Elaborate more on --rocm-path flag.

[arsenm]

Summary

I'm not sure what the conventions are for this documentation. The
format seems limiting. I don't see how to refer to other flags, or
mark flags as deprecated. The rst I believe these generate seems to be
in source, and out of date.

[yaxunl]

clang/include/clang/Driver/Options.td

612

we also want to use this for adding include and library path for HIP.

[arsenm]

clang/include/clang/Driver/Options.td

612

It doesn't actually do that yet though

[arsenm]

684dc1bebe5cb70cfd27923940f9f8cba4f13195

clang/include/clang/Driver/Options.td

def fgpu_rdc : Flag<["-"], "fgpu-rdc">, Flags<[CC1Option]>,
   HelpText<"Generate relocatable device code, also known as separate compilation mode.">;
 def fno_gpu_rdc : Flag<["-"], "fno-gpu-rdc">;
 def : Flag<["-"], "fcuda-rdc">, Alias<fgpu_rdc>;
 def : Flag<["-"], "fno-cuda-rdc">, Alias<fno_gpu_rdc>;
 def fcuda_short_ptr : Flag<["-"], "fcuda-short-ptr">, Flags<[CC1Option]>,
   HelpText<"Use 32-bit pointers for accessing const/local/shared address spaces.">;
 def fno_cuda_short_ptr : Flag<["-"], "fno-cuda-short-ptr">;
 def rocm_path_EQ : Joined<["--"], "rocm-path=">, Group<i_Group>,
-  HelpText<"ROCm installation path">;
+  HelpText<"ROCm installation path, used for finding and automatically linking required bitcode libraries.">;
 def hip_device_lib_path_EQ : Joined<["--"], "hip-device-lib-path=">, Group<Link_Group>,
-  HelpText<"HIP device library path">;
+  HelpText<"HIP device library path. Alternative to rocm-path.">;
 def hip_device_lib_EQ : Joined<["--"], "hip-device-lib=">, Group<Link_Group>,
   HelpText<"HIP device library">;
 def fhip_dump_offload_linker_script : Flag<["-"], "fhip-dump-offload-linker-script">,
   Group<f_Group>, Flags<[NoArgumentUnused, HelpHidden]>;
 def fhip_new_launch_api : Flag<["-"], "fhip-new-launch-api">,
   Flags<[CC1Option]>, HelpText<"Use new kernel launching API for HIP.">;
 def fno_hip_new_launch_api : Flag<["-"], "fno-hip-new-launch-api">;
 def fgpu_allow_device_init : Flag<["-"], "fgpu-allow-device-init">,