[clang] [CUDA][HIP] Add a __device__ version of std::__glibcxx_assert_fail() (PR #136133)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Juan Manuel Martinez Caamaño (jmmartinez)

<details>
<summary>Changes</summary>

libstdc++ 15 uses the non-constexpr function
std::__glibcxx_assert_fail() to trigger compilation errors when the __glibcxx_assert(cond) macro is used in a constantly evaluated context.

Compilation fails when using code from the libstdc++ (such as std::array) on device code, since these assertions invoke a non-constexpr host function from device code.

This patch proposes a cuda wrapper header "bits/c++config.h" which adds a __device__ version of std::__glibcxx_assert_fail().

---
Full diff: https://github.com/llvm/llvm-project/pull/136133.diff


2 Files Affected:

- (modified) clang/lib/Headers/CMakeLists.txt (+1) 
- (added) clang/lib/Headers/cuda_wrappers/bits/c++config.h (+39) 


``````````diff
diff --git a/clang/lib/Headers/CMakeLists.txt b/clang/lib/Headers/CMakeLists.txt
index acf49e40c447e..54395e053dbc4 100644
--- a/clang/lib/Headers/CMakeLists.txt
+++ b/clang/lib/Headers/CMakeLists.txt
@@ -333,6 +333,7 @@ set(cuda_wrapper_files
 )
 
 set(cuda_wrapper_bits_files
+  cuda_wrappers/bits/c++config.h
   cuda_wrappers/bits/shared_ptr_base.h
   cuda_wrappers/bits/basic_string.h
   cuda_wrappers/bits/basic_string.tcc
diff --git a/clang/lib/Headers/cuda_wrappers/bits/c++config.h b/clang/lib/Headers/cuda_wrappers/bits/c++config.h
new file mode 100644
index 0000000000000..583e595f7f529
--- /dev/null
+++ b/clang/lib/Headers/cuda_wrappers/bits/c++config.h
@@ -0,0 +1,39 @@
+// libstdc++ uses the non-constexpr function std::__glibcxx_assert_fail()
+// to trigger compilation errors when the __glibcxx_assert(cond) macro
+// is used in a constexpr context.
+// Compilation fails when using code from the libstdc++ (such as std::array) on
+// device code, since these assertions invoke a non-constexpr host function from
+// device code.
+//
+// To work around this issue, we declare our own device version of the function
+
+#ifndef __CLANG_CUDA_WRAPPERS_BITS_CPP_CONFIG
+#define __CLANG_CUDA_WRAPPERS_BITS_CPP_CONFIG
+
+#include_next <bits/c++config.h>
+
+#if _GLIBCXX_HAVE_IS_CONSTANT_EVALUATED
+
+#ifdef _LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_BEGIN_NAMESPACE_STD
+#else
+namespace std {
+#ifdef _GLIBCXX_BEGIN_NAMESPACE_VERSION
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+#endif
+#endif
+__device__
+    __attribute__((__always_inline__, __visibility__("default"))) inline void
+    __glibcxx_assert_fail() {}
+#ifdef _LIBCPP_END_NAMESPACE_STD
+_LIBCPP_END_NAMESPACE_STD
+#else
+#ifdef _GLIBCXX_BEGIN_NAMESPACE_VERSION
+_GLIBCXX_END_NAMESPACE_VERSION
+#endif
+} // namespace std
+#endif
+
+#endif
+
+#endif

``````````

</details>


https://github.com/llvm/llvm-project/pull/136133