https://gcc.gnu.org/g:3809b4d6ec385b51af300f570c0ed2895faa2c8e
commit r15-4002-g3809b4d6ec385b51af300f570c0ed2895faa2c8e
Author: Pan Li <pan2...@intel.com>
Date: Thu Sep 26 20:12:33 2024 +0800
Match: Support form 2 for scalar signed integer SAT_SUB
This patch would like to support the form 2 of the scalar signed
integer SAT_SUB. Aka below example:
Form 2:
#define DEF_SAT_S_SUB_FMT_2(T, UT, MIN, MAX) \
T __attribute__((noinline)) \
sat_s_sub_##T##_fmt_1 (T x, T y) \
{ \
T minus = (UT)x - (UT)y; \
if ((x ^ y) >= 0 || (minus ^ x) >= 0) \
return minus; \
return x < 0 ? MIN : MAX; \
}
DEF_SAT_S_SUB_FMT_2(int8_t, uint8_t, INT8_MIN, INT8_MAX)
Before this patch:
4 │ __attribute__((noinline))
5 │ int8_t sat_s_sub_int8_t_fmt_2 (int8_t x, int8_t y)
6 │ {
7 │ int8_t minus;
8 │ unsigned char x.0_1;
9 │ unsigned char y.1_2;
10 │ unsigned char _3;
11 │ signed char _4;
12 │ signed char _5;
13 │ int8_t _6;
14 │ _Bool _11;
15 │ signed char _12;
16 │ signed char _13;
17 │ signed char _14;
18 │ signed char _15;
19 │
20 │ ;; basic block 2, loop depth 0
21 │ ;; pred: ENTRY
22 │ x.0_1 = (unsigned char) x_7(D);
23 │ y.1_2 = (unsigned char) y_8(D);
24 │ _3 = x.0_1 - y.1_2;
25 │ minus_9 = (int8_t) _3;
26 │ _4 = x_7(D) ^ y_8(D);
27 │ _5 = x_7(D) ^ minus_9;
28 │ _15 = _4 & _5;
29 │ if (_15 >= 0)
30 │ goto <bb 4>; [42.57%]
31 │ else
32 │ goto <bb 3>; [57.43%]
33 │ ;; succ: 4
34 │ ;; 3
35 │
36 │ ;; basic block 3, loop depth 0
37 │ ;; pred: 2
38 │ _11 = x_7(D) < 0;
39 │ _12 = (signed char) _11;
40 │ _13 = -_12;
41 │ _14 = _13 ^ 127;
42 │ ;; succ: 4
43 │
44 │ ;; basic block 4, loop depth 0
45 │ ;; pred: 2
46 │ ;; 3
47 │ # _6 = PHI <minus_9(2), _14(3)>
48 │ return _6;
49 │ ;; succ: EXIT
50 │
51 │ }
After this patch:
4 │ __attribute__((noinline))
5 │ int8_t sat_s_sub_int8_t_fmt_2 (int8_t x, int8_t y)
6 │ {
7 │ int8_t _6;
8 │
9 │ ;; basic block 2, loop depth 0
10 │ ;; pred: ENTRY
11 │ _6 = .SAT_SUB (x_7(D), y_8(D)); [tail call]
12 │ return _6;
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 case 2 matching pattern for signed SAT_SUB.
Signed-off-by: Pan Li <pan2...@intel.com>
Diff:
---
gcc/match.pd | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/gcc/match.pd b/gcc/match.pd
index 5ec31ef6269a..ba83f0f29e61 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3374,6 +3374,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
@2)
(if (INTEGRAL_TYPE_P (type) && !TYPE_UNSIGNED (type))))
+/* Signed saturation sub, case 2:
+ T minus = (T)((UT)X - (UT)Y);
+ SAT_S_SUB = (X ^ Y) & (X ^ minus) < 0 ? (-(T)(X < 0) ^ MAX) : minus;
+
+ The T and UT are type pair like T=int8_t, UT=uint8_t. */
+(match (signed_integer_sat_sub @0 @1)
+ (cond^ (ge (bit_and:c (bit_xor:c @0 @1)
+ (bit_xor @0 (nop_convert@2 (minus (nop_convert @0)
+ (nop_convert @1)))))
+ integer_zerop)
+ @2
+ (bit_xor:c (negate (convert (lt @0 integer_zerop))) max_value))
+ (if (INTEGRAL_TYPE_P (type) && !TYPE_UNSIGNED (type))))
+
/* Unsigned saturation truncate, case 1, sizeof (WT) > sizeof (NT).
SAT_U_TRUNC = (NT)x | (NT)(-(X > (WT)(NT)(-1))). */
(match (unsigned_integer_sat_trunc @0)
