[llvm] Refine the examples in the debug info document (PR #86272)

[David Blaikie via llvm-commits]

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@@ -91,8 +91,12 @@ misattributed to a block containing one of the instructions-to-be-merged.
 
 Examples of transformations that should follow this rule include:
 
-* Merging identical loads/stores which occur on both sides of a CFG diamond
-  (see the ``MergedLoadStoreMotion`` pass).
+* Hoisting identical instructions from successors of a conditional branch or
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dwblaikie wrote:

if every path (sw1, sw2, exit1) out of a block has the same location, then I think it's OK to merge and preserve, rather than drop. So I don't think this is the scenario I was describing above - where two out of three (sw1 and sw2, but not exit1) might share an expression, then it has to be dropped.

https://github.com/llvm/llvm-project/pull/86272