From: Pan Li <pan2...@intel.com>
After we support the scalar unsigned form 1 and 2, we would like
to introduce more forms include the branch and branchless. There
are forms 3-10 list as below:
Form 3:
#define SAT_SUB_U_3(T) \
T sat_sub_u_3_##T (T x, T y) \
{ \
return x > y ? x - y : 0; \
}
Form 4:
#define SAT_SUB_U_4(T) \
T sat_sub_u_4_##T (T x, T y) \
{ \
return x >= y ? x - y : 0; \
}
Form 5:
#define SAT_SUB_U_5(T) \
T sat_sub_u_5_##T (T x, T y) \
{ \
return x < y ? 0 : x - y; \
}
Form 6:
#define SAT_SUB_U_6(T) \
T sat_sub_u_6_##T (T x, T y) \
{ \
return x <= y ? 0 : x - y; \
}
Form 7:
#define SAT_SUB_U_7(T) \
T sat_sub_u_7_##T (T x, T y) \
{ \
T ret; \
T overflow = __builtin_sub_overflow (x, y, &ret); \
return ret & (T)(overflow - 1); \
}
Form 8:
#define SAT_SUB_U_8(T) \
T sat_sub_u_8_##T (T x, T y) \
{ \
T ret; \
T overflow = __builtin_sub_overflow (x, y, &ret); \
return ret & (T)-(!overflow); \
}
Form 9:
#define SAT_SUB_U_9(T) \
T sat_sub_u_9_##T (T x, T y) \
{ \
T ret; \
T overflow = __builtin_sub_overflow (x, y, &ret); \
return overflow ? 0 : ret; \
}
Form 10:
#define SAT_SUB_U_10(T) \
T sat_sub_u_10_##T (T x, T y) \
{ \
T ret; \
T overflow = __builtin_sub_overflow (x, y, &ret); \
return !overflow ? ret : 0; \
}
Take form 10 as example:
SAT_SUB_U_10(uint64_t);
Before this patch:
uint8_t sat_sub_u_10_uint8_t (uint8_t x, uint8_t y)
{
unsigned char _1;
unsigned char _2;
uint8_t _3;
__complex__ unsigned char _6;
;; basic block 2, loop depth 0
;; pred: ENTRY
_6 = .SUB_OVERFLOW (x_4(D), y_5(D));
_2 = IMAGPART_EXPR <_6>;
if (_2 == 0)
goto <bb 3>; [50.00%]
else
goto <bb 4>; [50.00%]
;; succ: 3
;; 4
;; basic block 3, loop depth 0
;; pred: 2
_1 = REALPART_EXPR <_6>;
;; succ: 4
;; basic block 4, loop depth 0
;; pred: 2
;; 3
# _3 = PHI <0(2), _1(3)>
return _3;
;; succ: EXIT
}
After this patch:
uint8_t sat_sub_u_10_uint8_t (uint8_t x, uint8_t y)
{
uint8_t _3;
;; basic block 2, loop depth 0
;; pred: ENTRY
_3 = .SAT_SUB (x_4(D), y_5(D)); [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 rv64gcv build with glibc.
3. The x86 bootstrap test.
4. The x86 fully regression test.
gcc/ChangeLog:
* match.pd: Add more match for unsigned sat_sub.
* tree-ssa-math-opts.cc (match_unsigned_saturation_sub): Add new
func impl to match phi node for .SAT_SUB.
(math_opts_dom_walker::after_dom_children): Try match .SAT_SUB
for the phi node, MULT_EXPR, BIT_XOR_EXPR and BIT_AND_EXPR.
Signed-off-by: Pan Li <pan2...@intel.com>
---
gcc/match.pd | 25 +++++++++++++++++++++++--
gcc/tree-ssa-math-opts.cc | 33 +++++++++++++++++++++++++++++++++
2 files changed, 56 insertions(+), 2 deletions(-)
diff --git a/gcc/match.pd b/gcc/match.pd
index 5cfe81e80b3..66e411b3359 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3140,14 +3140,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Unsigned saturation sub, case 1 (branch with gt):
SAT_U_SUB = X > Y ? X - Y : 0 */
(match (unsigned_integer_sat_sub @0 @1)
- (cond (gt @0 @1) (minus @0 @1) integer_zerop)
+ (cond^ (gt @0 @1) (minus @0 @1) integer_zerop)
(if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
&& types_match (type, @0, @1))))
/* Unsigned saturation sub, case 2 (branch with ge):
SAT_U_SUB = X >= Y ? X - Y : 0. */
(match (unsigned_integer_sat_sub @0 @1)
- (cond (ge @0 @1) (minus @0 @1) integer_zerop)
+ (cond^ (ge @0 @1) (minus @0 @1) integer_zerop)
(if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
&& types_match (type, @0, @1))))
@@ -3165,6 +3165,27 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
&& types_match (type, @0, @1))))
+/* Unsigned saturation sub, case 5 (branchless bit_and with .SUB_OVERFLOW. */
+(match (unsigned_integer_sat_sub @0 @1)
+ (bit_and:c (realpart (IFN_SUB_OVERFLOW@2 @0 @1))
+ (plus:c (imagpart @2) integer_minus_onep))
+ (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
+ && types_match (type, @0, @1))))
+
+/* Unsigned saturation sub, case 6 (branchless mult with .SUB_OVERFLOW. */
+(match (unsigned_integer_sat_sub @0 @1)
+ (mult:c (realpart (IFN_SUB_OVERFLOW@2 @0 @1))
+ (bit_xor:c (imagpart @2) integer_onep))
+ (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
+ && types_match (type, @0, @1))))
+
+/* Unsigned saturation sub, case 7 (branch 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))))
+
/* x > y && x != XXX_MIN --> x > y
x > y && x == XXX_MIN --> false . */
(for eqne (eq ne)
diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
index fbb8e0ea306..05aa157611b 100644
--- a/gcc/tree-ssa-math-opts.cc
+++ b/gcc/tree-ssa-math-opts.cc
@@ -4186,6 +4186,36 @@ match_unsigned_saturation_sub (gimple_stmt_iterator
*gsi, gassign *stmt)
build_saturation_binary_arith_call (gsi, IFN_SAT_SUB, lhs, ops[0], ops[1]);
}
+/*
+ * Try to match saturation unsigned sub.
+ * <bb 2> [local count: 1073741824]:
+ * if (x_2(D) > y_3(D))
+ * goto <bb 3>; [50.00%]
+ * else
+ * goto <bb 4>; [50.00%]
+ *
+ * <bb 3> [local count: 536870912]:
+ * _4 = x_2(D) - y_3(D);
+ *
+ * <bb 4> [local count: 1073741824]:
+ * # _1 = PHI <0(2), _4(3)>
+ * =>
+ * <bb 4> [local count: 1073741824]:
+ * _1 = .SAT_SUB (x_2(D), y_3(D)); */
+static void
+match_unsigned_saturation_sub (gimple_stmt_iterator *gsi, gphi *phi)
+{
+ if (gimple_phi_num_args (phi) != 2)
+ return;
+
+ tree ops[2];
+ tree phi_result = gimple_phi_result (phi);
+
+ if (gimple_unsigned_integer_sat_sub (phi_result, ops, NULL))
+ build_saturation_binary_arith_call (gsi, phi, IFN_SAT_SUB, phi_result,
+ ops[0], ops[1]);
+}
+
/* Recognize for unsigned x
x = y - z;
if (x > y)
@@ -6104,6 +6134,7 @@ math_opts_dom_walker::after_dom_children (basic_block bb)
{
gimple_stmt_iterator gsi = gsi_start_bb (bb);
match_unsigned_saturation_add (&gsi, psi.phi ());
+ match_unsigned_saturation_sub (&gsi, psi.phi ());
}
for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi);)
@@ -6129,6 +6160,7 @@ math_opts_dom_walker::after_dom_children (basic_block bb)
continue;
}
match_arith_overflow (&gsi, stmt, code, m_cfg_changed_p);
+ match_unsigned_saturation_sub (&gsi, as_a<gassign *> (stmt));
break;
case PLUS_EXPR:
@@ -6167,6 +6199,7 @@ math_opts_dom_walker::after_dom_children (basic_block bb)
break;
case COND_EXPR:
+ case BIT_AND_EXPR:
match_unsigned_saturation_sub (&gsi, as_a<gassign *> (stmt));
break;
--
2.34.1
