| 1 | """
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| 2 | pass_state.py
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| 3 | """
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| 4 | from __future__ import print_function
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| 5 |
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| 6 | import os
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| 7 | from collections import defaultdict
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| 8 |
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| 9 | from mycpp.util import join_name, log, SymbolPath
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| 10 |
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| 11 | from typing import Optional
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| 12 |
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| 13 | _ = log
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| 14 |
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| 15 |
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| 16 | class Virtual(object):
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| 17 | """Calculate which C++ methods need the virtual keyword.
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| 18 |
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| 19 | See unit test for example usage.
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| 20 | """
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| 21 |
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| 22 | def __init__(self) -> None:
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| 23 | self.methods: dict[SymbolPath, list[str]] = defaultdict(list)
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| 24 | self.subclasses: dict[SymbolPath, list[tuple[str]]] = defaultdict(list)
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| 25 | self.virtuals: dict[tuple[SymbolPath, str], Optional[tuple[SymbolPath,
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| 26 | str]]] = {}
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| 27 | self.has_vtable: dict[SymbolPath, bool] = {}
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| 28 | self.can_reorder_fields: dict[SymbolPath, bool] = {}
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| 29 |
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| 30 | # _Executor -> vm::_Executor
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| 31 | self.base_class_unique: dict[str, SymbolPath] = {}
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| 32 |
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| 33 | # These are called on the Forward Declare pass
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| 34 | def OnMethod(self, class_name: SymbolPath, method_name: str) -> None:
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| 35 | #log('OnMethod %s %s', class_name, method_name)
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| 36 |
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| 37 | # __init__ and so forth don't count
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| 38 | if method_name.startswith('__') and method_name.endswith('__'):
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| 39 | return
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| 40 |
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| 41 | self.methods[class_name].append(method_name)
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| 42 |
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| 43 | def OnSubclass(self, base_class: SymbolPath, subclass: SymbolPath) -> None:
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| 44 | if len(base_class) > 1:
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| 45 | # Hack for
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| 46 | #
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| 47 | # class _Executor: pass
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| 48 | # versus
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| 49 | # class MyExecutor(vm._Executor): pass
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| 50 | base_key = base_class[-1]
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| 51 |
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| 52 | # Fail if we have two base classes in different namespaces with the same
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| 53 | # name.
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| 54 | if base_key in self.base_class_unique:
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| 55 | # Make sure we don't have collisions
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| 56 | assert (self.base_class_unique[base_key] == base_class or
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| 57 | base_class
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| 58 | in self.subclasses[self.base_class_unique[base_key]]
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| 59 | ), base_class
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| 60 | else:
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| 61 | self.base_class_unique[base_key] = base_class
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| 62 |
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| 63 | else:
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| 64 | base_key = base_class
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| 65 |
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| 66 | self.subclasses[base_class].append(subclass)
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| 67 |
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| 68 | def Calculate(self) -> None:
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| 69 | """Call this after the forward declare pass."""
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| 70 | for base_class, subclasses in self.subclasses.items():
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| 71 | self.can_reorder_fields[base_class] = False
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| 72 |
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| 73 | for subclass in subclasses:
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| 74 | self.can_reorder_fields[subclass] = False
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| 75 |
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| 76 | b_methods = self.methods[base_class]
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| 77 | s_methods = self.methods[subclass]
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| 78 | overlapping = set(b_methods) & set(s_methods)
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| 79 | for method in overlapping:
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| 80 | self.virtuals[(base_class, method)] = None
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| 81 | self.virtuals[(subclass, method)] = (base_class, method)
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| 82 | if overlapping:
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| 83 | self.has_vtable[base_class] = True
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| 84 | self.has_vtable[subclass] = True
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| 85 |
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| 86 | # These is called on the Decl pass
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| 87 | def IsVirtual(self, class_name: SymbolPath, method_name: str) -> bool:
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| 88 | return (class_name, method_name) in self.virtuals
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| 89 |
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| 90 | def HasVTable(self, class_name: SymbolPath) -> bool:
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| 91 | return class_name in self.has_vtable
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| 92 |
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| 93 | def CanReorderFields(self, class_name: SymbolPath) -> bool:
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| 94 | if class_name in self.can_reorder_fields:
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| 95 | return self.can_reorder_fields[class_name]
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| 96 | else:
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| 97 | return True # by default they can be reordered
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| 98 |
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| 99 |
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| 100 | class Fact(object):
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| 101 | """
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| 102 | An abstract fact. These can be used to build up datalog programs.
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| 103 | """
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| 104 |
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| 105 | def __init__(self) -> None:
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| 106 | pass
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| 107 |
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| 108 | def name(self) -> str:
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| 109 | raise NotImplementedError()
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| 110 |
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| 111 | def Generate(self, func: str, statement: int) -> str:
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| 112 | raise NotImplementedError()
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| 113 |
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| 114 |
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| 115 | class FunctionCall(Fact):
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| 116 | def __init__(self, callee: str) -> None:
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| 117 | self.callee = callee
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| 118 |
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| 119 | def name(self) -> str:
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| 120 | return 'call'
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| 121 |
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| 122 | def Generate(self, func: str, statement: int) -> str:
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| 123 | return '{}\t{}\t{}\n'.format(func, statement, self.callee)
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| 124 |
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| 125 |
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| 126 | class ControlFlowGraph(object):
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| 127 | """
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| 128 | A simple control-flow graph.
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| 129 |
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| 130 | Every statement in the program is represented as a node in a graph with
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| 131 | unique a numeric ID. Control flow is represented as directed edges through
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| 132 | the graph. Loops can introduce back-edges. Every node in the graph will
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| 133 | satisfy at least one of the following conditions:
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| 134 |
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| 135 | - Its indegree is at least one.
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| 136 |
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| 137 | - Its outdegree is at least one.
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| 138 |
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| 139 | For simple linear graphs all you need is the AddStatement method. For more
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| 140 | complex flows there is a set of context managers below to help simplify
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| 141 | construction.
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| 142 |
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| 143 | - For branches-like statements (e.g. if- and try- statements) use
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| 144 | CfgBranchContext. It will take care of the details associated with
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| 145 | stitching the different branches to statements in the next statement.
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| 146 |
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| 147 | - For loops, use CfgLoopContext. It will take care of adding back-edges
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| 148 | and connecting break statements to any statements that proceed the
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| 149 | loop.
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| 150 |
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| 151 | - CfgBlockContext can be used for simple cases where you just want to
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| 152 | track the beginning and end of a sequence of statements.
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| 153 |
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| 154 | Statements can carry annotations called facts, which are used as inputs to
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| 155 | datalog programs to perform dataflow diffrent kinds of dataflow analyses.
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| 156 | To annotate a statement, use the AddFact method with any object that
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| 157 | implements the Fact interface.
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| 158 |
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| 159 | See the unit tests in pass_state_test.py and the mycpp phase in
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| 160 | control_flow_pass.py for detailed examples of usage.
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| 161 | """
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| 162 |
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| 163 | def __init__(self) -> None:
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| 164 | self.statement_counter: int = 0
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| 165 | self.edges: set[tuple[int, int]] = set({})
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| 166 | self.block_stack: list[int] = []
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| 167 | self.predecessors: set[int] = set({})
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| 168 | self.deadends: set[int] = set({})
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| 169 |
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| 170 | # order doesn't actually matter here, but sets require elements to be
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| 171 | # hashable
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| 172 | self.facts: dict[int, list[Fact]] = defaultdict(list)
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| 173 |
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| 174 | def AddEdge(self, pred: int, succ: int) -> None:
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| 175 | """
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| 176 | Add a directed edge from pred to succ. If pred is a deadend, its
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| 177 | non-deadends will be used instead.
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| 178 | """
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| 179 | if pred in self.deadends:
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| 180 | for w in [u for (u, v) in self.edges if v == pred]:
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| 181 | self.AddEdge(w, succ)
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| 182 | else:
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| 183 | self.edges.add((pred, succ))
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| 184 |
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| 185 | def AddDeadend(self, statement: int):
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| 186 | """
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| 187 | Mark a statement as a dead-end (e.g. return or continue).
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| 188 | """
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| 189 | self.deadends.add(statement)
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| 190 |
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| 191 | def AddStatement(self) -> int:
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| 192 | """
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| 193 | Add a new statement and return its ID.
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| 194 | """
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| 195 | if len(self.predecessors) == 0:
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| 196 | if len(self.block_stack):
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| 197 | self.predecessors.add(self.block_stack[-1])
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| 198 | else:
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| 199 | self.predecessors.add(self.statement_counter)
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| 200 |
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| 201 | self.statement_counter += 1
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| 202 | for pred in self.predecessors:
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| 203 | self.AddEdge(pred, self.statement_counter)
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| 204 |
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| 205 | self.predecessors = set({})
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| 206 |
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| 207 | if len(self.block_stack):
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| 208 | self.block_stack[-1] = self.statement_counter
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| 209 |
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| 210 | return self.statement_counter
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| 211 |
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| 212 | def AddFact(self, statement: int, fact: Fact) -> None:
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| 213 | """
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| 214 | Annotate a statement with a fact.
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| 215 | """
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| 216 | self.facts[statement].append(fact)
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| 217 |
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| 218 | def _PushBlock(self, begin: Optional[int] = None) -> int:
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| 219 | """
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| 220 | Start a block at the given statement ID. If a beginning statement isn't
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| 221 | provided one will be created and its ID will be returend.
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| 222 |
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| 223 | Direct use of this function is discouraged. Consider using one of the
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| 224 | block context managers below instead.
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| 225 | """
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| 226 | if begin is None:
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| 227 | begin = self.AddStatement()
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| 228 | else:
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| 229 | self.predecessors.add(begin)
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| 230 |
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| 231 | self.block_stack.append(begin)
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| 232 | return begin
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| 233 |
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| 234 | def _PopBlock(self) -> int:
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| 235 | """
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| 236 | Pop a block from the top of the stack and return the ID of the block's
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| 237 | last statement.
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| 238 |
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| 239 | Direct use of this function is discouraged. Consider using one of the
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| 240 | block context managers below instead.
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| 241 | """
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| 242 | assert len(self.block_stack)
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| 243 | last = self.block_stack.pop()
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| 244 | if len(self.block_stack) and last not in self.deadends:
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| 245 | self.block_stack[-1] = last
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| 246 |
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| 247 | return last
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| 248 |
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| 249 |
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| 250 | class CfgBlockContext(object):
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| 251 | """
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| 252 | Context manager to make dealing with things like with-statements easier.
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| 253 | """
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| 254 |
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| 255 | def __init__(self,
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| 256 | cfg: ControlFlowGraph,
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| 257 | begin: Optional[int] = None) -> None:
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| 258 | self.cfg = cfg
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| 259 | if cfg is None:
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| 260 | return
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| 261 |
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| 262 | self.entry = self.cfg._PushBlock(begin)
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| 263 | self.exit = self.entry
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| 264 |
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| 265 | def __enter__(self) -> None:
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| 266 | return self if self.cfg else None
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| 267 |
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| 268 | def __exit__(self, *args) -> None:
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| 269 | if not self.cfg:
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| 270 | return
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| 271 |
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| 272 | self.exit = self.cfg._PopBlock()
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| 273 |
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| 274 |
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| 275 | class CfgBranchContext(object):
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| 276 | """
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| 277 | Context manager to make dealing with if-else blocks easier.
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| 278 | """
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| 279 |
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| 280 | def __init__(self, cfg: ControlFlowGraph, branch_point: int) -> None:
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| 281 | self.cfg = cfg
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| 282 | self.entry = branch_point
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| 283 | self.exit = self.entry
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| 284 | if cfg is None:
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| 285 | return
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| 286 |
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| 287 | self.arms = []
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| 288 | self.pushed = False
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| 289 |
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| 290 | def AddBranch(self, entry: Optional[int] = None):
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| 291 | if not self.cfg:
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| 292 | return CfgBranchContext(None, None)
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| 293 |
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| 294 | self.arms.append(CfgBranchContext(self.cfg, entry or self.entry))
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| 295 | self.cfg._PushBlock(self.arms[-1].entry)
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| 296 | self.arms[-1].pushed = True
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| 297 | return self.arms[-1]
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| 298 |
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| 299 | def __enter__(self) -> None:
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| 300 | return self
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| 301 |
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| 302 | def __exit__(self, *args) -> None:
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| 303 | if not self.cfg:
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| 304 | return
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| 305 |
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| 306 | if self.pushed:
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| 307 | self.exit = self.cfg._PopBlock()
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| 308 |
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| 309 | for arm in self.arms:
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| 310 | if arm.exit not in self.cfg.deadends:
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| 311 | self.cfg.predecessors.add(arm.exit)
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| 312 |
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| 313 |
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| 314 | class CfgLoopContext(object):
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| 315 | """
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| 316 | Context manager to make dealing with loops easier.
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| 317 | """
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| 318 |
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| 319 | def __init__(self, cfg: ControlFlowGraph, entry: Optional[int] = None) -> None:
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| 320 | self.cfg = cfg
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| 321 | self.breaks = set({})
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| 322 | if cfg is None:
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| 323 | return
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| 324 |
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| 325 | self.entry = self.cfg._PushBlock(entry)
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| 326 | self.exit = self.entry
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| 327 |
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| 328 | def AddBreak(self, statement: int) -> None:
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| 329 | assert self.cfg
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| 330 | self.breaks.add(statement)
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| 331 | self.cfg.AddDeadend(statement)
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| 332 |
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| 333 | def AddContinue(self, statement: int) -> None:
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| 334 | self.cfg.AddEdge(statement, self.entry)
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| 335 | self.cfg.AddDeadend(statement)
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| 336 |
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| 337 | def __enter__(self) -> None:
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| 338 | return self if self.cfg else None
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| 339 |
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| 340 | def __exit__(self, *args) -> None:
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| 341 | if not self.cfg:
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| 342 | return
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| 343 |
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| 344 | self.exit = self.cfg._PopBlock()
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| 345 | self.cfg.AddEdge(self.exit, self.entry)
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| 346 | for pred in self.cfg.predecessors:
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| 347 | self.cfg.AddEdge(pred, self.entry)
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| 348 |
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| 349 | # If we had any breaks, arm the predecessor set with the current
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| 350 | # statement and the break statements.
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| 351 | if len(self.breaks):
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| 352 | if len(self.cfg.block_stack):
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| 353 | self.cfg.predecessors.add(self.cfg.block_stack[-1])
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| 354 | else:
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| 355 | self.cfg.predecessors.add(self.cfg.statement_counter)
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| 356 |
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| 357 | for b in self.breaks:
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| 358 | self.cfg.deadends.remove(b)
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| 359 | self.cfg.predecessors.add(b)
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| 360 |
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| 361 |
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| 362 | def DumpControlFlowGraphs(cfgs: dict[str, ControlFlowGraph],
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| 363 | facts_dir='_tmp/mycpp-facts') -> None:
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| 364 | """
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| 365 | Dump the given control flow graphs and associated facts into the given
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| 366 | directory as text files that can be consumed by datalog.
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| 367 | """
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| 368 | edge_facts = '{}/cf_edge.facts'.format(facts_dir)
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| 369 | fact_files = {}
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| 370 | os.makedirs(facts_dir, exist_ok=True)
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| 371 | with open(edge_facts, 'w') as cfg_f:
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| 372 | for func, cfg in sorted(cfgs.items()):
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| 373 | joined = join_name(func, delim='.')
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| 374 | for (u, v) in sorted(cfg.edges):
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| 375 | cfg_f.write('{}\t{}\t{}\n'.format(joined, u, v))
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| 376 |
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| 377 | for statement, facts in sorted(cfg.facts.items()):
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| 378 | for fact in facts: # already sorted temporally
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| 379 | fact_f = fact_files.get(fact.name())
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| 380 | if not fact_f:
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| 381 | fact_f = open('{}/{}.facts'.format(facts_dir, fact.name()), 'w')
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| 382 | fact_files[fact.name()] = fact_f
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| 383 |
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| 384 | fact_f.write(fact.Generate(joined, statement))
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| 385 |
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| 386 | for f in fact_files.values():
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| 387 | f.close()
|