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perf: cache size and jump_target from first pass in to_bytecode #200

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Merged
MatthieuDartiailh merged 1 commit into from
May 22, 2026
Merged

perf: cache size and jump_target from first pass in to_bytecode #200

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11 changes: 7 additions & 4 deletions src/bytecode/concrete.py
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Original file line number Diff line number Diff line change
Expand Up @@ -782,16 +782,19 @@ def to_bytecode(
c_instructions = self[:]
self._remove_extended_args(c_instructions)

# Find jump targets
# Find jump targets; stash (size, jump_target) to avoid recomputing in the main loop
jump_targets: Set[int] = set()
_instr_props: List[Tuple[int, Optional[int]]] = []
offset = 0
for c_instr in c_instructions:
if isinstance(c_instr, SetLineno):
continue
size = c_instr.size
target = c_instr.get_jump_target(offset)
_instr_props.append((size, target))
if target is not None:
jump_targets.add(target)
offset += c_instr.size // 2
offset += size // 2

# On 3.11+ we need to also look at the exception table for jump targets
for ex_entry in self.exception_table:
Expand Down Expand Up @@ -839,6 +842,7 @@ def to_bytecode(
else:
locals_lookup = self.varnames

_props_iter = iter(_instr_props)
for lineno, c_instr in self._normalize_lineno(
c_instructions, self.first_lineno
):
Expand All @@ -864,8 +868,7 @@ def to_bytecode(
tb_instrs[entry] = tb_instr
instructions.append(tb_instr)

jump_target = c_instr.get_jump_target(offset)
size = c_instr.size
size, jump_target = next(_props_iter)
# If an instruction uses extended args, those appear before the instruction
# causing the instruction to appear at offset that accounts for extended
# args. So we first update the offset to account for extended args, then
Expand Down