| import re |
| from analyzer import StackItem, StackEffect, Instruction, Uop, PseudoInstruction |
| from dataclasses import dataclass |
| from cwriter import CWriter |
| from typing import Iterator |
| |
| UNUSED = {"unused"} |
| |
| |
| def maybe_parenthesize(sym: str) -> str: |
| """Add parentheses around a string if it contains an operator |
| and is not already parenthesized. |
| |
| An exception is made for '*' which is common and harmless |
| in the context where the symbolic size is used. |
| """ |
| if sym.startswith("(") and sym.endswith(")"): |
| return sym |
| if re.match(r"^[\s\w*]+$", sym): |
| return sym |
| else: |
| return f"({sym})" |
| |
| |
| def var_size(var: StackItem) -> str: |
| if var.condition: |
| # Special case simplifications |
| if var.condition == "0": |
| return "0" |
| elif var.condition == "1": |
| return var.get_size() |
| elif var.condition == "oparg & 1" and not var.size: |
| return f"({var.condition})" |
| else: |
| return f"(({var.condition}) ? {var.get_size()} : 0)" |
| elif var.size: |
| return var.size |
| else: |
| return "1" |
| |
| |
| @dataclass |
| class Local: |
| item: StackItem |
| cached: bool |
| in_memory: bool |
| defined: bool |
| |
| @staticmethod |
| def unused(defn: StackItem) -> "Local": |
| return Local(defn, False, defn.is_array(), False) |
| |
| @staticmethod |
| def local(defn: StackItem) -> "Local": |
| array = defn.is_array() |
| return Local(defn, not array, array, True) |
| |
| @staticmethod |
| def redefinition(var: StackItem, prev: "Local") -> "Local": |
| assert var.is_array() == prev.is_array() |
| return Local(var, prev.cached, prev.in_memory, True) |
| |
| @property |
| def size(self) -> str: |
| return self.item.size |
| |
| @property |
| def name(self) -> str: |
| return self.item.name |
| |
| @property |
| def condition(self) -> str | None: |
| return self.item.condition |
| |
| def is_array(self) -> bool: |
| return self.item.is_array() |
| |
| |
| @dataclass |
| class StackOffset: |
| "The stack offset of the virtual base of the stack from the physical stack pointer" |
| |
| popped: list[str] |
| pushed: list[str] |
| |
| @staticmethod |
| def empty() -> "StackOffset": |
| return StackOffset([], []) |
| |
| def copy(self) -> "StackOffset": |
| return StackOffset(self.popped[:], self.pushed[:]) |
| |
| 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 __sub__(self, other: "StackOffset") -> "StackOffset": |
| return StackOffset(self.popped + other.pushed, self.pushed + other.popped) |
| |
| def __neg__(self) -> "StackOffset": |
| return StackOffset(self.pushed, self.popped) |
| |
| def simplify(self) -> None: |
| "Remove matching values from both the popped and pushed list" |
| if not self.popped: |
| self.pushed.sort() |
| return |
| if not self.pushed: |
| self.popped.sort() |
| 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) |
| self.pushed.sort() |
| self.popped.sort() |
| |
| 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 StackError(Exception): |
| pass |
| |
| |
| class Stack: |
| def __init__(self) -> None: |
| self.top_offset = StackOffset.empty() |
| self.base_offset = StackOffset.empty() |
| self.variables: list[Local] = [] |
| self.defined: set[str] = set() |
| |
| def pop(self, var: StackItem, extract_bits: bool = False) -> tuple[str, Local]: |
| self.top_offset.pop(var) |
| indirect = "&" if var.is_array() else "" |
| if self.variables: |
| popped = self.variables.pop() |
| if popped.size != var.size: |
| raise StackError( |
| f"Size mismatch when popping '{popped.name}' from stack to assign to {var.name}. " |
| f"Expected {var.size} got {popped.size}" |
| ) |
| if var.name in UNUSED: |
| if popped.name not in UNUSED and popped.name in self.defined: |
| raise StackError( |
| f"Value is declared unused, but is already cached by prior operation" |
| ) |
| return "", popped |
| if not var.used: |
| return "", popped |
| self.defined.add(var.name) |
| if popped.defined: |
| if popped.name == var.name: |
| return "", popped |
| else: |
| defn = f"{var.name} = {popped.name};\n" |
| else: |
| if var.is_array(): |
| defn = f"{var.name} = &stack_pointer[{self.top_offset.to_c()}];\n" |
| else: |
| defn = f"{var.name} = stack_pointer[{self.top_offset.to_c()}];\n" |
| return defn, Local.redefinition(var, popped) |
| |
| self.base_offset.pop(var) |
| if var.name in UNUSED or not var.used: |
| return "", Local.unused(var) |
| self.defined.add(var.name) |
| cast = f"({var.type})" if (not indirect and var.type) else "" |
| bits = ".bits" if cast and not extract_bits else "" |
| assign = f"{var.name} = {cast}{indirect}stack_pointer[{self.base_offset.to_c()}]{bits};" |
| if var.condition: |
| if var.condition == "1": |
| assign = f"{assign}\n" |
| elif var.condition == "0": |
| return "", Local.unused(var) |
| else: |
| assign = f"if ({var.condition}) {{ {assign} }}\n" |
| else: |
| assign = f"{assign}\n" |
| in_memory = var.is_array() or var.peek |
| return assign, Local(var, not var.is_array(), in_memory, True) |
| |
| def push(self, var: Local) -> None: |
| self.variables.append(var) |
| self.top_offset.push(var.item) |
| if var.item.used: |
| self.defined.add(var.name) |
| var.defined = True |
| |
| def define_output_arrays(self, outputs: list[StackItem]) -> str: |
| res = [] |
| top_offset = self.top_offset.copy() |
| for var in outputs: |
| if var.is_array() and var.used and not var.peek: |
| c_offset = top_offset.to_c() |
| top_offset.push(var) |
| res.append(f"{var.name} = &stack_pointer[{c_offset}];\n") |
| else: |
| top_offset.push(var) |
| return "\n".join(res) |
| |
| @staticmethod |
| def _do_emit( |
| out: CWriter, |
| var: StackItem, |
| base_offset: StackOffset, |
| cast_type: str = "uintptr_t", |
| extract_bits: bool = False, |
| ) -> None: |
| cast = f"({cast_type})" if var.type else "" |
| bits = ".bits" if cast and not extract_bits else "" |
| if var.condition == "0": |
| return |
| if var.condition and var.condition != "1": |
| out.emit(f"if ({var.condition}) ") |
| out.emit(f"stack_pointer[{base_offset.to_c()}]{bits} = {cast}{var.name};\n") |
| |
| @staticmethod |
| def _do_flush( |
| out: CWriter, |
| variables: list[Local], |
| base_offset: StackOffset, |
| top_offset: StackOffset, |
| cast_type: str = "uintptr_t", |
| extract_bits: bool = False, |
| ) -> None: |
| out.start_line() |
| for var in variables: |
| if ( |
| var.cached |
| and not var.in_memory |
| and not var.item.peek |
| and not var.name in UNUSED |
| ): |
| Stack._do_emit(out, var.item, base_offset, cast_type, extract_bits) |
| base_offset.push(var.item) |
| if base_offset.to_c() != top_offset.to_c(): |
| print("base", base_offset, "top", top_offset) |
| assert False |
| number = base_offset.to_c() |
| if number != "0": |
| out.emit(f"stack_pointer += {number};\n") |
| out.emit("assert(WITHIN_STACK_BOUNDS());\n") |
| out.start_line() |
| |
| def flush_locally( |
| self, out: CWriter, cast_type: str = "uintptr_t", extract_bits: bool = False |
| ) -> None: |
| self._do_flush( |
| out, |
| self.variables[:], |
| self.base_offset.copy(), |
| self.top_offset.copy(), |
| cast_type, |
| extract_bits, |
| ) |
| |
| def flush( |
| self, out: CWriter, cast_type: str = "uintptr_t", extract_bits: bool = False |
| ) -> None: |
| self._do_flush( |
| out, |
| self.variables, |
| self.base_offset, |
| self.top_offset, |
| cast_type, |
| extract_bits, |
| ) |
| self.variables = [] |
| self.base_offset.clear() |
| self.top_offset.clear() |
| |
| def flush_single_var( |
| self, |
| out: CWriter, |
| var_name: str, |
| outputs: list[StackItem], |
| cast_type: str = "uintptr_t", |
| extract_bits: bool = False, |
| ) -> None: |
| assert any(var.name == var_name for var in outputs) |
| base_offset = self.base_offset.copy() |
| top_offset = self.top_offset.copy() |
| for var in self.variables: |
| base_offset.push(var.item) |
| for output in outputs: |
| if any(output == v.item for v in self.variables): |
| # The variable is already on the stack, such as a peeked value |
| # in the tier1 generator |
| continue |
| if output.name == var_name: |
| Stack._do_emit(out, output, base_offset, cast_type, extract_bits) |
| base_offset.push(output) |
| top_offset.push(output) |
| if base_offset.to_c() != top_offset.to_c(): |
| print("base", base_offset, "top", top_offset) |
| assert False |
| |
| def peek_offset(self) -> str: |
| return self.top_offset.to_c() |
| |
| 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()} */" |
| |
| |
| def get_stack_effect(inst: Instruction | PseudoInstruction) -> Stack: |
| stack = Stack() |
| |
| def stacks(inst: Instruction | PseudoInstruction) -> Iterator[StackEffect]: |
| if isinstance(inst, Instruction): |
| for uop in inst.parts: |
| if isinstance(uop, Uop): |
| yield uop.stack |
| else: |
| assert isinstance(inst, PseudoInstruction) |
| yield inst.stack |
| |
| for s in stacks(inst): |
| locals: dict[str, Local] = {} |
| for var in reversed(s.inputs): |
| _, local = stack.pop(var) |
| if var.name != "unused": |
| locals[local.name] = local |
| for var in s.outputs: |
| if var.name in locals: |
| local = locals[var.name] |
| else: |
| local = Local.unused(var) |
| stack.push(local) |
| return stack |
