[llvm] [Support] Add a fast path for KnownBits::udiv when RHS is constant. Also add overloads for shift ops with constant RHS. (PR #189779)

[Nikita Popov via llvm-commits]

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@@ -1209,6 +1213,10 @@ KnownBits KnownBits::udiv(const KnownBits &LHS, const KnownBits &RHS,
     return Known;
   }
 
+  if (RHS.isConstant() && RHS.getConstant().isPowerOf2()) {
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nikic wrote:

nit: Omit braces for one-line if.

https://github.com/llvm/llvm-project/pull/189779