cpython/Lib/opcode.py
Guido van Rossum bcce5e2718
gh-109039: Branch prediction for Tier 2 interpreter (#109038)
This adds a 16-bit inline cache entry to the conditional branch instructions POP_JUMP_IF_{FALSE,TRUE,NONE,NOT_NONE} and their instrumented variants, which is used to keep track of the branch direction.

Each time we encounter these instructions we shift the cache entry left by one and set the bottom bit to whether we jumped.

Then when it's time to translate such a branch to Tier 2 uops, we use the bit count from the cache entry to decided whether to continue translating the "didn't jump" branch or the "jumped" branch.

The counter is initialized to a pattern of alternating ones and zeros to avoid bias.

The .pyc file magic number is updated. There's a new test, some fixes for existing tests, and a few miscellaneous cleanups.
2023-09-11 18:20:24 +00:00

112 lines
2.7 KiB
Python

"""
opcode module - potentially shared between dis and other modules which
operate on bytecodes (e.g. peephole optimizers).
"""
__all__ = ["cmp_op", "stack_effect", "hascompare", "opname", "opmap",
"HAVE_ARGUMENT", "EXTENDED_ARG", "hasarg", "hasconst", "hasname",
"hasjump", "hasjrel", "hasjabs", "hasfree", "haslocal", "hasexc"]
import _opcode
from _opcode import stack_effect
from _opcode_metadata import (_specializations, _specialized_opmap, opmap,
HAVE_ARGUMENT, MIN_INSTRUMENTED_OPCODE)
EXTENDED_ARG = opmap['EXTENDED_ARG']
opname = ['<%r>' % (op,) for op in range(max(opmap.values()) + 1)]
for op, i in opmap.items():
opname[i] = op
cmp_op = ('<', '<=', '==', '!=', '>', '>=')
# These lists are documented as part of the dis module's API
hasarg = [op for op in opmap.values() if _opcode.has_arg(op)]
hasconst = [op for op in opmap.values() if _opcode.has_const(op)]
hasname = [op for op in opmap.values() if _opcode.has_name(op)]
hasjump = [op for op in opmap.values() if _opcode.has_jump(op)]
hasjrel = hasjump # for backward compatibility
hasjabs = []
hasfree = [op for op in opmap.values() if _opcode.has_free(op)]
haslocal = [op for op in opmap.values() if _opcode.has_local(op)]
hasexc = [op for op in opmap.values() if _opcode.has_exc(op)]
_intrinsic_1_descs = _opcode.get_intrinsic1_descs()
_intrinsic_2_descs = _opcode.get_intrinsic2_descs()
_nb_ops = _opcode.get_nb_ops()
hascompare = [opmap["COMPARE_OP"]]
_cache_format = {
"LOAD_GLOBAL": {
"counter": 1,
"index": 1,
"module_keys_version": 1,
"builtin_keys_version": 1,
},
"BINARY_OP": {
"counter": 1,
},
"UNPACK_SEQUENCE": {
"counter": 1,
},
"COMPARE_OP": {
"counter": 1,
},
"BINARY_SUBSCR": {
"counter": 1,
},
"FOR_ITER": {
"counter": 1,
},
"LOAD_SUPER_ATTR": {
"counter": 1,
},
"LOAD_ATTR": {
"counter": 1,
"version": 2,
"keys_version": 2,
"descr": 4,
},
"STORE_ATTR": {
"counter": 1,
"version": 2,
"index": 1,
},
"CALL": {
"counter": 1,
"func_version": 2,
},
"STORE_SUBSCR": {
"counter": 1,
},
"SEND": {
"counter": 1,
},
"JUMP_BACKWARD": {
"counter": 1,
},
"TO_BOOL": {
"counter": 1,
"version": 2,
},
"POP_JUMP_IF_TRUE": {
"counter": 1,
},
"POP_JUMP_IF_FALSE": {
"counter": 1,
},
"POP_JUMP_IF_NONE": {
"counter": 1,
},
"POP_JUMP_IF_NOT_NONE": {
"counter": 1,
},
}
_inline_cache_entries = {
name : sum(value.values()) for (name, value) in _cache_format.items()
}