bpo-40222: "Zero cost" exception handling (GH-25729)

"Zero cost" exception handling.

* Uses a lookup table to determine how to handle exceptions.
* Removes SETUP_FINALLY and POP_TOP block instructions, eliminating (most of) the runtime overhead of try statements.
* Reduces the size of the frame object by about 60%.

9 files changed, 193 insertions, 132 deletions

diff --git a/Lib/ctypes/test/test_values.py b/Lib/ctypes/test/test_values.py
index 7514fe8..80f4ed0 100644
--- a/Lib/ctypes/test/test_values.py
+++ b/Lib/ctypes/test/test_values.py
@@ -80,9 +80,9 @@ class PythonValuesTestCase(unittest.TestCase):
                 continue
             items.append((entry.name.decode("ascii"), entry.size))
 
-        expected = [("__hello__", 137),
-                    ("__phello__", -137),
-                    ("__phello__.spam", 137),
+        expected = [("__hello__", 142),
+                    ("__phello__", -142),
+                    ("__phello__.spam", 142),
                     ]
         self.assertEqual(items, expected, "PyImport_FrozenModules example "
             "in Doc/library/ctypes.rst may be out of date")
diff --git a/Lib/dis.py b/Lib/dis.py
index 3fee1ce..bc7c4d4 100644
--- a/Lib/dis.py
+++ b/Lib/dis.py
@@ -203,6 +203,9 @@ _Instruction.offset.__doc__ = "Start index of operation within bytecode sequence
 _Instruction.starts_line.__doc__ = "Line started by this opcode (if any), otherwise None"
 _Instruction.is_jump_target.__doc__ = "True if other code jumps to here, otherwise False"
 
+_ExceptionTableEntry = collections.namedtuple("_ExceptionTableEntry",
+    "start end target depth lasti")
+
 _OPNAME_WIDTH = 20
 _OPARG_WIDTH = 5
 
@@ -308,8 +311,33 @@ def _get_name_info(name_index, name_list):
     return argval, argrepr
 
 
+def parse_varint(iterator):
+    b = next(iterator)
+    val = b & 63
+    while b&64:
+        val <<= 6
+        b = next(iterator)
+        val |= b&63
+    return val
+
+def parse_exception_table(code):
+    iterator = iter(code.co_exceptiontable)
+    entries = []
+    try:
+        while True:
+            start = parse_varint(iterator)*2
+            length = parse_varint(iterator)*2
+            end = start + length
+            target = parse_varint(iterator)*2
+            dl = parse_varint(iterator)
+            depth = dl >> 1
+            lasti = bool(dl&1)
+            entries.append(_ExceptionTableEntry(start, end, target, depth, lasti))
+    except StopIteration:
+        return entries
+
 def _get_instructions_bytes(code, varnames=None, names=None, constants=None,
-                      cells=None, linestarts=None, line_offset=0):
+                      cells=None, linestarts=None, line_offset=0, exception_entries=()):
     """Iterate over the instructions in a bytecode string.
 
     Generates a sequence of Instruction namedtuples giving the details of each
@@ -318,7 +346,10 @@ def _get_instructions_bytes(code, varnames=None, names=None, constants=None,
     arguments.
 
     """
-    labels = findlabels(code)
+    labels = set(findlabels(code))
+    for start, end, target, _, _ in exception_entries:
+        for i in range(start, end):
+            labels.add(target)
     starts_line = None
     for offset, op, arg in _unpack_opargs(code):
         if linestarts is not None:
@@ -369,8 +400,10 @@ def disassemble(co, lasti=-1, *, file=None):
     """Disassemble a code object."""
     cell_names = co.co_cellvars + co.co_freevars
     linestarts = dict(findlinestarts(co))
+    exception_entries = parse_exception_table(co)
     _disassemble_bytes(co.co_code, lasti, co.co_varnames, co.co_names,
-                       co.co_consts, cell_names, linestarts, file=file)
+                       co.co_consts, cell_names, linestarts, file=file,
+                       exception_entries=exception_entries)
 
 def _disassemble_recursive(co, *, file=None, depth=None):
     disassemble(co, file=file)
@@ -385,7 +418,7 @@ def _disassemble_recursive(co, *, file=None, depth=None):
 
 def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,
                        constants=None, cells=None, linestarts=None,
-                       *, file=None, line_offset=0):
+                       *, file=None, line_offset=0, exception_entries=()):
     # Omit the line number column entirely if we have no line number info
     show_lineno = bool(linestarts)
     if show_lineno:
@@ -403,7 +436,7 @@ def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,
         offset_width = 4
     for instr in _get_instructions_bytes(code, varnames, names,
                                          constants, cells, linestarts,
-                                         line_offset=line_offset):
+                                         line_offset=line_offset, exception_entries=exception_entries):
         new_source_line = (show_lineno and
                            instr.starts_line is not None and
                            instr.offset > 0)
@@ -412,6 +445,12 @@ def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,
         is_current_instr = instr.offset == lasti
         print(instr._disassemble(lineno_width, is_current_instr, offset_width),
               file=file)
+    if exception_entries:
+        print("ExceptionTable:", file=file)
+        for entry in exception_entries:
+            lasti = " lasti" if entry.lasti else ""
+            end = entry.end-2
+            print(f"  {entry.start} to {end} -> {entry.target} [{entry.depth}]{lasti}", file=file)
 
 def _disassemble_str(source, **kwargs):
     """Compile the source string, then disassemble the code object."""
@@ -482,13 +521,15 @@ class Bytecode:
         self._linestarts = dict(findlinestarts(co))
         self._original_object = x
         self.current_offset = current_offset
+        self.exception_entries = parse_exception_table(co)
 
     def __iter__(self):
         co = self.codeobj
         return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,
                                        co.co_consts, self._cell_names,
                                        self._linestarts,
-                                       line_offset=self._line_offset)
+                                       line_offset=self._line_offset,
+                                       exception_entries=self.exception_entries)
 
     def __repr__(self):
         return "{}({!r})".format(self.__class__.__name__,
@@ -519,7 +560,8 @@ class Bytecode:
                                linestarts=self._linestarts,
                                line_offset=self._line_offset,
                                file=output,
-                               lasti=offset)
+                               lasti=offset,
+                                    exception_entries=self.exception_entries)
             return output.getvalue()
 
 
diff --git a/Lib/importlib/_bootstrap_external.py b/Lib/importlib/_bootstrap_external.py
index 9a73c7b..469610a 100644
--- a/Lib/importlib/_bootstrap_external.py
+++ b/Lib/importlib/_bootstrap_external.py
@@ -352,6 +352,7 @@ _code_type = type(_write_atomic.__code__)
 #     Python 3.10b1 3437 (Undo making 'annotations' future by default - We like to dance among core devs!)
 #     Python 3.10b1 3438 Safer line number table handling.
 #     Python 3.10b1 3439 (Add ROT_N)
+#     Python 3.11a1 3450 Use exception table for unwinding ("zero cost" exception handling)
 
 #
 # MAGIC must change whenever the bytecode emitted by the compiler may no
@@ -361,7 +362,7 @@ _code_type = type(_write_atomic.__code__)
 # Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
 # in PC/launcher.c must also be updated.
 
-MAGIC_NUMBER = (3439).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (3450).to_bytes(2, 'little') + b'\r\n'
 _RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little')  # For import.c
 
 _PYCACHE = '__pycache__'
diff --git a/Lib/opcode.py b/Lib/opcode.py
index 37e88e9..88022a4 100644
--- a/Lib/opcode.py
+++ b/Lib/opcode.py
@@ -86,11 +86,15 @@ def_op('MATCH_MAPPING', 31)
 def_op('MATCH_SEQUENCE', 32)
 def_op('MATCH_KEYS', 33)
 def_op('COPY_DICT_WITHOUT_KEYS', 34)
+def_op('PUSH_EXC_INFO', 35)
+
+def_op('POP_EXCEPT_AND_RERAISE', 37)
 
 def_op('WITH_EXCEPT_START', 49)
 def_op('GET_AITER', 50)
 def_op('GET_ANEXT', 51)
 def_op('BEFORE_ASYNC_WITH', 52)
+def_op('BEFORE_WITH', 53)
 
 def_op('END_ASYNC_FOR', 54)
 def_op('INPLACE_ADD', 55)
@@ -124,7 +128,6 @@ def_op('RETURN_VALUE', 83)
 def_op('IMPORT_STAR', 84)
 def_op('SETUP_ANNOTATIONS', 85)
 def_op('YIELD_VALUE', 86)
-def_op('POP_BLOCK', 87)
 
 def_op('POP_EXCEPT', 89)
 
@@ -164,7 +167,6 @@ def_op('CONTAINS_OP', 118)
 def_op('RERAISE', 119)
 
 jabs_op('JUMP_IF_NOT_EXC_MATCH', 121)
-jrel_op('SETUP_FINALLY', 122)   # Distance to target address
 
 def_op('LOAD_FAST', 124)        # Local variable number
 haslocal.append(124)
@@ -190,7 +192,7 @@ hasfree.append(138)
 
 def_op('CALL_FUNCTION_KW', 141)  # #args + #kwargs
 def_op('CALL_FUNCTION_EX', 142)  # Flags
-jrel_op('SETUP_WITH', 143)
+
 def_op('EXTENDED_ARG', 144)
 EXTENDED_ARG = 144
 def_op('LIST_APPEND', 145)
@@ -201,7 +203,6 @@ hasfree.append(148)
 
 def_op('MATCH_CLASS', 152)
 
-jrel_op('SETUP_ASYNC_WITH', 154)
 def_op('FORMAT_VALUE', 155)
 def_op('BUILD_CONST_KEY_MAP', 156)
 def_op('BUILD_STRING', 157)
diff --git a/Lib/test/test_code.py b/Lib/test/test_code.py
index 6aaf04c..c3dd678 100644
--- a/Lib/test/test_code.py
+++ b/Lib/test/test_code.py
@@ -227,6 +227,7 @@ class CodeTest(unittest.TestCase):
                         co.co_name,
                         co.co_firstlineno,
                         co.co_lnotab,
+                        co.co_exceptiontable,
                         co.co_freevars,
                         co.co_cellvars)
 
diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
index 21c68d4..f341a3e 100644
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -282,42 +282,47 @@ dis_compound_stmt_str = """\
 """
 
 dis_traceback = """\
-%3d           0 SETUP_FINALLY            7 (to 16)
+%3d           0 NOP
 
 %3d           2 LOAD_CONST               1 (1)
               4 LOAD_CONST               2 (0)
     -->       6 BINARY_TRUE_DIVIDE
               8 POP_TOP
-             10 POP_BLOCK
 
-%3d          12 LOAD_FAST                1 (tb)
-             14 RETURN_VALUE
+%3d          10 LOAD_FAST                1 (tb)
+             12 RETURN_VALUE
+        >>   14 PUSH_EXC_INFO
 
-%3d     >>   16 DUP_TOP
+%3d          16 DUP_TOP
              18 LOAD_GLOBAL              0 (Exception)
-             20 JUMP_IF_NOT_EXC_MATCH    29 (to 58)
+             20 JUMP_IF_NOT_EXC_MATCH    28 (to 56)
              22 POP_TOP
              24 STORE_FAST               0 (e)
              26 POP_TOP
-             28 SETUP_FINALLY           10 (to 50)
-
-%3d          30 LOAD_FAST                0 (e)
-             32 LOAD_ATTR                1 (__traceback__)
-             34 STORE_FAST               1 (tb)
-             36 POP_BLOCK
-             38 POP_EXCEPT
-             40 LOAD_CONST               0 (None)
-             42 STORE_FAST               0 (e)
-             44 DELETE_FAST              0 (e)
-
-%3d          46 LOAD_FAST                1 (tb)
-             48 RETURN_VALUE
-        >>   50 LOAD_CONST               0 (None)
-             52 STORE_FAST               0 (e)
-             54 DELETE_FAST              0 (e)
-             56 RERAISE                  1
-
-%3d     >>   58 RERAISE                  0
+
+%3d          28 LOAD_FAST                0 (e)
+             30 LOAD_ATTR                1 (__traceback__)
+             32 STORE_FAST               1 (tb)
+             34 POP_EXCEPT
+             36 LOAD_CONST               0 (None)
+             38 STORE_FAST               0 (e)
+             40 DELETE_FAST              0 (e)
+
+%3d          42 LOAD_FAST                1 (tb)
+             44 RETURN_VALUE
+        >>   46 LOAD_CONST               0 (None)
+             48 STORE_FAST               0 (e)
+             50 DELETE_FAST              0 (e)
+             52 RERAISE                  1
+        >>   54 POP_EXCEPT_AND_RERAISE
+
+%3d     >>   56 RERAISE                  0
+ExceptionTable:
+  2 to 8 -> 14 [0]
+  14 to 26 -> 54 [3] lasti
+  28 to 32 -> 46 [3] lasti
+  46 to 52 -> 54 [3] lasti
+  56 to 56 -> 54 [3] lasti
 """ % (TRACEBACK_CODE.co_firstlineno + 1,
        TRACEBACK_CODE.co_firstlineno + 2,
        TRACEBACK_CODE.co_firstlineno + 5,
@@ -360,38 +365,46 @@ def _tryfinallyconst(b):
         b()
 
 dis_tryfinally = """\
-%3d           0 SETUP_FINALLY            6 (to 14)
+%3d           0 NOP
 
 %3d           2 LOAD_FAST                0 (a)
-              4 POP_BLOCK
 
-%3d           6 LOAD_FAST                1 (b)
-              8 CALL_FUNCTION            0
-             10 POP_TOP
-             12 RETURN_VALUE
-        >>   14 LOAD_FAST                1 (b)
+%3d           4 LOAD_FAST                1 (b)
+              6 CALL_FUNCTION            0
+              8 POP_TOP
+             10 RETURN_VALUE
+        >>   12 PUSH_EXC_INFO
+             14 LOAD_FAST                1 (b)
              16 CALL_FUNCTION            0
              18 POP_TOP
              20 RERAISE                  0
+        >>   22 POP_EXCEPT_AND_RERAISE
+ExceptionTable:
+  2 to 2 -> 12 [0]
+  12 to 20 -> 22 [3] lasti
 """ % (_tryfinally.__code__.co_firstlineno + 1,
        _tryfinally.__code__.co_firstlineno + 2,
        _tryfinally.__code__.co_firstlineno + 4,
        )
 
 dis_tryfinallyconst = """\
-%3d           0 SETUP_FINALLY            6 (to 14)
+%3d           0 NOP
 
-%3d           2 POP_BLOCK
+%3d           2 NOP
 
 %3d           4 LOAD_FAST                0 (b)
               6 CALL_FUNCTION            0
               8 POP_TOP
              10 LOAD_CONST               1 (1)
              12 RETURN_VALUE
-        >>   14 LOAD_FAST                0 (b)
-             16 CALL_FUNCTION            0
-             18 POP_TOP
-             20 RERAISE                  0
+             14 PUSH_EXC_INFO
+             16 LOAD_FAST                0 (b)
+             18 CALL_FUNCTION            0
+             20 POP_TOP
+             22 RERAISE                  0
+        >>   24 POP_EXCEPT_AND_RERAISE
+ExceptionTable:
+  14 to 22 -> 24 [3] lasti
 """ % (_tryfinallyconst.__code__.co_firstlineno + 1,
        _tryfinallyconst.__code__.co_firstlineno + 2,
        _tryfinallyconst.__code__.co_firstlineno + 4,
@@ -833,7 +846,7 @@ Argument count:    0
 Positional-only arguments: 0
 Kw-only arguments: 0
 Number of locals:  2
-Stack size:        9
+Stack size:        10
 Flags:             OPTIMIZED, NEWLOCALS, NOFREE, COROUTINE
 Constants:
    0: None
@@ -1059,61 +1072,64 @@ expected_opinfo_jumpy = [
   Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=98, starts_line=None, is_jump_target=False),
   Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=100, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=102, starts_line=None, is_jump_target=False),
-  Instruction(opname='SETUP_FINALLY', opcode=122, arg=48, argval=202, argrepr='to 202', offset=104, starts_line=20, is_jump_target=True),
-  Instruction(opname='SETUP_FINALLY', opcode=122, arg=6, argval=120, argrepr='to 120', offset=106, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=108, starts_line=21, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=110, starts_line=None, is_jump_target=False),
-  Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=112, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=114, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=116, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=12, argval=144, argrepr='to 144', offset=118, starts_line=None, is_jump_target=False),
-  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=120, starts_line=22, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=122, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_IF_NOT_EXC_MATCH', opcode=121, arg=106, argval=212, argrepr='to 212', offset=124, starts_line=None, is_jump_target=False),
+  Instruction(opname='NOP', opcode=9, arg=None, argval=None, argrepr='', offset=104, starts_line=20, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=106, starts_line=21, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=108, starts_line=None, is_jump_target=False),
+  Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=110, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=112, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=14, argval=144, argrepr='to 144', offset=114, starts_line=None, is_jump_target=False),
+  Instruction(opname='PUSH_EXC_INFO', opcode=35, arg=None, argval=None, argrepr='', offset=116, starts_line=None, is_jump_target=False),
+  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=118, starts_line=22, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=120, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_IF_NOT_EXC_MATCH', opcode=121, arg=109, argval=218, argrepr='to 218', offset=122, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=124, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=126, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=128, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=130, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=132, starts_line=23, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval='Here we go, here we go, here we go...', argrepr="'Here we go, here we go, here we go...'", offset=134, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=136, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=138, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=140, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=22, argval=188, argrepr='to 188', offset=142, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=130, starts_line=23, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval='Here we go, here we go, here we go...', argrepr="'Here we go, here we go, here we go...'", offset=132, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=134, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=136, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=138, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=25, argval=192, argrepr='to 192', offset=140, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT_AND_RERAISE', opcode=37, arg=None, argval=None, argrepr='', offset=142, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=144, starts_line=25, is_jump_target=True),
-  Instruction(opname='SETUP_WITH', opcode=143, arg=12, argval=172, argrepr='to 172', offset=146, starts_line=None, is_jump_target=False),
+  Instruction(opname='BEFORE_WITH', opcode=53, arg=None, argval=None, argrepr='', offset=146, starts_line=None, is_jump_target=False),
   Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=148, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=150, starts_line=26, is_jump_target=False),
   Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=152, starts_line=None, is_jump_target=False),
   Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=154, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=156, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=158, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=160, starts_line=25, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=158, starts_line=25, is_jump_target=False),
+  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=160, starts_line=None, is_jump_target=False),
   Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=162, starts_line=None, is_jump_target=False),
-  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=164, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=3, argval=3, argrepr='', offset=166, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=168, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=8, argval=188, argrepr='to 188', offset=170, starts_line=None, is_jump_target=False),
-  Instruction(opname='WITH_EXCEPT_START', opcode=49, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=True),
-  Instruction(opname='POP_JUMP_IF_TRUE', opcode=115, arg=89, argval=178, argrepr='to 178', offset=174, starts_line=None, is_jump_target=False),
-  Instruction(opname='RERAISE', opcode=119, arg=1, argval=1, argrepr='', offset=176, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=178, starts_line=None, is_jump_target=True),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=180, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=3, argval=3, argrepr='', offset=164, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=11, argval=192, argrepr='to 192', offset=168, starts_line=None, is_jump_target=False),
+  Instruction(opname='PUSH_EXC_INFO', opcode=35, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=False),
+  Instruction(opname='WITH_EXCEPT_START', opcode=49, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_TRUE', opcode=115, arg=90, argval=180, argrepr='to 180', offset=174, starts_line=None, is_jump_target=False),
+  Instruction(opname='RERAISE', opcode=119, arg=4, argval=4, argrepr='', offset=176, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT_AND_RERAISE', opcode=37, arg=None, argval=None, argrepr='', offset=178, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=180, starts_line=None, is_jump_target=True),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=182, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=184, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=188, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=190, starts_line=28, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=192, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=194, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=196, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=198, starts_line=None, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=200, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=202, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=204, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=206, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=208, starts_line=None, is_jump_target=False),
-  Instruction(opname='RERAISE', opcode=119, arg=0, argval=0, argrepr='', offset=210, starts_line=None, is_jump_target=False),
-  Instruction(opname='RERAISE', opcode=119, arg=0, argval=0, argrepr='', offset=212, starts_line=22, is_jump_target=True),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=184, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=188, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=190, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=192, starts_line=28, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=194, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=196, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=198, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=200, starts_line=None, is_jump_target=False),
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=202, starts_line=None, is_jump_target=False),
+  Instruction(opname='PUSH_EXC_INFO', opcode=35, arg=None, argval=None, argrepr='', offset=204, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=206, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=208, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=210, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=212, starts_line=None, is_jump_target=False),
+  Instruction(opname='RERAISE', opcode=119, arg=0, argval=0, argrepr='', offset=214, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT_AND_RERAISE', opcode=37, arg=None, argval=None, argrepr='', offset=216, starts_line=None, is_jump_target=False),
+  Instruction(opname='RERAISE', opcode=119, arg=0, argval=0, argrepr='', offset=218, starts_line=22, is_jump_target=True),
 ]
 
 # One last piece of inspect fodder to check the default line number handling
@@ -1211,6 +1227,7 @@ class BytecodeTests(unittest.TestCase):
         self.assertEqual(b.current_offset, tb.tb_lasti)
 
     def test_from_traceback_dis(self):
+        self.maxDiff = None
         tb = get_tb()
         b = dis.Bytecode.from_traceback(tb)
         self.assertEqual(b.dis(), dis_traceback)
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index 3c427fe..1fe479f 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -218,7 +218,7 @@ class ExceptionTests(unittest.TestCase):
         check('class foo:return 1', 1, 11)
         check('def f():\n  continue', 2, 3)
         check('def f():\n  break', 2, 3)
-        check('try:\n  pass\nexcept:\n  pass\nexcept ValueError:\n  pass', 2, 3)
+        check('try:\n  pass\nexcept:\n  pass\nexcept ValueError:\n  pass', 3, 1)
 
         # Errors thrown by tokenizer.c
         check('(0x+1)', 1, 3)
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 1fd5247..4f26689 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1273,13 +1273,12 @@ class SizeofTest(unittest.TestCase):
         check(sys.float_info, vsize('') + self.P * len(sys.float_info))
         # frame
         import inspect
-        CO_MAXBLOCKS = 20
         x = inspect.currentframe()
         ncells = len(x.f_code.co_cellvars)
         nfrees = len(x.f_code.co_freevars)
-        extras = x.f_code.co_stacksize + x.f_code.co_nlocals +\
-                  ncells + nfrees - 1
-        check(x, vsize('4Pi2c4P3ic' + CO_MAXBLOCKS*'3i' + 'P' + extras*'P'))
+        localsplus = x.f_code.co_stacksize + x.f_code.co_nlocals +\
+                  ncells + nfrees
+        check(x, vsize('8P3i3c' + localsplus*'P'))
         # function
         def func(): pass
         check(func, size('14P'))
diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
index 40dd92c..12d4c28 100644
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -1253,7 +1253,7 @@ class JumpTestCase(unittest.TestCase):
             output.append(6)
         output.append(7)
 
-    @async_jump_test(4, 5, [3, 5])
+    @async_jump_test(4, 5, [3], (ValueError, 'into'))
     async def test_jump_out_of_async_for_block_forwards(output):
         for i in [1]:
             async for i in asynciter([1, 2]):
@@ -1295,7 +1295,7 @@ class JumpTestCase(unittest.TestCase):
                 output.append(8)
             output.append(9)
 
-    @jump_test(6, 7, [2, 7], (ZeroDivisionError, ''))
+    @jump_test(6, 7, [2], (ValueError, 'within'))
     def test_jump_in_nested_finally_2(output):
         try:
             output.append(2)
@@ -1306,7 +1306,7 @@ class JumpTestCase(unittest.TestCase):
             output.append(7)
         output.append(8)
 
-    @jump_test(6, 11, [2, 11], (ZeroDivisionError, ''))
+    @jump_test(6, 11, [2], (ValueError, 'within'))
     def test_jump_in_nested_finally_3(output):
         try:
             output.append(2)
@@ -1321,7 +1321,7 @@ class JumpTestCase(unittest.TestCase):
             output.append(11)
         output.append(12)
 
-    @jump_test(5, 11, [2, 4], (ValueError, 'after'))
+    @jump_test(5, 11, [2, 4], (ValueError, 'exception'))
     def test_no_jump_over_return_try_finally_in_finally_block(output):
         try:
             output.append(2)
@@ -1417,8 +1417,8 @@ class JumpTestCase(unittest.TestCase):
             output.append(5)
             raise
 
-    @jump_test(5, 7, [4, 7, 8])
-    def test_jump_between_except_blocks(output):
+    @jump_test(5, 7, [4], (ValueError, 'within'))
+    def test_no_jump_between_except_blocks(output):
         try:
             1/0
         except ZeroDivisionError:
@@ -1428,8 +1428,8 @@ class JumpTestCase(unittest.TestCase):
             output.append(7)
         output.append(8)
 
-    @jump_test(5, 6, [4, 6, 7])
-    def test_jump_within_except_block(output):
+    @jump_test(5, 6, [4], (ValueError, 'within'))
+    def test_no_jump_within_except_block(output):
         try:
             1/0
         except:
@@ -1654,54 +1654,54 @@ class JumpTestCase(unittest.TestCase):
             output.append(2)
         output.append(3)
 
-    @async_jump_test(3, 2, [2, 2], (ValueError, 'into'))
+    @async_jump_test(3, 2, [2, 2], (ValueError, 'within'))
     async def test_no_jump_backwards_into_async_for_block(output):
         async for i in asynciter([1, 2]):
             output.append(2)
         output.append(3)
 
-    @jump_test(1, 3, [], (ValueError, 'into'))
+    @jump_test(1, 3, [], (ValueError, 'depth'))
     def test_no_jump_forwards_into_with_block(output):
         output.append(1)
         with tracecontext(output, 2):
             output.append(3)
 
-    @async_jump_test(1, 3, [], (ValueError, 'into'))
+    @async_jump_test(1, 3, [], (ValueError, 'depth'))
     async def test_no_jump_forwards_into_async_with_block(output):
         output.append(1)
         async with asynctracecontext(output, 2):
             output.append(3)
 
-    @jump_test(3, 2, [1, 2, -1], (ValueError, 'into'))
+    @jump_test(3, 2, [1, 2, -1], (ValueError, 'depth'))
     def test_no_jump_backwards_into_with_block(output):
         with tracecontext(output, 1):
             output.append(2)
         output.append(3)
 
-    @async_jump_test(3, 2, [1, 2, -1], (ValueError, 'into'))
+    @async_jump_test(3, 2, [1, 2, -1], (ValueError, 'depth'))
     async def test_no_jump_backwards_into_async_with_block(output):
         async with asynctracecontext(output, 1):
             output.append(2)
         output.append(3)
 
-    @jump_test(1, 3, [], (ValueError, 'into'))
-    def test_no_jump_forwards_into_try_finally_block(output):
+    @jump_test(1, 3, [3, 5])
+    def test_jump_forwards_into_try_finally_block(output):
         output.append(1)
         try:
             output.append(3)
         finally:
             output.append(5)
 
-    @jump_test(5, 2, [2, 4], (ValueError, 'into'))
-    def test_no_jump_backwards_into_try_finally_block(output):
+    @jump_test(5, 2, [2, 4, 2, 4, 5])
+    def test_jump_backwards_into_try_finally_block(output):
         try:
             output.append(2)
         finally:
             output.append(4)
         output.append(5)
 
-    @jump_test(1, 3, [], (ValueError, 'into'))
-    def test_no_jump_forwards_into_try_except_block(output):
+    @jump_test(1, 3, [3])
+    def test_jump_forwards_into_try_except_block(output):
         output.append(1)
         try:
             output.append(3)
@@ -1709,8 +1709,8 @@ class JumpTestCase(unittest.TestCase):
             output.append(5)
             raise
 
-    @jump_test(6, 2, [2], (ValueError, 'into'))
-    def test_no_jump_backwards_into_try_except_block(output):
+    @jump_test(6, 2, [2, 2, 6])
+    def test_jump_backwards_into_try_except_block(output):
         try:
             output.append(2)
         except:
@@ -1719,7 +1719,7 @@ class JumpTestCase(unittest.TestCase):
         output.append(6)
 
     # 'except' with a variable creates an implicit finally block
-    @jump_test(5, 7, [4], (ValueError, 'into'))
+    @jump_test(5, 7, [4], (ValueError, 'within'))
     def test_no_jump_between_except_blocks_2(output):
         try:
             1/0
@@ -1756,7 +1756,7 @@ class JumpTestCase(unittest.TestCase):
         finally:
             output.append(5)
 
-    @jump_test(1, 5, [], (ValueError, "into an 'except'"))
+    @jump_test(1, 5, [], (ValueError, "into an exception"))
     def test_no_jump_into_bare_except_block(output):
         output.append(1)
         try:
@@ -1764,7 +1764,7 @@ class JumpTestCase(unittest.TestCase):
         except:
             output.append(5)
 
-    @jump_test(1, 5, [], (ValueError, "into an 'except'"))
+    @jump_test(1, 5, [], (ValueError, "into an exception"))
     def test_no_jump_into_qualified_except_block(output):
         output.append(1)
         try:
@@ -1772,7 +1772,7 @@ class JumpTestCase(unittest.TestCase):
         except Exception:
             output.append(5)
 
-    @jump_test(3, 6, [2, 5, 6], (ValueError, "into an 'except'"))
+    @jump_test(3, 6, [2, 5, 6], (ValueError, "into an exception"))
     def test_no_jump_into_bare_except_block_from_try_block(output):
         try:
             output.append(2)
@@ -1783,7 +1783,7 @@ class JumpTestCase(unittest.TestCase):
             raise
         output.append(8)
 
-    @jump_test(3, 6, [2], (ValueError, "into an 'except'"))
+    @jump_test(3, 6, [2], (ValueError, "into an exception"))
     def test_no_jump_into_qualified_except_block_from_try_block(output):
         try:
             output.append(2)
@@ -1794,7 +1794,7 @@ class JumpTestCase(unittest.TestCase):
             raise
         output.append(8)
 
-    @jump_test(7, 1, [1, 3, 6], (ValueError, "out of an 'except'"))
+    @jump_test(7, 1, [1, 3, 6], (ValueError, "within"))
     def test_no_jump_out_of_bare_except_block(output):
         output.append(1)
         try:
@@ -1804,7 +1804,7 @@ class JumpTestCase(unittest.TestCase):
             output.append(6)
             output.append(7)
 
-    @jump_test(7, 1, [1, 3, 6], (ValueError, "out of an 'except'"))
+    @jump_test(7, 1, [1, 3, 6], (ValueError, "within"))
     def test_no_jump_out_of_qualified_except_block(output):
         output.append(1)
         try: