[PATCH v1] Match: Support imm form for unsigned scalar .SAT_ADD

[pan2.li@intel.com]

From: Pan Li <pan2.li@intel.com>

This patch would like to support the form of unsigned scalar .SAT_ADD
when one of the op is IMM.  For example as below:

Form IMM:
  #define DEF_SAT_U_ADD_IMM_FMT_1(T)       \
  T __attribute__((noinline))              \
  sat_u_add_imm_##T##_fmt_1 (T x)          \
  {                                        \
    return (T)(x + 9) >= x ? (x + 9) : -1; \
  }

DEF_SAT_U_ADD_IMM_FMT_1(uint64_t)

Before this patch:
__attribute__((noinline))
uint64_t sat_u_add_imm_uint64_t_fmt_1 (uint64_t x)
{
  long unsigned int _1;
  uint64_t _3;

;;   basic block 2, loop depth 0
;;    pred:       ENTRY
  _1 = MIN_EXPR <x_2(D), 18446744073709551606>;
  _3 = _1 + 9;
  return _3;
;;    succ:       EXIT

}

After this patch:
__attribute__((noinline))
uint64_t sat_u_add_imm_uint64_t_fmt_1 (uint64_t x)
{
  uint64_t _3;

;;   basic block 2, loop depth 0
;;    pred:       ENTRY
  _3 = .SAT_ADD (x_2(D), 9); [tail call]
  return _3;
;;    succ:       EXIT

}

The below test suites are passed for this patch:
1. The rv64gcv fully regression test with newlib.
2. The x86 bootstrap test.
3. The x86 fully regression test.

gcc/ChangeLog:

	* match.pd: Add imm form for .SAT_ADD matching.
	* tree-ssa-math-opts.cc (math_opts_dom_walker::after_dom_children):
	Add .SAT_ADD matching under PLUS_EXPR.

Signed-off-by: Pan Li <pan2.li@intel.com>
---
 gcc/match.pd              | 22 ++++++++++++++++++++++
 gcc/tree-ssa-math-opts.cc |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/gcc/match.pd b/gcc/match.pd
index 3fa3f2e8296..d738c7ee9b4 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3154,6 +3154,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 (match (unsigned_integer_sat_add @0 @1)
  (cond^ (gt @0 (usadd_left_part_1@2 @0 @1)) integer_minus_onep @2))
 
+/* Unsigned saturation add, case 9 (one op is imm):
+   SAT_U_ADD = (X + 3) >= x ? (X + 3) : -1.  */
+(match (unsigned_integer_sat_add @0 @1)
+ (plus:c (min @0 INTEGER_CST@2) INTEGER_CST@1)
+ (with {
+   unsigned precision = TYPE_PRECISION (type);
+   wide_int cst_1 = wi::to_wide (@1, precision);
+   wide_int cst_2 = wi::to_wide (@2, precision);
+   wide_int max = wi::mask (precision, false, precision);
+   wide_int sum = wi::add (cst_1, cst_2);
+  }
+  (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
+      && types_match (type, @0, @1) && wi::eq_p (max, sum)))))
+
+/* Unsigned saturation add, case 10 (one op is imm):
+   SAT_U_ADD = __builtin_add_overflow (X, 3, &ret) == 0 ? ret : -1.  */
+(match (unsigned_integer_sat_add @0 @1)
+ (cond^ (ne (imagpart (IFN_ADD_OVERFLOW:c@2 @0 INTEGER_CST@1)) integer_zerop)
+  integer_minus_onep (realpart @2))
+  (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
+      && types_match (type, @0))))
+
 /* Unsigned saturation sub, case 1 (branch with gt):
    SAT_U_SUB = X > Y ? X - Y : 0  */
 (match (unsigned_integer_sat_sub @0 @1)
diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
index 3783a874699..3b5433ec000 100644
--- a/gcc/tree-ssa-math-opts.cc
+++ b/gcc/tree-ssa-math-opts.cc
@@ -6195,6 +6195,8 @@ math_opts_dom_walker::after_dom_children (basic_block bb)
 	      break;
 
 	    case PLUS_EXPR:
+	      match_unsigned_saturation_add (&gsi, as_a<gassign *> (stmt));
+	      /* fall-through  */
 	    case MINUS_EXPR:
 	      if (!convert_plusminus_to_widen (&gsi, stmt, code))
 		{
-- 
2.34.1