On Thu, May 24, 2018 at 10:07 AM Richard Sandiford <
richard.sandif...@linaro.org> wrote:
> The folds in r260348 kicked in before vectorisation, which hurts
> for two reasons:
> (1) the current suboptimal handling of nothrow meant that we could
> drop the flag early and so prevent if-conversion
> (2) some architectures provide more scalar forms than vector forms
> (true for Advanced SIMD)
> (1) is a bug in itself that needs to be fixed eventually, but delaying
> the folds is still needed for (2).
> Tested on aarch64-linux-gnu (with and without SVE), aarch64_be-elf
> and x86_64-linux-gnu. OK to install?
OK.
Richard.
> (Patch is mostly just reindent.)
> Richard
> 2018-05-24 Richard Sandiford <richard.sandif...@linaro.org>
> gcc/
> * match.pd: Delay FMA folds until after vectorization.
> gcc/testsuite/
> * gcc.dg/vect/vect-fma-1.c: New test.
> Index: gcc/match.pd
> ===================================================================
> --- gcc/match.pd 2018-05-18 09:26:37.735714314 +0100
> +++ gcc/match.pd 2018-05-24 09:05:10.432158893 +0100
> @@ -4703,59 +4703,60 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> wi::to_wide (@ipos) + isize))
> (BIT_FIELD_REF @0 @rsize @rpos)))))
> -(for fmas (FMA)
> +(if (canonicalize_math_after_vectorization_p ())
> + (for fmas (FMA)
> + (simplify
> + (fmas:c (negate @0) @1 @2)
> + (IFN_FNMA @0 @1 @2))
> + (simplify
> + (fmas @0 @1 (negate @2))
> + (IFN_FMS @0 @1 @2))
> + (simplify
> + (fmas:c (negate @0) @1 (negate @2))
> + (IFN_FNMS @0 @1 @2))
> + (simplify
> + (negate (fmas@3 @0 @1 @2))
> + (if (single_use (@3))
> + (IFN_FNMS @0 @1 @2))))
> +
> + (simplify
> + (IFN_FMS:c (negate @0) @1 @2)
> + (IFN_FNMS @0 @1 @2))
> (simplify
> - (fmas:c (negate @0) @1 @2)
> + (IFN_FMS @0 @1 (negate @2))
> + (IFN_FMA @0 @1 @2))
> + (simplify
> + (IFN_FMS:c (negate @0) @1 (negate @2))
> (IFN_FNMA @0 @1 @2))
> (simplify
> - (fmas @0 @1 (negate @2))
> - (IFN_FMS @0 @1 @2))
> + (negate (IFN_FMS@3 @0 @1 @2))
> + (if (single_use (@3))
> + (IFN_FNMA @0 @1 @2)))
> +
> + (simplify
> + (IFN_FNMA:c (negate @0) @1 @2)
> + (IFN_FMA @0 @1 @2))
> (simplify
> - (fmas:c (negate @0) @1 (negate @2))
> + (IFN_FNMA @0 @1 (negate @2))
> (IFN_FNMS @0 @1 @2))
> (simplify
> - (negate (fmas@3 @0 @1 @2))
> + (IFN_FNMA:c (negate @0) @1 (negate @2))
> + (IFN_FMS @0 @1 @2))
> + (simplify
> + (negate (IFN_FNMA@3 @0 @1 @2))
> (if (single_use (@3))
> - (IFN_FNMS @0 @1 @2))))
> + (IFN_FMS @0 @1 @2)))
> -(simplify
> - (IFN_FMS:c (negate @0) @1 @2)
> - (IFN_FNMS @0 @1 @2))
> -(simplify
> - (IFN_FMS @0 @1 (negate @2))
> - (IFN_FMA @0 @1 @2))
> -(simplify
> - (IFN_FMS:c (negate @0) @1 (negate @2))
> - (IFN_FNMA @0 @1 @2))
> -(simplify
> - (negate (IFN_FMS@3 @0 @1 @2))
> + (simplify
> + (IFN_FNMS:c (negate @0) @1 @2)
> + (IFN_FMS @0 @1 @2))
> + (simplify
> + (IFN_FNMS @0 @1 (negate @2))
> + (IFN_FNMA @0 @1 @2))
> + (simplify
> + (IFN_FNMS:c (negate @0) @1 (negate @2))
> + (IFN_FMA @0 @1 @2))
> + (simplify
> + (negate (IFN_FNMS@3 @0 @1 @2))
> (if (single_use (@3))
> - (IFN_FNMA @0 @1 @2)))
> -
> -(simplify
> - (IFN_FNMA:c (negate @0) @1 @2)
> - (IFN_FMA @0 @1 @2))
> -(simplify
> - (IFN_FNMA @0 @1 (negate @2))
> - (IFN_FNMS @0 @1 @2))
> -(simplify
> - (IFN_FNMA:c (negate @0) @1 (negate @2))
> - (IFN_FMS @0 @1 @2))
> -(simplify
> - (negate (IFN_FNMA@3 @0 @1 @2))
> - (if (single_use (@3))
> - (IFN_FMS @0 @1 @2)))
> -
> -(simplify
> - (IFN_FNMS:c (negate @0) @1 @2)
> - (IFN_FMS @0 @1 @2))
> -(simplify
> - (IFN_FNMS @0 @1 (negate @2))
> - (IFN_FNMA @0 @1 @2))
> -(simplify
> - (IFN_FNMS:c (negate @0) @1 (negate @2))
> - (IFN_FMA @0 @1 @2))
> -(simplify
> - (negate (IFN_FNMS@3 @0 @1 @2))
> - (if (single_use (@3))
> - (IFN_FMA @0 @1 @2)))
> + (IFN_FMA @0 @1 @2))))
> Index: gcc/testsuite/gcc.dg/vect/vect-fma-1.c
> ===================================================================
> --- /dev/null 2018-04-20 16:19:46.369131350 +0100
> +++ gcc/testsuite/gcc.dg/vect/vect-fma-1.c 2018-05-24
09:05:10.432158893 +0100
> @@ -0,0 +1,58 @@
> +/* { dg-require-effective-target scalar_all_fma } */
> +
> +#include "tree-vect.h"
> +
> +#define N (VECTOR_BITS * 11 / 64 + 3)
> +
> +#define DEF(INV) \
> + void __attribute__ ((noipa)) \
> + f_##INV (double *restrict a, double *restrict b, \
> + double *restrict c, double *restrict d) \
> + { \
> + for (int i = 0; i < N; ++i) \
> + { \
> + double mb = (INV & 1 ? -b[i] : b[i]); \
> + double mc = c[i]; \
> + double md = (INV & 2 ? -d[i] : d[i]); \
> + double fma = __builtin_fma (mb, mc, md); \
> + a[i] = (INV & 4 ? -fma : fma); \
> + } \
> + }
> +
> +#define TEST(INV) \
> + { \
> + f_##INV (a, b, c, d); \
> + for (int i = 0; i < N; ++i) \
> + { \
> + double mb = (INV & 1 ? -b[i] : b[i]); \
> + double mc = c[i]; \
> + double md = (INV & 2 ? -d[i] : d[i]); \
> + double fma = __builtin_fma (mb, mc, md); \
> + double expected = (INV & 4 ? -fma : fma); \
> + if (a[i] != expected) \
> + __builtin_abort (); \
> + asm volatile ("" ::: "memory"); \
> + } \
> + }
> +
> +#define FOR_EACH_INV(T) \
> + T (0) T (1) T (2) T (3) T (4) T (5) T (6) T (7)
> +
> +FOR_EACH_INV (DEF)
> +
> +int
> +main (void)
> +{
> + double a[N], b[N], c[N], d[N];
> + for (int i = 0; i < N; ++i)
> + {
> + b[i] = i % 17;
> + c[i] = i % 9 + 11;
> + d[i] = i % 13 + 14;
> + asm volatile ("" ::: "memory");
> + }
> + FOR_EACH_INV (TEST)
> + return 0;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "LOOP VECTORIZED" 8 "vect" { target
vect_double } } } */
