[OpenMP] Do not add wrapper headers if using '-nogpuinc'

[jhuber6]

Summary

The OpenMP offloading toolchain uses wrapper headers to implement some
standard features on the GPU. Currently there is no way to turn these
off without also disabling all the standard includes altogether. This
patch makes -nogpuinc apply to these wrapper headers so we can use a
sterile toolchain. This was causing problems when attempting to compile
a libc for the GPU using OpenMP.

[jdoerfert]

LG

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 offloading to a target via OpenMP we need to include the
   // openmp_wrappers folder which contains alternative system headers.
   if (JA.isDeviceOffloading(Action::OFK_OpenMP) &&
       !Args.hasArg(options::OPT_nostdinc) &&
+      !Args.hasArg(options::OPT_nogpuinc) &&
       (getToolChain().getTriple().isNVPTX() ||
        getToolChain().getTriple().isAMDGCN())) {
     if (!Args.hasArg(options::OPT_nobuiltininc)) {
       // Add openmp_wrappers/* to our system include path.  This lets us wrap
       // standard library headers.
       SmallString<128> P(D.ResourceDir);
       llvm::sys::path::append(P, "include");
       llvm::sys::path::append(P, "openmp_wrappers");

clang/test/Driver/openmp-offload-headers.c

+// REQUIRES: nvptx-registered-target
+// REQUIRES: amdgpu-registered-target
+
+// RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=nvptx64-nvidia-cuda --offload-arch=sm_70 \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa --offload-arch=gfx908  \
+// RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS
+// CHECK-HEADERS: "-cc1"{{.*}}"-internal-isystem" "{{.*}}openmp_wrappers" "-include" "__clang_openmp_device_functions.h"
+// CHECK-HEADERS: "-cc1"{{.*}}"-internal-isystem" "{{.*}}openmp_wrappers" "-include" "__clang_openmp_device_functions.h"
+
+// RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -nobuiltininc \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=nvptx64-nvidia-cuda --offload-arch=sm_70 \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa --offload-arch=gfx908  \
+// RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-BUILTIN
+// CHECK-HEADERS-BUILTIN: "-cc1"{{.*}}"-include" "__clang_openmp_device_functions.h"
+// CHECK-HEADERS-BUILTIN: "-cc1"{{.*}}"-include" "__clang_openmp_device_functions.h"
+
+// RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -nostdinc \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=nvptx64-nvidia-cuda --offload-arch=sm_70 \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa --offload-arch=gfx908  \
+// RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-DISABLED
+// RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -nogpuinc \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=nvptx64-nvidia-cuda --offload-arch=sm_70 \
+// RUN:     -fopenmp-targets=nvptx64-nvidia-cuda,amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa --offload-arch=gfx908  \
+// RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-DISABLED
+// CHECK-HEADERS-DISABLED-NOT: "-cc1"{{.*}}"__clang_openmp_device_functions.h"