[clang] [CIR] Add bit reverse and byte reverse operations (PR #147200)

[Sirui Mu via cfe-commits]

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@@ -2661,6 +2661,45 @@ def BitPopcountOp : CIR_BitOpBase<"bit.popcnt",
   }];
 }
 
+def BitReverseOp : CIR_BitOpBase<"bit.reverse",
+                                 CIR_UIntOfWidths<[8, 16, 32, 64]>> {
+  let summary = "Reverse the bit pattern of the operand integer";
+  let description = [{
+    The `cir.bit.reverse` operation reverses the bits of the operand integer.
+    Its only argument must be of unsigned integer types of width 8, 16, 32, or
+    64.
+
+    This operation covers the C/C++ builtin function `__builtin_bitreverse`.
+
+    Example:
+
+    ```mlir
+    %1 = cir.bit.reverse(%0 : !u32i): !u32i
+    ```
+  }];
+}
+
+def ByteSwapOp : CIR_BitOpBase<"bit.bswap", CIR_UIntOfWidths<[16, 32, 64]>> {
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Lancern wrote:

> For the same reason, I’d like to eliminate the bit. prefix entirely and use the builtin names directly, like bitreverse (This can be, and probably should be done as separate PR).

I'll send a separate PR for this after this PR lands.

https://github.com/llvm/llvm-project/pull/147200