Vect: Support IFN SAT_SUB for unsigned vector int

This patch would like to support the .SAT_SUB for the unsigned
vector int.  Given we have below example code:

void
vec_sat_sub_u64 (uint64_t *out, uint64_t *x, uint64_t *y, unsigned n)
{
  for (unsigned i = 0; i < n; i++)
    out[i] = (x[i] - y[i]) & (-(uint64_t)(x[i] >= y[i]));
}

Before this patch:
void
vec_sat_sub_u64 (uint64_t *out, uint64_t *x, uint64_t *y, unsigned n)
{
  ...
  _77 = .SELECT_VL (ivtmp_75, POLY_INT_CST [2, 2]);
  ivtmp_56 = _77 * 8;
  vect__4.7_59 = .MASK_LEN_LOAD (vectp_x.5_57, 64B, { -1, ... }, _77, 0);
  vect__6.10_63 = .MASK_LEN_LOAD (vectp_y.8_61, 64B, { -1, ... }, _77, 0);

  mask__7.11_64 = vect__4.7_59 >= vect__6.10_63;
  _66 = .COND_SUB (mask__7.11_64, vect__4.7_59, vect__6.10_63, { 0, ... });

  .MASK_LEN_STORE (vectp_out.15_71, 64B, { -1, ... }, _77, 0, _66);
  vectp_x.5_58 = vectp_x.5_57 + ivtmp_56;
  vectp_y.8_62 = vectp_y.8_61 + ivtmp_56;
  vectp_out.15_72 = vectp_out.15_71 + ivtmp_56;
  ivtmp_76 = ivtmp_75 - _77;
  ...
}

After this patch:
void
vec_sat_sub_u64 (uint64_t *out, uint64_t *x, uint64_t *y, unsigned n)
{
  ...
  _76 = .SELECT_VL (ivtmp_74, POLY_INT_CST [2, 2]);
  ivtmp_60 = _76 * 8;
  vect__4.7_63 = .MASK_LEN_LOAD (vectp_x.5_61, 64B, { -1, ... }, _76, 0);
  vect__6.10_67 = .MASK_LEN_LOAD (vectp_y.8_65, 64B, { -1, ... }, _76, 0);

  vect_patt_37.11_68 = .SAT_SUB (vect__4.7_63, vect__6.10_67);

  .MASK_LEN_STORE (vectp_out.12_70, 64B, { -1, ... }, _76, 0, vect_patt_37.11_68);
  vectp_x.5_62 = vectp_x.5_61 + ivtmp_60;
  vectp_y.8_66 = vectp_y.8_65 + ivtmp_60;
  vectp_out.12_71 = vectp_out.12_70 + ivtmp_60;
  ivtmp_75 = ivtmp_74 - _76;
  ...
}

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

gcc/ChangeLog:

	* match.pd: Add new form for vector mode recog.
	* tree-vect-patterns.cc (gimple_unsigned_integer_sat_sub): Add
	new match func decl;
	(vect_recog_build_binary_gimple_call): Extract helper func to
	build gcall with given internal_fn.
	(vect_recog_sat_sub_pattern): Add new func impl to recog .SAT_SUB.

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

1 files changed, 14 insertions, 0 deletions

diff --git a/gcc/match.pd b/gcc/match.pd
index 7c1ad42..ebc60eb 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3110,6 +3110,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
       && types_match (type, @0, @1))))
 
+/* Unsigned saturation sub, case 3 (branchless with gt):
+   SAT_U_SUB = (X - Y) * (X > Y).  */
+(match (unsigned_integer_sat_sub @0 @1)
+ (mult:c (minus @0 @1) (convert (gt @0 @1)))
+ (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
+      && types_match (type, @0, @1))))
+
+/* Unsigned saturation sub, case 4 (branchless with ge):
+   SAT_U_SUB = (X - Y) * (X >= Y).  */
+(match (unsigned_integer_sat_sub @0 @1)
+ (mult:c (minus @0 @1) (convert (ge @0 @1)))
+ (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)