[llvm] [KnownBits] Add operator<<=(unsigned) and operator>>=(unsigned). NFC (PR #155751)

[Jay Foad via llvm-commits]

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@@ -487,6 +487,20 @@ struct KnownBits {
   /// Update known bits based on XORing with RHS.
   LLVM_ABI KnownBits &operator^=(const KnownBits &RHS);
 
+  /// Shift known bits left by ShAmt. Shift in bits are unknown.
+  KnownBits &operator<<=(unsigned ShAmt) {
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jayfoad wrote:

> Ideally

Well, that's an opinion... Personally I like the ergonomics of `operator&` etc and would have liked to use it in more cases like `operator+` instead of `add`, but that didn't work out because those functions needed extra arguments.

Anyway please don't consider my comments as blocking. I don't really object to the patch.

https://github.com/llvm/llvm-project/pull/155751