkarni<prathamesh.kulka...@linaro.org>
> >
> > * config/arm/neon.md (div<mode>3): New pattern.
> >
> > testsuite/
> > * gcc.target/arm/neon-vect-div-1.c: New test.
> > * gcc.target/arm/neon-vect-div-2.c: Likewise.
> >
> > diff --git a/gcc/config/arm/neon.md b/gcc/config/arm/neon.md
> > index 5aeee4b08c1..25ed45d381a 100644
> > --- a/gcc/config/arm/neon.md
> > +++ b/gcc/config/arm/neon.md
> > @@ -620,6 +620,38 @@
> > (const_string "neon_mul_<V_elem_ch><q>")))]
> > )
> >
> > +/* Perform division using multiply-by-reciprocal.
> > + Reciprocal is calculated using Newton-Raphson method.
> > + Enabled with -funsafe-math-optimizations -freciprocal-math
> > + and disabled for -Os since it increases code size . */ > +
> > +(define_expand "div<mode>3"
> > + [(set (match_operand:VCVTF 0 "s_register_operand" "=w")
> > + (div:VCVTF (match_operand:VCVTF 1 "s_register_operand" "w")
> > + (match_operand:VCVTF 2 "s_register_operand" "w")))]
> > + "TARGET_NEON && !optimize_size
> > + && flag_unsafe_math_optimizations && flag_reciprocal_math"
>
> I would prefer this to be more granular than
> flag_unsafe_math_optimization && flag_reciprocal_math which really is
> flag_reciprocal_math as it is turned on by default with
> funsafe-math-optimizations.
>
> I think this should really be just flag_reciprocal_math.
>
>
> Otherwise ok.
Thanks, committed it in r265948 after removing check for
flag_unsafe_math_optimizations.
Regards,
Prathamesh
>
> regards
> Ramana
>
>
>
>
> > + {
> > + rtx rec = gen_reg_rtx (<MODE>mode);
> > + rtx vrecps_temp = gen_reg_rtx (<MODE>mode);
> > +
> > + /* Reciprocal estimate. */
> > + emit_insn (gen_neon_vrecpe<mode> (rec, operands[2]));
> > +
> > + /* Perform 2 iterations of newton-raphson method. */
> > + for (int i = 0; i < 2; i++)
> > + {
> > + emit_insn (gen_neon_vrecps<mode> (vrecps_temp, rec, operands[2]));
> > + emit_insn (gen_mul<mode>3 (rec, rec, vrecps_temp));
> > + }
> > +
> > + /* We now have reciprocal in rec, perform operands[0] = operands[1] *
> > rec. */
> > + emit_insn (gen_mul<mode>3 (operands[0], operands[1], rec));
> > + DONE;
> > + }
> > +)
> > +
> > +
> > (define_insn "mul<mode>3add<mode>_neon"
> > [(set (match_operand:VDQW 0 "s_register_operand" "=w")
> > (plus:VDQW (mult:VDQW (match_operand:VDQW 2 "s_register_operand"
> > "w")
> > diff --git a/gcc/testsuite/gcc.target/arm/neon-vect-div-1.c
> > b/gcc/testsuite/gcc.target/arm/neon-vect-div-1.c
> > new file mode 100644
> > index 00000000000..50d04b4175b
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/arm/neon-vect-div-1.c
> > @@ -0,0 +1,16 @@
> > +/* Test pattern div<mode>3. */
> > +/* { dg-do compile } */
> > +/* { dg-require-effective-target arm_neon_ok } */
> > +/* { dg-require-effective-target vect_hw_misalign } */
> > +/* { dg-options "-O2 -ftree-vectorize -funsafe-math-optimizations
> > -fdump-tree-vect-details" } */
> > +/* { dg-add-options arm_neon } */
> > +
> > +void
> > +foo (int len, float * __restrict p, float *__restrict x)
> > +{
> > + len = len & ~31;
> > + for (int i = 0; i < len; i++)
> > + p[i] = p[i] / x[i];
> > +}
> > +
> > +/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
> > diff --git a/gcc/testsuite/gcc.target/arm/neon-vect-div-2.c
> > b/gcc/testsuite/gcc.target/arm/neon-vect-div-2.c
> > new file mode 100644
> > index 00000000000..606f54b4e0e
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/arm/neon-vect-div-2.c
> > @@ -0,0 +1,16 @@
> > +/* Test pattern div<mode>3. */
> > +/* { dg-do compile } */
> > +/* { dg-require-effective-target arm_neon_ok } */
> > +/* { dg-require-effective-target vect_hw_misalign } */
> > +/* { dg-options "-O3 -ftree-vectorize -funsafe-math-optimizations
> > -fdump-tree-vect-details -fno-reciprocal-math" } */
> > +/* { dg-add-options arm_neon } */
> > +
> > +void
> > +foo (int len, float * __restrict p, float *__restrict x)
> > +{
> > + len = len & ~31;
> > + for (int i = 0; i < len; i++)
> > + p[i] = p[i] / x[i];
> > +}
> > +
> > +/* { dg-final { scan-tree-dump-not "vectorized 1 loops" "vect" } } */
> >
>
