[gcc r17-1946] Match: Support unsigned scalar SAT_MUL form 14

[Pan Li via Gcc-cvs]

https://gcc.gnu.org/g:95540e74f33dad23ce29efd7dcade29fc7b2e7bf

commit r17-1946-g95540e74f33dad23ce29efd7dcade29fc7b2e7bf
Author: Pan Li <pan2...@intel.com>
Date:   Tue Jun 23 21:04:44 2026 +0800

    Match: Support unsigned scalar SAT_MUL form 14
    
    This patch would like to try to match the the unsigned
    SAT_MUL form 14, aka below
    
      #define DEF_SAT_U_MUL_FMT_14(NT, WT)             \
      NT __attribute__((noinline))                     \
      sat_u_mul_##NT##_from_##WT##_fmt_14 (NT a, NT b) \
      {                                                \
        WT x = (WT)a * (WT)b;                          \
        NT hi = x >> (sizeof(NT) * 8);                 \
        NT lo = (NT)x;                                 \
        return hi == 0 ? lo : -1;                      \
      }
    
    while WT is uint128_t, uint64_t, uint32_t and uint16_t, and
    NT is uint64_t, uint32_t, uint16_t or uint8_t.
    
    gcc/ChangeLog:
    
            * match-sat-alu.pd: Add pattern for unsigned scalar
            SAT_MUL form 14.
    
    Signed-off-by: Pan Li <pan2...@intel.com>

Diff:
---
 gcc/match-sat-alu.pd | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/gcc/match-sat-alu.pd b/gcc/match-sat-alu.pd
index 6e6fd2afda76..ede87138d495 100644
--- a/gcc/match-sat-alu.pd
+++ b/gcc/match-sat-alu.pd
@@ -569,6 +569,30 @@ along with GCC; see the file COPYING3.  If not see
       bool c2_is_type_precision_p = tree_to_uhwi (@2) == prec;
      }
      (if (c2_is_type_precision_p)))))
+  (match (unsigned_integer_sat_mul @0 @1)
+   /* SAT_U_MUL (X, Y) = {
+       WT x = (WT)a * (WT)b;
+       NT hi = x >> (sizeof(NT) * 8);
+       NT lo = (NT)x;
+       NT lo = (NT)x;
+       return hi == 0 ? lo : -1;
+      } while WT is uint128_t, uint64_t, uint32_t, uint16_t,
+       and T is uint64_t, uint32_t, uint16_t, uint8_t.  */
+   (convert (cond^ (eq (convert (rshift (mult:c@3 (convert @0) (convert @1))
+                                       INTEGER_CST@2))
+                       integer_zerop)
+                  @3 INTEGER_CST@4))
+   (if (types_match (type, @0, @1) && tree_fits_uhwi_p (@2))
+    (with
+     {
+      unsigned prec = TYPE_PRECISION (type);
+      unsigned widen_prec = TYPE_PRECISION (TREE_TYPE (@3));
+      wide_int max = wi::mask (prec, false, widen_prec);
+
+      bool c2_is_type_prec_p = tree_to_uhwi (@2) == prec;
+      bool c4_is_max_p = wi::eq_p (wi::to_wide (@4), max);
+     }
+     (if (c2_is_type_prec_p && c4_is_max_p)))))
   (match (unsigned_integer_sat_mul @0 @1)
    /* SAT_U_MUL (X, Y) = {
        WT x = (WT)a * (WT)b;