[amdgpu-arch] Guard hsa.h with __has_include

[pdhaliwal]

Summary

This patch is suppose to fix the issue of hsa.h not found.
Issue was reported in D99949

[JonChesterfield]

Logic doesn't look quite right to me. If the compiler supports has_include, but neither of those headers exist, we fall through to main() which won't compile.

How about:

#if defined(__has_include)
  #if __has_include("hsa.h")
    #define HSA_FOUND 1 // name tbd
    #include "hsa.h"
  #elif __has_include("hsa/hsa.h")
    #define HSA_FOUND 1
    #include "hsa/hsa.h"
  #else
    #define HSA_FOUND 0
  #endif
#else
  #define HSA_FOUND 0
#endif


#if !HSA_FOUND
int main() { return 1; }
#else
// all the current stuff
#endif

That takes the approach that missing __has_include is a bad sign and immediately gives up. As far as I can tell it was introduced ~ 10 years ago, and was more recently added to c++17 (https://en.cppreference.com/w/cpp/preprocessor/include, which uses a similar pattern to the above in terms of booleans). Seems to be present in gcc, clang, msvc and we have a safe fallback if it isn't.

edit: We could also start down the dlopen path, but let's not do that if we can avoid it

[pdhaliwal]

Added fallback in case __has_include is not defined or header is not found anywhere.

[JonChesterfield]

LGTM, thanks. I think this leaves us totally sure the clang build will succeed with a best effort chance of having a working amdgpu ident tool afterwards.

[JonChesterfield]

A thought - we need to keep return 0 for success, but could return a different integer for each failure mode. That would be useful when guessing why it failed. Orthogonal to this patch.

clang/tools/amdgpu-arch/AMDGPUArch.cpp

 //===- AMDGPUArch.cpp - list AMDGPU installed ----------*- 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 a tool for detecting name of AMDGPU installed in system
 // using HSA. This tool is used by AMDGPU OpenMP driver.
 //
 //===----------------------------------------------------------------------===//
 
-#include <hsa.h>
+#if defined(__has_include)
+#if __has_include("hsa.h")
+#define HSA_HEADER_FOUND 1
+#include "hsa.h"
+#elif __has_include("hsa/hsa.h")
+#define HSA_HEADER_FOUND 1
+#include "hsa/hsa.h"
+#else
+#define HSA_HEADER_FOUND 0
+#endif
+#else
+#define HSA_HEADER_FOUND 0
+#endif
+
+#if !HSA_HEADER_FOUND
+int main() { return 1; }
+#else
+
 #include <string>
 #include <vector>
 
 static hsa_status_t iterateAgentsCallback(hsa_agent_t Agent, void *Data) {
   hsa_device_type_t DeviceType;
   hsa_status_t Status =
       hsa_agent_get_info(Agent, HSA_AGENT_INFO_DEVICE, &DeviceType);
 
for (const auto &GPU : GPUs)
     printf("%s\n", GPU.c_str());
 
   if (GPUs.size() < 1)
     return 1;
 
   hsa_shut_down();
   return 0;
 }
+
+#endif