Match: Support form 1 for scalar signed integer .SAT_ADD

This patch would like to support the form 1 of the scalar signed
integer .SAT_ADD.  Aka below example:

Form 1:
  #define DEF_SAT_S_ADD_FMT_1(T, UT, MIN, MAX) \
  T __attribute__((noinline))                  \
  sat_s_add_##T##_fmt_1 (T x, T y)             \
  {                                            \
    T sum = (UT)x + (UT)y;                     \
    return (x ^ y) < 0                         \
      ? sum                                    \
      : (sum ^ x) >= 0                         \
        ? sum                                  \
        : x < 0 ? MIN : MAX;                   \
  }

DEF_SAT_S_ADD_FMT_1(int64_t, uint64_t, INT64_MIN, INT64_MAX)

We can tell the difference before and after this patch if backend
implemented the ssadd<m>3 pattern similar as below.

Before this patch:
   4   │ __attribute__((noinline))
   5   │ int64_t sat_s_add_int64_t_fmt_1 (int64_t x, int64_t y)
   6   │ {
   7   │   int64_t sum;
   8   │   long unsigned int x.0_1;
   9   │   long unsigned int y.1_2;
  10   │   long unsigned int _3;
  11   │   long int _4;
  12   │   long int _5;
  13   │   int64_t _6;
  14   │   _Bool _11;
  15   │   long int _12;
  16   │   long int _13;
  17   │   long int _14;
  18   │   long int _16;
  19   │   long int _17;
  20   │
  21   │ ;;   basic block 2, loop depth 0
  22   │ ;;    pred:       ENTRY
  23   │   x.0_1 = (long unsigned int) x_7(D);
  24   │   y.1_2 = (long unsigned int) y_8(D);
  25   │   _3 = x.0_1 + y.1_2;
  26   │   sum_9 = (int64_t) _3;
  27   │   _4 = x_7(D) ^ y_8(D);
  28   │   _5 = x_7(D) ^ sum_9;
  29   │   _17 = ~_4;
  30   │   _16 = _5 & _17;
  31   │   if (_16 < 0)
  32   │     goto <bb 3>; [41.00%]
  33   │   else
  34   │     goto <bb 4>; [59.00%]
  35   │ ;;    succ:       3
  36   │ ;;                4
  37   │
  38   │ ;;   basic block 3, loop depth 0
  39   │ ;;    pred:       2
  40   │   _11 = x_7(D) < 0;
  41   │   _12 = (long int) _11;
  42   │   _13 = -_12;
  43   │   _14 = _13 ^ 9223372036854775807;
  44   │ ;;    succ:       4
  45   │
  46   │ ;;   basic block 4, loop depth 0
  47   │ ;;    pred:       2
  48   │ ;;                3
  49   │   # _6 = PHI <sum_9(2), _14(3)>
  50   │   return _6;
  51   │ ;;    succ:       EXIT
  52   │
  53   │ }

After this patch:
   4   │ __attribute__((noinline))
   5   │ int64_t sat_s_add_int64_t_fmt_1 (int64_t x, int64_t y)
   6   │ {
   7   │   int64_t _4;
   8   │
   9   │ ;;   basic block 2, loop depth 0
  10   │ ;;    pred:       ENTRY
  11   │   _4 = .SAT_ADD (x_5(D), y_6(D)); [tail call]
  12   │   return _4;
  13   │ ;;    succ:       EXIT
  14   │
  15   │ }

The below test suites are passed for this patch.
* The rv64gcv fully regression test.
* The x86 bootstrap test.
* The x86 fully regression test.

gcc/ChangeLog:

	* match.pd: Add the matching for signed .SAT_ADD.
	* tree-ssa-math-opts.cc (gimple_signed_integer_sat_add): Add new
	matching func decl.
	(match_unsigned_saturation_add): Try signed .SAT_ADD and rename
	to ...
	(match_saturation_add): ... here.
	(math_opts_dom_walker::after_dom_children): Update the above renamed
	func from caller.

Signed-off-by: Pan Li <pan2.li@intel.com>

2 files changed, 45 insertions, 5 deletions

diff --git a/gcc/match.pd b/gcc/match.pd
index 5ee6096..be21153 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3192,6 +3192,21 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
        && types_match (type, @0) && int_fits_type_p (@1, type))))
 
+/* Signed saturation add, case 1:
+   T sum = (T)((UT)X + (UT)Y)
+   SAT_S_ADD = (X ^ sum) & !(X ^ Y) < 0 ? (-(T)(X < 0) ^ MAX) : sum;
+
+   The T and UT are type pair like T=int8_t, UT=uint8_t.  */
+(match (signed_integer_sat_add @0 @1)
+ (cond^ (lt (bit_and:c (bit_xor:c @0 (nop_convert@2 (plus (nop_convert @0)
+							  (nop_convert @1))))
+		       (bit_not (bit_xor:c @0 @1)))
+	    integer_zerop)
+	(bit_xor:c (negate (convert (lt @0 integer_zerop))) max_value)
+	@2)
+ (if (INTEGRAL_TYPE_P (type) && !TYPE_UNSIGNED (type)
+      && types_match (type, @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)
diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
index 8d96a4c..3c93fca 100644
--- a/gcc/tree-ssa-math-opts.cc
+++ b/gcc/tree-ssa-math-opts.cc
@@ -4023,6 +4023,8 @@ extern bool gimple_unsigned_integer_sat_add (tree, tree*, tree (*)(tree));
 extern bool gimple_unsigned_integer_sat_sub (tree, tree*, tree (*)(tree));
 extern bool gimple_unsigned_integer_sat_trunc (tree, tree*, tree (*)(tree));
 
+extern bool gimple_signed_integer_sat_add (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)
@@ -4072,7 +4074,8 @@ match_unsigned_saturation_add (gimple_stmt_iterator *gsi, gassign *stmt)
 }
 
 /*
- * Try to match saturation unsigned add with PHI.
+ * Try to match saturation add with PHI.
+ * For unsigned integer:
  *   <bb 2> :
  *   _1 = x_3(D) + y_4(D);
  *   if (_1 >= x_3(D))
@@ -4086,10 +4089,31 @@ match_unsigned_saturation_add (gimple_stmt_iterator *gsi, gassign *stmt)
  *   # _2 = PHI <255(2), _1(3)>
  *   =>
  *   <bb 4> [local count: 1073741824]:
- *   _2 = .SAT_ADD (x_4(D), y_5(D));  */
+ *   _2 = .SAT_ADD (x_4(D), y_5(D));
+ *
+ * For signed integer:
+ *   x.0_1 = (long unsigned int) x_7(D);
+ *   y.1_2 = (long unsigned int) y_8(D);
+ *   _3 = x.0_1 + y.1_2;
+ *   sum_9 = (int64_t) _3;
+ *   _4 = x_7(D) ^ y_8(D);
+ *   _5 = x_7(D) ^ sum_9;
+ *   _15 = ~_4;
+ *   _16 = _5 & _15;
+ *   if (_16 < 0)
+ *     goto <bb 3>; [41.00%]
+ *   else
+ *     goto <bb 4>; [59.00%]
+ *   _11 = x_7(D) < 0;
+ *   _12 = (long int) _11;
+ *   _13 = -_12;
+ *   _14 = _13 ^ 9223372036854775807;
+ *   # _6 = PHI <_14(3), sum_9(2)>
+ *   =>
+ *   _6 = .SAT_ADD (x_5(D), y_6(D)); [tail call]  */
 
 static void
-match_unsigned_saturation_add (gimple_stmt_iterator *gsi, gphi *phi)
+match_saturation_add (gimple_stmt_iterator *gsi, gphi *phi)
 {
   if (gimple_phi_num_args (phi) != 2)
     return;
@@ -4097,7 +4121,8 @@ match_unsigned_saturation_add (gimple_stmt_iterator *gsi, gphi *phi)
   tree ops[2];
   tree phi_result = gimple_phi_result (phi);
 
-  if (gimple_unsigned_integer_sat_add (phi_result, ops, NULL))
+  if (gimple_unsigned_integer_sat_add (phi_result, ops, NULL)
+      || gimple_signed_integer_sat_add (phi_result, ops, NULL))
     build_saturation_binary_arith_call (gsi, phi, IFN_SAT_ADD, phi_result,
 					ops[0], ops[1]);
 }
@@ -6097,7 +6122,7 @@ math_opts_dom_walker::after_dom_children (basic_block bb)
     gsi_next (&psi))
     {
       gimple_stmt_iterator gsi = gsi_after_labels (bb);
-      match_unsigned_saturation_add (&gsi, psi.phi ());
+      match_saturation_add (&gsi, psi.phi ());
       match_unsigned_saturation_sub (&gsi, psi.phi ());
     }