Revert "[OpenMP] Introduce -fopenmp-force-usm flag"

This reverts commit 4ecd07d786a5a994b33b9177d4e21d839bfe3fc9.

To test the other solution.

Author: jplehr

clang/include/clang/Driver/Options.td

@@ -3381,8 +3381,6 @@ def fopenmp_cuda_blocks_per_sm_EQ : Joined<["-"], "fopenmp-cuda-blocks-per-sm=">
   Flags<[NoArgumentUnused, HelpHidden]>, Visibility<[ClangOption, CC1Option]>;
 def fopenmp_cuda_teams_reduction_recs_num_EQ : Joined<["-"], "fopenmp-cuda-teams-reduction-recs-num=">, Group<f_Group>,
   Flags<[NoArgumentUnused, HelpHidden]>, Visibility<[ClangOption, CC1Option]>;
-def fopenmp_force_usm : Flag<["-"], "fopenmp-force-usm">, Group<f_Group>,
-  Flags<[NoArgumentUnused, HelpHidden]>, Visibility<[ClangOption, CC1Option]>;
 
 //===----------------------------------------------------------------------===//
 // Shared cc1 + fc1 OpenMP Target Options

clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp

@@ -129,22 +129,6 @@ AMDGPUOpenMPToolChain::GetCXXStdlibType(const ArgList &Args) const {
 void AMDGPUOpenMPToolChain::AddClangSystemIncludeArgs(
     const ArgList &DriverArgs, ArgStringList &CC1Args) const {
   HostTC.AddClangSystemIncludeArgs(DriverArgs, CC1Args);
-
-  CC1Args.push_back("-internal-isystem");
-  SmallString<128> P(HostTC.getDriver().ResourceDir);
-  llvm::sys::path::append(P, "include/cuda_wrappers");
-  CC1Args.push_back(DriverArgs.MakeArgString(P));
-
-  // Force USM mode will forcefully include #pragma omp requires
-  // unified_shared_memory via the force_usm header
-  // XXX This may result in a compilation error if the source
-  // file already includes that pragma.
-  if (DriverArgs.hasArg(options::OPT_fopenmp_force_usm)) {
-    CC1Args.push_back("-include");
-    CC1Args.push_back(
-        DriverArgs.MakeArgString(HostTC.getDriver().ResourceDir +
-                                 "/include/openmp_wrappers/force_usm.h"));
-  }
 }
 
 void AMDGPUOpenMPToolChain::AddIAMCUIncludeArgs(const ArgList &Args,

clang/lib/Headers/CMakeLists.txt

@@ -320,7 +320,6 @@ set(openmp_wrapper_files
   openmp_wrappers/__clang_openmp_device_functions.h
   openmp_wrappers/complex_cmath.h
   openmp_wrappers/new
-  openmp_wrappers/usm/force_usm.h
 )
 
 set(llvm_libc_wrapper_files