[flang][driver] Add support for `--target`/`--triple`

[awarzynski]

Summary

This patch adds support for:

• --target in the compiler driver (flang-new)
• --triple in the frontend driver (flang-new -fc1)

The semantics of these flags are inherited from clangDriver, i.e.
consistent with clang --target and clang -cc1 --triple,
respectively.

A new structure is defined, TargetOptions, that will hold various
Frontend options related to the target. Currently, this is mostly a
placeholder that contains the target triple. In the future, it will be
used for storing e.g. the CPU to tune for or the target features to
enable.

Additionally, the following target/triple related options are enabled
[*]: -print-ffective-triple, -print-target-triple. Definitions in
Options.td are updated accordingly and, to facilated testing,
-emit-llvm is added to the list of options available in flang-new
(previously it was only enabled in flang-new -fc1).

• These options were actually available before (like all other options

defined in clangDriver), but not included in flang-new --help.
Before this change, flang-new would just use native for defining the
target, so these options were of little value.

[awarzynski]

Add TargetOptions.h (that I forgot to add earlier)

[rovka]

Nit: Should we also have a test for print-effective-triple?

Otherwise LGTM, although I'm not sure that -emit-llvm is necessarily something we'd want flang users to be exposed to.

flang/include/flang/Frontend/TargetOptions.h

21

[tschuett]

https://reviews.llvm.org/D117809

There was a discussion that -emit-llvm is considered a mistake.

@MaskRay

[awarzynski]

Add a test for --print-effective-triple

[awarzynski]

Thank you both for taking a look!

In D120246#3339284, @rovka wrote:

Nit: Should we also have a test for print-effective-triple?

Added.

I'm not sure that -emit-llvm is necessarily something we'd want flang users to be exposed to.

Hm, but that's what clang does and we probably want to keep flang-new and clang consistent. And we can't hide -emit-llvm without hiding it in clangas well (so HelpHidden is not really an option).

In D120246#3339289, @tschuett wrote:

https://reviews.llvm.org/D117809

There was a discussion that -emit-llvm is considered a mistake.

Which comment are you referring to specifically? Also, -emit-llvm is something that Flang inherits from Clang. I'm merely making it available in flang-new rather than re-defining it.

[schweitz]

In D120246#3339289, @tschuett wrote:

https://reviews.llvm.org/D117809

There was a discussion that -emit-llvm is considered a mistake.

Which comment are you referring to specifically? Also, -emit-llvm is something that Flang inherits from Clang. I'm merely making it available in flang-new rather than re-defining it.

Following clang's precedent with regard to spelling the option -emit-llvm seems to both follow the principle of least surprise and most obvious for sharing common code.

[schweitz]

clang/include/clang/Driver/Options.td

4815–4831

Is this comment something left over from edits?

[awarzynski]

clang/include/clang/Driver/Options.td

4815–4831

This is intentional (there's already a precedent in this file).

The nesting of let statements in this file can be very confusing. Also, some let blocks are really large. I think that adding such comments helps to separate them visually.

[awarzynski]

Rebase on top of main

[MatsPetersson]

LGTM

[awarzynski]

Thank you all for taking a look!

I've just realised this: "This revision was not accepted when it landed; it landed in state Needs Review." Just to clarify, I merged this as two reviewers accepted this in comments (with "LGTM"). Also, I believe that I addressed all your comments. If you feel otherwise, I'm happy to re-open the discussion.

clang/include/clang/Driver/Options.td

 def dylinker__install__name : JoinedOrSeparate<["-"], "dylinker_install_name">;
 def dylinker : Flag<["-"], "dylinker">;
 def dynamiclib : Flag<["-"], "dynamiclib">;
 def dynamic : Flag<["-"], "dynamic">, Flags<[NoArgumentUnused]>;
 def d_Flag : Flag<["-"], "d">, Group<d_Group>;
 def d_Joined : Joined<["-"], "d">, Group<d_Group>;
 def emit_ast : Flag<["-"], "emit-ast">,
   HelpText<"Emit Clang AST files for source inputs">;
-def emit_llvm : Flag<["-"], "emit-llvm">, Flags<[CC1Option, FC1Option]>, Group<Action_Group>,
+def emit_llvm : Flag<["-"], "emit-llvm">, Flags<[CC1Option, FC1Option, FlangOption]>, Group<Action_Group>,
   HelpText<"Use the LLVM representation for assembler and object files">;
 def emit_interface_stubs : Flag<["-"], "emit-interface-stubs">, Flags<[CC1Option]>, Group<Action_Group>,
   HelpText<"Generate Interface Stub Files.">;
 def emit_merged_ifs : Flag<["-"], "emit-merged-ifs">,
   Flags<[CC1Option]>, Group<Action_Group>,
   HelpText<"Generate Interface Stub Files, emit merged text not binary.">;
 def end_no_unused_arguments : Flag<["--"], "end-no-unused-arguments">, Flags<[CoreOption]>,
   HelpText<"Start emitting warnings for unused driver arguments">;

 def print_libgcc_file_name : Flag<["-", "--"], "print-libgcc-file-name">,
   HelpText<"Print the library path for the currently used compiler runtime "
            "library (\"libgcc.a\" or \"libclang_rt.builtins.*.a\")">;
 def print_multi_directory : Flag<["-", "--"], "print-multi-directory">;
 def print_multi_lib : Flag<["-", "--"], "print-multi-lib">;
 def print_multi_os_directory : Flag<["-", "--"], "print-multi-os-directory">,
   Flags<[Unsupported]>;
 def print_target_triple : Flag<["-", "--"], "print-target-triple">,
-  HelpText<"Print the normalized target triple">;
+  HelpText<"Print the normalized target triple">, Flags<[FlangOption]>;
 def print_effective_triple : Flag<["-", "--"], "print-effective-triple">,
-  HelpText<"Print the effective target triple">;
+  HelpText<"Print the effective target triple">, Flags<[FlangOption]>;
 def print_multiarch : Flag<["-", "--"], "print-multiarch">,
   HelpText<"Print the multiarch target triple">;
 def print_prog_name_EQ : Joined<["-", "--"], "print-prog-name=">,
   HelpText<"Print the full program path of <name>">, MetaVarName<"<name>">;
 def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
   HelpText<"Print the resource directory pathname">;
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">;
HelpText<"Treat all #include paths starting with <prefix> as including a "
            "system header.">;
 def : Separate<["--"], "system-header-prefix">, Alias<system_header_prefix>;
 def no_system_header_prefix : Joined<["--"], "no-system-header-prefix=">,
   Group<clang_i_Group>, Flags<[CC1Option]>, MetaVarName<"<prefix>">,
   HelpText<"Treat all #include paths starting with <prefix> as not including a "
            "system header.">;
 def : Separate<["--"], "no-system-header-prefix">, Alias<no_system_header_prefix>;
 def s : Flag<["-"], "s">, Group<Link_Group>;
-def target : Joined<["--"], "target=">, Flags<[NoXarchOption, CoreOption]>,
+def target : Joined<["--"], "target=">, Flags<[NoXarchOption, CoreOption, FlangOption]>,
   HelpText<"Generate code for the given target">;
 def darwin_target_variant : Separate<["-"], "darwin-target-variant">,
   Flags<[NoXarchOption, CoreOption]>,
   HelpText<"Generate code for an additional runtime variant of the deployment target">;
 def print_supported_cpus : Flag<["-", "--"], "print-supported-cpus">,
   Group<CompileOnly_Group>, Flags<[CC1Option, CoreOption]>,
   HelpText<"Print supported cpu models for the given target (if target is not specified,"
            " it will print the supported cpus for the default target)">,

 
 //===----------------------------------------------------------------------===//
 // CC1 Options
 //===----------------------------------------------------------------------===//
 
 let Flags = [CC1Option, NoDriverOption] in {
 
 //===----------------------------------------------------------------------===//
-// Target Options
+// 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 triple : Separate<["-"], "triple">,
-  HelpText<"Specify target triple (e.g. i686-apple-darwin9)">,
-  MarshallingInfoString<TargetOpts<"Triple">, "llvm::Triple::normalize(llvm::sys::getDefaultTargetTriple())">,
-  AlwaysEmit, Normalizer<"normalizeTriple">;
 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_triple : Separate<["-"], "darwin-target-variant-triple">,
   HelpText<"Specify the darwin target variant triple">,
   MarshallingInfoString<TargetOpts<"DarwinTargetVariantTriple">>,
   Normalizer<"normalizeTriple">;
 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, NoDriverOption]
+
+//===----------------------------------------------------------------------===//
+// Target Options (cc1 + cc1as + fc1)
+//===----------------------------------------------------------------------===//
+let Flags = [CC1Option, CC1AsOption, FC1Option, NoDriverOption] in {
+
+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]
+
+//===----------------------------------------------------------------------===//
+// Target Options (other)
+//===----------------------------------------------------------------------===//
 
 def target_linker_version : Separate<["-"], "target-linker-version">,
   HelpText<"Target linker version">,
   MarshallingInfoString<TargetOpts<"LinkerVersion">>;
 def triple_EQ : Joined<["-"], "triple=">, Alias<triple>;
 def mfpmath : Separate<["-"], "mfpmath">,
   HelpText<"Which unit to use for fp math">,
   MarshallingInfoString<TargetOpts<"FPMath">>;

clang/lib/Driver/ToolChains/Flang.cpp

Args.AddAllArgs(CmdArgs,
                    options::OPT_fintrinsic_modules_path, options::OPT_pedantic,
                    options::OPT_std_EQ, options::OPT_W_Joined});
 }
 
 void Flang::ConstructJob(Compilation &C, const JobAction &JA,
                          const InputInfo &Output, const InputInfoList &Inputs,
                          const ArgList &Args, const char *LinkingOutput) const {
   const auto &TC = getToolChain();
-  // TODO: Once code-generation is available, this will need to be commented
-  // out.
-  // const llvm::Triple &Triple = TC.getEffectiveTriple();
-  // const std::string &TripleStr = Triple.getTriple();
+  const llvm::Triple &Triple = TC.getEffectiveTriple();
+  const std::string &TripleStr = Triple.getTriple();
 
   ArgStringList CmdArgs;
 
   // Invoke ourselves in -fc1 mode.
   CmdArgs.push_back("-fc1");
 
-  // TODO: Once code-generation is available, this will need to be commented
-  // out.
   // Add the "effective" target triple.
-  // CmdArgs.push_back("-triple");
-  // CmdArgs.push_back(Args.MakeArgString(TripleStr));
+  CmdArgs.push_back("-triple");
+  CmdArgs.push_back(Args.MakeArgString(TripleStr));
 
   if (isa<PreprocessJobAction>(JA)) {
       CmdArgs.push_back("-E");
   } else if (isa<CompileJobAction>(JA) || isa<BackendJobAction>(JA)) {
     if (JA.getType() == types::TY_Nothing) {
       CmdArgs.push_back("-fsyntax-only");
     } else if (JA.getType() == types::TY_AST) {
       CmdArgs.push_back("-emit-ast");

flang/include/flang/Frontend/CompilerInvocation.h

 //===- CompilerInvocation.h - Compiler Invocation Helper Data ---*- 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
 //
 //===----------------------------------------------------------------------===//
 #ifndef LLVM_FLANG_FRONTEND_COMPILERINVOCATION_H
 #define LLVM_FLANG_FRONTEND_COMPILERINVOCATION_H
 
 #include "flang/Frontend/FrontendOptions.h"
 #include "flang/Frontend/PreprocessorOptions.h"
+#include "flang/Frontend/TargetOptions.h"
 #include "flang/Parser/parsing.h"
 #include "flang/Semantics/semantics.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/DiagnosticOptions.h"
 #include "llvm/Option/ArgList.h"
 #include <memory>
 
 namespace Fortran::frontend {
class CompilerInvocation : public CompilerInvocationBase {
   // options.
   FrontendOptions frontendOpts_;
 
   /// Options for Flang parser
   // TODO: Merge with or translate to frontendOpts_. We shouldn't need two sets
   // of options.
   Fortran::parser::Options parserOpts_;
 
+  /// Options controlling the target.
+  Fortran::frontend::TargetOptions targetOpts_;
+
   // Semantics context
   std::unique_ptr<Fortran::semantics::SemanticsContext> semanticsContext_;
 
   /// Semantic options
   // TODO: Merge with or translate to frontendOpts_. We shouldn't need two sets
   // of options.
   std::string moduleDir_ = ".";
 
public:
   CompilerInvocation() = default;
 
   FrontendOptions &frontendOpts() { return frontendOpts_; }
   const FrontendOptions &frontendOpts() const { return frontendOpts_; }
 
   Fortran::parser::Options &fortranOpts() { return parserOpts_; }
   const Fortran::parser::Options &fortranOpts() const { return parserOpts_; }
 
+  TargetOptions &targetOpts() { return targetOpts_; }
+  const TargetOptions &TargetOpts() const { return targetOpts_; }
+
   Fortran::semantics::SemanticsContext &semanticsContext() {
     return *semanticsContext_;
   }
   const Fortran::semantics::SemanticsContext &semanticsContext() const {
     return *semanticsContext_;
   }
 
   std::string &moduleDir() { return moduleDir_; }

flang/include/flang/Frontend/TargetOptions.h

+//===--- TargetOptions.h ----------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Defines the flang::TargetOptions class.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_FLANG_TARGETOPTIONS_H
+#define LLVM_FLANG_TARGETOPTIONS_H
+
+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;
+};
+
+} // end namespace Fortran::frontend
+
+#endif

flang/lib/Frontend/CompilerInvocation.cpp

 //===- CompilerInvocation.cpp ---------------------------------------------===//
 //
 // 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 "flang/Frontend/CompilerInvocation.h"
 #include "flang/Common/Fortran-features.h"
 #include "flang/Frontend/PreprocessorOptions.h"
+#include "flang/Frontend/TargetOptions.h"
 #include "flang/Semantics/semantics.h"
 #include "flang/Version.inc"
 #include "clang/Basic/AllDiagnostics.h"
 #include "clang/Basic/DiagnosticDriver.h"
 #include "clang/Basic/DiagnosticOptions.h"
 #include "clang/Driver/DriverDiagnostic.h"
 #include "clang/Driver/Options.h"
 #include "llvm/ADT/StringRef.h"

 
 bool Fortran::frontend::ParseDiagnosticArgs(clang::DiagnosticOptions &opts,
     llvm::opt::ArgList &args, bool defaultDiagColor) {
   opts.ShowColors = parseShowColorsArgs(args, defaultDiagColor);
 
   return true;
 }
 
+/// Parses all target input arguments and populates the target
+/// 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) {
+  opts.triple = args.getLastArgValue(clang::driver::options::OPT_triple);
+}
+
 // Tweak the frontend configuration based on the frontend action
 static void setUpFrontendBasedOnAction(FrontendOptions &opts) {
   assert(opts.programAction != Fortran::frontend::InvalidAction &&
       "Fortran frontend action not set!");
 
   if (opts.programAction == DebugDumpParsingLog)
     opts.instrumentedParse = true;
 
if (opts.findNearest(argString, nearest, includedFlagsBitmask) > 1)
       diags.Report(clang::diag::err_drv_unknown_argument) << argString;
     else
       diags.Report(clang::diag::err_drv_unknown_argument_with_suggestion)
           << argString << nearest;
     success = false;
   }
 
   success &= ParseFrontendArgs(res.frontendOpts(), args, diags);
+  ParseTargetArgs(res.targetOpts(), args);
   parsePreprocessorArgs(res.preprocessorOpts(), args);
   success &= parseSemaArgs(res, args, diags);
   success &= parseDialectArgs(res, args, diags);
   success &= parseDiagArgs(res, args, diags);
 
   return success;
 }
 

flang/lib/Frontend/FrontendActions.cpp

bool CodeGenAction::BeginSourceFileAction() {
 
   // Create a LoweringBridge
   const common::IntrinsicTypeDefaultKinds &defKinds =
       ci.invocation().semanticsContext().defaultKinds();
   fir::KindMapping kindMap(mlirCtx.get(),
       llvm::ArrayRef<fir::KindTy>{fir::fromDefaultKinds(defKinds)});
   lower::LoweringBridge lb = Fortran::lower::LoweringBridge::create(*mlirCtx,
       defKinds, ci.invocation().semanticsContext().intrinsics(),
-      ci.parsing().allCooked(), /*triple=*/"native", kindMap);
+      ci.parsing().allCooked(), ci.invocation().targetOpts().triple, kindMap);
 
   // Create a parse tree and lower it to FIR
   Fortran::parser::Program &parseTree{*ci.parsing().parseTree()};
   lb.lower(parseTree, ci.invocation().semanticsContext());
   mlirModule = std::make_unique<mlir::ModuleOp>(lb.getModule());
 
   // Run the default passes.
   mlir::PassManager pm(mlirCtx.get(), mlir::OpPassManager::Nesting::Implicit);

flang/test/Driver/driver-help-hidden.f90

 !----------------------------------------------------
 ! CHECK:USAGE: flang-new
 ! CHECK-EMPTY:
 ! CHECK-NEXT:OPTIONS:
 ! CHECK-NEXT: -###      Print (but do not run) the commands to run for this compilation
 ! CHECK-NEXT: -cpp      Enable predefined and command line preprocessor macros
 ! CHECK-NEXT: -c        Only run preprocess, compile, and assemble steps
 ! CHECK-NEXT: -D <macro>=<value>     Define <macro> to <value> (or 1 if <value> omitted)
+! CHECK-NEXT: -emit-llvm             Use the LLVM representation for assembler and object files
 ! CHECK-NEXT: -E        Only run the preprocessor
 ! CHECK-NEXT: -falternative-parameter-statement
 ! CHECK-NEXT: Enable the old style PARAMETER statement
 ! CHECK-NEXT: -fbackslash            Specify that backslash in string introduces an escape character
 ! CHECK-NEXT: -fcolor-diagnostics    Enable colors in diagnostics
 ! CHECK-NEXT: -fdefault-double-8     Set the default double precision kind to an 8 byte wide type
 ! CHECK-NEXT: -fdefault-integer-8    Set the default integer kind to an 8 byte wide type
 ! CHECK-NEXT: -fdefault-real-8       Set the default real kind to an 8 byte wide type

 ! CHECK-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
 ! CHECK-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
 ! CHECK-NEXT: -help     Display available options
 ! CHECK-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! CHECK-NEXT: -module-dir <dir>      Put MODULE files in <dir>
 ! CHECK-NEXT: -nocpp                 Disable predefined and command line preprocessor macros
 ! CHECK-NEXT: -o <file> Write output to <file>
 ! CHECK-NEXT: -pedantic              Warn on language extensions
+! CHECK-NEXT: -print-effective-triple Print the effective target triple
+! CHECK-NEXT: -print-target-triple    Print the normalized target triple
 ! CHECK-NEXT: -P                     Disable linemarker output in -E mode
 ! CHECK-NEXT: -std=<value>           Language standard to compile for
+! CHECK-NEXT: --target=<value>        Generate code for the given target
 ! CHECK-NEXT: -U <macro>             Undefine macro <macro>
 ! CHECK-NEXT: --version Print version information
 ! CHECK-NEXT: -W<warning>            Enable the specified warning
 ! CHECK-NEXT: -Xflang <arg>          Pass <arg> to the flang compiler
 
 !-------------------------------------------------------------
 ! EXPECTED OUTPUT FOR FLANG DRIVER (flang-new)
 !-------------------------------------------------------------
 ! ERROR-FLANG: error: unknown argument '-help-hidden'; did you mean '--help-hidden'?
 
 !-------------------------------------------------------------
 ! EXPECTED OUTPUT FOR FLANG FRONTEND DRIVER (flang-new -fc1)
 !-------------------------------------------------------------
 ! Frontend driver -help-hidden is not supported
 ! ERROR-FLANG-FC1: error: unknown argument: '{{.*}}'
 

flang/test/Driver/driver-help.f90

 !----------------------------------------------------
 ! HELP:USAGE: flang
 ! HELP-EMPTY:
 ! HELP-NEXT:OPTIONS:
 ! HELP-NEXT: -###                   Print (but do not run) the commands to run for this compilation
 ! HELP-NEXT: -cpp                   Enable predefined and command line preprocessor macros
 ! HELP-NEXT: -c                     Only run preprocess, compile, and assemble steps
 ! HELP-NEXT: -D <macro>=<value>     Define <macro> to <value> (or 1 if <value> omitted)
+! HELP-NEXT: -emit-llvm             Use the LLVM representation for assembler and object files
 ! HELP-NEXT: -E                     Only run the preprocessor
 ! HELP-NEXT: -falternative-parameter-statement
 ! HELP-NEXT: Enable the old style PARAMETER statement
 ! HELP-NEXT: -fbackslash            Specify that backslash in string introduces an escape character
 ! HELP-NEXT: -fcolor-diagnostics    Enable colors in diagnostics
 ! HELP-NEXT: -fdefault-double-8     Set the default double precision kind to an 8 byte wide type
 ! HELP-NEXT: -fdefault-integer-8    Set the default integer kind to an 8 byte wide type
 ! HELP-NEXT: -fdefault-real-8       Set the default real kind to an 8 byte wide type

 ! HELP-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
 ! HELP-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
 ! HELP-NEXT: -help                  Display available options
 ! HELP-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! HELP-NEXT: -module-dir <dir>      Put MODULE files in <dir>
 ! HELP-NEXT: -nocpp                 Disable predefined and command line preprocessor macros
 ! HELP-NEXT: -o <file>              Write output to <file>
 ! HELP-NEXT: -pedantic              Warn on language extensions
+! HELP-NEXT: -print-effective-triple Print the effective target triple
+! HELP-NEXT: -print-target-triple    Print the normalized target triple
 ! HELP-NEXT: -P                     Disable linemarker output in -E mode
 ! HELP-NEXT: -std=<value>           Language standard to compile for
+! HELP-NEXT: --target=<value>       Generate code for the given target
 ! HELP-NEXT: -U <macro>             Undefine macro <macro>
 ! HELP-NEXT: --version              Print version information
 ! HELP-NEXT: -W<warning>            Enable the specified warning
 ! HELP-NEXT: -Xflang <arg>          Pass <arg> to the flang compiler
 
 !-------------------------------------------------------------
 ! EXPECTED OUTPUT FOR FLANG FRONTEND DRIVER (flang -fc1)
 !-------------------------------------------------------------

 ! HELP-FC1-NEXT: -module-suffix <suffix> Use <suffix> as the suffix for module files (the default value is `.mod`)
 ! HELP-FC1-NEXT: -nocpp                 Disable predefined and command line preprocessor macros
 ! HELP-FC1-NEXT: -o <file>              Write output to <file>
 ! HELP-FC1-NEXT: -pedantic              Warn on language extensions
 ! 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: -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 version information
 ! HELP-FC1-NEXT: -W<warning>            Enable the specified warning
 
 !---------------
 ! EXPECTED ERROR
 !---------------
 ! ERROR: error: unknown argument '-helps'; did you mean '-help'

flang/test/Driver/print-effective-triple.f90

+! Test that -print-target-triple prints correct triple.
+
+!-----------------------------------------
+! RUN LINE
+!-----------------------------------------
+! RUN: %flang -print-effective-triple 2>&1 --target=thumb-linux-gnu | FileCheck %s
+
+!-----------------
+! EXPECTED OUTPUT
+!-----------------
+! CHECK: armv4t-unknown-linux-gnu

flang/test/Driver/print-target-triple.f90

+! Test that -print-target-triple prints correct triple
+
+!-----------------------------------------
+! RUN LINES
+!-----------------------------------------
+! RUN: %flang -print-target-triple 2>&1 --target=aarch64-linux-gnu \
+! RUN:   | FileCheck --check-prefix=AARCH64 %s
+
+! RUN: %flang -print-target-triple 2>&1 --target=x86_64-linux-gnu \
+! RUN:   | FileCheck --check-prefix=X86_64 %s
+
+!-----------------
+! EXPECTED OUTPUT
+!-----------------
+! X86_64: x86_64-unknown-linux-gnu
+! AARCH64: aarch64-unknown-linux-gnu

flang/test/Driver/target.f90

+!  Test that --target indeed sets the target
+
+!-----------------------------------------
+! RUN LINES
+!-----------------------------------------
+! RUN: %flang --target=unknown-unknown-unknown -emit-llvm -c %s \
+! RUN:   -o %t.o -### 2>&1 | FileCheck %s
+
+!-----------------
+! EXPECTED OUTPUT
+!-----------------
+! CHECK: Target: unknown-unknown-unknown
+! CHECK: "-triple" "unknown-unknown-unknown"