gh-91462: Make lltrace output human-readable. (GH-91463)

* Transform opcodes into opnames
* Print the whole stack at each opcode, and eliminate prtrace output at each (push/pop/stackadj)
* Display info about the function at each resume_frame

1 files changed, 89 insertions, 8 deletions

diff --git a/Lib/test/test_lltrace.py b/Lib/test/test_lltrace.py
index 06e33f4..75b377b 100644
--- a/Lib/test/test_lltrace.py
+++ b/Lib/test/test_lltrace.py
@@ -1,21 +1,103 @@
-import os
+import dis
+import sys
 import textwrap
 import unittest
 
-from test.support import os_helper
+from test.support import os_helper, verbose
 from test.support.script_helper import assert_python_ok
 
+def example():
+    x = []
+    for i in range(1):
+        x.append(i)
+    x = "this is"
+    y = "an example"
+    print(x, y)
 
+Py_DEBUG = hasattr(sys, 'gettotalrefcount')
+
+@unittest.skipUnless(Py_DEBUG, "lltrace requires Py_DEBUG")
 class TestLLTrace(unittest.TestCase):
 
+    def run_code(self, code):
+        code = textwrap.dedent(code).strip()
+        with open(os_helper.TESTFN, 'w', encoding='utf-8') as fd:
+            self.addCleanup(os_helper.unlink, os_helper.TESTFN)
+            fd.write(code)
+        status, stdout, stderr = assert_python_ok(os_helper.TESTFN)
+        self.assertEqual(stderr, b"")
+        self.assertEqual(status, 0)
+        result = stdout.decode('utf-8')
+        if verbose:
+            print("\n\n--- code ---")
+            print(code)
+            print("\n--- stdout ---")
+            print(result)
+            print()
+        return result
+
+    def test_lltrace(self):
+        stdout = self.run_code("""
+            def dont_trace_1():
+                a = "a"
+                a = 10 * a
+            def trace_me():
+                for i in range(3):
+                    +i
+            def dont_trace_2():
+                x = 42
+                y = -x
+            dont_trace_1()
+            __ltrace__ = 1
+            trace_me()
+            del __ltrace__
+            dont_trace_2()
+        """)
+        self.assertIn("GET_ITER", stdout)
+        self.assertIn("FOR_ITER", stdout)
+        self.assertIn("UNARY_POSITIVE", stdout)
+        self.assertIn("POP_TOP", stdout)
+        self.assertNotIn("BINARY_OP", stdout)
+        self.assertNotIn("UNARY_NEGATIVE", stdout)
+
+        self.assertIn("'trace_me' in module '__main__'", stdout)
+        self.assertNotIn("dont_trace_1", stdout)
+        self.assertNotIn("'dont_trace_2' in module", stdout)
+
+    def test_lltrace_different_module(self):
+        stdout = self.run_code("""
+            from test import test_lltrace
+            test_lltrace.__ltrace__ = 1
+            test_lltrace.example()
+        """)
+        self.assertIn("'example' in module 'test.test_lltrace'", stdout)
+        self.assertIn('LOAD_CONST', stdout)
+        self.assertIn('FOR_ITER', stdout)
+        self.assertIn('this is an example', stdout)
+
+        # check that offsets match the output of dis.dis()
+        instr_map = {i.offset: i for i in dis.get_instructions(example)}
+        for line in stdout.splitlines():
+            offset, colon, opname_oparg = line.partition(":")
+            if not colon:
+                continue
+            offset = int(offset)
+            opname_oparg = opname_oparg.split()
+            if len(opname_oparg) == 2:
+                opname, oparg = opname_oparg
+                oparg = int(oparg)
+            else:
+                (opname,) = opname_oparg
+                oparg = None
+            self.assertEqual(instr_map[offset].opname, opname)
+            self.assertEqual(instr_map[offset].arg, oparg)
+
     def test_lltrace_does_not_crash_on_subscript_operator(self):
         # If this test fails, it will reproduce a crash reported as
         # bpo-34113. The crash happened at the command line console of
         # debug Python builds with __ltrace__ enabled (only possible in console),
         # when the internal Python stack was negatively adjusted
-        with open(os_helper.TESTFN, 'w', encoding='utf-8') as fd:
-            self.addCleanup(os_helper.unlink, os_helper.TESTFN)
-            fd.write(textwrap.dedent("""\
+        stdout = self.run_code("""
             import code
 
             console = code.InteractiveConsole()
@@ -23,9 +105,8 @@ class TestLLTrace(unittest.TestCase):
             console.push('a = [1, 2, 3]')
             console.push('a[0] = 1')
             print('unreachable if bug exists')
-            """))
-
-            assert_python_ok(os_helper.TESTFN)
+        """)
+        self.assertIn("unreachable if bug exists", stdout)
 
 if __name__ == "__main__":
     unittest.main()