mirror of
https://github.com/cea-sec/miasm
synced 2026-06-21 13:48:18 +00:00
Ivan “CLOVIS” Canet
e71c3152d1
Previously, the test would not do anything, as the simplification added in the test is already a part of the default enabled simplifications: ``` Without adding the simplification: a + a + a = a * 0x3 After adding the simplification: a + a + a = a * 0x3 ``` This also meant that editing the added simplification would have no effect (since the expression was already modified by the default simplifier, it would never match the custom one). This commit replaces `expr_simp` by a newly-created `simp` that doesn't have any simplifications enabled, so the one added by the test has an impact.
53 lines
1.7 KiB
Python
53 lines
1.7 KiB
Python
from __future__ import print_function
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import miasm.expression.expression as m2_expr
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from miasm.expression.simplifications import ExpressionSimplifier
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# Creates an expression simplifier that (by default) applies no simplifications.
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# Other instances with simplifications enabled by default can be found in `expressions/simplifications.py`.
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simp = ExpressionSimplifier()
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print("""
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Expression simplification demo: Adding a simplification:
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a + a + a == a * 3
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More detailed examples can be found in miasm/expression/simplification*.
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""")
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# Define the simplification method
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## @expr_simp is the current expression simplifier instance
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## (for recursive simplifications)
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## @expr is the expression to (perhaps) simplify
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def simp_add_mul(expr_simp, expr):
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"Naive Simplification: a + a + a == a * 3"
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# Match the expected form
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## isinstance(expr, m2_expr.ExprOp) is not needed: simplifications are
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## attached to expression types
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if expr.op == "+" and \
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len(expr.args) == 3 and \
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expr.args.count(expr.args[0]) == len(expr.args):
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# Effective simplification
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return m2_expr.ExprOp("*", expr.args[0],
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m2_expr.ExprInt(3, expr.args[0].size))
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else:
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# Do not simplify
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return expr
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a = m2_expr.ExprId('a', 32)
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base_expr = a + a + a
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print("Without adding the simplification:")
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print("\t%s = %s" % (base_expr, simp(base_expr)))
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# Enable pass
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simp.enable_passes({m2_expr.ExprOp: [simp_add_mul]})
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print("After adding the simplification:")
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print("\t%s = %s" % (base_expr, simp(base_expr)))
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assert simp(base_expr) == m2_expr.ExprOp("*", a,
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m2_expr.ExprInt(3, a.size))
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