[clang] [CUDA] pass -fno-threadsafe-statics to GPU sub-compilations. (PR #117074)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Artem Belevich (Artem-B)

<details>
<summary>Changes</summary>

We do not have support for the threadsafe statics on the GPU side.

However, we do sometimes end up with empty local static initializers, and those happen to trigger calls to `__cxa_guard*`, which breaks compilation.

Partially addresses https://github.com/llvm/llvm-project/issues/117023

---
Full diff: https://github.com/llvm/llvm-project/pull/117074.diff


2 Files Affected:

- (modified) clang/lib/Driver/ToolChains/Cuda.cpp (+3-2) 
- (added) clang/test/Driver/cuda-no-threadsafe-statics.cu (+10) 


``````````diff
diff --git a/clang/lib/Driver/ToolChains/Cuda.cpp b/clang/lib/Driver/ToolChains/Cuda.cpp
index ddd5ea248ca0cc..102794829795da 100644
--- a/clang/lib/Driver/ToolChains/Cuda.cpp
+++ b/clang/lib/Driver/ToolChains/Cuda.cpp
@@ -856,8 +856,9 @@ void CudaToolChain::addClangTargetOptions(
           DeviceOffloadingKind == Action::OFK_Cuda) &&
          "Only OpenMP or CUDA offloading kinds are supported for NVIDIA GPUs.");
 
-  CC1Args.append(
-      {"-fcuda-is-device", "-mllvm", "-enable-memcpyopt-without-libcalls"});
+  CC1Args.append({"-fcuda-is-device", "-mllvm",
+                  "-enable-memcpyopt-without-libcalls",
+                  "-fno-threadsafe-statics"});
 
   // Unsized function arguments used for variadics were introduced in CUDA-9.0
   // We still do not support generating code that actually uses variadic
diff --git a/clang/test/Driver/cuda-no-threadsafe-statics.cu b/clang/test/Driver/cuda-no-threadsafe-statics.cu
new file mode 100644
index 00000000000000..fd0465f175846d
--- /dev/null
+++ b/clang/test/Driver/cuda-no-threadsafe-statics.cu
@@ -0,0 +1,10 @@
+// Check that -fno-thread-safe-statics get passed down to device-side
+// compilation only.
+//
+// RUN: not %clang -### --target=x86_64-linux-gnu -c --cuda-gpu-arch=sm_20 %s 2>&1 \
+// RUN:   | FileCheck %s
+//
+// CHECK: "-fcuda-is-device"
+// CHECK-SAME: "-fno-threadsafe-statics"
+// CHECK: "-triple" "x86_64-unknown-linux-gnu"
+// CHECK-NOT: "-fno-threadsafe-statics"

``````````

</details>


https://github.com/llvm/llvm-project/pull/117074