[OpenMP] Ensure wrapper headers are included on both host and device

[jhuber6]

Summary

For the in-progress GPU libc project we are relying on overlay headers to
handle the interfacing between the libc project and the host libc.
We need this to be included on both the host and device so they agree
one what is present on the device, otherwise we will end up with random
errors. For whatever reason this was not being included on the host
although it previously worked. This patch ensures that it's included on
both.

[arsenm]

clang/lib/Driver/ToolChains/Clang.cpp

1190–1193

can we do something better than this NVPTX||AMDGCN checks

[jhuber6]

clang/lib/Driver/ToolChains/Clang.cpp

1190–1193

This is more or less "Are we one of the GPUs libc supports". This is for cross-compiling so there's no existing infrastructure.

[yaxunl]

clang/lib/Driver/ToolChains/Clang.cpp

1190–1193

maybe add a variable bool HasGPULibC as it is also used in other places below

[jhuber6]

clang/lib/Driver/ToolChains/Clang.cpp

1190–1193

I think this is the only use right now.

[yaxunl]

LGTM. Thanks

clang/lib/Driver/ToolChains/Clang.cpp

if (JA.isOffloading(Action::OFK_Cuda))
     getToolChain().AddCudaIncludeArgs(Args, CmdArgs);
   if (JA.isOffloading(Action::OFK_HIP))
     getToolChain().AddHIPIncludeArgs(Args, CmdArgs);
 
   // If we are compiling for a GPU target we want to override the system headers
   // with ones created by the 'libc' project if present.
   if (!Args.hasArg(options::OPT_nostdinc) &&
       !Args.hasArg(options::OPT_nogpuinc) &&
-      !Args.hasArg(options::OPT_nobuiltininc) &&
-      (getToolChain().getTriple().isNVPTX() ||
-       getToolChain().getTriple().isAMDGCN())) {
-
+      !Args.hasArg(options::OPT_nobuiltininc)) {
     // Without an offloading language we will include these headers directly.
     // Offloading languages will instead only use the declarations stored in
     // the resource directory at clang/lib/Headers/llvm_libc_wrappers.
-    if (C.getActiveOffloadKinds() == Action::OFK_None) {
+    if ((getToolChain().getTriple().isNVPTX() ||
+         getToolChain().getTriple().isAMDGCN()) &&
+        C.getActiveOffloadKinds() == Action::OFK_None) {
       SmallString<128> P(llvm::sys::path::parent_path(D.InstalledDir));
       llvm::sys::path::append(P, "include");
       llvm::sys::path::append(P, "gpu-none-llvm");
       CmdArgs.push_back("-c-isystem");
       CmdArgs.push_back(Args.MakeArgString(P));
     } else if (C.getActiveOffloadKinds() == Action::OFK_OpenMP) {
       // TODO: CUDA / HIP include their own headers for some common functions
       // implemented here. We'll need to clean those up so they do not conflict.
       SmallString<128> P(D.ResourceDir);

clang/test/Driver/gpu-libc-headers.c

 // REQUIRES: nvptx-registered-target
 // REQUIRES: amdgpu-registered-target
 
 // RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp=libomp --sysroot=./ \
 // RUN:     -fopenmp-targets=amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa --offload-arch=gfx908  \
 // RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS
 // RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp=libomp --sysroot=./ \
 // RUN:     -fopenmp-targets=nvptx64-nvidia-cuda -Xopenmp-target=nvptx64-nvidia-cuda --offload-arch=sm_70  \
 // RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS
 // CHECK-HEADERS: "-cc1"{{.*}}"-internal-isystem" "{{.*}}include{{.*}}llvm_libc_wrappers"{{.*}}"-isysroot" "./"
+// CHECK-HEADERS: "-cc1"{{.*}}"-internal-isystem" "{{.*}}include{{.*}}llvm_libc_wrappers"{{.*}}"-isysroot" "./"
 
 // RUN:   %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx1030 -nogpulib \
 // RUN:     -nogpuinc %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-DISABLED
 // RUN:   %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx1030 -nogpulib \
 // RUN:     -nostdinc %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-DISABLED
 // RUN:   %clang -### --target=amdgcn-amd-amdhsa -mcpu=gfx1030 -nogpulib \
 // RUN:     -nobuiltininc %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-DISABLED
 // CHECK-HEADERS-DISABLED-NOT: "-cc1"{{.*}}"-c-isystem" "{{.*}}include{{.*}}gpu-none-llvm"