On Mon, Jun 17, 2024 at 3:41 AM <pan2...@intel.com> wrote:
>
> From: Pan Li <pan2...@intel.com>
>
> When investigate the vectorization of .SAT_ADD, we notice there
> are additional 2 forms, aka form 7 and 8 for .SAT_ADD.
>
> Form 7:
> #define DEF_SAT_U_ADD_FMT_7(T) \
> T __attribute__((noinline)) \
> sat_u_add_##T##_fmt_7 (T x, T y) \
> { \
> return x > (T)(x + y) ? -1 : (x + y); \
> }
>
> Form 8:
> #define DEF_SAT_U_ADD_FMT_8(T) \
> T __attribute__((noinline)) \
> sat_u_add_##T##_fmt_8 (T x, T y) \
> { \
> return x <= (T)(x + y) ? (x + y) : -1; \
> }
>
> Thus, add above 2 forms to the match gimple_unsigned_integer_sat_add,
> and then the vectorizer can try to recog the pattern like form 7 and
> form 8.
>
> The below test suites are passed for this patch:
> 1. The rv64gcv fully regression test with newlib.
> 2. The rv64gcv build with glibc.
> 3. The x86 bootstrap test.
> 4. The x86 fully regression test.
OK.
Note that fold-const.cc has canonicalization for the minus one to be put last:
/* If the second operand is simpler than the third, swap them
since that produces better jump optimization results. */
if (truth_value_p (TREE_CODE (arg0))
&& tree_swap_operands_p (op1, op2))
{
location_t loc0 = expr_location_or (arg0, loc);
/* See if this can be inverted. If it can't, possibly because
it was a floating-point inequality comparison, don't do
anything. */
tem = fold_invert_truthvalue (loc0, arg0);
if (tem)
return fold_build3_loc (loc, code, type, tem, op2, op1);
we might want to consider such transform in match.pd, in this case this
would allow to elide one of the patterns.
Richard.
> gcc/ChangeLog:
>
> * match.pd: Add form 7 and 8 for the unsigned .SAT_ADD match.
>
> Signed-off-by: Pan Li <pan2...@intel.com>
> ---
> gcc/match.pd | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 99968d316ed..aae6d30a5e4 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -3144,6 +3144,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (cond^ (ne (imagpart (IFN_ADD_OVERFLOW:c @0 @1)) integer_zerop)
> integer_minus_onep (usadd_left_part_2 @0 @1)))
>
> +/* 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))
> +
> +/* Unsigned saturation add, case 8 (branch with gt):
> + SAT_ADD = x > (X + Y) ? -1 : (X + Y). */
> +(match (unsigned_integer_sat_add @0 @1)
> + (cond^ (gt @0 (usadd_left_part_1@2 @0 @1)) integer_minus_onep @2))
> +
> /* Unsigned saturation sub, case 1 (branch with gt):
> SAT_U_SUB = X > Y ? X - Y : 0 */
> (match (unsigned_integer_sat_sub @0 @1)
> --
> 2.34.1
>
