[llvm] [KnownBits] Make `avg{Ceil,Floor}S` optimal (PR #110329)

[via llvm-commits]

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@@ -306,14 +306,14 @@ TEST(KnownBitsTest, BinaryExhaustive) {
         return KnownBits::add(Known1, Known2);
       },
       [](const APInt &N1, const APInt &N2) { return N1 + N2; },
-      /*CheckOptimality=*/false);
+      /*CheckOptimality=*/true);
   testBinaryOpExhaustive(
       "sub",
       [](const KnownBits &Known1, const KnownBits &Known2) {
         return KnownBits::sub(Known1, Known2);
       },
       [](const APInt &N1, const APInt &N2) { return N1 - N2; },
-      /*CheckOptimality=*/false);
+      /*CheckOptimality=*/true);
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goldsteinn wrote:

No, this was just motivated by the fact that I noticed we had incorrectly labelled a lot of the tests. I pushed an NFC change to correctly label them.

https://github.com/llvm/llvm-project/pull/110329