[OpenMP] Fix passing target id features to AMDGPU offloading (#94765)

Summary:
AMDGPU supports a `target-id` feature which is used to qualify targets
with different incompatible features. These are both rules and target
features. Currently, we pass `-target-cpu` twice when offloading to
OpenMP, and do not pass the target-id features at all. The effect was
that passing something like `--offload-arch=gfx90a:xnack+` would show up
as `-target-cpu=gfx90a:xnack+ -target-cpu=gfx90a`. Thus ignoring the
xnack completely and passing it twice. This patch fixes that to pass it
once and then separate it like how HIP does.

Author: jhuber6

clang/lib/Driver/ToolChains/AMDGPU.cpp

@@ -645,7 +645,11 @@ void amdgpu::getAMDGPUTargetFeatures(const Driver &D,
                                      std::vector<StringRef> &Features) {
   // Add target ID features to -target-feature options. No diagnostics should
   // be emitted here since invalid target ID is diagnosed at other places.
-  StringRef TargetID = Args.getLastArgValue(options::OPT_mcpu_EQ);
+  StringRef TargetID;
+  if (Args.hasArg(options::OPT_mcpu_EQ))
+    TargetID = Args.getLastArgValue(options::OPT_mcpu_EQ);
+  else if (Args.hasArg(options::OPT_march_EQ))
+    TargetID = Args.getLastArgValue(options::OPT_march_EQ);
   if (!TargetID.empty()) {
     llvm::StringMap<bool> FeatureMap;
     auto OptionalGpuArch = parseTargetID(Triple, TargetID, &FeatureMap);

clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp

@@ -44,14 +44,9 @@ void AMDGPUOpenMPToolChain::addClangTargetOptions(
     Action::OffloadKind DeviceOffloadingKind) const {
   HostTC.addClangTargetOptions(DriverArgs, CC1Args, DeviceOffloadingKind);
 
-  StringRef GPUArch = DriverArgs.getLastArgValue(options::OPT_march_EQ);
-  assert(!GPUArch.empty() && "Must have an explicit GPU arch.");
-
   assert(DeviceOffloadingKind == Action::OFK_OpenMP &&
          "Only OpenMP offloading kinds are supported.");
 
-  CC1Args.push_back("-target-cpu");
-  CC1Args.push_back(DriverArgs.MakeArgStringRef(GPUArch));
   CC1Args.push_back("-fcuda-is-device");
 
   if (DriverArgs.hasArg(options::OPT_nogpulib))

clang/test/Driver/amdgpu-openmp-toolchain.c

@@ -7,7 +7,7 @@
 
 // verify the tools invocations
 // CHECK: "-cc1" "-triple" "x86_64-unknown-linux-gnu"{{.*}}"-emit-llvm-bc"{{.*}}"-x" "c"
-// CHECK: "-cc1" "-triple" "amdgcn-amd-amdhsa" "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}}"-target-cpu" "gfx906"{{.*}}"-fcuda-is-device"{{.*}}
+// CHECK: "-cc1" "-triple" "amdgcn-amd-amdhsa" "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}}"-fcuda-is-device"{{.*}}"-target-cpu" "gfx906"
 // CHECK: "-cc1" "-triple" "x86_64-unknown-linux-gnu"{{.*}}"-emit-obj"
 // CHECK: clang-linker-wrapper{{.*}} "-o" "a.out"
 
@@ -63,6 +63,7 @@
 
 // RUN: %clang -### -target x86_64-pc-linux-gnu -fopenmp --offload-arch=gfx90a:sramecc-:xnack+ \
 // RUN:   -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-TARGET-ID
+// CHECK-TARGET-ID: "-cc1" "-triple" "amdgcn-amd-amdhsa" {{.*}} "-target-cpu" "gfx90a" "-target-feature" "-sramecc" "-target-feature" "+xnack"
 // CHECK-TARGET-ID: clang-offload-packager{{.*}}arch=gfx90a:sramecc-:xnack+,kind=openmp,feature=-sramecc,feature=+xnack
 
 // RUN: not %clang -### -target x86_64-pc-linux-gnu -fopenmp --offload-arch=gfx90a,gfx90a:xnack+ \