Python: CG trace: Avoid handling jumps for now

RasmusWL · RasmusWL · commit 0a7e6a99385c · 2020-07-21T20:07:33.000+02:00
diff --git a/python/tools/recorded-call-graph-metrics/example/problem-1.py b/python/tools/recorded-call-graph-metrics/example/problem-1.py
@@ -0,0 +1,26 @@
+class Foo:
+    def __init__(self):
+        self.list = []
+
+    def func(self, kwargs=None, result_callback=None):
+        self.list.append((kwargs or {}, result_callback))
+
+
+foo = Foo()
+foo.func()
+
+"""
+Has problematic bytecode, since to find out what method is called from instruction 16, we need
+to traverse the JUMP_IF_TRUE_OR_POP which requires some more sophistication.
+
+Disassembly of <code object func at 0x7f98f64ee030, file "example/problem-1.py", line 5>:
+  6           0 LOAD_FAST                0 (self)
+              2 LOAD_ATTR                0 (list)
+              4 LOAD_METHOD              1 (append)
+              6 LOAD_FAST                1 (kwargs)
+              8 JUMP_IF_TRUE_OR_POP     12
+             10 BUILD_MAP                0
+        >>   12 LOAD_FAST                2 (result_callback)
+             14 BUILD_TUPLE              2
+             16 CALL_METHOD              1
+"""
diff --git a/python/tools/recorded-call-graph-metrics/src/cg_trace/bytecode_reconstructor.py b/python/tools/recorded-call-graph-metrics/src/cg_trace/bytecode_reconstructor.py
@@ -71,6 +71,14 @@ def __str__(self):
         return f"<MAKE_FUNCTION>(qualified_name={self.qualified_name})>"
 
 
+@dataclasses.dataclass(frozen=True, eq=True, order=True)
+class SomethingInvolvingScaryBytecodeJump(BytecodeExpr):
+    opname: str
+
+    def __str__(self):
+        return "<SomethingInvolvingScaryBytecodeJump>"
+
+
 def expr_that_added_elem_to_stack(
     instructions: List[Instruction], start_index: int, stack_pos: int
 ):
@@ -95,10 +103,18 @@ def expr_that_added_elem_to_stack(
     It is assumed that if `stack_pos == 0` then the instruction you are looking for is
     the one at `instructions[start_index]`. This might not hold, in case of using `NOP`
     instructions.
+
+    If any jump instruction is found, `SomethingInvolvingScaryBytecodeJump` is returned
+    immediately. (since correctly process the bytecode when faced with jumps is not as
+    straight forward).
     """
     LOGGER.debug(f"find_inst_that_added_elem_to_stack {start_index=} {stack_pos=}")
     assert stack_pos >= 0
     for inst in reversed(instructions[: start_index + 1]):
+        # Return immediately if faced with a jump
+        if inst.opcode in dis.hasjabs or inst.opcode in dis.hasjrel:
+            return SomethingInvolvingScaryBytecodeJump(inst.opname)
+
         if stack_pos == 0:
             LOGGER.debug(f"Found it: {inst}")
             found_index = instructions.index(inst)
