[Clang][HIP] Warn when __AMDGCN_WAVEFRONT_SIZE is used in host code

The __AMDGCN_WAVEFRONT_SIZE and __AMDGCN_WAVEFRONT_SIZE__ macros in HIP can
only provide meaningful values during device compilation. They are currently
usable in host code, but only contain the default value of 64, independent of
the target device(s).
This patch redefines them during host compilation to issue a deprecation
warning if the macros are used in host code. Their value during host
compilation in actual HIP code as well as in preprocessing directives stays 64
as before. Macro uses in preprocessing directives are not diagnosed. Macro uses
in device code are not affected.

Implements SWDEV-449015.

Author: ritter-x2a

clang/lib/Driver/ToolChains/AMDGPU.cpp

@@ -551,6 +551,17 @@ void RocmInstallationDetector::AddHIPIncludeArgs(const ArgList &DriverArgs,
     CC1Args.push_back(DriverArgs.MakeArgString(P));
   }
 
+  {
+    // This header implements diagnostics for problematic uses of
+    // device-specific macros. Since these diagnostics should be issued even
+    // when GPU headers are not included, this header is included separately.
+    SmallString<128> P(D.ResourceDir);
+    llvm::sys::path::append(P, "include");
+    CC1Args.push_back("-internal-isystem");
+    CC1Args.push_back(DriverArgs.MakeArgString(P));
+    CC1Args.append({"-include", "__clang_hip_device_macro_guards.h"});
+  }
+
   const auto HandleHipStdPar = [=, &DriverArgs, &CC1Args]() {
     StringRef Inc = getIncludePath();
     auto &FS = D.getVFS();

clang/lib/Headers/CMakeLists.txt

@@ -79,6 +79,7 @@ set(hip_files
   __clang_hip_math.h
   __clang_hip_stdlib.h
   __clang_hip_runtime_wrapper.h
+  __clang_hip_device_macro_guards.h
   )
 
 set(hlsl_h

clang/lib/Headers/__clang_hip_device_macro_guards.h

@@ -0,0 +1,55 @@
+/*===---- __clang_hip_device_macro_guards.h - guards for HIP device macros -===
+ *
+ * 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
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+/*
+ * WARNING: This header is intended to be directly -include'd by
+ * the compiler and is not supposed to be included by users.
+ *
+ */
+
+#ifndef __CLANG_HIP_DEVICE_MACRO_GUARDS_H__
+#define __CLANG_HIP_DEVICE_MACRO_GUARDS_H__
+
+#if __HIP__
+#if !defined(__HIP_DEVICE_COMPILE__)
+// The __AMDGCN_WAVEFRONT_SIZE macros cannot hold meaningful values during host
+// compilation as devices are not initialized when the macros are defined and
+// there may indeed be devices with differing wavefront sizes in the same
+// system. This code issues diagnostics when the macros are used in host code.
+
+#undef __AMDGCN_WAVEFRONT_SIZE
+#undef __AMDGCN_WAVEFRONT_SIZE__
+
+// Reference __hip_device_macro_guard in a way that is legal in preprocessor
+// directives and does not affect the value so that appropriate diagnostics are
+// issued. Function calls, casts, or the comma operator would make the macro
+// illegal for use in preprocessor directives.
+#define __AMDGCN_WAVEFRONT_SIZE (!__hip_device_macro_guard ? 64 : 64)
+#define __AMDGCN_WAVEFRONT_SIZE__ (!__hip_device_macro_guard ? 64 : 64)
+
+// This function is referenced by the macro in device functions during host
+// compilation, it SHOULD NOT cause a diagnostic.
+__attribute__((device)) static constexpr int __hip_device_macro_guard(void) {
+  return -1;
+}
+
+// This function is referenced by the macro in host functions during host
+// compilation, it SHOULD cause a diagnostic.
+__attribute__((
+    host, deprecated("The __AMDGCN_WAVEFRONT_SIZE macros do not correspond "
+                     "to the device(s) when used in host code and may only "
+                     "be used in device code."))) static constexpr int
+__hip_device_macro_guard(void) {
+  return -1;
+}
+// TODO Change "deprecated" to "unavailable" to cause hard errors instead of
+// warnings.
+#endif
+#endif // __HIP__
+#endif // __CLANG_HIP_DEVICE_MACRO_GUARDS_H__

clang/test/Driver/hip-wavefront-size-host-diagnostics.hip

@@ -0,0 +1,52 @@
+// REQUIRES: amdgpu-registered-target
+// RUN: %clang -xhip --offload-arch=gfx1030 --offload-host-only -pedantic -nogpuinc -nogpulib -nobuiltininc -nostdinc -fsyntax-only -Xclang -verify=onhost %s
+// RUN: %clang -xhip --offload-arch=gfx1030 --offload-device-only -pedantic -nogpuinc -nogpulib -nobuiltininc -nostdinc -fsyntax-only -Xclang -verify=ondevice %s
+
+// ondevice-no-diagnostics
+
+#define WRAPPED __AMDGCN_WAVEFRONT_SIZE__
+
+__attribute__((host, device)) void use(int, const char*);
+
+template<int N> __attribute__((host, device)) int templatify(int x) {
+    return x + N;
+}
+
+// no warning expected
+#if defined(__HIP_DEVICE_COMPILE__) && (__AMDGCN_WAVEFRONT_SIZE__ == 64) && (__AMDGCN_WAVEFRONT_SIZE == 64)
+int foo(void);
+#endif
+
+// no warning expected
+__attribute__((device)) int device_var = __AMDGCN_WAVEFRONT_SIZE__;
+
+__attribute__((device))
+void device_fun() {
+    // no warnings expected
+    use(__AMDGCN_WAVEFRONT_SIZE, "device function");
+    use(__AMDGCN_WAVEFRONT_SIZE__, "device function");
+    use(WRAPPED, "device function");
+    use(templatify<__AMDGCN_WAVEFRONT_SIZE__>(42), "device function");
+}
+
+// warning expected
+int host_var = __AMDGCN_WAVEFRONT_SIZE__;  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+
+__attribute__((host))
+void host_fun() {
+    // warnings expected
+    use(__AMDGCN_WAVEFRONT_SIZE, "host function");  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+    use(__AMDGCN_WAVEFRONT_SIZE__, "host function");  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+    use(WRAPPED, "host function");  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+    use(templatify<__AMDGCN_WAVEFRONT_SIZE__>(42), "host function");  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+}
+
+__attribute((host, device))
+void host_device_fun() {
+    // warnings expected
+    use(__AMDGCN_WAVEFRONT_SIZE__, "host device function");  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+    use(WRAPPED, "host device function");  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+    use(templatify<__AMDGCN_WAVEFRONT_SIZE__>(42), "host device function");  // onhost-warning {{'__hip_device_macro_guard' is deprecated: The __AMDGCN_WAVEFRONT_SIZE macros do not correspond to the device(s) when used in host code and may only be used in device code.}}
+}
+
+// onhost-note@__clang_hip_device_macro_guards.h:45 0+ {{'__hip_device_macro_guard' has been explicitly marked deprecated here}}

clang/test/Preprocessor/predefined-arch-macros.c

@@ -4399,7 +4399,6 @@
 // RUN: %clang -x hip -E -dM %s -o - 2>&1 --offload-host-only -nogpulib \
 // RUN:     -nogpuinc --offload-arch=gfx803 -target x86_64-unknown-linux \
 // RUN:   | FileCheck -match-full-lines %s -check-prefixes=CHECK_HIP_HOST
-// CHECK_HIP_HOST: #define __AMDGCN_WAVEFRONT_SIZE__ 64
 // CHECK_HIP_HOST: #define __AMDGPU__ 1
 // CHECK_HIP_HOST: #define __AMD__ 1