[libclc] libclc: Add subgroup scan functions (PR #188828)

[Wenju He via cfe-commits]

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@@ -0,0 +1,77 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(__CLC_SCALAR)
+
+#if (defined(__CLC_GENSIZE) && __CLC_GENSIZE <= 32) ||                         \
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wenju-he wrote:

do you mean `__CLC_GENSIZE == 32`? otherwise the elif branch at line 40 won't be taken.

https://github.com/llvm/llvm-project/pull/188828