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GH-111843: Tier 2 exponential backoff (GH-111850)

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Mark Shannon 2023-11-09 13:49:51 +00:00 • committed by GitHub
parent 25c4956488
commit 34a03e951b
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5 changed files with 47 additions and 14 deletions
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23
Python/generated_cases.c.h generated
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@ -3409,10 +3409,12 @@
JUMPBY(-oparg);
#if ENABLE_SPECIALIZATION
this_instr[1].cache += (1 << OPTIMIZER_BITS_IN_COUNTER);
if (this_instr[1].cache > tstate->interp->optimizer_backedge_threshold &&
// Double-check that the opcode isn't instrumented or something:
this_instr->op.code == JUMP_BACKWARD)
{
/* We are using unsigned values, but we really want signed values, so
* do the 2s complement comparison manually */
uint16_t ucounter = this_instr[1].cache + (1 << 15);
uint16_t threshold = tstate->interp->optimizer_backedge_threshold + (1 << 15);
// Double-check that the opcode isn't instrumented or something:
if (ucounter > threshold && this_instr->op.code == JUMP_BACKWARD) {
OPT_STAT_INC(attempts);
int optimized = _PyOptimizer_BackEdge(frame, this_instr, next_instr, stack_pointer);
if (optimized < 0) goto error;
@ -3420,8 +3422,19 @@
// Rewind and enter the executor:
assert(this_instr->op.code == ENTER_EXECUTOR);
next_instr = this_instr;
this_instr[1].cache &= ((1 << OPTIMIZER_BITS_IN_COUNTER) - 1);
}
else {
int backoff = this_instr[1].cache & ((1 << OPTIMIZER_BITS_IN_COUNTER) - 1);
if (backoff < MINIMUM_TIER2_BACKOFF) {
backoff = MINIMUM_TIER2_BACKOFF;
}
else if (backoff < 15 - OPTIMIZER_BITS_IN_COUNTER) {
backoff++;
}
assert(backoff <= 15 - OPTIMIZER_BITS_IN_COUNTER);
this_instr[1].cache = ((1 << 16) - ((1 << OPTIMIZER_BITS_IN_COUNTER) << backoff)) | backoff;
}
this_instr[1].cache &= ((1 << OPTIMIZER_BITS_IN_COUNTER) - 1);
}
#endif /* ENABLE_SPECIALIZATION */
DISPATCH();