[clang] [CIR] Add cir.libc.memcpy Op (PR #176781)

[Andrzej Warzyński via cfe-commits]

================
@@ -3439,6 +3439,53 @@ def CIR_CopyOp : CIR_Op<"copy",[
   }];
 }
 
+//===----------------------------------------------------------------------===//
+// MemCpyOp && MemMoveOp
+//===----------------------------------------------------------------------===//
+
+class CIR_MemOp<string mnemonic> : CIR_Op<mnemonic, [
+  AllTypesMatch<["dst", "src"]>
+]> {
+  dag commonArgs = (ins
+    Arg<CIR_VoidPtrType, "", [MemWrite]>:$dst,
+    Arg<CIR_VoidPtrType, "", [MemRead]>:$src
+  );
+}
+
+def CIR_MemCpyOp : CIR_MemOp<"libc.memcpy"> {
+  let summary = "Equivalent to libc's `memcpy`";
+  let description = [{
+    Given two CIR pointers, `src` and `dst`, `cir.libc.memcpy` will copy `len`
+    bytes from the memory pointed by `src` to the memory pointed by `dst`.
+
+    While `cir.copy` is meant to be used for implicit copies in the code where
+    the length of the copy is known, `cir.memcpy` copies only from and to void
+    pointers, requiring the copy length to be passed as an argument.
----------------
banach-space wrote:

Thanks for the clear, prescriptive comment - that's much appreciated!

https://github.com/llvm/llvm-project/pull/176781