Possible compiler bug: continue is skipped after or-condition

[Roland Illig]

On 08.02.2020 20:05, Roland Illig wrote:
> /* - */ public class Demo {
> /* - */     static String[] strings = {"1a", "1b", "2", "3"};
> /* - */
> /* - */     public static void main(String[] args) {
> /* 5 */         for (String s : strings) {
> /* 6 */             if (s.equals("1a") || s.equals("1b")) {
> /* 7 */                 continue;
> /* - */             }
> /* 9 */             if (s.equals("2")) {
> /* - */                 continue;
> /* - */             }
> /* - */             System.out.println(s);
> /* - */         }
> /* - */     }
> /* - */ }

I investigated the problem a bit and found the cause.

The documentation for Code.pendingJumps says:
 > A chain for jumps to be resolved before the next opcode
 > is emitted. We do this lazily to avoid jumps to jumps.

This "jumps to jumps" that the pendingJumps successfully avoids is
exactly the code I expect to be generated. The first jump to line 7 is
necessary to visit the breakpoint there, even if that jump is followed
directly by another jump to line 5.

I stepped through the code using a debugger, and when I skipped over the
following two lines in Code.branch once, the code was generated exactly
as I had expected it from the beginning.

     result = pendingJumps;
     pendingJumps = null;

Commenting these lines out will of course have other side effects, but
at least it makes the breakpoint in line 7 work again as expected.