diff options
| -rw-r--r-- | erts/emulator/beam/beam_debug.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/erts/emulator/beam/beam_debug.c b/erts/emulator/beam/beam_debug.c index afde45ba71..7017656476 100644 --- a/erts/emulator/beam/beam_debug.c +++ b/erts/emulator/beam/beam_debug.c @@ -629,13 +629,20 @@ print_op(fmtfn_t to, void *to_arg, int op, int size, BeamInstr* addr) unpacked = ap; ap = addr + size; + + /* + * In the code below, never use ap[-1], ap[-2], ... + * (will not work if the arguments have been packed). + * + * Instead use unpacked[-1], unpacked[-2], ... + */ switch (op) { case op_i_select_val_lins_xfI: case op_i_select_val_lins_yfI: case op_i_select_val_bins_xfI: case op_i_select_val_bins_yfI: { - int n = ap[-1]; + int n = unpacked[-1]; int ix = n; Sint32* jump_tab = (Sint32 *)(ap + n); @@ -656,7 +663,7 @@ print_op(fmtfn_t to, void *to_arg, int op, int size, BeamInstr* addr) case op_i_select_tuple_arity_xfI: case op_i_select_tuple_arity_yfI: { - int n = ap[-1]; + int n = unpacked[-1]; int ix = n - 1; /* without sentinel */ Sint32* jump_tab = (Sint32 *)(ap + n); @@ -698,7 +705,7 @@ print_op(fmtfn_t to, void *to_arg, int op, int size, BeamInstr* addr) case op_i_jump_on_val_xfIW: case op_i_jump_on_val_yfIW: { - int n = ap[-2]; + int n = unpacked[-2]; Sint32* jump_tab = (Sint32 *) ap; size += (n+1) / 2; @@ -712,7 +719,7 @@ print_op(fmtfn_t to, void *to_arg, int op, int size, BeamInstr* addr) case op_i_jump_on_val_zero_xfI: case op_i_jump_on_val_zero_yfI: { - int n = ap[-1]; + int n = unpacked[-1]; Sint32* jump_tab = (Sint32 *) ap; size += (n+1) / 2; |