https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90574
--- Comment #2 from Yibiao Yang <yangyibiao at nju dot edu.cn> ---
(In reply to Richard Biener from comment #1)
> We somehow build a broken(?) CFG from the start:
>
> ;; basic block 2, loop depth 0
> ;; pred: ENTRY
> if (argc == 0)
> ;; succ: 3
>
> ;; basic block 3, loop depth 0
> ;; pred: 2
> label:
> if (argc == 1)
> goto <bb 4>; [INV]
> else
> goto <bb 5>; [INV]
>
> see how BB2 only has a single outgoing edge. CFG cleanup fixes this for us.
>
> .gimple has
>
> [t.c:2:1] {
> void label = <<< error >>>;
>
> [t.c:3:6] if (argc == 0) goto <D.1912>; else goto <D.1913>;
> <D.1912>:
> [t.c:4:5] {
> int * ptr;
>
> [t.c:6:1] label:
> }
> <D.1913>:
> [t.c:10:6] if (argc == 1) goto <D.1914>; else goto <D.1915>;
>
> so that looks good, likewise .lower:
>
> [t.c:3:6] if (argc == 0) goto <D.1912>; else goto <D.1913>;
> <D.1912>:
> [t.c:6:1] label:
> <D.1913>:
> [t.c:10:6] if (argc == 1) goto <D.1914>; else goto <D.1915>;
>
> iff we'd elide an empty block as having no side-effects we would have
> deleted the label.
>
> Thus confirmed as CFG build bug.
Thanks for the comfirmation.
Another bug I reported seems also a valid bug with a different code structure.
I am not quite sure whether it is a valid or not.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90584
