bpo-47120: Replace the JUMP_ABSOLUTE opcode by the relative JUMP_BACKWARD (GH-32115)

1 files changed, 5 insertions, 1 deletions

diff --git a/Lib/dis.py b/Lib/dis.py
index 3b7747b..d9936ce 100644
--- a/Lib/dis.py
+++ b/Lib/dis.py
@@ -30,6 +30,7 @@ MAKE_FUNCTION_FLAGS = ('defaults', 'kwdefaults', 'annotations', 'closure')
 LOAD_CONST = opmap['LOAD_CONST']
 LOAD_GLOBAL = opmap['LOAD_GLOBAL']
 BINARY_OP = opmap['BINARY_OP']
+JUMP_BACKWARD = opmap['JUMP_BACKWARD']
 
 CACHE = opmap["CACHE"]
 
@@ -441,7 +442,8 @@ def _get_instructions_bytes(code, varname_from_oparg=None,
                 argval = arg*2
                 argrepr = "to " + repr(argval)
             elif op in hasjrel:
-                argval = offset + 2 + arg*2
+                signed_arg = -arg if op == JUMP_BACKWARD else arg
+                argval = offset + 2 + signed_arg*2
                 argrepr = "to " + repr(argval)
             elif op in haslocal or op in hasfree:
                 argval, argrepr = _get_name_info(arg, varname_from_oparg)
@@ -566,6 +568,8 @@ def findlabels(code):
     for offset, op, arg in _unpack_opargs(code):
         if arg is not None:
             if op in hasjrel:
+                if op == JUMP_BACKWARD:
+                    arg = -arg
                 label = offset + 2 + arg*2
             elif op in hasjabs:
                 label = arg*2