[llvm] [KnownBits] Add KnownBits::absdiff to compute the absolute difference of 2 unsigned values (PR #82354)

[Simon Pilgrim via llvm-commits]

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@@ -281,7 +281,14 @@ TEST(KnownBitsTest, BinaryExhaustive) {
         return KnownBits::smin(Known1, Known2);
       },
       [](const APInt &N1, const APInt &N2) { return APIntOps::smin(N1, N2); });
-
+  testBinaryOpExhaustive(
+      [](const KnownBits &Known1, const KnownBits &Known2) {
+        return KnownBits::absdiff(Known1, Known2);
+      },
+      [](const APInt &N1, const APInt &N2) {
+        return APIntOps::absdiff(N1, N2);
+      },
+      checkCorrectnessOnlyBinary);
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RKSimon wrote:

I've added an example for each absdiff path

https://github.com/llvm/llvm-project/pull/82354