[Clang] Append target search paths for direct offloading compilation (#82699)

Summary:
Recent changes to the `libc` project caused the headers to be installed
to `include/<triple>` for the GPU and the libraries to be in
`lib/<triple>`. This means we should automatically append these search
paths so they can be found by default. This allows the following to work
targeting AMDGPU.

```shell
$ clang foo.c -flto -mcpu=native --target=amdgcn-amd-amdhsa -lc <install>/lib/amdgcn-amd-amdhsa/crt1.o
$ amdhsa-loader a.out
```

Author: jhuber6

clang/lib/Driver/ToolChains/AMDGPU.cpp

@@ -625,6 +625,7 @@ void amdgpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   addLinkerCompressDebugSectionsOption(getToolChain(), Args, CmdArgs);
   Args.AddAllArgs(CmdArgs, options::OPT_L);
+  getToolChain().AddFilePathLibArgs(Args, CmdArgs);
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);
   if (C.getDriver().isUsingLTO())
     addLTOOptions(getToolChain(), Args, CmdArgs, Output, Inputs[0],

clang/lib/Driver/ToolChains/Clang.cpp

@@ -1111,8 +1111,8 @@ void Clang::AddPreprocessingOptions(Compilation &C, const JobAction &JA,
         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");
+      llvm::sys::path::append(P, getToolChain().getTripleString());
+      CmdArgs.push_back("-internal-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

clang/lib/Driver/ToolChains/Cuda.cpp

@@ -609,6 +609,10 @@ void NVPTX::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   // Add paths specified in LIBRARY_PATH environment variable as -L options.
   addDirectoryList(Args, CmdArgs, "-L", "LIBRARY_PATH");
 
+  // Add standard library search paths passed on the command line.
+  Args.AddAllArgs(CmdArgs, options::OPT_L);
+  getToolChain().AddFilePathLibArgs(Args, CmdArgs);
+
   // Add paths for the default clang library path.
   SmallString<256> DefaultLibPath =
       llvm::sys::path::parent_path(TC.getDriver().Dir);

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

@@ -10,10 +10,17 @@
 // 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=gfx90a --sysroot=./ \
+// RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-AMDGPU
+// RUN:   %clang -### --target=nvptx64-nvidia-cuda -march=sm_89 --sysroot=./ \
+// RUN:     -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-HEADERS-NVPTX
+// CHECK-HEADERS-AMDGPU: "-cc1"{{.*}}"-internal-isystem" "{{.*}}include{{.*}}amdgcn-amd-amdhsa"{{.*}}"-isysroot" "./"
+// CHECK-HEADERS-NVPTX: "-cc1"{{.*}}"-internal-isystem" "{{.*}}include{{.*}}nvptx64-nvidia-cuda"{{.*}}"-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"
+// CHECK-HEADERS-DISABLED-NOT: "-cc1"{{.*}}"-internal-isystem" "{{.*}}include{{.*}}gpu-none-llvm"