[llvm] [AMDGPU] - Add constant folding for s_bitreplicate (PR #72366)

[Jay Foad via llvm-commits]

================
@@ -2422,6 +2423,23 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
 
       return ConstantFP::get(Ty->getContext(), Val);
     }
+
+    case Intrinsic::amdgcn_s_bitreplicate: {
+      uint64_t Val = Op->getZExtValue();
+      uint64_t ReplicatedVal = 0;
+      uint64_t ReplicatedOnes = 0b11;
+      // Input operand is always b32
+      for (unsigned i = 0; i < 32; ++i, ReplicatedOnes <<= 2, Val >>= 1) {
+        uint64_t Bit = Val & 1;
----------------
jayfoad wrote:

Nit: could fold this into the only use of `Bit`.

https://github.com/llvm/llvm-project/pull/72366