New semantics for the integer 'for' loop

The numerical 'for' loop over integers now uses a precomputed counter
to control its number of iteractions. This change eliminates several
weird cases caused by overflows (wrap-around) in the control variable.
(It also ensures that every integer loop halts.)

Also, the special opcodes for the usual case of step==1 were removed.
(The new code is already somewhat complex for the usual case,
but efficient.)

1 files changed, 0 insertions, 2 deletions

diff --git a/lopcodes.c b/lopcodes.c
index 3f0d551a..c35a0aaf 100644
--- a/lopcodes.c
+++ b/lopcodes.c
@@ -93,8 +93,6 @@ LUAI_DDEF const lu_byte luaP_opmodes[NUM_OPCODES] = {
  ,opmode(0, 1, 0, 0, iABC)              /* OP_RETURN */
  ,opmode(0, 0, 0, 0, iABC)              /* OP_RETURN0 */
  ,opmode(0, 0, 0, 0, iABC)              /* OP_RETURN1 */
- ,opmode(0, 0, 0, 1, iABx)              /* OP_FORLOOP1 */
- ,opmode(0, 0, 0, 1, iABx)              /* OP_FORPREP1 */
  ,opmode(0, 0, 0, 1, iABx)              /* OP_FORLOOP */
  ,opmode(0, 0, 0, 1, iABx)              /* OP_FORPREP */
  ,opmode(0, 0, 0, 0, iABx)              /* OP_TFORPREP */