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- """Constant folding of IR values.
- For example, 3 + 5 can be constant folded into 8.
- This is mostly like mypy.constant_fold, but we can bind some additional
- NameExpr and MemberExpr references here, since we have more knowledge
- about which definitions can be trusted -- we constant fold only references
- to other compiled modules in the same compilation unit.
- """
- from __future__ import annotations
- from typing import Union
- from typing_extensions import Final
- from mypy.constant_fold import (
- constant_fold_binary_int_op,
- constant_fold_binary_str_op,
- constant_fold_unary_float_op,
- constant_fold_unary_int_op,
- )
- from mypy.nodes import (
- Expression,
- FloatExpr,
- IntExpr,
- MemberExpr,
- NameExpr,
- OpExpr,
- StrExpr,
- UnaryExpr,
- Var,
- )
- from mypyc.irbuild.builder import IRBuilder
- # All possible result types of constant folding
- ConstantValue = Union[int, str, float]
- CONST_TYPES: Final = (int, str, float)
- def constant_fold_expr(builder: IRBuilder, expr: Expression) -> ConstantValue | None:
- """Return the constant value of an expression for supported operations.
- Return None otherwise.
- """
- if isinstance(expr, IntExpr):
- return expr.value
- if isinstance(expr, StrExpr):
- return expr.value
- if isinstance(expr, FloatExpr):
- return expr.value
- elif isinstance(expr, NameExpr):
- node = expr.node
- if isinstance(node, Var) and node.is_final:
- value = node.final_value
- if isinstance(value, (CONST_TYPES)):
- return value
- elif isinstance(expr, MemberExpr):
- final = builder.get_final_ref(expr)
- if final is not None:
- fn, final_var, native = final
- if final_var.is_final:
- value = final_var.final_value
- if isinstance(value, (CONST_TYPES)):
- return value
- elif isinstance(expr, OpExpr):
- left = constant_fold_expr(builder, expr.left)
- right = constant_fold_expr(builder, expr.right)
- if isinstance(left, int) and isinstance(right, int):
- return constant_fold_binary_int_op(expr.op, left, right)
- elif isinstance(left, str) and isinstance(right, str):
- return constant_fold_binary_str_op(expr.op, left, right)
- elif isinstance(expr, UnaryExpr):
- value = constant_fold_expr(builder, expr.expr)
- if isinstance(value, int):
- return constant_fold_unary_int_op(expr.op, value)
- if isinstance(value, float):
- return constant_fold_unary_float_op(expr.op, value)
- return None
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