On Tue, May 28, 2024 at 10:29 AM <pan2...@intel.com> wrote:
>
> From: Pan Li <pan2...@intel.com>
>
> This patch would like to add the middle-end presentation for the
> saturation sub. Aka set the result of add to the min when downflow.
> It will take the pattern similar as below.
>
> SAT_SUB (x, y) => (x - y) & (-(TYPE)(x >= y));
>
> For example for uint8_t, we have
>
> * SAT_SUB (255, 0) => 255
> * SAT_SUB (1, 2) => 0
> * SAT_SUB (254, 255) => 0
> * SAT_SUB (0, 255) => 0
>
> Given below SAT_SUB for uint64
>
> uint64_t sat_sub_u64 (uint64_t x, uint64_t y)
> {
> return (x + y) & (- (uint64_t)((x >= y)));
> }
>
> Before this patch:
> uint64_t sat_sub_u_0_uint64_t (uint64_t x, uint64_t y)
> {
> _Bool _1;
> long unsigned int _3;
> uint64_t _6;
>
> ;; basic block 2, loop depth 0
> ;; pred: ENTRY
> _1 = x_4(D) >= y_5(D);
> _3 = x_4(D) - y_5(D);
> _6 = _1 ? _3 : 0;
> return _6;
> ;; succ: EXIT
> }
>
> After this patch:
> uint64_t sat_sub_u_0_uint64_t (uint64_t x, uint64_t y)
> {
> uint64_t _6;
>
> ;; basic block 2, loop depth 0
> ;; pred: ENTRY
> _6 = .SAT_SUB (x_4(D), y_5(D)); [tail call]
> return _6;
> ;; succ: EXIT
> }
>
> The below tests are running for this patch:
> *. The riscv fully regression tests.
> *. The x86 bootstrap tests.
> *. The x86 fully regression tests.
OK.
Thanks,
Richard.
> PR target/51492
> PR target/112600
>
> gcc/ChangeLog:
>
> * internal-fn.def (SAT_SUB): Add new IFN define for SAT_SUB.
> * match.pd: Add new match for SAT_SUB.
> * optabs.def (OPTAB_NL): Remove fixed-point for ussub/ssub.
> * tree-ssa-math-opts.cc (gimple_unsigned_integer_sat_sub): Add
> new decl for generated in match.pd.
> (build_saturation_binary_arith_call): Add new helper function
> to build the gimple call to binary SAT alu.
> (match_saturation_arith): Rename from.
> (match_unsigned_saturation_add): Rename to.
> (match_unsigned_saturation_sub): Add new func to match the
> unsigned sat sub.
> (math_opts_dom_walker::after_dom_children): Add SAT_SUB matching
> try when COND_EXPR.
>
> Signed-off-by: Pan Li <pan2...@intel.com>
> ---
> gcc/internal-fn.def | 1 +
> gcc/match.pd | 14 ++++++++
> gcc/optabs.def | 4 +--
> gcc/tree-ssa-math-opts.cc | 67 +++++++++++++++++++++++++++------------
> 4 files changed, 64 insertions(+), 22 deletions(-)
>
> diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
> index 25badbb86e5..24539716e5b 100644
> --- a/gcc/internal-fn.def
> +++ b/gcc/internal-fn.def
> @@ -276,6 +276,7 @@ DEF_INTERNAL_SIGNED_OPTAB_FN (MULHRS, ECF_CONST |
> ECF_NOTHROW, first,
> smulhrs, umulhrs, binary)
>
> DEF_INTERNAL_SIGNED_OPTAB_FN (SAT_ADD, ECF_CONST, first, ssadd, usadd,
> binary)
> +DEF_INTERNAL_SIGNED_OPTAB_FN (SAT_SUB, ECF_CONST, first, sssub, ussub,
> binary)
>
> DEF_INTERNAL_COND_FN (ADD, ECF_CONST, add, binary)
> DEF_INTERNAL_COND_FN (SUB, ECF_CONST, sub, binary)
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 024e3350465..3e334533ff8 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -3086,6 +3086,20 @@ 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 sub, case 1 (branch with gt):
> + SAT_U_SUB = X > Y ? X - Y : 0 */
> +(match (unsigned_integer_sat_sub @0 @1)
> + (cond (gt @0 @1) (minus @0 @1) integer_zerop)
> + (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
> + && types_match (type, @0, @1))))
> +
> +/* Unsigned saturation sub, case 2 (branch with ge):
> + SAT_U_SUB = X >= Y ? X - Y : 0. */
> +(match (unsigned_integer_sat_sub @0 @1)
> + (cond (ge @0 @1) (minus @0 @1) integer_zerop)
> + (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
> + && types_match (type, @0, @1))))
> +
> /* x > y && x != XXX_MIN --> x > y
> x > y && x == XXX_MIN --> false . */
> (for eqne (eq ne)
> diff --git a/gcc/optabs.def b/gcc/optabs.def
> index 3f2cb46aff8..bc2611abdc2 100644
> --- a/gcc/optabs.def
> +++ b/gcc/optabs.def
> @@ -118,8 +118,8 @@ OPTAB_NX(sub_optab, "sub$F$a3")
> OPTAB_NX(sub_optab, "sub$Q$a3")
> OPTAB_VL(subv_optab, "subv$I$a3", MINUS, "sub", '3', gen_intv_fp_libfunc)
> OPTAB_VX(subv_optab, "sub$F$a3")
> -OPTAB_NL(sssub_optab, "sssub$Q$a3", SS_MINUS, "sssub", '3',
> gen_signed_fixed_libfunc)
> -OPTAB_NL(ussub_optab, "ussub$Q$a3", US_MINUS, "ussub", '3',
> gen_unsigned_fixed_libfunc)
> +OPTAB_NL(sssub_optab, "sssub$a3", SS_MINUS, "sssub", '3',
> gen_signed_fixed_libfunc)
> +OPTAB_NL(ussub_optab, "ussub$a3", US_MINUS, "ussub", '3',
> gen_unsigned_fixed_libfunc)
> OPTAB_NL(smul_optab, "mul$Q$a3", MULT, "mul", '3', gen_int_fp_fixed_libfunc)
> OPTAB_NX(smul_optab, "mul$P$a3")
> OPTAB_NX(smul_optab, "mul$F$a3")
> diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
> index 62da1c5ee08..4717302b728 100644
> --- a/gcc/tree-ssa-math-opts.cc
> +++ b/gcc/tree-ssa-math-opts.cc
> @@ -4087,33 +4087,56 @@ arith_overflow_check_p (gimple *stmt, gimple
> *cast_stmt, gimple *&use_stmt,
> }
>
> extern bool gimple_unsigned_integer_sat_add (tree, tree*, tree (*)(tree));
> +extern bool gimple_unsigned_integer_sat_sub (tree, tree*, tree (*)(tree));
> +
> +static void
> +build_saturation_binary_arith_call (gimple_stmt_iterator *gsi, internal_fn
> fn,
> + tree lhs, tree op_0, tree op_1)
> +{
> + if (direct_internal_fn_supported_p (fn, TREE_TYPE (lhs),
> OPTIMIZE_FOR_BOTH))
> + {
> + gcall *call = gimple_build_call_internal (fn, 2, op_0, op_1);
> + gimple_call_set_lhs (call, lhs);
> + gsi_replace (gsi, call, /* update_eh_info */ true);
> + }
> +}
>
> /*
> - * Try to match saturation arith pattern(s).
> - * 1. SAT_ADD (unsigned)
> - * _7 = _4 + _6;
> - * _8 = _4 > _7;
> - * _9 = (long unsigned int) _8;
> - * _10 = -_9;
> - * _12 = _7 | _10;
> - * =>
> - * _12 = .SAT_ADD (_4, _6); */
> + * Try to match saturation unsigned add.
> + * _7 = _4 + _6;
> + * _8 = _4 > _7;
> + * _9 = (long unsigned int) _8;
> + * _10 = -_9;
> + * _12 = _7 | _10;
> + * =>
> + * _12 = .SAT_ADD (_4, _6); */
> +
> static void
> -match_saturation_arith (gimple_stmt_iterator *gsi, gassign *stmt)
> +match_unsigned_saturation_add (gimple_stmt_iterator *gsi, gassign *stmt)
> {
> - gcall *call = NULL;
> + tree ops[2];
> + tree lhs = gimple_assign_lhs (stmt);
>
> + if (gimple_unsigned_integer_sat_add (lhs, ops, NULL))
> + build_saturation_binary_arith_call (gsi, IFN_SAT_ADD, lhs, ops[0],
> ops[1]);
> +}
> +
> +/*
> + * Try to match saturation unsigned sub.
> + * _1 = _4 >= _5;
> + * _3 = _4 - _5;
> + * _6 = _1 ? _3 : 0;
> + * =>
> + * _6 = .SAT_SUB (_4, _5); */
> +
> +static void
> +match_unsigned_saturation_sub (gimple_stmt_iterator *gsi, gassign *stmt)
> +{
> tree ops[2];
> tree lhs = gimple_assign_lhs (stmt);
>
> - if (gimple_unsigned_integer_sat_add (lhs, ops, NULL)
> - && direct_internal_fn_supported_p (IFN_SAT_ADD, TREE_TYPE (lhs),
> - OPTIMIZE_FOR_BOTH))
> - {
> - call = gimple_build_call_internal (IFN_SAT_ADD, 2, ops[0], ops[1]);
> - gimple_call_set_lhs (call, lhs);
> - gsi_replace (gsi, call, true);
> - }
> + if (gimple_unsigned_integer_sat_sub (lhs, ops, NULL))
> + build_saturation_binary_arith_call (gsi, IFN_SAT_SUB, lhs, ops[0],
> ops[1]);
> }
>
> /* Recognize for unsigned x
> @@ -6078,7 +6101,7 @@ math_opts_dom_walker::after_dom_children (basic_block
> bb)
> break;
>
> case BIT_IOR_EXPR:
> - match_saturation_arith (&gsi, as_a<gassign *> (stmt));
> + match_unsigned_saturation_add (&gsi, as_a<gassign *> (stmt));
> /* fall-through */
> case BIT_XOR_EXPR:
> match_uaddc_usubc (&gsi, stmt, code);
> @@ -6089,6 +6112,10 @@ math_opts_dom_walker::after_dom_children (basic_block
> bb)
> match_single_bit_test (&gsi, stmt);
> break;
>
> + case COND_EXPR:
> + match_unsigned_saturation_sub (&gsi, as_a<gassign *> (stmt));
> + break;
> +
> default:;
> }
> }
> --
> 2.34.1
>
