[clang] [CIR][X86] Add support for `cpuid`/`cpuidex` (PR #173197)

[Roberto Turrado Camblor via cfe-commits]

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@@ -5819,4 +5762,31 @@ def CIR_BlockAddressOp : CIR_Op<"block_address", [Pure]> {
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// CpuIdOp
+//===----------------------------------------------------------------------===//
+
+def CIR_CpuIdOp : CIR_Op<"cpuid"> {
+  let summary = "Get information about the CPU";
+  let description = [{
+    The `cir.cpuid` operation takes a base pointer to an array of 4 integers, a
+    function ID and a sub-function ID. The array of 4 integers is filled with
+    different information about the processor.
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rturrado wrote:

Do you think we have to set `let hasVerifier = 1` and implement `verify()` to add extra checks on `basePtr`?

https://github.com/llvm/llvm-project/pull/173197