[clang] [AMDGPU] Correctly use the auxiliary toolchain to include libc++ (PR #109366)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 updated https://github.com/llvm/llvm-project/pull/109366

>From f47b67c20014fbedc5ce9764be2e2687258a474e Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Thu, 19 Sep 2024 22:03:42 -0500
Subject: [PATCH] [AMDGPU] Correctly use the auxiliary toolchain to include
 libc++

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`.
---
 clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp | 5 +++++
 clang/lib/Driver/ToolChains/AMDGPUOpenMP.h   | 3 +++
 clang/test/Driver/amdgpu-openmp-toolchain.c  | 4 ++++
 3 files changed, 12 insertions(+)

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;
diff --git a/clang/test/Driver/amdgpu-openmp-toolchain.c b/clang/test/Driver/amdgpu-openmp-toolchain.c
index a153c4afb0ce8c..184819b790c4ff 100644
--- a/clang/test/Driver/amdgpu-openmp-toolchain.c
+++ b/clang/test/Driver/amdgpu-openmp-toolchain.c
@@ -77,3 +77,7 @@
 // RUN:   %clang -### --target=x86_64-unknown-linux-gnu -emit-llvm -S -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa -march=gfx803 -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-WARN-ATOMIC
 // CHECK-WARN-ATOMIC-NOT: "-cc1" "-triple" "x86_64-unknown-linux-gnu"{{.*}}"-Werror=atomic-alignment"
 // CHECK-WARN-ATOMIC: "-cc1" "-triple" "amdgcn-amd-amdhsa"{{.*}}"-Werror=atomic-alignment"
+
+// RUN:   %clang -### --target=x86_64-unknown-linux-gnu -emit-llvm -S -fopenmp --offload-arch=gfx803 \
+// RUN:     -stdlib=libc++ -nogpulib %s 2>&1 | FileCheck %s --check-prefix=LIBCXX
+// LIBCXX-NOT: include/amdgcn-amd-amdhsa/c++/v1