[llvm] [PHIElimination] Handle subranges in LiveInterval updates (PR #69429)

[Matthias Braun via llvm-commits]

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@@ -563,13 +563,18 @@ VNInfo *LiveRange::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) {
   return CalcLiveRangeUtilVector(this).extendInBlock(StartIdx, Kill);
 }
 
-/// Remove the specified segment from this range.  Note that the segment must
-/// be in a single Segment in its entirety.
+/// Remove the specified interval from this live range.
+/// Does nothing if interval is not part of this live range.
+/// Note that the interval must be within a single Segment in its entirety.
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MatzeB wrote:

Given this is already documented in the header. Can we remove the comment here to avoid duplication and comments getting out of sync?

https://github.com/llvm/llvm-project/pull/69429