[PATCH] D75233: [LoopTerminology] LCSSA Form

[Michael Kruse via Phabricator via llvm-commits]

Meinersbur added a comment.

In D75233#1932574 <https://reviews.llvm.org/D75233#1932574>, @baziotis wrote:

> 2 questions:
>
> 1. Is it "loop closed PHI node" or "loop closing PHI node"?


Not being an expert of the English language, I;d say "loop-closing PHI node"

> 2. Does LCSSA pass have to do this deep analysis? Because to me, it seems it can just use `RAUW`?

The most complicated thing is finding the dominator nodes to add the PHI nodes in (especially with multiple loop exits).

If possible, could you avoid "deep analysis", but instead refer the kind of analysis needed?



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Comment at: llvm/docs/LoopTerminology.rst:261-264
+to take effect.  However, we should note one thing:
+LLVM keeps all the uses of a value in an internal data structure.
+That means we don't have to do deep analysis to find and replace
+all uses of a value, we can just iterate this data structure (there
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You you replace "deep analysis" by "data flow analysis"? Also mention this the use-def list is a property of SSA in general. Without mentioning these terms, I had to read this paragraph 3 times before I understood what ou want to say.


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Comment at: llvm/docs/LoopTerminology.rst:266
+is even a utility function, replaceAllUsesWith(), that performs
+this transformation).
+
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If you think it's worth mentioning, you could add that it's also easy to find all values that are used outside the loop: iterate over the PHINodes in the exit nodes (instead looking of all use-lists of all instructions in the loop).


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Comment at: llvm/docs/LoopTerminology.rst:285-287
+base 100 and step 1.  Although, in practice, and in the LLVM context,
+SCEV should have no problem with it (it's just two AddRecExpr
+in a SCEVExpr).
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Could you add a sentence introducing SCEV? In this sentence it appears without context.


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