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

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.

Reviewed By: yaxunl

Differential Revision: https://reviews.llvm.org/D157438

Author: jhuber6

clang/lib/Driver/ToolChains/Clang.cpp

@@ -1183,14 +1183,13 @@ void Clang::AddPreprocessingOptions(Compilation &C, const JobAction &JA,
   // 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");

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

@@ -8,6 +8,7 @@
 // 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