[compiler-rt] [builtins] Refactor cpu_model support to reduce #if nesting. NFCI (PR #75635)

[Jon Roelofs via llvm-commits]

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@@ -0,0 +1,41 @@
+//===-- cpu_model_common.c - Utilities for cpu model detection ----*- C -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements common utilities for runtime cpu model detection.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef COMPILER_RT_LIB_BUILTINS_CPU_MODEL_COMMON_H
+#define COMPILER_RT_LIB_BUILTINS_CPU_MODEL_COMMON_H
+
+#define bool int
+#define true 1
+#define false 0
+
+#ifndef __has_attribute
+#define __has_attribute(attr) 0
+#endif
+
+#if __has_attribute(constructor)
+#if __GNUC__ >= 9
+// Ordinarily init priorities below 101 are disallowed as they are reserved for the
+// implementation. However, we are the implementation, so silence the diagnostic,
+// since it doesn't apply to us.
+#pragma GCC diagnostic ignored "-Wprio-ctor-dtor"
+#endif
+// We're choosing init priority 90 to force our constructors to run before any
+// constructors in the end user application (starting at priority 101). This value
+// matches the libgcc choice for the same functions.
+#define CONSTRUCTOR_ATTRIBUTE __attribute__((constructor(90)))
+#else
+// FIXME: For MSVC, we should make a function pointer global in .CRT$X?? so that
+// this runs during initialization.
+#define CONSTRUCTOR_ATTRIBUTE
+#endif
+
+#endif
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jroelofs wrote:

- [ ] FIXME: needs EOF newline

https://github.com/llvm/llvm-project/pull/75635