make FOR_END a relative jump

sweeneyde · Feb 20, 2022 · Feb 20, 2022 · Feb 20, 2022 · Mar 1, 2022 · Mar 20, 2022
commit 0af7e1eefb3fff797e7e57869d3a3c14833d6aac
diff --git a/Include/opcode.h b/Include/opcode.h
diff --git a/Lib/dis.py b/Lib/dis.py
@@ -30,7 +30,9 @@
 LOAD_CONST = opmap['LOAD_CONST']
 LOAD_GLOBAL = opmap['LOAD_GLOBAL']
 BINARY_OP = opmap['BINARY_OP']
-JUMP_BACKWARD = opmap['JUMP_BACKWARD']
+
+BACK_JUMPS = {code for name, code in opmap.items()
+              if 'JUMP_BACKWARD' in name} | {opmap['FOR_END']}
 
 CACHE = opmap["CACHE"]
 
@@ -442,7 +444,7 @@ def _get_instructions_bytes(code, varname_from_oparg=None,
                 argval = arg*2
                 argrepr = "to " + repr(argval)
             elif op in hasjrel:
-                signed_arg = -arg if op == JUMP_BACKWARD else arg
+                signed_arg = -arg if op in BACK_JUMPS else arg
                 argval = offset + 2 + signed_arg*2
                 argrepr = "to " + repr(argval)
             elif op in haslocal or op in hasfree:
@@ -568,7 +570,7 @@ def findlabels(code):
     for offset, op, arg in _unpack_opargs(code):
         if arg is not None:
             if op in hasjrel:
-                if op == JUMP_BACKWARD:
+                if op in BACK_JUMPS:
                     arg = -arg
                 label = offset + 2 + arg*2
             elif op in hasjabs:

@@ -414,7 +414,7 @@ def _write_atomic(path, data, mode=0o666):
 # Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
 # in PC/launcher.c must also be updated.
 
-MAGIC_NUMBER = (3494).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (3493).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
@@ -196,7 +196,7 @@ def jabs_op(name, op, entries=0):
 def_op('KW_NAMES', 172)
 hasconst.append(172)
 
-jabs_op('FOR_END', 173)
+jrel_op('FOR_END', 173)
 
 del def_op, name_op, jrel_op, jabs_op
 

diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
@@ -151,7 +151,7 @@ def bug708901():
 
 %3d        NOP
 
-%3d     >> FOR_END                 18 (to 36)
+%3d     >> FOR_END                  3 (to 36)
            LOAD_CONST               0 (None)
            RETURN_VALUE
 """ % (bug708901.__code__.co_firstlineno,
@@ -576,7 +576,7 @@ def foo(x):
            LOAD_FAST                1 (z)
            BINARY_OP                0 (+)
            LIST_APPEND              2
-        >> FOR_END                  5 (to 10)
+        >> FOR_END                  7 (to 10)
            RETURN_VALUE
 """ % (dis_nested_1,
        __file__,
@@ -1236,7 +1236,7 @@ def _prepare_test_cases():
   Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=48, argval=96, argrepr='to 96', offset=90, starts_line=None, is_jump_target=False, positions=None),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=92, starts_line=8, is_jump_target=False, positions=None),
   Instruction(opname='JUMP_FORWARD', opcode=110, arg=16, argval=128, argrepr='to 128', offset=94, starts_line=None, is_jump_target=False, positions=None),
-  Instruction(opname='FOR_END', opcode=173, arg=17, argval=34, argrepr='to 34', offset=96, starts_line=3, is_jump_target=True, positions=None),
+  Instruction(opname='FOR_END', opcode=173, arg=32, argval=34, argrepr='to 34', offset=96, starts_line=3, is_jump_target=True, positions=None),
   Instruction(opname='LOAD_GLOBAL', opcode=116, arg=3, argval='print', argrepr='NULL + print', offset=98, starts_line=10, is_jump_target=False, positions=None),
   Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='I can haz else clause?', argrepr="'I can haz else clause?'", offset=110, starts_line=None, is_jump_target=False, positions=None),
   Instruction(opname='PRECALL', opcode=166, arg=1, argval=1, argrepr='', offset=112, starts_line=None, is_jump_target=False, positions=None),

@@ -267,7 +267,7 @@ mark_stacks(PyCodeObject *code_obj, int len)
                 {
                     int64_t target_stack = push_value(next_stack, Object);
                     stacks[i+1] = pop_value(next_stack);
-                    j = get_arg(code, i);
+                    j = i + 1 - get_arg(code, i);
                     if (stacks[j] == UNINITIALIZED && j < i) {
                         todo = 1;
                     }

@@ -4193,7 +4193,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             PyObject *next = (*Py_TYPE(iter)->tp_iternext)(iter);
             if (next != NULL) {
                 PUSH(next);
-                JUMPTO(oparg);
+                JUMPBY(-oparg);
                 CHECK_EVAL_BREAKER();
                 PREDICT(STORE_FAST);
                 PREDICT(UNPACK_SEQUENCE);

@@ -7657,12 +7657,14 @@ assemble_jump_offsets(struct assembler *a, struct compiler *c)
                     if (is_relative_jump(instr)) {
                         if (instr->i_oparg < bsize) {
                             assert(instr->i_opcode == JUMP_BACKWARD ||
-                                   instr->i_opcode == JUMP_BACKWARD_NO_INTERRUPT);
+                                   instr->i_opcode == JUMP_BACKWARD_NO_INTERRUPT ||
+                                   instr->i_opcode == FOR_END);
                             instr->i_oparg = bsize - instr->i_oparg;
                         }
                         else {
                             assert(instr->i_opcode != JUMP_BACKWARD);
                             assert(instr->i_opcode != JUMP_BACKWARD_NO_INTERRUPT);
+                            assert(instr->i_opcode != FOR_END);
                             instr->i_oparg -= bsize;
                         }
                     }