On Thu, Oct 24, 2024 at 4:08 PM <pan2...@intel.com> wrote:
>
> From: Pan Li <pan2...@intel.com>
>
> There are sorts of forms for the unsigned SAT_ADD. Some of them are
> complicated while others are cheap. This patch would like to simplify
> the complicated form into the cheap ones. For example as below:
>
> From the form 3 (branch):
> SAT_U_ADD = (X + Y) >= x ? (X + Y) : -1.
>
> To (branchless):
> SAT_U_ADD = (X + Y) | - ((X + Y) < X).
>
> #define T uint8_t
>
> T sat_add_u_1 (T x, T y)
> {
> return (T)(x + y) >= x ? (x + y) : -1;
> }
>
> Before this patch:
> 1 │ uint8_t sat_add_u_1 (uint8_t x, uint8_t y)
> 2 │ {
> 3 │ uint8_t D.2809;
> 4 │
> 5 │ _1 = x + y;
> 6 │ if (x <= _1) goto <D.2810>; else goto <D.2811>;
> 7 │ <D.2810>:
> 8 │ D.2809 = x + y;
> 9 │ goto <D.2812>;
> 10 │ <D.2811>:
> 11 │ D.2809 = 255;
> 12 │ <D.2812>:
> 13 │ return D.2809;
> 14 │ }
>
> After this patch:
> 1 │ uint8_t sat_add_u_1 (uint8_t x, uint8_t y)
> 2 │ {
> 3 │ uint8_t D.2809;
> 4 │
> 5 │ _1 = x + y;
> 6 │ _2 = x + y;
> 7 │ _3 = x > _2;
> 8 │ _4 = (unsigned char) _3;
> 9 │ _5 = -_4;
> 10 │ D.2809 = _1 | _5;
> 11 │ return D.2809;
> 12 │ }
>
> The simplify doesn't need to check if target support the SAT_ADD, it
> is somehow the optimization in gimple level.
>
> The below test suites are passed for this patch.
> * The rv64gcv fully regression test.
> * The x86 bootstrap test.
> * The x86 fully regression test.
OK.
Richard.
> gcc/ChangeLog:
>
> * match.pd: Remove unsigned branch form 3 for SAT_ADD, and
> add simplify to branchless instead.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/sat_u_add-simplify-1-u16.c: New test.
> * gcc.dg/tree-ssa/sat_u_add-simplify-1-u32.c: New test.
> * gcc.dg/tree-ssa/sat_u_add-simplify-1-u64.c: New test.
> * gcc.dg/tree-ssa/sat_u_add-simplify-1-u8.c: New test.
>
> Signed-off-by: Pan Li <pan2...@intel.com>
> ---
> gcc/match.pd | 11 +++++++----
> .../gcc.dg/tree-ssa/sat_u_add-simplify-1-u16.c | 15 +++++++++++++++
> .../gcc.dg/tree-ssa/sat_u_add-simplify-1-u32.c | 15 +++++++++++++++
> .../gcc.dg/tree-ssa/sat_u_add-simplify-1-u64.c | 15 +++++++++++++++
> .../gcc.dg/tree-ssa/sat_u_add-simplify-1-u8.c | 15 +++++++++++++++
> 5 files changed, 67 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u16.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u32.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u64.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u8.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 0455dfa6993..0ecd44bd51a 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -3141,10 +3141,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (match (unsigned_integer_sat_add @0 @1)
> (bit_ior:c (usadd_left_part_2 @0 @1) (usadd_right_part_2 @0 @1)))
>
> -/* Unsigned saturation add, case 3 (branch with ge):
> - SAT_U_ADD = (X + Y) >= x ? (X + Y) : -1. */
> -(match (unsigned_integer_sat_add @0 @1)
> - (cond^ (ge (usadd_left_part_1@2 @0 @1) @0) @2 integer_minus_onep))
> +/* Simplify SAT_U_ADD to the cheap form
> + From: SAT_U_ADD = (X + Y) >= x ? (X + Y) : -1.
> + To: SAT_U_ADD = (X + Y) | - ((X + Y) < X). */
> +(simplify (cond (ge (plus:c@2 @0 @1) @0) @2 integer_minus_onep)
> + (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
> + && types_match (type, @0, @1))
> + (bit_ior @2 (negate (convert (lt @2 @0))))))
>
> /* Unsigned saturation add, case 4 (branch with lt):
> SAT_U_ADD = (X + Y) < x ? -1 : (X + Y). */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u16.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u16.c
> new file mode 100644
> index 00000000000..7617fbaca45
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u16.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-gimple-details" } */
> +
> +#include <stdint.h>
> +
> +#define T uint16_t
> +
> +T sat_add_u_1 (T x, T y)
> +{
> + return (T)(x + y) >= x ? (x + y) : -1;
> +}
> +
> +/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u32.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u32.c
> new file mode 100644
> index 00000000000..efea85bfbb7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u32.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-gimple-details" } */
> +
> +#include <stdint.h>
> +
> +#define T uint32_t
> +
> +T sat_add_u_1 (T x, T y)
> +{
> + return (T)(x + y) >= x ? (x + y) : -1;
> +}
> +
> +/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u64.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u64.c
> new file mode 100644
> index 00000000000..b7b55d72ede
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u64.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-gimple-details" } */
> +
> +#include <stdint.h>
> +
> +#define T uint64_t
> +
> +T sat_add_u_1 (T x, T y)
> +{
> + return (T)(x + y) >= x ? (x + y) : -1;
> +}
> +
> +/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u8.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u8.c
> new file mode 100644
> index 00000000000..77e9af3dd29
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat_u_add-simplify-1-u8.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-gimple-details" } */
> +
> +#include <stdint.h>
> +
> +#define T uint8_t
> +
> +T sat_add_u_1 (T x, T y)
> +{
> + return (T)(x + y) >= x ? (x + y) : -1;
> +}
> +
> +/* { dg-final { scan-tree-dump-not " if " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " else " "gimple" } } */
> +/* { dg-final { scan-tree-dump-not " goto " "gimple" } } */
> --
> 2.43.0
>
