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, 4 deletions

diff --git a/lopcodes.h b/lopcodes.h
index 3e100259..f867a01b 100644
--- a/lopcodes.h
+++ b/lopcodes.h
@@ -280,10 +280,6 @@ OP_RETURN,/*	A B C	return R(A), ... ,R(A+B-2)	(see note)	*/
 OP_RETURN0,/*           return                                          */
 OP_RETURN1,/*   A       return R(A)                                     */
 
-OP_FORLOOP1,/*  A Bx    R(A)++;
-                        if R(A) <= R(A+1) then { pc-=Bx; R(A+3)=R(A) }  */
-OP_FORPREP1,/*  A Bx    R(A)--; pc+=Bx                                  */
-
 OP_FORLOOP,/*   A Bx    R(A)+=R(A+2);
                         if R(A) <?= R(A+1) then { pc-=Bx; R(A+3)=R(A) } */
 OP_FORPREP,/*   A Bx    R(A)-=R(A+2); pc+=Bx                            */