[AMDGPU] Correctly use the auxiliary toolchain to include libc++

[jhuber6]

Summary:
Now that we have a functional build for libc++ on the GPU, it will now
find the target specific headers in include/amdgcn-amd-amdhsa. This is
a problem for offloading via OpenMP because we need the CPU and GPU
headers to match exactly. All the other toolchains forward this
correctly except the AMDGPU OpenMP one, fix this by overriding it to use
the host toolchain instead of the device one, so the triple is not
returned as amdgcn-amd-amdhsa.

[llvmbot]

@llvm/pr-subscribers-backend-amdgpu
@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Joseph Huber (jhuber6)

Changes

Summary:
Now that we have a functional build for libc++ on the GPU, it will now
find the target specific headers in include/amdgcn-amd-amdhsa. This is
a problem for offloading via OpenMP because we need the CPU and GPU
headers to match exactly. All the other toolchains forward this
correctly except the AMDGPU OpenMP one, fix this by overriding it to use
the host toolchain instead of the device one, so the triple is not
returned as amdgcn-amd-amdhsa.

---

Full diff: https://github.com/llvm/llvm-project/pull/109366.diff

2 Files Affected:

• (modified) clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp (+5)
• (modified) clang/lib/Driver/ToolChains/AMDGPUOpenMP.h (+3)

diff --git a/clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp b/clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp
index d43e683e46852d..3f0b3f2d86b3ed 100644
--- a/clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp
+++ b/clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp
@@ -120,6 +120,11 @@ AMDGPUOpenMPToolChain::GetCXXStdlibType(const ArgList &Args) const {
   return HostTC.GetCXXStdlibType(Args);
 }
 
+void AMDGPUOpenMPToolChain::AddClangCXXStdlibIncludeArgs(
+    const llvm::opt::ArgList &Args, llvm::opt::ArgStringList &CC1Args) const {
+  HostTC.AddClangCXXStdlibIncludeArgs(Args, CC1Args);
+}
+
 void AMDGPUOpenMPToolChain::AddClangSystemIncludeArgs(
     const ArgList &DriverArgs, ArgStringList &CC1Args) const {
   HostTC.AddClangSystemIncludeArgs(DriverArgs, CC1Args);
diff --git a/clang/lib/Driver/ToolChains/AMDGPUOpenMP.h b/clang/lib/Driver/ToolChains/AMDGPUOpenMP.h
index 2be444a42c55fa..0536c9f7f564c8 100644
--- a/clang/lib/Driver/ToolChains/AMDGPUOpenMP.h
+++ b/clang/lib/Driver/ToolChains/AMDGPUOpenMP.h
@@ -42,6 +42,9 @@ class LLVM_LIBRARY_VISIBILITY AMDGPUOpenMPToolChain final
                         Action::OffloadKind DeviceOffloadKind) const override;
   void addClangWarningOptions(llvm::opt::ArgStringList &CC1Args) const override;
   CXXStdlibType GetCXXStdlibType(const llvm::opt::ArgList &Args) const override;
+  void AddClangCXXStdlibIncludeArgs(
+      const llvm::opt::ArgList &Args,
+      llvm::opt::ArgStringList &CC1Args) const override;
   void
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;

[shiltian]

The fix looks good. A test would be preferred.

[jhuber6]

The fix looks good. A test would be preferred.

Done