[Bug target/124137] [16 Regression] build doesn't finish after 4h+

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124137

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #12)
> A testcase could be reduced with
> 
> diff --git a/gcc/config/i386/i386-features.cc
> b/gcc/config/i386/i386-features.cc
> index 8e277843f23..df04decda7f 100644
> --- a/gcc/config/i386/i386-features.cc
> +++ b/gcc/config/i386/i386-features.cc
> @@ -4042,7 +4042,9 @@ ix86_emit_tls_call (rtx tls_set, x86_cse_kind kind,
> basic_block bb,
>               /* Place the call before all FLAGS_REG setting BBs since
>                  we can't place a call before nor after a conditional
>                  jump.  */
> -             bb = ix86_get_dominator_for_reg (FLAGS_REG, bb);
> +             auto bb1 = ix86_get_dominator_for_reg (FLAGS_REG, bb);
> +             gcc_assert (bb1 != bb);
> +             bb = bb1;
>  
>               /* Start over again.  */
>               repeat = true;

Doing that.