[Flang][Driver] Handle target CPU and features

[mnadeem]

Summary

This patch:

• Adds target-feature and target-cpu to FC1Options.
• Moves getTargetFeatures() from Clang.cpp to CommonArgs.cpp.
• Processes target cpu and features in the flang driver. Right now features are only added for AArch64/x86 because I only did basic testing on them but it should generally work for others as well. Option handling is similar to clang.
• Adds appropriate structures in TargetOptions and passes them to the target machine.

What's missing:

• Adding the CPU info and the features as attributes in the LLVM IR module.
• Processing target specific flags, e.g. SVE vector bits for AArch64, ABI etc.

[kiranchandramohan]

Thanks @mnadeem for this patch. A few minor comments first. Try to replace auto in all places except where the type is on the RHS.

We might need -fc1 tests as well.

clang/lib/Driver/ToolChains/Flang.cpp

85

Nit: leftover code?

86

Nit: replace auto.

99

I get a segfault in Fortran::frontend::CodeGenAction::setUpTargetMachine() currently when using ./bin/flang-new --target=x86_64-linux-gnu file.f90

flang/lib/Frontend/CompilerInvocation.cpp

179

Nit: Can you remove the auto here?

flang/lib/Frontend/FrontendActions.cpp

594

Nit: Can you remove the auto here?

[awarzynski]

Thanks for implementing this!

Processes target cpu and features in the flang driver. Right now features are only added for AArch64 because I only did basic testing on AArch64 but it should generally work for others as well.

X86 is a very popular target and we have pre-commit CI as well. And X86 buildbots :) Please include X86.

Question: are the option semantics identical that what you get in clang -cc1? If yes, could you add a comment in the summary?

[mnadeem]

In D137995#3944145, @awarzynski wrote:

Thanks for implementing this!

Processes target cpu and features in the flang driver. Right now features are only added for AArch64 because I only did basic testing on AArch64 but it should generally work for others as well.

X86 is a very popular target and we have pre-commit CI as well. And X86 buildbots :) Please include X86.

Question: are the option semantics identical that what you get in clang -cc1? If yes, could you add a comment in the summary?

Included x86 and added a comment in the summary.

[mnadeem]

In D137995#3931005, @kiranchandramohan wrote:

We might need -fc1 tests as well.

What kind of tests do you think would be appropriate here? Can you point me to any examples, maybe from clang?

[mnadeem]

clang/lib/Driver/ToolChains/Flang.cpp

99

I am unable to reproduce this, do you have your toolchain built for x86 target as well?

[mnadeem]

clang/lib/Driver/ToolChains/Flang.cpp

99

It might be unrelated to this patch.

[awarzynski]

Thanks for all the updates @mnadeem! Mostly looks good. A few more nits, but nothing substantial :)

In D137995#3958824, @mnadeem wrote:

In D137995#3931005, @kiranchandramohan wrote:

We might need -fc1 tests as well.

What kind of tests do you think would be appropriate here? Can you point me to any examples, maybe from clang?

I didn't see any tests in Clang specifically for the frontend driver flags taht are added here (i.e. -target-cpu` and -target-feature). However, you could add a test for situations like this: -target-cpu=my-imaginary-cpu and -target-fature=my-amazing-non-existent-feature.

clang/lib/Driver/ToolChains/Flang.cpp

98

[nit] I don't think that this comment contributes much. To me it is self-explanatory that only the triples that are actually present here are tested. Having said that, I don't mind keeping it here.

100

nit

flang/include/flang/Frontend/TargetOptions.h

25–30

I think that we can trim this now. WDYT?

flang/test/Driver/target-cpu-features.f90

26–27

1. By adding -fc1 you make it clear that it's the frontend driver invocation that's being tested.
2. CHECK-SAME makes sure the triple is matched with the right set of features.

[mnadeem]

• Address comments.
• Add fc1 tests.

[awarzynski]

LGTM, thank you!

clang/include/clang/Driver/Options.td

 } // let Flags = [FC1Option, FlangOnlyOption]
 
 //===----------------------------------------------------------------------===//
 // Target Options (cc1 + cc1as)
 //===----------------------------------------------------------------------===//
 
 let Flags = [CC1Option, CC1AsOption, NoDriverOption] in {
 
-def target_cpu : Separate<["-"], "target-cpu">,
-  HelpText<"Target a specific cpu type">,
-  MarshallingInfoString<TargetOpts<"CPU">>;
 def tune_cpu : Separate<["-"], "tune-cpu">,
   HelpText<"Tune for a specific cpu type">,
   MarshallingInfoString<TargetOpts<"TuneCPU">>;
-def target_feature : Separate<["-"], "target-feature">,
-  HelpText<"Target specific attributes">,
-  MarshallingInfoStringVector<TargetOpts<"FeaturesAsWritten">>;
 def target_abi : Separate<["-"], "target-abi">,
   HelpText<"Target a particular ABI type">,
   MarshallingInfoString<TargetOpts<"ABI">>;
 def target_sdk_version_EQ : Joined<["-"], "target-sdk-version=">,
   HelpText<"The version of target SDK used for compilation">;
 def darwin_target_variant_sdk_version_EQ : Joined<["-"],
   "darwin-target-variant-sdk-version=">,
   HelpText<"The version of darwin target variant SDK used for compilation">;

 } // let Flags = [CC1Option, CC1AsOption]
 
 //===----------------------------------------------------------------------===//
 // Target Options (cc1 + cc1as + fc1)
 //===----------------------------------------------------------------------===//
 
 let Flags = [CC1Option, CC1AsOption, FC1Option, NoDriverOption] in {
 
+def target_cpu : Separate<["-"], "target-cpu">,
+  HelpText<"Target a specific cpu type">,
+  MarshallingInfoString<TargetOpts<"CPU">>;
+def target_feature : Separate<["-"], "target-feature">,
+  HelpText<"Target specific attributes">,
+  MarshallingInfoStringVector<TargetOpts<"FeaturesAsWritten">>;
 def triple : Separate<["-"], "triple">,
   HelpText<"Specify target triple (e.g. i686-apple-darwin9)">,
   MarshallingInfoString<TargetOpts<"Triple">, "llvm::Triple::normalize(llvm::sys::getDefaultTargetTriple())">,
   AlwaysEmit, Normalizer<"normalizeTriple">;
 
 } // let Flags = [CC1Option, CC1ASOption, FC1Option, NoDriverOption]
 
 //===----------------------------------------------------------------------===//

clang/lib/Driver/ToolChains/Clang.cpp

if (Value == "none") {
     if (Value.getAsInteger(10, Width)) {
       D.Diag(diag::err_drv_invalid_value) << A->getOption().getName() << Value;
       return;
     }
     CmdArgs.push_back(Args.MakeArgString("-mprefer-vector-width=" + Value));
   }
 }
 
-static void getWebAssemblyTargetFeatures(const ArgList &Args,
-                                         std::vector<StringRef> &Features) {
-  handleTargetFeaturesGroup(Args, Features, options::OPT_m_wasm_Features_Group);
-}
-
-static void getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
-                              const ArgList &Args, ArgStringList &CmdArgs,
-                              bool ForAS, bool IsAux = false) {
-  std::vector<StringRef> Features;
-  switch (Triple.getArch()) {
-  default:
-    break;
-  case llvm::Triple::mips:
-  case llvm::Triple::mipsel:
-  case llvm::Triple::mips64:
-  case llvm::Triple::mips64el:
-    mips::getMIPSTargetFeatures(D, Triple, Args, Features);
-    break;
-
-  case llvm::Triple::arm:
-  case llvm::Triple::armeb:
-  case llvm::Triple::thumb:
-  case llvm::Triple::thumbeb:
-    arm::getARMTargetFeatures(D, Triple, Args, Features, ForAS);
-    break;
-
-  case llvm::Triple::ppc:
-  case llvm::Triple::ppcle:
-  case llvm::Triple::ppc64:
-  case llvm::Triple::ppc64le:
-    ppc::getPPCTargetFeatures(D, Triple, Args, Features);
-    break;
-  case llvm::Triple::riscv32:
-  case llvm::Triple::riscv64:
-    riscv::getRISCVTargetFeatures(D, Triple, Args, Features);
-    break;
-  case llvm::Triple::systemz:
-    systemz::getSystemZTargetFeatures(D, Args, Features);
-    break;
-  case llvm::Triple::aarch64:
-  case llvm::Triple::aarch64_32:
-  case llvm::Triple::aarch64_be:
-    aarch64::getAArch64TargetFeatures(D, Triple, Args, Features, ForAS);
-    break;
-  case llvm::Triple::x86:
-  case llvm::Triple::x86_64:
-    x86::getX86TargetFeatures(D, Triple, Args, Features);
-    break;
-  case llvm::Triple::hexagon:
-    hexagon::getHexagonTargetFeatures(D, Args, Features);
-    break;
-  case llvm::Triple::wasm32:
-  case llvm::Triple::wasm64:
-    getWebAssemblyTargetFeatures(Args, Features);
-    break;
-  case llvm::Triple::sparc:
-  case llvm::Triple::sparcel:
-  case llvm::Triple::sparcv9:
-    sparc::getSparcTargetFeatures(D, Args, Features);
-    break;
-  case llvm::Triple::r600:
-  case llvm::Triple::amdgcn:
-    amdgpu::getAMDGPUTargetFeatures(D, Triple, Args, Features);
-    break;
-  case llvm::Triple::nvptx:
-  case llvm::Triple::nvptx64:
-    NVPTX::getNVPTXTargetFeatures(D, Triple, Args, Features);
-    break;
-  case llvm::Triple::m68k:
-    m68k::getM68kTargetFeatures(D, Triple, Args, Features);
-    break;
-  case llvm::Triple::msp430:
-    msp430::getMSP430TargetFeatures(D, Args, Features);
-    break;
-  case llvm::Triple::ve:
-    ve::getVETargetFeatures(D, Args, Features);
-    break;
-  case llvm::Triple::csky:
-    csky::getCSKYTargetFeatures(D, Triple, Args, CmdArgs, Features);
-    break;
-  case llvm::Triple::loongarch32:
-  case llvm::Triple::loongarch64:
-    loongarch::getLoongArchTargetFeatures(D, Triple, Args, Features);
-    break;
-  }
-
-  for (auto Feature : unifyTargetFeatures(Features)) {
-    CmdArgs.push_back(IsAux ? "-aux-target-feature" : "-target-feature");
-    CmdArgs.push_back(Feature.data());
-  }
-}
-
 static bool
 shouldUseExceptionTablesForObjCExceptions(const ObjCRuntime &runtime,
                                           const llvm::Triple &Triple) {
   // We use the zero-cost exception tables for Objective-C if the non-fragile
   // ABI is enabled or when compiling for x86_64 and ARM on Snow Leopard and
   // later.
   if (runtime.isNonFragile())
     return true;

clang/lib/Driver/ToolChains/CommonArgs.h

 void AddTargetFeature(const llvm::opt::ArgList &Args,
                       std::vector<StringRef> &Features,
                       llvm::opt::OptSpecifier OnOpt,
                       llvm::opt::OptSpecifier OffOpt, StringRef FeatureName);
 
 std::string getCPUName(const Driver &D, const llvm::opt::ArgList &Args,
                        const llvm::Triple &T, bool FromAs = false);
 
+void getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
+                       const llvm::opt::ArgList &Args,
+                       llvm::opt::ArgStringList &CmdArgs, bool ForAS,
+                       bool IsAux = false);
+
 /// Iterate \p Args and convert -mxxx to +xxx and -mno-xxx to -xxx and
 /// append it to \p Features.
 ///
 /// Note: Since \p Features may contain default values before calling
 /// this function, or may be appended with entries to override arguments,
 /// entries in \p Features are not unique.
 void handleTargetFeaturesGroup(const llvm::opt::ArgList &Args,
                                std::vector<StringRef> &Features,

clang/lib/Driver/ToolChains/CommonArgs.cpp

 //===--- CommonArgs.cpp - Args handling for multiple toolchains -*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "CommonArgs.h"
 #include "Arch/AArch64.h"
 #include "Arch/ARM.h"
+#include "Arch/CSKY.h"
+#include "Arch/LoongArch.h"
 #include "Arch/M68k.h"
 #include "Arch/Mips.h"
 #include "Arch/PPC.h"
 #include "Arch/RISCV.h"
 #include "Arch/Sparc.h"
 #include "Arch/SystemZ.h"
 #include "Arch/VE.h"
 #include "Arch/X86.h"
 #include "HIPAMD.h"
 #include "Hexagon.h"
+#include "MSP430.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/ObjCRuntime.h"
 #include "clang/Basic/Version.h"
 #include "clang/Config/config.h"
 #include "clang/Driver/Action.h"
 #include "clang/Driver/Compilation.h"
 #include "clang/Driver/Driver.h"
case llvm::Triple::amdgcn:
     return getAMDGPUTargetGPU(T, Args);
 
   case llvm::Triple::wasm32:
   case llvm::Triple::wasm64:
     return std::string(getWebAssemblyTargetCPU(Args));
   }
 }
 
+static void getWebAssemblyTargetFeatures(const ArgList &Args,
+                                         std::vector<StringRef> &Features) {
+  handleTargetFeaturesGroup(Args, Features, options::OPT_m_wasm_Features_Group);
+}
+
+void tools::getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
+                              const ArgList &Args, ArgStringList &CmdArgs,
+                              bool ForAS, bool IsAux) {
+  std::vector<StringRef> Features;
+  switch (Triple.getArch()) {
+  default:
+    break;
+  case llvm::Triple::mips:
+  case llvm::Triple::mipsel:
+  case llvm::Triple::mips64:
+  case llvm::Triple::mips64el:
+    mips::getMIPSTargetFeatures(D, Triple, Args, Features);
+    break;
+  case llvm::Triple::arm:
+  case llvm::Triple::armeb:
+  case llvm::Triple::thumb:
+  case llvm::Triple::thumbeb:
+    arm::getARMTargetFeatures(D, Triple, Args, Features, ForAS);
+    break;
+  case llvm::Triple::ppc:
+  case llvm::Triple::ppcle:
+  case llvm::Triple::ppc64:
+  case llvm::Triple::ppc64le:
+    ppc::getPPCTargetFeatures(D, Triple, Args, Features);
+    break;
+  case llvm::Triple::riscv32:
+  case llvm::Triple::riscv64:
+    riscv::getRISCVTargetFeatures(D, Triple, Args, Features);
+    break;
+  case llvm::Triple::systemz:
+    systemz::getSystemZTargetFeatures(D, Args, Features);
+    break;
+  case llvm::Triple::aarch64:
+  case llvm::Triple::aarch64_32:
+  case llvm::Triple::aarch64_be:
+    aarch64::getAArch64TargetFeatures(D, Triple, Args, Features, ForAS);
+    break;
+  case llvm::Triple::x86:
+  case llvm::Triple::x86_64:
+    x86::getX86TargetFeatures(D, Triple, Args, Features);
+    break;
+  case llvm::Triple::hexagon:
+    hexagon::getHexagonTargetFeatures(D, Args, Features);
+    break;
+  case llvm::Triple::wasm32:
+  case llvm::Triple::wasm64:
+    getWebAssemblyTargetFeatures(Args, Features);
+    break;
+  case llvm::Triple::sparc:
+  case llvm::Triple::sparcel:
+  case llvm::Triple::sparcv9:
+    sparc::getSparcTargetFeatures(D, Args, Features);
+    break;
+  case llvm::Triple::r600:
+  case llvm::Triple::amdgcn:
+    amdgpu::getAMDGPUTargetFeatures(D, Triple, Args, Features);
+    break;
+  case llvm::Triple::nvptx:
+  case llvm::Triple::nvptx64:
+    NVPTX::getNVPTXTargetFeatures(D, Triple, Args, Features);
+    break;
+  case llvm::Triple::m68k:
+    m68k::getM68kTargetFeatures(D, Triple, Args, Features);
+    break;
+  case llvm::Triple::msp430:
+    msp430::getMSP430TargetFeatures(D, Args, Features);
+    break;
+  case llvm::Triple::ve:
+    ve::getVETargetFeatures(D, Args, Features);
+    break;
+  case llvm::Triple::csky:
+    csky::getCSKYTargetFeatures(D, Triple, Args, CmdArgs, Features);
+    break;
+  case llvm::Triple::loongarch32:
+  case llvm::Triple::loongarch64:
+    loongarch::getLoongArchTargetFeatures(D, Triple, Args, Features);
+    break;
+  }
+
+  for (auto Feature : unifyTargetFeatures(Features)) {
+    CmdArgs.push_back(IsAux ? "-aux-target-feature" : "-target-feature");
+    CmdArgs.push_back(Feature.data());
+  }
+}
+
 llvm::StringRef tools::getLTOParallelism(const ArgList &Args, const Driver &D) {
   Arg *LtoJobsArg = Args.getLastArg(options::OPT_flto_jobs_EQ);
   if (!LtoJobsArg)
     return {};
   if (!llvm::get_threadpool_strategy(LtoJobsArg->getValue()))
     D.Diag(diag::err_drv_invalid_int_value)
         << LtoJobsArg->getAsString(Args) << LtoJobsArg->getValue();
   return LtoJobsArg->getValue();

clang/lib/Driver/ToolChains/Flang.h

private:
   /// Extract PIC options from the driver arguments and add them to
   /// the command arguments.
   ///
   /// \param [in] Args The list of input driver arguments
   /// \param [out] CmdArgs The list of output command arguments
   void addPicOptions(const llvm::opt::ArgList &Args,
                      llvm::opt::ArgStringList &CmdArgs) const;
 
+  /// Extract target options from the driver arguments and add them to
+  /// the command arguments.
+  ///
+  /// \param [in] Args The list of input driver arguments
+  /// \param [out] CmdArgs The list of output command arguments
+  void addTargetOptions(const llvm::opt::ArgList &Args,
+                        llvm::opt::ArgStringList &CmdArgs) const;
+
   /// Extract other compilation options from the driver arguments and add them
   /// to the command arguments.
   ///
   /// \param [in] Args The list of input driver arguments
   /// \param [out] CmdArgs The list of output command arguments
   void addOtherOptions(const llvm::opt::ArgList &Args,
                        llvm::opt::ArgStringList &CmdArgs) const;
 

clang/lib/Driver/ToolChains/Flang.cpp

void Flang::addPicOptions(const ArgList &Args, ArgStringList &CmdArgs) const {
   if (PICLevel > 0) {
     CmdArgs.push_back("-pic-level");
     CmdArgs.push_back(PICLevel == 1 ? "1" : "2");
     if (IsPIE)
       CmdArgs.push_back("-pic-is-pie");
   }
 }
 
+void Flang::addTargetOptions(const ArgList &Args,
+                             ArgStringList &CmdArgs) const {
+  // return;
+  const auto &TC = getToolChain();
+  const llvm::Triple &Triple = TC.getEffectiveTriple();
+  const Driver &D = TC.getDriver();
+
+  std::string CPU = getCPUName(D, Args, Triple);
+  if (!CPU.empty()) {
+    CmdArgs.push_back("-target-cpu");
+    CmdArgs.push_back(Args.MakeArgString(CPU));
+  }
+
+  // Add the target features.
+  switch (TC.getArch()) {
+  default:
+    // Untested for other targets but should work generally.
+    break;
+  case llvm::Triple::aarch64:
+    getTargetFeatures(D, Triple, Args, CmdArgs, /*ForAs*/ false);
+    break;
+  }
+
+  // TODO: Add target specific flags, ABI, mtune option etc.
+}
+
 static void addFloatingPointOptions(const Driver &D, const ArgList &Args,
                                     ArgStringList &CmdArgs) {
   StringRef FPContract;
   bool HonorINFs = true;
   bool HonorNaNs = true;
   bool ApproxFunc = false;
   bool SignedZeros = true;
   bool AssociativeMath = false;
if (D.getDiags().getDiagnosticOptions().ShowColors)
     CmdArgs.push_back("-fcolor-diagnostics");
 
   // -fPIC and related options.
   addPicOptions(Args, CmdArgs);
 
   // Floating point related options
   addFloatingPointOptions(D, Args, CmdArgs);
 
+  // Add target args, features, etc.
+  addTargetOptions(Args, CmdArgs);
+
   // Add other compile options
   addOtherOptions(Args, CmdArgs);
 
   // Forward -Xflang arguments to -fc1
   Args.AddAllArgValues(CmdArgs, options::OPT_Xflang);
 
   // Forward -mllvm options to the LLVM option parser. In practice, this means
   // forwarding to `-fc1` as that's where the LLVM parser is run.

flang/include/flang/Frontend/TargetOptions.h

 
 #ifndef FORTRAN_FRONTEND_TARGETOPTIONS_H
 #define FORTRAN_FRONTEND_TARGETOPTIONS_H
 
 #include <string>
 
 namespace Fortran::frontend {
 
 /// Options for controlling the target. Currently this is just a placeholder.
 /// In the future, we will use this to specify various target options that
 /// will affect the generated code e.g.:
 ///   * CPU to tune the code for
-///   * available CPU/hardware extensions
-///   * target specific features to enable/disable
 ///   * options for accelerators (e.g. GPUs)
 ///   * (...)
 class TargetOptions {
 public:
   /// The name of the target triple to compile for.
   std::string triple;
+
+  /// If given, the name of the target CPU to generate code for.
+  std::string cpu;
+
+  /// The list of target specific features to enable or disable, as written on
+  /// the command line.
+  std::vector<std::string> featuresAsWritten;
 };
 
 } // end namespace Fortran::frontend
 
 #endif

flang/lib/Frontend/CompilerInvocation.cpp

 /// options accordingly.
 ///
 /// \param [in] opts The target options instance to update
 /// \param [in] args The list of input arguments (from the compiler invocation)
 static void parseTargetArgs(TargetOptions &opts, llvm::opt::ArgList &args) {
   if (const llvm::opt::Arg *a =
           args.getLastArg(clang::driver::options::OPT_triple))
     opts.triple = a->getValue();
+
+  if (const llvm::opt::Arg *a =
+          args.getLastArg(clang::driver::options::OPT_target_cpu))
+    opts.cpu = a->getValue();
+
+  for (const auto *currentArg :
+       args.filtered(clang::driver::options::OPT_target_feature))
+    opts.featuresAsWritten.emplace_back(currentArg->getValue());
 }
 
 // Tweak the frontend configuration based on the frontend action
 static void setUpFrontendBasedOnAction(FrontendOptions &opts) {
   if (opts.programAction == DebugDumpParsingLog)
     opts.instrumentedParse = true;
 
   if (opts.programAction == DebugDumpProvenance ||

flang/lib/Frontend/FrontendActions.cpp

getCGOptLevel(const Fortran::frontend::CodeGenOptions &opts) {
   case 3:
     return llvm::CodeGenOpt::Aggressive;
   }
 }
 
 void CodeGenAction::setUpTargetMachine() {
   CompilerInstance &ci = this->getInstance();
 
-  const std::string &theTriple = ci.getInvocation().getTargetOpts().triple;
+  const auto &targetOpts = ci.getInvocation().getTargetOpts();
+  const std::string &theTriple = targetOpts.triple;
 
   // Create `Target`
   std::string error;
   const llvm::Target *theTarget =
       llvm::TargetRegistry::lookupTarget(theTriple, error);
   assert(theTarget && "Failed to create Target");
 
   // Create `TargetMachine`
   const auto &CGOpts = ci.getInvocation().getCodeGenOpts();
   llvm::CodeGenOpt::Level OptLevel = getCGOptLevel(CGOpts);
+  std::string featuresStr = llvm::join(targetOpts.featuresAsWritten.begin(),
+                                       targetOpts.featuresAsWritten.end(), ",");
   tm.reset(theTarget->createTargetMachine(
-      theTriple, /*CPU=*/"",
-      /*Features=*/"", llvm::TargetOptions(),
+      theTriple, /*CPU=*/targetOpts.cpu,
+      /*Features=*/featuresStr, llvm::TargetOptions(),
       /*Reloc::Model=*/CGOpts.getRelocationModel(),
       /*CodeModel::Model=*/llvm::None, OptLevel));
   assert(tm && "Failed to create TargetMachine");
 }
 
 static std::unique_ptr<llvm::raw_pwrite_stream>
 getOutputStream(CompilerInstance &ci, llvm::StringRef inFile,
                 BackendActionTy action) {

flang/test/Driver/driver-help.f90

 ! HELP-FC1-NEXT: -o <file>              Write output to <file>
 ! HELP-FC1-NEXT: -pedantic              Warn on language extensions
 ! HELP-FC1-NEXT: -pic-is-pie             File is for a position independent executable
 ! HELP-FC1-NEXT: -pic-level <value>      Value for __PIC__
 ! HELP-FC1-NEXT: -plugin <name>         Use the named plugin action instead of the default action (use "help" to list available options)
 ! HELP-FC1-NEXT: -P                     Disable linemarker output in -E mode
 ! HELP-FC1-NEXT: -std=<value>           Language standard to compile for
 ! HELP-FC1-NEXT: -S                     Only run preprocess and compilation steps
+! HELP-FC1-NEXT: -target-cpu <value>    Target a specific cpu type
+! HELP-FC1-NEXT: -target-feature <value> Target specific attributes
 ! HELP-FC1-NEXT: -test-io               Run the InputOuputTest action. Use for development and testing only.
 ! HELP-FC1-NEXT: -triple <value>        Specify target triple (e.g. i686-apple-darwin9)
 ! HELP-FC1-NEXT: -U <macro>             Undefine macro <macro>
 ! HELP-FC1-NEXT: -version               Print the compiler version
 ! HELP-FC1-NEXT: -W<warning>            Enable the specified warning
 
 ! ERROR: error: unknown argument '-helps'; did you mean '-help'

flang/test/Driver/target-cpu-features.f90

+! REQUIRES: aarch64-registered-target, x86-registered-target
+
+! Test that -mcpu is forwarded to -target-cpu and that the target features are
+! also added.
+
+! RUN: %flang --target=aarch64-linux-gnu -mcpu=cortex-a57 -emit-llvm -c %s \
+! RUN:   -o %t.o -### 2>&1 | FileCheck %s -check-prefix=CHECK-A57
+
+! RUN: %flang --target=aarch64-linux-gnu -mcpu=cortex-a76 -emit-llvm -c %s \
+! RUN:   -o %t.o -### 2>&1 | FileCheck %s -check-prefix=CHECK-A76
+
+! RUN: %flang --target=x86_64-linux-gnu -mcpu=cortex-a57 -emit-llvm -c %s \
+! RUN:   -o %t.o -### 2>&1 | FileCheck %s -check-prefix=CHECK-NO-A57
+
+! CHECK-A57: "-triple" "aarch64-unknown-linux-gnu"
+! CHECK-A57: "-target-cpu" "cortex-a57" "-target-feature" "+v8a" "-target-feature" "+crc" "-target-feature" "+crypto" "-target-feature" "+fp-armv8" "-target-feature" "+neon" "-target-feature" "+sha2" "-target-feature" "+aes"
+
+! CHECK-A76: "-triple" "aarch64-unknown-linux-gnu"
+! CHECK-A76: "-target-cpu" "cortex-a76" "-target-feature" "+v8.2a" "-target-feature" "+crc" "-target-feature" "+lse" "-target-feature" "+rdm" "-target-feature" "+crypto" "-target-feature" "+dotprod" "-target-feature" "+fp-armv8" "-target-feature" "+neon" "-target-feature" "+fullfp16" "-target-feature" "+ras" "-target-feature" "+rcpc" "-target-feature" "+ssbs" "-target-feature" "+sha2" "-target-feature" "+aes"
+
+! CHECK-NO-A57: "-fc1"
+! CHECK-NO-A57-NOT: cortex-a57