[PATCH] D73435: [ValueTracking] Add DemandedElts support to computeKnownBits/ComputeNumSignBits (PR36319)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/lib/Analysis/ValueTracking.cpp:1729-1732
+  case Instruction::InsertElement: {
+    // If we know the element index, split the demand between the
+    // source vector and the inserted element, otherwise assume we need
+    // the original demanded vector elements and the value.
----------------
This case is really hard to follow.
This may be missing some comments.


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Comment at: llvm/lib/Analysis/ValueTracking.cpp:1748-1749
+    Known.Zero.setAllBits();
+    if (DemandedVal)
+      computeKnownBits(Elt, Known, Depth + 1, Q);
+    // If we don't know any bits, early out.
----------------
If `Idx` is not a constant, or out-of-bounds, why do we still `computeKnownBits()` of `Elt`?
If `Idx` is in-bounds constant, why do we call `computeKnownBits()` only on `Elt`?



Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73435/new/

https://reviews.llvm.org/D73435