On Mon, Oct 28, 2024 at 4:45 PM Akram Ahmad <akram.ah...@arm.com> wrote:
>
> Case 7 of unsigned scalar saturating addition defines
> SAT_ADD = X <= (X + Y) ? (X + Y) : -1. This is the same as
> SAT_ADD = Y <= (X + Y) ? (X + Y) : -1 due to usadd_left_part_1
> being commutative.
>
> The pattern for case 7 currently does not accept the alternative
> where Y is used in the condition. Therefore, this commit adds the
> commutative property to this case which causes more valid cases of
> unsigned saturating arithmetic to be recognised.
>
> Before:
> <bb 2>
> _1 = BIT_FIELD_REF <b_3(D), 8, 0>;
> sum_5 = _1 + a_4(D);
> if (a_4(D) <= sum_5)
> goto <bb 4>; [INV]
> else
> goto <bb 3>; [INV]
>
> <bb 3> :
>
> <bb 4> :
> _2 = PHI <255(3), sum_5(2)>
> return _2;
>
> After:
> <bb 2> [local count: 1073741824]:
> _1 = BIT_FIELD_REF <b_3(D), 8, 0>;
> _2 = .SAT_ADD (_1, a_4(D)); [tail call]
> return _2;
>
> This passes the aarch64-none-linux-gnu regression tests with no new
> failures. The tests written in this patch will fail on targets which
> do not implement the standard names for IFN SAT_ADD.
>
> gcc/ChangeLog:
>
> * match.pd: Modify existing case for SAT_ADD.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/sat-u-add-match-1-u16.c: New test.
> * gcc.dg/tree-ssa/sat-u-add-match-1-u32.c: New test.
> * gcc.dg/tree-ssa/sat-u-add-match-1-u64.c: New test.
> * gcc.dg/tree-ssa/sat-u-add-match-1-u8.c: New test.
> ---
> gcc/match.pd | 4 ++--
> .../gcc.dg/tree-ssa/sat-u-add-match-1-u16.c | 21 +++++++++++++++++++
> .../gcc.dg/tree-ssa/sat-u-add-match-1-u32.c | 21 +++++++++++++++++++
> .../gcc.dg/tree-ssa/sat-u-add-match-1-u64.c | 21 +++++++++++++++++++
> .../gcc.dg/tree-ssa/sat-u-add-match-1-u8.c | 21 +++++++++++++++++++
> 5 files changed, 86 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u16.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u32.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u64.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u8.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 4fc5efa6247..98c50ab097f 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -3085,7 +3085,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> /* SAT_ADD = usadd_left_part_1 | usadd_right_part_1, aka:
> SAT_ADD = (X + Y) | -((X + Y) < X) */
> (match (usadd_left_part_1 @0 @1)
> - (plus:c @0 @1)
> + (plus @0 @1)
> (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
> && types_match (type, @0, @1))))
>
> @@ -3166,7 +3166,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> /* Unsigned saturation add, case 7 (branch with le):
> SAT_ADD = x <= (X + Y) ? (X + Y) : -1. */
> (match (unsigned_integer_sat_add @0 @1)
> - (cond^ (le @0 (usadd_left_part_1@2 @0 @1)) @2 integer_minus_onep))
> + (cond^ (le @0 (usadd_left_part_1:C@2 @0 @1)) @2 integer_minus_onep))
>
> /* Unsigned saturation add, case 8 (branch with gt):
> SAT_ADD = x > (X + Y) ? -1 : (X + Y). */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u16.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u16.c
> new file mode 100644
> index 00000000000..0202c70cc83
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u16.c
> @@ -0,0 +1,21 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +#include <stdint.h>
> +
> +#define T uint16_t
> +#define UMAX (T) -1
> +
> +T sat_u_add_1 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < a ? UMAX : sum;
> +}
> +
> +T sat_u_add_2 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < b ? UMAX : sum;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " .SAT_ADD " 2 "optimized" } } */
The testcases will FAIL unless the target has support for .SAT_ADD - you want to
add proper effective target tests here.
The match.pd part looks OK to me.
Richard.
> \ No newline at end of file
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u32.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u32.c
> new file mode 100644
> index 00000000000..34c80ba3854
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u32.c
> @@ -0,0 +1,21 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +#include <stdint.h>
> +
> +#define T uint32_t
> +#define UMAX (T) -1
> +
> +T sat_u_add_1 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < a ? UMAX : sum;
> +}
> +
> +T sat_u_add_2 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < b ? UMAX : sum;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " .SAT_ADD " 2 "optimized" } } */
> \ No newline at end of file
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u64.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u64.c
> new file mode 100644
> index 00000000000..0718cb566d3
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u64.c
> @@ -0,0 +1,21 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +#include <stdint.h>
> +
> +#define T uint64_t
> +#define UMAX (T) -1
> +
> +T sat_u_add_1 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < a ? UMAX : sum;
> +}
> +
> +T sat_u_add_2 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < b ? UMAX : sum;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " .SAT_ADD " 2 "optimized" } } */
> \ No newline at end of file
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u8.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u8.c
> new file mode 100644
> index 00000000000..c3e0cc6c456
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sat-u-add-match-1-u8.c
> @@ -0,0 +1,21 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +#include <stdint.h>
> +
> +#define T uint8_t
> +#define UMAX (T) -1
> +
> +T sat_u_add_1 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < a ? UMAX : sum;
> +}
> +
> +T sat_u_add_2 (T a, T b)
> +{
> + T sum = a + b;
> + return sum < b ? UMAX : sum;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " .SAT_ADD " 2 "optimized" } } */
> \ No newline at end of file
> --
> 2.34.1
>
