https://github.com/python/cpython/commit/f55273b3b7124dc570911724107c2440f37905fc
commit: f55273b3b7124dc570911724107c2440f37905fc
branch: main
author: Mark Shannon <[email protected]>
committer: markshannon <[email protected]>
date: 2024-10-07T11:46:33+01:00
summary:
GH-116968: Remove branch from advance_backoff_counter (GH-124469)
files:
M Include/internal/pycore_backoff.h
M Python/bytecodes.c
M Python/executor_cases.c.h
M Python/instrumentation.c
diff --git a/Include/internal/pycore_backoff.h
b/Include/internal/pycore_backoff.h
index a9d1bce127e63d..20436a68b69677 100644
--- a/Include/internal/pycore_backoff.h
+++ b/Include/internal/pycore_backoff.h
@@ -15,13 +15,7 @@ extern "C" {
typedef struct {
- union {
- struct {
- uint16_t backoff : 4;
- uint16_t value : 12;
- };
- uint16_t as_counter; // For printf("%#x", ...)
- };
+ uint16_t value_and_backoff;
} _Py_BackoffCounter;
@@ -38,17 +32,19 @@ typedef struct {
and a 4-bit 'backoff' field. When resetting the counter, the
backoff field is incremented (until it reaches a limit) and the
value is set to a bit mask representing the value 2**backoff - 1.
- The maximum backoff is 12 (the number of value bits).
+ The maximum backoff is 12 (the number of bits in the value).
There is an exceptional value which must not be updated, 0xFFFF.
*/
-#define UNREACHABLE_BACKOFF 0xFFFF
+#define BACKOFF_BITS 4
+#define MAX_BACKOFF 12
+#define UNREACHABLE_BACKOFF 15
static inline bool
is_unreachable_backoff_counter(_Py_BackoffCounter counter)
{
- return counter.as_counter == UNREACHABLE_BACKOFF;
+ return counter.value_and_backoff == UNREACHABLE_BACKOFF;
}
static inline _Py_BackoffCounter
@@ -57,8 +53,7 @@ make_backoff_counter(uint16_t value, uint16_t backoff)
assert(backoff <= 15);
assert(value <= 0xFFF);
_Py_BackoffCounter result;
- result.value = value;
- result.backoff = backoff;
+ result.value_and_backoff = (value << BACKOFF_BITS) | backoff;
return result;
}
@@ -66,7 +61,7 @@ static inline _Py_BackoffCounter
forge_backoff_counter(uint16_t counter)
{
_Py_BackoffCounter result;
- result.as_counter = counter;
+ result.value_and_backoff = counter;
return result;
}
@@ -74,35 +69,36 @@ static inline _Py_BackoffCounter
restart_backoff_counter(_Py_BackoffCounter counter)
{
assert(!is_unreachable_backoff_counter(counter));
- if (counter.backoff < 12) {
- return make_backoff_counter((1 << (counter.backoff + 1)) - 1,
counter.backoff + 1);
+ int backoff = counter.value_and_backoff & 15;
+ if (backoff < MAX_BACKOFF) {
+ return make_backoff_counter((1 << (backoff + 1)) - 1, backoff + 1);
}
else {
- return make_backoff_counter((1 << 12) - 1, 12);
+ return make_backoff_counter((1 << MAX_BACKOFF) - 1, MAX_BACKOFF);
}
}
static inline _Py_BackoffCounter
pause_backoff_counter(_Py_BackoffCounter counter)
{
- return make_backoff_counter(counter.value | 1, counter.backoff);
+ _Py_BackoffCounter result;
+ result.value_and_backoff = counter.value_and_backoff | (1 << BACKOFF_BITS);
+ return result;
}
static inline _Py_BackoffCounter
advance_backoff_counter(_Py_BackoffCounter counter)
{
- if (!is_unreachable_backoff_counter(counter)) {
- return make_backoff_counter((counter.value - 1) & 0xFFF,
counter.backoff);
- }
- else {
- return counter;
- }
+ _Py_BackoffCounter result;
+ result.value_and_backoff = counter.value_and_backoff - (1 << BACKOFF_BITS);
+ return result;
}
static inline bool
backoff_counter_triggers(_Py_BackoffCounter counter)
{
- return counter.value == 0;
+ /* Test whether the value is zero and the backoff is not
UNREACHABLE_BACKOFF */
+ return counter.value_and_backoff < UNREACHABLE_BACKOFF;
}
/* Initial JUMP_BACKWARD counter.
@@ -136,7 +132,7 @@ initial_temperature_backoff_counter(void)
static inline _Py_BackoffCounter
initial_unreachable_backoff_counter(void)
{
- return forge_backoff_counter(UNREACHABLE_BACKOFF);
+ return make_backoff_counter(0, UNREACHABLE_BACKOFF);
}
#ifdef __cplusplus
diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index c712c772201e10..f251b79e00ebe7 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -4705,7 +4705,7 @@ dummy_func(
printf("SIDE EXIT: [UOp ");
_PyUOpPrint(&next_uop[-1]);
printf(", exit %u, temp %d, target %d -> %s]\n",
- exit - current_executor->exits,
exit->temperature.as_counter,
+ exit - current_executor->exits,
exit->temperature.value_and_backoff,
(int)(target - _PyCode_CODE(code)),
_PyOpcode_OpName[target->op.code]);
}
@@ -4794,7 +4794,7 @@ dummy_func(
printf("DYNAMIC EXIT: [UOp ");
_PyUOpPrint(&next_uop[-1]);
printf(", exit %u, temp %d, target %d -> %s]\n",
- exit - current_executor->exits,
exit->temperature.as_counter,
+ exit - current_executor->exits,
exit->temperature.value_and_backoff,
(int)(target - _PyCode_CODE(_PyFrame_GetCode(frame))),
_PyOpcode_OpName[target->op.code]);
}
diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index fdfec66b73c730..1716d5d8e68827 100644
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -5252,7 +5252,7 @@
printf("SIDE EXIT: [UOp ");
_PyUOpPrint(&next_uop[-1]);
printf(", exit %u, temp %d, target %d -> %s]\n",
- exit - current_executor->exits,
exit->temperature.as_counter,
+ exit - current_executor->exits,
exit->temperature.value_and_backoff,
(int)(target - _PyCode_CODE(code)),
_PyOpcode_OpName[target->op.code]);
}
@@ -5390,7 +5390,7 @@
printf("DYNAMIC EXIT: [UOp ");
_PyUOpPrint(&next_uop[-1]);
printf(", exit %u, temp %d, target %d -> %s]\n",
- exit - current_executor->exits,
exit->temperature.as_counter,
+ exit - current_executor->exits,
exit->temperature.value_and_backoff,
(int)(target - _PyCode_CODE(_PyFrame_GetCode(frame))),
_PyOpcode_OpName[target->op.code]);
}
diff --git a/Python/instrumentation.c b/Python/instrumentation.c
index 8fd7c08beac92a..e1e494c31a1120 100644
--- a/Python/instrumentation.c
+++ b/Python/instrumentation.c
@@ -643,8 +643,8 @@ de_instrument(PyCodeObject *code, int i, int event)
CHECK(_PyOpcode_Deopt[deinstrumented] == deinstrumented);
FT_ATOMIC_STORE_UINT8_RELAXED(*opcode_ptr, deinstrumented);
if (_PyOpcode_Caches[deinstrumented]) {
- FT_ATOMIC_STORE_UINT16_RELAXED(instr[1].counter.as_counter,
- adaptive_counter_warmup().as_counter);
+ FT_ATOMIC_STORE_UINT16_RELAXED(instr[1].counter.value_and_backoff,
+
adaptive_counter_warmup().value_and_backoff);
}
}
@@ -719,8 +719,8 @@ instrument(PyCodeObject *code, int i)
assert(instrumented);
FT_ATOMIC_STORE_UINT8_RELAXED(*opcode_ptr, instrumented);
if (_PyOpcode_Caches[deopt]) {
- FT_ATOMIC_STORE_UINT16_RELAXED(instr[1].counter.as_counter,
- adaptive_counter_warmup().as_counter);
+ FT_ATOMIC_STORE_UINT16_RELAXED(instr[1].counter.value_and_backoff,
+
adaptive_counter_warmup().value_and_backoff);
instr[1].counter = adaptive_counter_warmup();
}
}
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