mirror of
https://github.com/python/cpython.git
synced 2025-10-31 13:41:24 +00:00
639 lines
22 KiB
Python
639 lines
22 KiB
Python
import re
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from analyzer import StackItem, StackEffect, Instruction, Uop, PseudoInstruction
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from collections import defaultdict
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from dataclasses import dataclass
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from cwriter import CWriter
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from typing import Iterator, Tuple
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UNUSED = {"unused"}
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def maybe_parenthesize(sym: str) -> str:
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"""Add parentheses around a string if it contains an operator
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and is not already parenthesized.
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An exception is made for '*' which is common and harmless
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in the context where the symbolic size is used.
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"""
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if sym.startswith("(") and sym.endswith(")"):
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return sym
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if re.match(r"^[\s\w*]+$", sym):
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return sym
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else:
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return f"({sym})"
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def var_size(var: StackItem) -> str:
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if var.condition:
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# Special case simplifications
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if var.condition == "0":
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return "0"
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elif var.condition == "1":
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return var.get_size()
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elif var.condition == "oparg & 1" and not var.size:
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return f"({var.condition})"
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else:
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return f"(({var.condition}) ? {var.get_size()} : 0)"
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elif var.size:
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return var.size
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else:
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return "1"
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@dataclass
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class Local:
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item: StackItem
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cached: bool
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in_memory: bool
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defined: bool
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def __repr__(self) -> str:
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return f"Local('{self.item.name}', mem={self.in_memory}, defined={self.defined}, array={self.is_array()})"
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def compact_str(self) -> str:
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mtag = "M" if self.in_memory else ""
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dtag = "D" if self.defined else ""
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atag = "A" if self.is_array() else ""
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return f"'{self.item.name}'{mtag}{dtag}{atag}"
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@staticmethod
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def unused(defn: StackItem) -> "Local":
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return Local(defn, False, defn.is_array(), False)
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@staticmethod
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def undefined(defn: StackItem) -> "Local":
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array = defn.is_array()
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return Local(defn, not array, array, False)
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@staticmethod
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def redefinition(var: StackItem, prev: "Local") -> "Local":
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assert var.is_array() == prev.is_array()
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return Local(var, prev.cached, prev.in_memory, True)
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@staticmethod
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def from_memory(defn: StackItem) -> "Local":
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return Local(defn, True, True, True)
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def copy(self) -> "Local":
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return Local(
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self.item,
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self.cached,
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self.in_memory,
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self.defined
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)
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@property
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def size(self) -> str:
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return self.item.size
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@property
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def name(self) -> str:
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return self.item.name
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@property
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def condition(self) -> str | None:
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return self.item.condition
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def is_array(self) -> bool:
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return self.item.is_array()
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def __eq__(self, other: object) -> bool:
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if not isinstance(other, Local):
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return NotImplemented
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return (
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self.item is other.item
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and self.cached is other.cached
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and self.in_memory is other.in_memory
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and self.defined is other.defined
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)
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@dataclass
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class StackOffset:
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"The stack offset of the virtual base of the stack from the physical stack pointer"
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popped: list[str]
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pushed: list[str]
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@staticmethod
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def empty() -> "StackOffset":
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return StackOffset([], [])
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def copy(self) -> "StackOffset":
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return StackOffset(self.popped[:], self.pushed[:])
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def pop(self, item: StackItem) -> None:
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self.popped.append(var_size(item))
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def push(self, item: StackItem) -> None:
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self.pushed.append(var_size(item))
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def __sub__(self, other: "StackOffset") -> "StackOffset":
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return StackOffset(self.popped + other.pushed, self.pushed + other.popped)
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def __neg__(self) -> "StackOffset":
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return StackOffset(self.pushed, self.popped)
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def simplify(self) -> None:
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"Remove matching values from both the popped and pushed list"
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if not self.popped:
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self.pushed.sort()
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return
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if not self.pushed:
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self.popped.sort()
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return
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# Sort the list so the lexically largest element is last.
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popped = sorted(self.popped)
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pushed = sorted(self.pushed)
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self.popped = []
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self.pushed = []
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while popped and pushed:
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pop = popped.pop()
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push = pushed.pop()
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if pop == push:
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pass
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elif pop > push:
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# if pop > push, there can be no element in pushed matching pop.
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self.popped.append(pop)
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pushed.append(push)
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else:
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self.pushed.append(push)
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popped.append(pop)
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self.popped.extend(popped)
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self.pushed.extend(pushed)
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self.pushed.sort()
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self.popped.sort()
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def to_c(self) -> str:
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self.simplify()
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int_offset = 0
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symbol_offset = ""
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for item in self.popped:
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try:
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int_offset -= int(item)
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except ValueError:
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symbol_offset += f" - {maybe_parenthesize(item)}"
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for item in self.pushed:
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try:
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int_offset += int(item)
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except ValueError:
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symbol_offset += f" + {maybe_parenthesize(item)}"
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if symbol_offset and not int_offset:
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res = symbol_offset
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else:
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res = f"{int_offset}{symbol_offset}"
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if res.startswith(" + "):
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res = res[3:]
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if res.startswith(" - "):
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res = "-" + res[3:]
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return res
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def as_int(self) -> int | None:
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self.simplify()
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int_offset = 0
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for item in self.popped:
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try:
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int_offset -= int(item)
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except ValueError:
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return None
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for item in self.pushed:
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try:
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int_offset += int(item)
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except ValueError:
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return None
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return int_offset
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def clear(self) -> None:
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self.popped = []
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self.pushed = []
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def __bool__(self) -> bool:
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self.simplify()
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return bool(self.popped) or bool(self.pushed)
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def __eq__(self, other: object) -> bool:
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if not isinstance(other, StackOffset):
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return NotImplemented
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return self.to_c() == other.to_c()
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class StackError(Exception):
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pass
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def array_or_scalar(var: StackItem | Local) -> str:
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return "array" if var.is_array() else "scalar"
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class Stack:
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def __init__(self, extract_bits: bool=True) -> None:
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self.top_offset = StackOffset.empty()
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self.base_offset = StackOffset.empty()
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self.variables: list[Local] = []
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self.defined: set[str] = set()
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self.extract_bits = extract_bits
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def pop(self, var: StackItem) -> tuple[str, Local]:
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self.top_offset.pop(var)
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indirect = "&" if var.is_array() else ""
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if self.variables:
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popped = self.variables.pop()
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if var.is_array() ^ popped.is_array():
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raise StackError(
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f"Array mismatch when popping '{popped.name}' from stack to assign to '{var.name}'. "
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f"Expected {array_or_scalar(var)} got {array_or_scalar(popped)}"
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)
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if popped.size != var.size:
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raise StackError(
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f"Size mismatch when popping '{popped.name}' from stack to assign to '{var.name}'. "
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f"Expected {var_size(var)} got {var_size(popped.item)}"
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)
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if var.name in UNUSED:
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if popped.name not in UNUSED and popped.name in self.defined:
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raise StackError(
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f"Value is declared unused, but is already cached by prior operation as '{popped.name}'"
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)
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return "", popped
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if not var.used:
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return "", popped
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self.defined.add(var.name)
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if popped.defined:
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if popped.name == var.name:
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return "", popped
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else:
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defn = f"{var.name} = {popped.name};\n"
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else:
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if var.is_array():
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defn = f"{var.name} = &stack_pointer[{self.top_offset.to_c()}];\n"
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else:
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defn = f"{var.name} = stack_pointer[{self.top_offset.to_c()}];\n"
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popped.in_memory = True
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return defn, Local.redefinition(var, popped)
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self.base_offset.pop(var)
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if var.name in UNUSED or not var.used:
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return "", Local.unused(var)
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self.defined.add(var.name)
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cast = f"({var.type})" if (not indirect and var.type) else ""
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bits = ".bits" if cast and self.extract_bits else ""
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assign = f"{var.name} = {cast}{indirect}stack_pointer[{self.base_offset.to_c()}]{bits};"
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if var.condition:
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if var.condition == "1":
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assign = f"{assign}\n"
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elif var.condition == "0":
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return "", Local.unused(var)
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else:
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assign = f"if ({var.condition}) {{ {assign} }}\n"
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else:
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assign = f"{assign}\n"
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return assign, Local.from_memory(var)
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def push(self, var: Local) -> None:
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assert(var not in self.variables)
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self.variables.append(var)
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self.top_offset.push(var.item)
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if var.item.used:
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self.defined.add(var.name)
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@staticmethod
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def _do_emit(
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out: CWriter,
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var: StackItem,
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base_offset: StackOffset,
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cast_type: str = "uintptr_t",
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extract_bits: bool = True,
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) -> None:
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cast = f"({cast_type})" if var.type else ""
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bits = ".bits" if cast and extract_bits else ""
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if var.condition == "0":
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return
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if var.condition and var.condition != "1":
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out.emit(f"if ({var.condition}) ")
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out.emit(f"stack_pointer[{base_offset.to_c()}]{bits} = {cast}{var.name};\n")
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def _adjust_stack_pointer(self, out: CWriter, number: str) -> None:
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if number != "0":
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out.start_line()
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out.emit(f"stack_pointer += {number};\n")
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out.emit("assert(WITHIN_STACK_BOUNDS());\n")
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def flush(
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self, out: CWriter, cast_type: str = "uintptr_t"
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) -> None:
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out.start_line()
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var_offset = self.base_offset.copy()
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for var in self.variables:
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if (
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var.defined and
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not var.in_memory
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):
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Stack._do_emit(out, var.item, var_offset, cast_type, self.extract_bits)
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var.in_memory = True
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var_offset.push(var.item)
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number = self.top_offset.to_c()
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self._adjust_stack_pointer(out, number)
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self.base_offset -= self.top_offset
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self.top_offset.clear()
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out.start_line()
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def is_flushed(self) -> bool:
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return not self.variables and not self.base_offset and not self.top_offset
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def peek_offset(self) -> str:
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return self.top_offset.to_c()
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def as_comment(self) -> str:
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variables = ", ".join([v.compact_str() for v in self.variables])
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return (
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f"/* Variables: {variables}. base: {self.base_offset.to_c()}. top: {self.top_offset.to_c()} */"
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)
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def copy(self) -> "Stack":
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other = Stack(self.extract_bits)
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other.top_offset = self.top_offset.copy()
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other.base_offset = self.base_offset.copy()
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other.variables = [var.copy() for var in self.variables]
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other.defined = set(self.defined)
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return other
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def __eq__(self, other: object) -> bool:
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if not isinstance(other, Stack):
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return NotImplemented
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return (
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self.top_offset == other.top_offset
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and self.base_offset == other.base_offset
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and self.variables == other.variables
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)
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def align(self, other: "Stack", out: CWriter) -> None:
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if len(self.variables) != len(other.variables):
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raise StackError("Cannot align stacks: differing variables")
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if self.top_offset == other.top_offset:
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return
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diff = self.top_offset - other.top_offset
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try:
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self.top_offset -= diff
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self.base_offset -= diff
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self._adjust_stack_pointer(out, diff.to_c())
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except ValueError:
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raise StackError("Cannot align stacks: cannot adjust stack pointer")
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def merge(self, other: "Stack", out: CWriter) -> None:
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if len(self.variables) != len(other.variables):
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raise StackError("Cannot merge stacks: differing variables")
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for self_var, other_var in zip(self.variables, other.variables):
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if self_var.name != other_var.name:
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raise StackError(f"Mismatched variables on stack: {self_var.name} and {other_var.name}")
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self_var.defined = self_var.defined and other_var.defined
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self_var.in_memory = self_var.in_memory and other_var.in_memory
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self.align(other, out)
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def stacks(inst: Instruction | PseudoInstruction) -> Iterator[StackEffect]:
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if isinstance(inst, Instruction):
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for uop in inst.parts:
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if isinstance(uop, Uop):
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yield uop.stack
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else:
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assert isinstance(inst, PseudoInstruction)
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yield inst.stack
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def apply_stack_effect(stack: Stack, effect: StackEffect) -> None:
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locals: dict[str, Local] = {}
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for var in reversed(effect.inputs):
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_, local = stack.pop(var)
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if var.name != "unused":
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locals[local.name] = local
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for var in effect.outputs:
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if var.name in locals:
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local = locals[var.name]
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else:
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local = Local.unused(var)
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stack.push(local)
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def get_stack_effect(inst: Instruction | PseudoInstruction) -> Stack:
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stack = Stack()
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for s in stacks(inst):
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apply_stack_effect(stack, s)
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return stack
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def get_stack_effects(inst: Instruction | PseudoInstruction) -> list[Stack]:
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"""Returns a list of stack effects after each uop"""
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result = []
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stack = Stack()
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for s in stacks(inst):
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apply_stack_effect(stack, s)
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result.append(stack.copy())
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return result
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@dataclass
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class Storage:
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stack: Stack
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inputs: list[Local]
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outputs: list[Local]
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peeks: list[Local]
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spilled: int = 0
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@staticmethod
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def needs_defining(var: Local) -> bool:
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return (
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not var.defined and
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not var.is_array() and
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var.name != "unused"
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)
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@staticmethod
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def is_live(var: Local) -> bool:
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return (
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var.defined and
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var.name != "unused"
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)
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def first_input_not_cleared(self) -> str:
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for input in self.inputs:
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if input.defined:
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return input.name
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return ""
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def clear_inputs(self, reason:str) -> None:
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while self.inputs:
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tos = self.inputs.pop()
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if self.is_live(tos) and not tos.is_array():
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raise StackError(
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f"Input '{tos.name}' is still live {reason}"
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)
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self.stack.pop(tos.item)
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def clear_dead_inputs(self) -> None:
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live = ""
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while self.inputs:
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tos = self.inputs[-1]
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if self.is_live(tos):
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live = tos.name
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break
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self.inputs.pop()
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self.stack.pop(tos.item)
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for var in self.inputs:
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if not var.defined and not var.is_array() and var.name != "unused":
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raise StackError(
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f"Input '{var.name}' is not live, but '{live}' is"
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)
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def _push_defined_outputs(self) -> None:
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defined_output = ""
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for output in self.outputs:
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if output.defined and not output.in_memory:
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defined_output = output.name
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if not defined_output:
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return
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self.clear_inputs(f"when output '{defined_output}' is defined")
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undefined = ""
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for out in self.outputs:
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if out.defined:
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if undefined:
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f"Locals not defined in stack order. "
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f"Expected '{undefined}' to be defined before '{out.name}'"
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else:
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undefined = out.name
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while self.outputs and not self.needs_defining(self.outputs[0]):
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out = self.outputs.pop(0)
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self.stack.push(out)
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def locals_cached(self) -> bool:
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for out in self.outputs:
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if out.defined:
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return True
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return False
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def flush(self, out: CWriter, cast_type: str = "uintptr_t") -> None:
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self.clear_dead_inputs()
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self._push_defined_outputs()
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self.stack.flush(out, cast_type)
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def save(self, out: CWriter) -> None:
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assert self.spilled >= 0
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if self.spilled == 0:
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self.flush(out)
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out.start_line()
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out.emit("_PyFrame_SetStackPointer(frame, stack_pointer);\n")
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self.spilled += 1
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def reload(self, out: CWriter) -> None:
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if self.spilled == 0:
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raise StackError("Cannot reload stack as it hasn't been saved")
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assert self.spilled > 0
|
|
self.spilled -= 1
|
|
if self.spilled == 0:
|
|
out.start_line()
|
|
out.emit("stack_pointer = _PyFrame_GetStackPointer(frame);\n")
|
|
|
|
@staticmethod
|
|
def for_uop(stack: Stack, uop: Uop) -> tuple[list[str], "Storage"]:
|
|
code_list: list[str] = []
|
|
inputs: list[Local] = []
|
|
peeks: list[Local] = []
|
|
for input in reversed(uop.stack.inputs):
|
|
code, local = stack.pop(input)
|
|
code_list.append(code)
|
|
if input.peek:
|
|
peeks.append(local)
|
|
else:
|
|
inputs.append(local)
|
|
inputs.reverse()
|
|
peeks.reverse()
|
|
for peek in peeks:
|
|
stack.push(peek)
|
|
top_offset = stack.top_offset.copy()
|
|
for ouput in uop.stack.outputs:
|
|
if ouput.is_array() and ouput.used and not ouput.peek:
|
|
c_offset = top_offset.to_c()
|
|
top_offset.push(ouput)
|
|
code_list.append(f"{ouput.name} = &stack_pointer[{c_offset}];\n")
|
|
else:
|
|
top_offset.push(ouput)
|
|
for var in inputs:
|
|
stack.push(var)
|
|
outputs = [ Local.undefined(var) for var in uop.stack.outputs if not var.peek ]
|
|
return code_list, Storage(stack, inputs, outputs, peeks)
|
|
|
|
@staticmethod
|
|
def copy_list(arg: list[Local]) -> list[Local]:
|
|
return [ l.copy() for l in arg ]
|
|
|
|
def copy(self) -> "Storage":
|
|
new_stack = self.stack.copy()
|
|
variables = { var.name: var for var in new_stack.variables }
|
|
inputs = [ variables[var.name] for var in self.inputs]
|
|
assert [v.name for v in inputs] == [v.name for v in self.inputs], (inputs, self.inputs)
|
|
return Storage(
|
|
new_stack, inputs,
|
|
self.copy_list(self.outputs), self.copy_list(self.peeks), self.spilled
|
|
)
|
|
|
|
def sanity_check(self) -> None:
|
|
names: set[str] = set()
|
|
for var in self.inputs:
|
|
if var.name in names:
|
|
raise StackError(f"Duplicate name {var.name}")
|
|
names.add(var.name)
|
|
names = set()
|
|
for var in self.outputs:
|
|
if var.name in names:
|
|
raise StackError(f"Duplicate name {var.name}")
|
|
names.add(var.name)
|
|
names = set()
|
|
for var in self.stack.variables:
|
|
if var.name in names:
|
|
raise StackError(f"Duplicate name {var.name}")
|
|
names.add(var.name)
|
|
|
|
def is_flushed(self) -> bool:
|
|
for var in self.outputs:
|
|
if var.defined and not var.in_memory:
|
|
return False
|
|
return self.stack.is_flushed()
|
|
|
|
def merge(self, other: "Storage", out: CWriter) -> None:
|
|
self.sanity_check()
|
|
if len(self.inputs) != len(other.inputs):
|
|
self.clear_dead_inputs()
|
|
other.clear_dead_inputs()
|
|
if len(self.inputs) != len(other.inputs):
|
|
diff = self.inputs[-1] if len(self.inputs) > len(other.inputs) else other.inputs[-1]
|
|
raise StackError(f"Unmergeable inputs. Differing state of '{diff.name}'")
|
|
for var, other_var in zip(self.inputs, other.inputs):
|
|
if var.defined != other_var.defined:
|
|
raise StackError(f"'{var.name}' is cleared on some paths, but not all")
|
|
if len(self.outputs) != len(other.outputs):
|
|
self._push_defined_outputs()
|
|
other._push_defined_outputs()
|
|
if len(self.outputs) != len(other.outputs):
|
|
var = self.outputs[0] if len(self.outputs) > len(other.outputs) else other.outputs[0]
|
|
raise StackError(f"'{var.name}' is set on some paths, but not all")
|
|
self.stack.merge(other.stack, out)
|
|
self.sanity_check()
|
|
|
|
def push_outputs(self) -> None:
|
|
if self.spilled:
|
|
raise StackError(f"Unbalanced stack spills")
|
|
self.clear_inputs("at the end of the micro-op")
|
|
if self.inputs:
|
|
raise StackError(f"Input variable '{self.inputs[-1].name}' is still live")
|
|
self._push_defined_outputs()
|
|
if self.outputs:
|
|
for out in self.outputs:
|
|
if self.needs_defining(out):
|
|
raise StackError(f"Output variable '{self.outputs[0].name}' is not defined")
|
|
self.stack.push(out)
|
|
self.outputs = []
|
|
|
|
def as_comment(self) -> str:
|
|
stack_comment = self.stack.as_comment()
|
|
next_line = "\n "
|
|
inputs = ", ".join([var.compact_str() for var in self.inputs])
|
|
outputs = ", ".join([var.compact_str() for var in self.outputs])
|
|
peeks = ", ".join([var.name for var in self.peeks])
|
|
return f"{stack_comment[:-2]}{next_line}inputs: {inputs}{next_line}outputs: {outputs}{next_line}peeks: {peeks} */"
|