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from __future__ import print_function
import miasm.expression.expression as m2_expr
from miasm.expression.simplifications import ExpressionSimplifier
# Creates an expression simplifier that (by default) applies no simplifications.
# Other instances with simplifications enabled by default can be found in `expressions/simplifications.py`.
simp = ExpressionSimplifier()
print("""
Expression simplification demo: Adding a simplification:
a + a + a == a * 3
More detailed examples can be found in miasm/expression/simplification*.
""")
# Define the simplification method
## @expr_simp is the current expression simplifier instance
## (for recursive simplifications)
## @expr is the expression to (perhaps) simplify
def simp_add_mul(expr_simp, expr):
"Naive Simplification: a + a + a == a * 3"
# Match the expected form
## isinstance(expr, m2_expr.ExprOp) is not needed: simplifications are
## attached to expression types
if expr.op == "+" and \
len(expr.args) == 3 and \
expr.args.count(expr.args[0]) == len(expr.args):
# Effective simplification
return m2_expr.ExprOp("*", expr.args[0],
m2_expr.ExprInt(3, expr.args[0].size))
else:
# Do not simplify
return expr
a = m2_expr.ExprId('a', 32)
base_expr = a + a + a
print("Without adding the simplification:")
print("\t%s = %s" % (base_expr, simp(base_expr)))
# Enable pass
simp.enable_passes({m2_expr.ExprOp: [simp_add_mul]})
print("After adding the simplification:")
print("\t%s = %s" % (base_expr, simp(base_expr)))
assert simp(base_expr) == m2_expr.ExprOp("*", a,
m2_expr.ExprInt(3, a.size))
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