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import sys
from analyzer import StackItem
from dataclasses import dataclass
from formatting import maybe_parenthesize
from cwriter import CWriter
def var_size(var: StackItem) -> str:
if var.condition:
# Special case simplification
if var.condition == "oparg & 1" and var.size == "1":
return f"({var.condition})"
else:
return f"(({var.condition}) ? {var.size} : 0)"
else:
return var.size
class StackOffset:
"The stack offset of the virtual base of the stack from the physical stack pointer"
def __init__(self) -> None:
self.popped: list[str] = []
self.pushed: list[str] = []
def pop(self, item: StackItem) -> None:
self.popped.append(var_size(item))
def push(self, item: StackItem) -> None:
self.pushed.append(var_size(item))
def simplify(self) -> None:
"Remove matching values from both the popped and pushed list"
if not self.popped or not self.pushed:
return
# Sort the list so the lexically largest element is last.
popped = sorted(self.popped)
pushed = sorted(self.pushed)
self.popped = []
self.pushed = []
while popped and pushed:
pop = popped.pop()
push = pushed.pop()
if pop == push:
pass
elif pop > push:
# if pop > push, there can be no element in pushed matching pop.
self.popped.append(pop)
pushed.append(push)
else:
self.pushed.append(push)
popped.append(pop)
self.popped.extend(popped)
self.pushed.extend(pushed)
def to_c(self) -> str:
self.simplify()
int_offset = 0
symbol_offset = ""
for item in self.popped:
try:
int_offset -= int(item)
except ValueError:
symbol_offset += f" - {maybe_parenthesize(item)}"
for item in self.pushed:
try:
int_offset += int(item)
except ValueError:
symbol_offset += f" + {maybe_parenthesize(item)}"
if symbol_offset and not int_offset:
res = symbol_offset
else:
res = f"{int_offset}{symbol_offset}"
if res.startswith(" + "):
res = res[3:]
if res.startswith(" - "):
res = "-" + res[3:]
return res
def clear(self) -> None:
self.popped = []
self.pushed = []
class SizeMismatch(Exception):
pass
class Stack:
def __init__(self) -> None:
self.top_offset = StackOffset()
self.base_offset = StackOffset()
self.peek_offset = StackOffset()
self.variables: list[StackItem] = []
self.defined: set[str] = set()
def pop(self, var: StackItem) -> str:
self.top_offset.pop(var)
if not var.peek:
self.peek_offset.pop(var)
indirect = "&" if var.is_array() else ""
if self.variables:
popped = self.variables.pop()
if popped.size != var.size:
raise SizeMismatch(
f"Size mismatch when popping '{popped.name}' from stack to assign to {var.name}. "
f"Expected {var.size} got {popped.size}"
)
if popped.name == var.name:
return ""
elif popped.name == "unused":
self.defined.add(var.name)
return (
f"{var.name} = {indirect}stack_pointer[{self.top_offset.to_c()}];\n"
)
elif var.name == "unused":
return ""
else:
self.defined.add(var.name)
return f"{var.name} = {popped.name};\n"
self.base_offset.pop(var)
if var.name == "unused":
return ""
else:
self.defined.add(var.name)
cast = f"({var.type})" if (not indirect and var.type) else ""
assign = (
f"{var.name} = {cast}{indirect}stack_pointer[{self.base_offset.to_c()}];"
)
if var.condition:
return f"if ({var.condition}) {{ {assign} }}\n"
return f"{assign}\n"
def push(self, var: StackItem) -> str:
self.variables.append(var)
if var.is_array() and var.name not in self.defined and var.name != "unused":
c_offset = self.top_offset.to_c()
self.top_offset.push(var)
self.defined.add(var.name)
return f"{var.name} = &stack_pointer[{c_offset}];\n"
else:
self.top_offset.push(var)
return ""
def flush(self, out: CWriter) -> None:
for var in self.variables:
if not var.peek:
cast = "(PyObject *)" if var.type else ""
if var.name != "unused" and not var.is_array():
if var.condition:
out.emit(f" if ({var.condition}) ")
out.emit(
f"stack_pointer[{self.base_offset.to_c()}] = {cast}{var.name};\n"
)
self.base_offset.push(var)
if self.base_offset.to_c() != self.top_offset.to_c():
print("base", self.base_offset.to_c(), "top", self.top_offset.to_c())
assert False
number = self.base_offset.to_c()
if number != "0":
out.emit(f"stack_pointer += {number};\n")
self.variables = []
self.base_offset.clear()
self.top_offset.clear()
self.peek_offset.clear()
def as_comment(self) -> str:
return f"/* Variables: {[v.name for v in self.variables]}. Base offset: {self.base_offset.to_c()}. Top offset: {self.top_offset.to_c()} */"
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