https://gcc.gnu.org/g:35f5a18872127e18aadcbbc08df7885974280c79
commit r16-2058-g35f5a18872127e18aadcbbc08df7885974280c79
Author: Pan Li <pan2...@intel.com>
Date: Wed Jul 2 09:46:08 2025 +0800
Internal-fn: Introduce new IFN_SAT_MUL for unsigned int
This patch would like to add the middle-end presentation for the
unsigend saturation mul. Aka set the result of mul to the max
when overflow.
Take uint8_t as example, we will have:
* SAT_MUL (1, 127) => 127.
* SAT_MUL (2, 127) => 254.
* SAT_MUL (3, 127) => 255.
* SAT_MUL (255, 127) => 255.
Given below example for uint16_t from uint128_t
#define DEF_SAT_U_MUL_FMT_1(NT, WT) \
NT __attribute__((noinline)) \
sat_u_mul_##NT##_from_##WT##_fmt_1 (NT a, NT b) \
{ \
WT x = (WT)a * (WT)b; \
NT max = -1; \
if (x > (WT)(max)) \
return max; \
else \
return (NT)x; \
}
DEF_SAT_U_MUL_FMT_1(uint16_t, uint128_t)
Before this patch:
15 │ <bb 2> [local count: 1073741824]:
16 │ _1 = (__int128 unsigned) a_4(D);
17 │ _2 = (__int128 unsigned) b_5(D);
18 │ _9 = (unsigned long) _1;
19 │ _10 = (unsigned long) _2;
20 │ x_6 = _9 w* _10;
21 │ _7 = MIN_EXPR <x_6, 255>;
22 │ _3 = (uint8_t) _7;
23 │ return _3;
After this patch:
9 │ <bb 2> [local count: 1073741824]:
10 │ _3 = .SAT_MUL (a_4(D), b_5(D)); [tail call]
11 │ return _3;
gcc/ChangeLog:
* internal-fn.cc (commutative_binary_fn_p): Add new case
for SAT_MUL.
* internal-fn.def (SAT_MUL): Add new IFN_SAT_MUL.
* optabs.def (OPTAB_NL): Remove fixed point limitation.
Signed-off-by: Pan Li <pan2...@intel.com>
Diff:
---
gcc/internal-fn.cc | 1 +
gcc/internal-fn.def | 1 +
gcc/optabs.def | 4 ++--
3 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc
index 39048d77d23b..ed6ef0e4c647 100644
--- a/gcc/internal-fn.cc
+++ b/gcc/internal-fn.cc
@@ -4428,6 +4428,7 @@ commutative_binary_fn_p (internal_fn fn)
case IFN_ADD_OVERFLOW:
case IFN_MUL_OVERFLOW:
case IFN_SAT_ADD:
+ case IFN_SAT_MUL:
case IFN_VEC_WIDEN_PLUS:
case IFN_VEC_WIDEN_PLUS_LO:
case IFN_VEC_WIDEN_PLUS_HI:
diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
index 8edfa3540f8c..914ee9f278cd 100644
--- a/gcc/internal-fn.def
+++ b/gcc/internal-fn.def
@@ -282,6 +282,7 @@ DEF_INTERNAL_SIGNED_OPTAB_FN (MULHRS, ECF_CONST |
ECF_NOTHROW, first,
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_SIGNED_OPTAB_FN (SAT_MUL, ECF_CONST, first, ssmul, usmul, binary)
DEF_INTERNAL_SIGNED_OPTAB_FN (SAT_TRUNC, ECF_CONST, first, sstrunc, ustrunc,
unary_convert)
diff --git a/gcc/optabs.def b/gcc/optabs.def
index 0c1435d4ecd7..87a8b85da159 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -134,8 +134,8 @@ OPTAB_NX(smul_optab, "mul$P$a3")
OPTAB_NX(smul_optab, "mul$F$a3")
OPTAB_VL(smulv_optab, "mulv$I$a3", MULT, "mul", '3', gen_intv_fp_libfunc)
OPTAB_VX(smulv_optab, "mul$F$a3")
-OPTAB_NL(ssmul_optab, "ssmul$Q$a3", SS_MULT, "ssmul", '3',
gen_signed_fixed_libfunc)
-OPTAB_NL(usmul_optab, "usmul$Q$a3", US_MULT, "usmul", '3',
gen_unsigned_fixed_libfunc)
+OPTAB_NL(ssmul_optab, "ssmul$a3", SS_MULT, "ssmul", '3',
gen_signed_fixed_libfunc)
+OPTAB_NL(usmul_optab, "usmul$a3", US_MULT, "usmul", '3',
gen_unsigned_fixed_libfunc)
OPTAB_NL(sdiv_optab, "div$a3", DIV, "div", '3',
gen_int_fp_signed_fixed_libfunc)
OPTAB_VL(sdivv_optab, "divv$I$a3", DIV, "divv", '3', gen_int_libfunc)
OPTAB_VX(sdivv_optab, "div$F$a3")
