Match: Support form 11 for the unsigned scalar .SAT_SUB

We missed one match pattern for the unsigned scalar .SAT_SUB,  aka
form 11.

Form 11:
  #define SAT_SUB_U_11(T) \
  T sat_sub_u_11_##T (T x, T y) \
  { \
    T ret; \
    bool overflow = __builtin_sub_overflow (x, y, &ret); \
    return overflow ? 0 : ret; \
  }

Thus,  add above form 11 to the match pattern gimple_unsigned_integer_sat_sub.

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

gcc/ChangeLog:

	* match.pd: Add form 11 match pattern for .SAT_SUB.

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

diff --git a/gcc/match.pd b/gcc/match.pd
index 99968d316eda05cc802b3c54b97b36d900811443..5c330a43ed013221604b57c359481f5e484a98c3 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3186,13 +3186,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
       && types_match (type, @0, @1))))
 
-/* Unsigned saturation sub, case 7 (branch with .SUB_OVERFLOW).  */
+/* Unsigned saturation sub, case 7 (branch eq with .SUB_OVERFLOW).  */
 (match (unsigned_integer_sat_sub @0 @1)
  (cond^ (eq (imagpart (IFN_SUB_OVERFLOW@2 @0 @1)) integer_zerop)
   (realpart @2) integer_zerop)
  (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
       && types_match (type, @0, @1))))
 
+/* Unsigned saturation sub, case 8 (branch ne with .SUB_OVERFLOW).  */
+(match (unsigned_integer_sat_sub @0 @1)
+ (cond^ (ne (imagpart (IFN_SUB_OVERFLOW@2 @0 @1)) integer_zerop)
+   integer_zerop (realpart @2))
+ (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)