On 1/2/25 1:34 AM, Li Xu wrote:
From: xuli <xu...@eswincomputing.com>
This patch would like to support .SAT_ADD when IMM=-1.
Form1:
T __attribute__((noinline)) \
sat_s_add_imm_##T##_fmt_1##_##INDEX (T x) \
{ \
T sum = (UT)x + (UT)IMM; \
return (x ^ IMM) < 0 \
? sum \
: (sum ^ x) >= 0 \
? sum \
: x < 0 ? MIN : MAX; \
}
Take below form1 as example:
DEF_SAT_S_ADD_IMM_FMT_1(0, int8_t, uint8_t, -1, INT8_MIN, INT8_MAX)
Before this patch:
__attribute__((noinline))
int8_t sat_s_add_imm_int8_t_fmt_1_0 (int8_t x)
{
unsigned char x.0_1;
unsigned char _2;
unsigned char _3;
int8_t iftmp.1_4;
signed char _8;
unsigned char _9;
signed char _10;
<bb 2> [local count: 1073741824]:
x.0_1 = (unsigned char) x_5(D);
_3 = -x.0_1;
_10 = (signed char) _3;
_8 = x_5(D) & _10;
if (_8 < 0)
goto <bb 4>; [1.40%]
else
goto <bb 3>; [98.60%]
<bb 3> [local count: 434070867]:
_2 = x.0_1 + 255;
<bb 4> [local count: 1073741824]:
# _9 = PHI <_2(3), 128(2)>
iftmp.1_4 = (int8_t) _9;
return iftmp.1_4;
}
After this patch:
__attribute__((noinline))
int8_t sat_s_add_imm_int8_t_fmt_1_0 (int8_t x)
{
int8_t _4;
<bb 2> [local count: 1073741824]:
gimple_call <.SAT_ADD, _4, x_5(D), 255> [tail call]
gimple_return <_4>
}
The below test suites are passed for this patch:
1. The rv64gcv fully regression tests.
2. The x86 bootstrap tests.
3. The x86 fully regression tests.
Signed-off-by: Li Xu <xu...@eswincomputing.com>
gcc/ChangeLog:
* match.pd: Add signed scalar SAT_ADD IMM form1 with IMM=-1 matching.
* tree-ssa-math-opts.cc (match_unsigned_saturation_add): Adapt function
name.
(match_saturation_add_with_assign): Match signed and unsigned SAT_ADD
with assign.
(math_opts_dom_walker::after_dom_children): Match imm=-1 signed SAT_ADD
with NOP_EXPR case.
So is there anything special about the constant -1 that allows this to
simplify in ways that don't work for other constants? If yes, then what
is it? If not, then why are we treating -1 specially?
jeff
