The original patch failed to handle the case where the loopback
condition compared against a constant exceeding 64 bit unsigned range -
which caused a buildbot failure.
This PR fixes this and relands the original PR #95002.
The current loop idiom code for recognising and inserting a CTLZ
intrinsic does not support loops where the loopback control is based on
an unsigned less-than condition. This patch adds support for recognising
these loops and inserting a CTLZ intrinsic.
Fixes the missed optimization cases in #51064.
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Co-authored-by: David Sherwood <david.sherwood@arm.com>
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