RFR: 8374889: C2 VectorAPI: must handle impossible combination of signed cast from float [v2]

[Quan Anh Mai]

On Wed, 14 Jan 2026 03:38:07 GMT, John R Rose <jrose at openjdk.org> wrote:

>> It seems there is an opportunity to create a method `GraphKit::halt(const char* reason)` that can be called by these places.
>
> Yes.  I recommend doing this cleanup in this PR.
> Unless we think there is a risk that gvn.transform and set_type_bottom will have different effects?
> I think they amount to the same thing for a halt node.

Also, the `reachable` parameter here seems misleading, of course a `Halt` is unreachable. The parameter seems to be about whether we will emit code for the `HaltNode`.

    instruct ShouldNotReachHere() %{
      match(Halt);
      format %{ "stop\t# ShouldNotReachHere" %}
      ins_encode %{
        if (is_reachable()) {
          const char* str = __ code_string(_halt_reason);
          __ stop(str);
        }
      %}
      ins_pipe(pipe_slow);
    %}

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PR Review Comment: https://git.openjdk.org/jdk/pull/29169#discussion_r2688827029