[PATCH] D76305: [RS4GC] Fix algorithm to avoid setting vector BDV for scalar derived pointer

[Denis Antrushin via Phabricator via llvm-commits]

dantrushin added a comment.

I hoped Philip will review this, because I'm not very familiar with this part of RS4GC and I have couple quetions here, see inline.



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Comment at: llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp:641
 /// is it known to be a base pointer?  Or do we need to continue searching.
-static bool isKnownBaseResult(Value *V) {
+static bool isKnownBaseResult(Value *V, Value *Input) {
   if (!isa<PHINode>(V) && !isa<SelectInst>(V) &&
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Is `Input` a derived pointer here for which we check if `V` is a base of?.. Or vice versa?


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Comment at: llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp:884
       Value *BDV = Pair.first;
-      assert(!isKnownBaseResult(BDV) && "why did it get added?");
+      assert(!isKnownBaseResult(BDV, Pair.second.getBaseValue()) &&
+             "why did it get added?");
----------------
Here I am confused.
Isn't `Pair.second.getBaseValue()` supposed to be base value for `BDV`? And we're asking the other way?
Same question for lines 944, 977 and few more below.


Repository:
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  https://reviews.llvm.org/D76305/new/

https://reviews.llvm.org/D76305