[Flang][Driver] Introduce -fopenmp-targets offloading option

clang/include/clang/Driver/Options.td

@@ -3532,7 +3532,7 @@ def fopenmp_use_tls : Flag<["-"], "fopenmp-use-tls">, Group<f_Group>,
 def fnoopenmp_use_tls : Flag<["-"], "fnoopenmp-use-tls">, Group<f_Group>,
   Flags<[NoArgumentUnused, HelpHidden]>, Visibility<[ClangOption, CC1Option]>;
 def fopenmp_targets_EQ : CommaJoined<["-"], "fopenmp-targets=">,
-  Flags<[NoXarchOption]>, Visibility<[ClangOption, CC1Option, FlangOption]>,
+  Flags<[NoXarchOption]>, Visibility<[ClangOption, CC1Option, FlangOption, FC1Option]>,
   HelpText<"Specify comma-separated list of triples OpenMP offloading targets to be supported">;
 def fopenmp_relocatable_target : Flag<["-"], "fopenmp-relocatable-target">,
   Group<f_Group>, Flags<[NoArgumentUnused, HelpHidden]>,

clang/lib/Driver/ToolChains/Clang.cpp

@@ -7789,17 +7789,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                        options::OPT_mno_amdgpu_ieee);
   }
 
-  // For all the host OpenMP offloading compile jobs we need to pass the targets
-  // information using -fopenmp-targets= option.
-  if (JA.isHostOffloading(Action::OFK_OpenMP)) {
-    SmallString<128> Targets("-fopenmp-targets=");
-
-    SmallVector<std::string, 4> Triples;
-    auto TCRange = C.getOffloadToolChains<Action::OFK_OpenMP>();
-    std::transform(TCRange.first, TCRange.second, std::back_inserter(Triples),
-                   [](auto TC) { return TC.second->getTripleString(); });
-    CmdArgs.push_back(Args.MakeArgString(Targets + llvm::join(Triples, ",")));
-  }
+  addOpenMPHostOffloadingArgs(C, JA, Args, CmdArgs);
 
   bool VirtualFunctionElimination =
       Args.hasFlag(options::OPT_fvirtual_function_elimination,

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -1244,6 +1244,25 @@ bool tools::addOpenMPRuntime(const Compilation &C, ArgStringList &CmdArgs,
   return true;
 }
 
+void tools::addOpenMPHostOffloadingArgs(const Compilation &C,
+                                        const JobAction &JA,
+                                        const llvm::opt::ArgList &Args,
+                                        llvm::opt::ArgStringList &CmdArgs) {
+  if (!JA.isHostOffloading(Action::OFK_OpenMP))
+    return;
+
+  // For all the host OpenMP offloading compile jobs we need to pass the targets
+  // information using -fopenmp-targets= option.
+  constexpr llvm::StringLiteral Targets("-fopenmp-targets=");
+
+  SmallVector<std::string> Triples;
+  auto TCRange = C.getOffloadToolChains<Action::OFK_OpenMP>();
+  std::transform(TCRange.first, TCRange.second, std::back_inserter(Triples),
+                 [](auto TC) { return TC.second->getTripleString(); });
+  CmdArgs.push_back(
+      Args.MakeArgString(Twine(Targets) + llvm::join(Triples, ",")));
+}
+
 /// Add Fortran runtime libs
 void tools::addFortranRuntimeLibs(const ToolChain &TC, const ArgList &Args,
                                   llvm::opt::ArgStringList &CmdArgs) {

clang/lib/Driver/ToolChains/CommonArgs.h

@@ -119,6 +119,11 @@ bool addOpenMPRuntime(const Compilation &C, llvm::opt::ArgStringList &CmdArgs,
                       bool ForceStaticHostRuntime = false,
                       bool IsOffloadingHost = false, bool GompNeedsRT = false);
 
+/// Adds offloading options for OpenMP host compilation to \p CmdArgs.
+void addOpenMPHostOffloadingArgs(const Compilation &C, const JobAction &JA,
+                                 const llvm::opt::ArgList &Args,
+                                 llvm::opt::ArgStringList &CmdArgs);
+
 /// Adds Fortran runtime libraries to \p CmdArgs.
 void addFortranRuntimeLibs(const ToolChain &TC, const llvm::opt::ArgList &Args,
                            llvm::opt::ArgStringList &CmdArgs);

clang/lib/Driver/ToolChains/Flang.cpp

@@ -495,6 +495,8 @@ void Flang::addOffloadOptions(Compilation &C, const InputInfoList &Inputs,
     if (Args.hasArg(options::OPT_nogpulib))
       CmdArgs.push_back("-nogpulib");
   }
+
+  addOpenMPHostOffloadingArgs(C, JA, Args, CmdArgs);
 }
 
 static void addFloatingPointOptions(const Driver &D, const ArgList &Args,

flang/test/Driver/omp-driver-offload.f90

@@ -207,3 +207,21 @@
 ! RUN:   | FileCheck --check-prefix=MLINK-BUILTIN-BITCODE  %s
 ! MLINK-BUILTIN-BITCODE:      "{{[^"]*}}flang-new" "-fc1" "-triple" "amdgcn-amd-amdhsa"
 ! MLINK-BUILTIN-BITCODE-SAME: "-mlink-builtin-bitcode" {{.*Inputs.*rocm.*amdgcn.*bitcode.*}}oclc_isa_version_900.bc
+
+! Test that the -fopenmp-targets option is added to host compilation invocations
+! when --offload-arch or -fopenmp-targets are set.
+! RUN: %flang -S -### %s -o %t 2>&1 \
+! RUN: -fopenmp --offload-arch=gfx90a \
+! RUN: --target=x86_64-unknown-linux-gnu -nogpulib \
+! RUN: | FileCheck %s --check-prefix=OFFLOAD-TARGETS
+! RUN: %flang -S -### %s -o %t 2>&1 \
+! RUN: -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa --offload-arch=gfx90a \
+! RUN: --target=x86_64-unknown-linux-gnu -nogpulib \
+! RUN: | FileCheck %s --check-prefix=OFFLOAD-TARGETS
+
+! OFFLOAD-TARGETS: "{{[^"]*}}flang-new" "-fc1" "-triple" "x86_64-unknown-linux-gnu"
+! OFFLOAD-TARGETS-SAME: "-fopenmp-targets=amdgcn-amd-amdhsa"
+! OFFLOAD-TARGETS-NEXT: "{{[^"]*}}flang-new" "-fc1" "-triple" "amdgcn-amd-amdhsa"
+! OFFLOAD-TARGETS-NOT: -fopenmp-targets
+! OFFLOAD-TARGETS: "{{[^"]*}}flang-new" "-fc1" "-triple" "x86_64-unknown-linux-gnu"
+! OFFLOAD-TARGETS-SAME: "-fopenmp-targets=amdgcn-amd-amdhsa"