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bpo-47120: define virtual opcodes in opcode.py. Better organization of jump opcodes. #32353

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bpo-47120: define virtual opcodes in opcode.py. Better organization of jump opcodes. #32353

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63cc814
reclassify jump definitions in opcode.py. Generate virtual opcodes in…
iritkatriel Apr 5, 2022
e9f2c33
fix test
iritkatriel Apr 6, 2022
d0a1d5c
magic number
iritkatriel Apr 6, 2022
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92 changes: 57 additions & 35 deletions Include/opcode.h
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3 changes: 2 additions & 1 deletion Lib/importlib/_bootstrap_external.py
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Original file line number Diff line number Diff line change
Expand Up @@ -400,6 +400,7 @@ def _write_atomic(path, data, mode=0o666):
# Python 3.11a6 3490 (remove JUMP_IF_NOT_EXC_MATCH, add CHECK_EXC_MATCH)
# Python 3.11a6 3491 (remove JUMP_IF_NOT_EG_MATCH, add CHECK_EG_MATCH,
# add JUMP_BACKWARD_NO_INTERRUPT, make JUMP_NO_INTERRUPT virtual)
# Python 3.11a7 3492 (Reorganize jump opcodes)

# Python 3.12 will start with magic number 3500

Expand All @@ -414,7 +415,7 @@ def _write_atomic(path, data, mode=0o666):
# Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
# in PC/launcher.c must also be updated.

MAGIC_NUMBER = (3491).to_bytes(2, 'little') + b'\r\n'
MAGIC_NUMBER = (3492).to_bytes(2, 'little') + b'\r\n'
_RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little') # For import.c

_PYCACHE = '__pycache__'
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74 changes: 53 additions & 21 deletions Lib/opcode.py
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Original file line number Diff line number Diff line change
Expand Up @@ -31,28 +31,47 @@
hascompare = []
hasfree = []
hasnargs = [] # unused
assembler = []

opmap = {}
opname = ['<%r>' % (op,) for op in range(256)]
virtual = {}

RELATIVE = 0x1
ABSOLUTE = 0x2
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Aren't we about to remove all absolute jumps?

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Yes, and then this flag will not be needed.

BACKWARD = 0x4
FORWARD = 0x8
ASSEMBLER = 0x10 # Not emitted in codegen stage, only by assembler

_inline_cache_entries = [0] * 256


def jump_flags(op, flags):
assert flags & RELATIVE != flags & ABSOLUTE
if flags & RELATIVE:
assert not (flags & BACKWARD) or not (flags & FORWARD)
hasjrel.append(op)
elif flags & ABSOLUTE:
hasjabs.append(op)
if flags & ASSEMBLER:
assembler.append(op)

def def_op(name, op, entries=0):
opname[op] = name
opmap[name] = op
if op >= 0:
opname[op] = name
opmap[name] = op
else:
virtual[name] = op
_inline_cache_entries[op] = entries

def jump_op(flags, name, op, entries=0):
jump_flags(op, flags)
def_op(name, op, entries=entries)

def name_op(name, op, entries=0):
def_op(name, op, entries)
hasname.append(op)

def jrel_op(name, op, entries=0):
def_op(name, op, entries)
hasjrel.append(op)

def jabs_op(name, op, entries=0):
def_op(name, op, entries)
hasjabs.append(op)

# Instruction opcodes for compiled code
# Blank lines correspond to available opcodes
Expand Down Expand Up @@ -111,7 +130,6 @@ def jabs_op(name, op, entries=0):
name_op('STORE_NAME', 90) # Index in name list
name_op('DELETE_NAME', 91) # ""
def_op('UNPACK_SEQUENCE', 92, 1) # Number of tuple items
jrel_op('FOR_ITER', 93)
def_op('UNPACK_EX', 94)
name_op('STORE_ATTR', 95, 4) # Index in name list
name_op('DELETE_ATTR', 96) # ""
Expand All @@ -130,31 +148,22 @@ def jabs_op(name, op, entries=0):
hascompare.append(107)
name_op('IMPORT_NAME', 108) # Index in name list
name_op('IMPORT_FROM', 109) # Index in name list
jrel_op('JUMP_FORWARD', 110) # Number of words to skip
jabs_op('JUMP_IF_FALSE_OR_POP', 111) # Target byte offset from beginning of code
jabs_op('JUMP_IF_TRUE_OR_POP', 112) # ""
jabs_op('POP_JUMP_IF_FALSE', 114) # ""
jabs_op('POP_JUMP_IF_TRUE', 115) # ""
name_op('LOAD_GLOBAL', 116, 5) # Index in name list
def_op('IS_OP', 117)
def_op('CONTAINS_OP', 118)
def_op('RERAISE', 119)
def_op('COPY', 120)
def_op('BINARY_OP', 122, 1)
jrel_op('SEND', 123) # Number of bytes to skip
def_op('LOAD_FAST', 124) # Local variable number
haslocal.append(124)
def_op('STORE_FAST', 125) # Local variable number
haslocal.append(125)
def_op('DELETE_FAST', 126) # Local variable number
haslocal.append(126)
jabs_op('POP_JUMP_IF_NOT_NONE', 128)
jabs_op('POP_JUMP_IF_NONE', 129)
def_op('RAISE_VARARGS', 130) # Number of raise arguments (1, 2, or 3)
def_op('GET_AWAITABLE', 131)
def_op('MAKE_FUNCTION', 132) # Flags
def_op('BUILD_SLICE', 133) # Number of items
jrel_op('JUMP_BACKWARD_NO_INTERRUPT', 134) # Number of words to skip (backwards)
def_op('MAKE_CELL', 135)
hasfree.append(135)
def_op('LOAD_CLOSURE', 136)
Expand All @@ -165,7 +174,6 @@ def jabs_op(name, op, entries=0):
hasfree.append(138)
def_op('DELETE_DEREF', 139)
hasfree.append(139)
jrel_op('JUMP_BACKWARD', 140) # Number of words to skip (backwards)

def_op('CALL_FUNCTION_EX', 142) # Flags

Expand Down Expand Up @@ -197,8 +205,32 @@ def jabs_op(name, op, entries=0):
def_op('KW_NAMES', 172)
hasconst.append(172)

jump_op(RELATIVE | FORWARD, 'FOR_ITER', 173)
jump_op(RELATIVE | FORWARD, 'SEND', 174)
jump_op(RELATIVE | FORWARD | ASSEMBLER, 'JUMP_FORWARD', 175)
jump_op(RELATIVE | BACKWARD | ASSEMBLER, 'JUMP_BACKWARD', 176)
jump_op(RELATIVE | BACKWARD | ASSEMBLER, 'JUMP_BACKWARD_NO_INTERRUPT', 177)

jump_op(ABSOLUTE, 'JUMP_IF_FALSE_OR_POP', 178)
jump_op(ABSOLUTE, 'JUMP_IF_TRUE_OR_POP', 179)
jump_op(ABSOLUTE, 'POP_JUMP_IF_FALSE', 180)
jump_op(ABSOLUTE, 'POP_JUMP_IF_TRUE', 181)
jump_op(ABSOLUTE, 'POP_JUMP_IF_NOT_NONE', 182)
jump_op(ABSOLUTE, 'POP_JUMP_IF_NONE', 183)


# Virtual Opcodes
# (Pseudo-instructions used in the compiler,
# but turned into NOPs by the assembler)

def_op('SETUP_FINALLY', -1)
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These are an internal detail of the compiler. They never exist in the final bytecode, so I don't think they should be here.

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The point was to autogenerate some of the macros around them.

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If the code to generate the macro is large than macros, that suggests to me that it isn't worth it.

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@iritkatriel iritkatriel Apr 6, 2022 •
edited
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For me it's not about how long the code is, but about how many places we need to change when we add/remove/change an opcode (i.e., maintainability).

def_op('SETUP_CLEANUP', -2)
def_op('SETUP_WITH', -3)
def_op('POP_BLOCK', -4)
jump_op(RELATIVE, 'JUMP', -5)
jump_op(RELATIVE, 'JUMP_NO_INTERRUPT', -6)

del def_op, name_op, jrel_op, jabs_op
del def_op, name_op, jump_op, jump_flags

_nb_ops = [
("NB_ADD", "+"),
Expand Down
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