This PR pulls the following upstream changes into DXC:
[llc/opt] Add an option to run all passes twice
(04464cf731)
> Lately, I have submitted a number of patches to fix bugs that only
occurred when using the same pass manager to compile
> multiple modules (generally these bugs are failure to reset some
persistent state).
>
> Unfortunately I don't think there is currently a way to test that from
the command line. This adds a very simple flag to both
> llc and opt, under which the tools will simply re-run their respective
> pass pipelines using the same pass manager on (a clone of the same
module). Additionally, we verify that both outputs are
> bitwise the same.
>
> Reviewers: yaron.keren
[opt] Fix sanitizer complaints about r254774
(38707c45be)
> `Out` can be null if no output is requested, so move any access
> to it inside the conditional. Thanks to Justin Bogner for finding
> this.
This is for the test of this change
(ef8761fd3b)
to fix#6659.
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Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Adam Yang <31109344+adam-yang@users.noreply.github.com>
b79169bc85