Address reviewer comments.

- Move the options into a commented block. The -print-supported-extensions and
  related options can be moved into this block in a future PR.

- Combine the tests for the different architectures into a single file.

Author: Tarun Prabhu

clang/include/clang/Driver/Options.td

@@ -5888,12 +5888,24 @@ def target : Joined<["--"], "target=">, Flags<[NoXarchOption]>,
 def darwin_target_variant : Separate<["-"], "darwin-target-variant">,
   Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption]>,
   HelpText<"Generate code for an additional runtime variant of the deployment target">;
+
+//===----------------------------------------------------------------------===//
+// Print CPU info options (clang, clang-cl, flang)
+//===----------------------------------------------------------------------===//
+
+let Visibility = [ClangOption, CC1Option, CLOption, FlangOption, FC1Option] in {
+
 def print_supported_cpus : Flag<["-", "--"], "print-supported-cpus">,
   Group<CompileOnly_Group>,
-  Visibility<[ClangOption, CC1Option, CLOption, FlangOption, FC1Option]>,
-  HelpText<"Print supported cpu models for the given target (if target is not specified,"
-           " it will print the supported cpus for the default target)">,
+  HelpText<"Print supported cpu models for the given target (if target is not "
+           "specified,it will print the supported cpus for the default target)">,
   MarshallingInfoFlag<FrontendOpts<"PrintSupportedCPUs">>;
+
+def : Flag<["-"], "mcpu=help">, Alias<print_supported_cpus>;
+def : Flag<["-"], "mtune=help">, Alias<print_supported_cpus>;
+
+} // let Visibility = [ClangOption, CC1Option, CLOption, FlangOption, FC1Option]
+
 def print_supported_extensions : Flag<["-", "--"], "print-supported-extensions">,
   Visibility<[ClangOption, CC1Option, CLOption]>,
   HelpText<"Print supported -march extensions (RISC-V, AArch64 and ARM only)">,
@@ -5903,10 +5915,6 @@ def print_enabled_extensions : Flag<["-", "--"], "print-enabled-extensions">,
   HelpText<"Print the extensions enabled by the given target and -march/-mcpu options."
            " (AArch64 and RISC-V only)">,
   MarshallingInfoFlag<FrontendOpts<"PrintEnabledExtensions">>;
-def : Flag<["-"], "mcpu=help">, Alias<print_supported_cpus>,
-  Visibility<[ClangOption, CC1Option, CLOption, FlangOption, FC1Option]>;
-def : Flag<["-"], "mtune=help">, Alias<print_supported_cpus>,
-  Visibility<[ClangOption, CC1Option, CLOption, FlangOption, FC1Option]>;
 def time : Flag<["-"], "time">,
   HelpText<"Time individual commands">;
 def traditional_cpp : Flag<["-", "--"], "traditional-cpp">,

flang/test/Driver/print-supported-cpus-aarch64.f90

@@ -0,0 +1,43 @@
+! Test --print-supported-cpus and associated aliases, -mcpu=help and
+! -mtune=help
+
+! RUN: %if x86-registered-target %{ \
+! RUN:   %flang --target=x86_64-unknown-linux-gnu --print-supported-cpus 2>&1 \
+! RUN:     | FileCheck %s --check-prefixes=X86,CHECK \
+! RUN: %}
+! RUN: %if x86-registered-target %{ \
+! RUN:   %flang --target=x86_64-unknown-linux-gnu -mcpu=help 2>&1 \
+! RUN:     | FileCheck %s --check-prefixes=X86,CHECK \
+! RUN: %}
+! RUN: %if x86-registered-target %{ \
+! RUN:   %flang --target=x86_64-unknown-linux-gnu -mtune=help 2>&1 \
+! RUN:     | FileCheck %s --check-prefixes=X86,CHECK \
+! RUN: %}
+
+! RUN: %if aarch64-registered-target %{ \
+! RUN:   %flang --target=aarch64-unknown-linux-gnu --print-supported-cpus 2>&1 \
+! RUN:     | FileCheck %s --check-prefixes=AARCH64,CHECK \
+! RUN: %}
+! RUN: %if x86-registered-target %{ \
+! RUN:   %flang --target=aarch64-unknown-linux-gnu -mcpu=help 2>&1 \
+! RUN:     | FileCheck %s --check-prefixes=AARCH64,CHECK \
+! RUN: %}
+! RUN: %if x86-registered-target %{ \
+! RUN:   %flang --target=aarch64-unknown-linux-gnu -mtune=help 2>&1 \
+! RUN:     | FileCheck %s --check-prefixes=AARCH64,CHECK \
+! RUN: %}
+
+! CHECK-NOT: warning: argument unused during compilation
+
+! X86: Target: x86_64-unknown-linux-gnu
+! X86: corei7
+
+! AARCH64: Target: aarch64-unknown-linux-gnu
+! AARCH64: cortex-a73
+! AARCH64: cortex-a75
+
+! TODO: This is a line that is printed at the end of the output. The full line
+! also includes an example that references clang. That needs to be fixed and a
+! a check added here to make sure that it references flang, not clang.
+
+! CHECK: Use -mcpu or -mtune to specify the target's processor.