[llvm/OptTable] Print options without documentation

[j0le]

Summary

When printing the help (most likely triggered by the tool’s option
"--help"), then list also those options, that don’t have a
documentation, i.e. no help text. That makes those options more
discoverable. The user is then able to search online, for example in an
alternate, non-official documentation, for example in the GCC or MSVC
documentaion in case of Clang.

An example of an option without help text is Clang’s option "-static",
which is well established, but couldn’t be found previously in the help
output.

If we want to hide specific options without help text, we should flag
them with llvm::opt::DriverFlag::HelpHidden, instead of relying on them
being hidden, because they have no help text.

With these changes:

$ ./clang.exe --help | wc -l
2451

$ ./clang.exe --help-hidden | wc -l
2556

Without these changes (on commit 2854852f4f0f):

$ ./clang.exe --help | wc -l
1358

$ ./clang.exe --help-hidden | wc -l
1427

[MaskRay]

Haven't looked closely(on my phone), but the new behavior makes sense. We probably need a unit test in llvm.

[j0le]

In D156436#4540180, @MaskRay wrote:

Haven't looked closely(on my phone), but the new behavior makes sense.

I'm glad to hear that ☺.

In D156436#4540180, @MaskRay wrote:

We probably need a unit test in llvm.

Seems like we already have a unit test for Flang:

Failed Tests (2):
  Flang :: Driver/driver-help-hidden.f90
  Flang :: Driver/driver-help.f90

Sorry, that I didn't noticed earlier. I will look into it tomorrow.

I said “unit test for Flang”, but is it a unit test or regression test?

[MaskRay]

LLVMOption used to be part of Clang and certain features are heavily coupled with Clang Driver behaviors.
Ideally we should have llvm/ tests (llvm/unittests/Option, or somewhere in llvm/test) for better layering (https://maskray.me/blog/2021-08-08-toolchain-testing#the-test-checks-at-the-wrong-layer), but if not applicable, somewhere in clang/unittests/Driver is fine as well.
Many contributors don't build flang and consider clang more "core", so having clang tests seems important if we don't have a good place in llvm/

[serge-sans-paille]

llvm/include/llvm/Option/OptTable.h

260–261

[j0le]

I added the missing undocumented options of Flang to the tests:

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

For the most part that are options starting with "-fno-".

I also changed quite a lot of white space in these tests, so that the help texts are aligned. I don't know if that's good or bad.
With git show --ignore-all-space one can see the relevant lines.

Furthermore I remove the comma, as suggested by @serge-sans-paille

[j0le]

Now that the Flang tests are fixed, I can think about how to write the unit tests.

Should we add a little executable, that uses the Option support library and has all sorts of options (hidden, aliases, long, short, ...)? The output of that executable can then be checked by FileCheck. Or should we use gtest.h? (I guess that's Google Test.)

I see there is already llvm/unittests/Option/Opts.td. Maybe that can be reused.

I believe checking with FileCheck is the easiest.

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

102

How do check for the end of file (EOF) with FileCheck? I didn't find anything better that CHECK-EMPTY in https://www.llvm.org/docs/CommandGuide/FileCheck.html . Maybe we should use a special regex.

The reason, why we should check for EOF is, that we don't want to miss new options that start with a letter at the end of the alphabet.

[awarzynski]

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

51

IMHO, printing (no help text for the -fno-<option> variant):

-fno-backslash

on top of:

-fbackslash   Specify that backslash in string introduces an escape character

is of little value. To me this is noise that we should avoid. If both -fbackslash and -fno-backslash are printed, then both should contain "help" text.

[awarzynski]

@j0le, thanks for caring about --help - it could really benefit from a bit of love. However, I'm not convinced that this is the right direction:

With these changes:

$ ./clang.exe --help | wc -l
2451

$ ./clang.exe --help-hidden | wc -l
2556

We should focus on quality rather than the quantity of the help text being printed. Personally, I find clang --help of little help because it is just a very long dump of unfiltered/uncategorized text. As pointed out in my inline comment, it's perfectly fine to skip some options from the --help dump if they don't really contribute any new information. However, categorizing options so that clang --help would greatly improve the user experience. At least for Clang. In the case of Flang the list of supported options is still very short and --help is quite "manageable".

[j0le]

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

51

I agree, it is of little value. But the value is, that the user now knows, that she/he/they/... can toggle of the -fbackslash option explicitly. Maybe some wrapper around flang (like a build system), that the user has little control of, sets the option -fbackslash, then the user can turn it of with -fno-backslash.

But if we realy want to hide -fno-backslash and other -fno-<option> options, but still show options that have no help text (but don't have a related negated option), we can come up with some ideas.

But first let's analyze the implementation:
If I understand this correctly, the flang options also come from the clang source tree, i.e. from the file "clang/include/clang/Driver/Options.td".

Both -fbackslash and -fno-backslash are defined with this line:

defm backslash : OptInFC1FFlag<"backslash", "Specify that backslash in string introduces an escape character">;

That corresponds to the following lines in the generated "Options.inc" file:

OPTION(prefix_1, llvm::StringLiteral("fbackslash"), fbackslash, Flag, f_Group, INVALID, nullptr, FC1Option | FlangOption | FlangOnlyOption, 0, "Specify that backslash in string introduces an escape character", nullptr, nullptr)
OPTION(prefix_1, llvm::StringLiteral("fno-backslash"), fno_backslash, Flag, f_Group, INVALID, nullptr, FC1Option | FlangOption | FlangOnlyOption, 0, "", nullptr, nullptr)

I don't totally understand how this table generation works. And I don't know how we can tell (programmatically) from this table that fbackslash and fno_backslash are related. But maybe there is a way, or we have to change the table generation.

Possible solutions:

1. For OptInFC1FFlag the "-fno-..." options are marked as hidden.
2. We detect in OptTable::printHelp that those options are related and group them together
3. A help text for the "-fno-..." option is generated from help text of "-f..." option. Either in table generation or in C++ code.

[j0le]

In D156436#4542676, @awarzynski wrote:

@j0le, thanks for caring about --help - it could really benefit from a bit of love. However, I'm not convinced that this is the right direction:

[...]

We should focus on quality rather than the quantity of the help text being printed.
Personally, I find clang --help of little help because it is just a very long dump of unfiltered/uncategorized text. As pointed out in my inline comment, it's perfectly fine to skip some options from the --help dump if they don't really contribute any new information. However, categorizing options so that clang --help would greatly improve the user experience. At least for Clang. In the case of Flang the list of supported options is still very short and --help is quite "manageable".

Yeah, I would also find it better, if we grouped the options some how. Maybe I will find some time for that some day, because this a little bit more work than this small patch.

I'm fine with discarding this patch, because I can still search for options in https://clang.llvm.org/docs/ClangCommandLineReference.html (But it is a little bit broken at the end.)
But I wanna say: The user might be fooled and think the output of "--help" is complete, or identical to https://clang.llvm.org/docs/ClangCommandLineReference.html, but that's not the case.

Thanks for your feedback, @awarzynski!

[MaskRay]

I agree that displaying all options will be useful. And with OptInFC1FFlag, displaying just the negative option in --help will be nice.

lichray has a point that (a) this allows determining whether an option is accepted by a specific version of Clang and (b) without a string like "(Undocumented)", an option without a message can be confused with a preceding option.

flang/test/Driver/driver-help.f90

17

See https://llvm.org/docs/CommandGuide/FileCheck.html#cmdoption-filecheck-strict-whitespace , you can remove space updates from this patch.

[awarzynski]

Thanks for the reply and apologies for the delay.

In D156436#4542942, @j0le wrote:

In D156436#4542676, @awarzynski wrote:

@j0le, thanks for caring about --help - it could really benefit from a bit of love. However, I'm not convinced that this is the right direction:

[...]

We should focus on quality rather than the quantity of the help text being printed.
Personally, I find clang --help of little help because it is just a very long dump of unfiltered/uncategorized text. As pointed out in my inline comment, it's perfectly fine to skip some options from the --help dump if they don't really contribute any new information. However, categorizing options so that clang --help would greatly improve the user experience. At least for Clang. In the case of Flang the list of supported options is still very short and --help is quite "manageable".

Yeah, I would also find it better, if we grouped the options some how. Maybe I will find some time for that some day, because this a little bit more work than this small patch.

This would be a non-trivial task - you'd need to "properly" categorise all options in Options.td. But, IMHO, that would be hugely beneficial to the community.

But I wanna say: The user might be fooled and think the output of "--help" is complete, or identical to https://clang.llvm.org/docs/ClangCommandLineReference.html, but that's not the case.

Yes, but I wouldn't put -f<option and -fno-<option> into this category. Folks usually know that often both forms are possible. As for -static specifically, you could simply add a HelpText. In fact, your patch should allow you to identify all options for which a HelpText is missing.

I'm fine with discarding this patch,

That would be my suggestion. I really appreciate the effort and, in general, Clang/Flang would greatly benefit from somebody taking greater care of Options.td. However, I don't believe that this patch is the direction that we should be taking. At least not without some additional refactoring that would take care of duplication in the --help output (printing -fbackslash and -fno-backslash is, IMHO, duplication).

If you do decide to purse this further, I will happily review your TableGen changes.

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

51

But the value is, that the user now knows, that she/he/they/... can toggle of the -fbackslash option explicitly.

But to document that, do we really need:

-fno-backslash
-fbackslash   Specify that backslash in string introduces an escape character

? Why not something like this:

-fbackslash   Specify that backslash in string introduces an escape character (default)

And then, somewhere in the documentation:

Options with default values (marked with `(default)` at the end of their help text) support both positive (`-f<option>`) and negative (`-fno-<option>`) versions.

Or something similar.

With things like this it's often very helpful to see what GNU do (https://gcc.gnu.org/onlinedocs/gcc/Invoking-GCC.html):

Many options have long names starting with ‘-f’ or with ‘-W’—for example, -fmove-loop-invariants, -Wformat and so on. Most of these have both positive and negative forms; the negative form of -ffoo is -fno-foo. This manual documents only one of these two forms, whichever one is not the default.

Following GNU would the path of least surprises :)

If I understand this correctly, the flang options also come from the clang source tree, i.e. from the file "clang/include/clang/Driver/Options.td".

Yes, Flang's driver is implemented in terms of Clang's clangDriver library and these options are defined within that library. Historically, only Clang would use it. However, with the introduction of Flang, that library has gained a new client - Flang's compiler driver :) This helps us create more consistence experience for end users (there are many other benefits too). Note that the long term plan is to extract the driver library out of Clang.

I don't totally understand how this table generation works.

It's a bit tricky, yes :) Have you checked whether this is a problem specific to Flang options? I would imagine that your change would affect Clang options in a similar way. It just happens that for Flang it's more visible as there's fewer options.

Possible solutions:

Like hinted above, I suggest that in cases like this, instead of printing two options:

-fno-backslash <potentially some help text>
-fbackslash   Specify that backslash in string introduces an escape character

Clang and Flang print only one:

-fbackslash   Specify that backslash in string introduces an escape character (perhaps some extra marker here?)

As for your suggestions:

• Option 1. makes sense to me, though it would pollute -help-hidden. You could, though, use some other flag instead of HelpHidden.
• Option 3 means duplication that I would rather avoid.
• Not sure about Option 2 without seeing a prototype/PoC.

And I don't know how we can tell (programmatically) from this table that fbackslash and fno_backslash are related.

I don't believe they are.

But maybe there is a way, or we have to change the table generation.

There's always a way :) I think that in this case it would require a bit of design work, but nothing too extensive.

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

 
 !--------------------------
 ! FLANG DRIVER (flang-new)
 !--------------------------
 ! RUN: %flang --help-hidden 2>&1 | FileCheck %s
 ! RUN: not %flang  -help-hidden 2>&1 | FileCheck %s --check-prefix=ERROR-FLANG
 
 !----------------------------------------
 ! FLANG FRONTEND DRIVER (flang-new -fc1)
 !----------------------------------------
 ! RUN: not %flang_fc1 --help-hidden 2>&1 | FileCheck %s --check-prefix=ERROR-FLANG-FC1
 ! RUN: not %flang_fc1  -help-hidden 2>&1 | FileCheck %s --check-prefix=ERROR-FLANG-FC1
 
 ! 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: -###                    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: -fapprox-func          Allow certain math function calls to be replaced with an approximately equivalent calculation
-! CHECK-NEXT: -fbackslash            Specify that backslash in string introduces an escape character
-! CHECK-NEXT: -fcolor-diagnostics    Enable colors in diagnostics
-! CHECK-NEXT: -fconvert=<value>      Set endian conversion of data for unformatted files
-! 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 and logical 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: -ffast-math            Allow aggressive, lossy floating-point optimizations
-! CHECK-NEXT: -ffixed-form           Process source files in fixed form
+! CHECK-NEXT:                         Enable the old style PARAMETER statement
+! CHECK-NEXT: -fapprox-func           Allow certain math function calls to be replaced with an approximately equivalent calculation
+! CHECK-NEXT: -fbackslash             Specify that backslash in string introduces an escape character
+! CHECK-NEXT: -fcolor-diagnostics     Enable colors in diagnostics
+! CHECK-NEXT: -fconvert=<value>       Set endian conversion of data for unformatted files
+! 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 and logical 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: -ffast-math             Allow aggressive, lossy floating-point optimizations
+! CHECK-NEXT: -ffixed-form            Process source files in fixed form
 ! CHECK-NEXT: -ffixed-line-length=<value>
-! CHECK-NEXT: Use <value> as character line width in fixed mode
-! CHECK-NEXT: -ffp-contract=<value> Form fused FP ops (e.g. FMAs)
-! CHECK-NEXT: -ffree-form            Process source files in free form
-! CHECK-NEXT: -fimplicit-none        No implicit typing allowed unless overridden by IMPLICIT statements
+! CHECK-NEXT:                         Use <value> as character line width in fixed mode
+! CHECK-NEXT: -ffp-contract=<value>   Form fused FP ops (e.g. FMAs)
+! CHECK-NEXT: -ffree-form             Process source files in free form
+! CHECK-NEXT: -fimplicit-none         No implicit typing allowed unless overridden by IMPLICIT statements
 ! CHECK-NEXT: -finput-charset=<value> Specify the default character set for source files
 ! CHECK-NEXT: -fintrinsic-modules-path <dir>
-! CHECK-NEXT:                        Specify where to find the compiled intrinsic modules
+! CHECK-NEXT:                         Specify where to find the compiled intrinsic modules
 ! CHECK-NEXT: -flang-experimental-hlfir
-! CHECK-NEXT:                        Use HLFIR lowering (experimental)
+! CHECK-NEXT:                         Use HLFIR lowering (experimental)
 ! CHECK-NEXT: -flang-experimental-polymorphism
-! CHECK-NEXT:                        Enable Fortran 2003 polymorphism (experimental)
-! CHECK-NEXT: -flarge-sizes          Use INTEGER(KIND=8) for the result type in size-related intrinsics
+! CHECK-NEXT:                         Enable Fortran 2003 polymorphism (experimental)
+! CHECK-NEXT: -flarge-sizes           Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! CHECK-NEXT: -flogical-abbreviations Enable logical abbreviations
-! CHECK-NEXT: -flto=<value> Set LTO mode
-! CHECK-NEXT: -flto Enable LTO in 'full' mode
-! CHECK-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
+! CHECK-NEXT: -flto=<value>           Set LTO mode
+! CHECK-NEXT: -flto                   Enable LTO in 'full' mode
+! CHECK-NEXT: -fno-automatic          Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
+! CHECK-NEXT: -fno-backslash
 ! CHECK-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
-! CHECK-NEXT: -fno-integrated-as     Disable the integrated assembler
-! CHECK-NEXT: -fno-signed-zeros      Allow optimizations that ignore the sign of floating point zeros
-! CHECK-NEXT: -fno-stack-arrays      Allocate array temporaries on the heap (default)
+! CHECK-NEXT: -fno-implicit-none
+! CHECK-NEXT: -fno-integrated-as      Disable the integrated assembler
+! CHECK-NEXT: -fno-logical-abbreviations
+! CHECK-NEXT: -fno-signed-zeros       Allow optimizations that ignore the sign of floating point zeros
+! CHECK-NEXT: -fno-stack-arrays       Allocate array temporaries on the heap (default)
+! CHECK-NEXT: -fno-underscoring
 ! CHECK-NEXT: -fno-version-loops-for-stride
-! CHECK-NEXT:                        Do not create unit-strided loops (default)
-! CHECK-NEXT: -fopenacc              Enable OpenACC
+! CHECK-NEXT:                         Do not create unit-strided loops (default)
+! CHECK-NEXT: -fno-xor-operator
+! CHECK-NEXT: -fopenacc               Enable OpenACC
 ! CHECK-NEXT: -fopenmp-version=<value>
-! CHECK-NEXT:                        Set OpenMP version (e.g. 45 for OpenMP 4.5, 50 for OpenMP 5.0). Default value is 50 for Clang and 11 for Flang
-! CHECK-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
+! CHECK-NEXT:                         Set OpenMP version (e.g. 45 for OpenMP 4.5, 50 for OpenMP 5.0). Default value is 50 for Clang and 11 for Flang
+! CHECK-NEXT: -fopenmp                Parse OpenMP pragmas and generate parallel code.
 ! CHECK-NEXT: -fpass-plugin=<dsopath> Load pass plugin from a dynamic shared object file (only with new pass manager).
-! CHECK-NEXT: -freciprocal-math      Allow division operations to be reassociated
-! CHECK-NEXT: -fstack-arrays         Attempt to allocate array temporaries on the stack, no matter their size
-! CHECK-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
-! CHECK-NEXT: -funderscoring         Appends one trailing underscore to external names
+! CHECK-NEXT: -freciprocal-math       Allow division operations to be reassociated
+! CHECK-NEXT: -fstack-arrays          Attempt to allocate array temporaries on the stack, no matter their size
+! CHECK-NEXT: -fsyntax-only           Run the preprocessor, parser and semantic analysis stages
+! CHECK-NEXT: -funderscoring          Appends one trailing underscore to external names
 ! CHECK-NEXT: -fversion-loops-for-stride
-! CHECK-NEXT:                        Create unit-strided versions of loops
-! CHECK-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
-! CHECK-NEXT: -gline-tables-only     Emit debug line number tables only
-! CHECK-NEXT: -g                     Generate source-level debug information
-! CHECK-NEXT: -help     Display available options
-! CHECK-NEXT: -I <dir>               Add directory to the end of the list of include search paths
-! CHECK-NEXT: -mllvm=<arg>           Alias for -mllvm
-! CHECK-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing
-! CHECK-NEXT: -mmlir <value>         Additional arguments to forward to MLIR's option processing
-! CHECK-NEXT: -module-dir <dir>      Put MODULE files in <dir>
-! CHECK-NEXT: -nocpp                 Disable predefined and command line preprocessor macros
+! CHECK-NEXT:                         Create unit-strided versions of loops
+! CHECK-NEXT: -fxor-operator          Enable .XOR. as a synonym of .NEQV.
+! CHECK-NEXT: -gline-tables-only      Emit debug line number tables only
+! CHECK-NEXT: -g                      Generate source-level debug information
+! CHECK-NEXT: -help                   Display available options
+! CHECK-NEXT: -I <dir>                Add directory to the end of the list of include search paths
+! CHECK-NEXT: -mllvm=<arg>            Alias for -mllvm
+! CHECK-NEXT: -mllvm <value>          Additional arguments to forward to LLVM's option processing
+! CHECK-NEXT: -mmlir <value>          Additional arguments to forward to MLIR's option processing
+! CHECK-NEXT: -module-dir <dir>       Put MODULE files in <dir>
+! CHECK-NEXT: -nocpp                  Disable predefined and command line preprocessor macros
+! CHECK-NEXT: -Ofast<value>
 ! CHECK-NEXT: --offload-device-only   Only compile for the offloading device.
 ! CHECK-NEXT: --offload-host-device   Only compile for the offloading host.
 ! CHECK-NEXT: --offload-host-only     Only compile for the offloading host.
-! CHECK-NEXT: -o <file> Write output to <file>
-! CHECK-NEXT: -pedantic              Warn on language extensions
+! 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: -save-temps=<value>    Save intermediate compilation results.
-! CHECK-NEXT: -save-temps            Save intermediate compilation results
-! CHECK-NEXT: -std=<value>           Language standard to compile for
-! CHECK-NEXT: -S                     Only run preprocess and compilation steps
+! CHECK-NEXT: -P                      Disable linemarker output in -E mode
+! CHECK-NEXT: -save-temps=<value>     Save intermediate compilation results.
+! CHECK-NEXT: -save-temps             Save intermediate compilation results
+! CHECK-NEXT: -std=<value>            Language standard to compile for
+! CHECK-NEXT: -S                      Only run preprocess and compilation steps
 ! 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
+! 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
+! CHECK-NEXT: -x <language>           Treat subsequent input files as having type <language>
+! CHECK-EMPTY:
 
 ! ERROR-FLANG: error: unknown argument '-help-hidden'; did you mean '--help-hidden'?
 
 ! Frontend driver -help-hidden is not supported
 ! ERROR-FLANG-FC1: error: unknown argument: '{{.*}}'

flang/test/Driver/driver-help.f90

 
 !--------------------------
 ! FLANG DRIVER (flang)
 !--------------------------
 ! RUN: %flang -help 2>&1 | FileCheck %s --check-prefix=HELP
 ! RUN: not %flang -helps 2>&1 | FileCheck %s --check-prefix=ERROR
 
 !----------------------------------------
 ! FLANG FRONTEND DRIVER (flang -fc1)
 !----------------------------------------
 ! RUN: %flang_fc1 -help 2>&1 | FileCheck %s --check-prefix=HELP-FC1
 ! RUN: not %flang_fc1 -helps 2>&1 | FileCheck %s --check-prefix=ERROR
 
 ! 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: -###                    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: -fapprox-func          Allow certain math function calls to be replaced with an approximately equivalent calculation
-! HELP-NEXT: -fbackslash            Specify that backslash in string introduces an escape character
-! HELP-NEXT: -fcolor-diagnostics    Enable colors in diagnostics
-! HELP-NEXT: -fconvert=<value>      Set endian conversion of data for unformatted files
-! 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 and logical 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: -ffast-math            Allow aggressive, lossy floating-point optimizations
-! HELP-NEXT: -ffixed-form           Process source files in fixed form
+! HELP-NEXT:                         Enable the old style PARAMETER statement
+! HELP-NEXT: -fapprox-func           Allow certain math function calls to be replaced with an approximately equivalent calculation
+! HELP-NEXT: -fbackslash             Specify that backslash in string introduces an escape character
+! HELP-NEXT: -fcolor-diagnostics     Enable colors in diagnostics
+! HELP-NEXT: -fconvert=<value>       Set endian conversion of data for unformatted files
+! 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 and logical 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: -ffast-math             Allow aggressive, lossy floating-point optimizations
+! HELP-NEXT: -ffixed-form            Process source files in fixed form
 ! HELP-NEXT: -ffixed-line-length=<value>
-! HELP-NEXT: Use <value> as character line width in fixed mode
-! HELP-NEXT: -ffp-contract=<value> Form fused FP ops (e.g. FMAs)
-! HELP-NEXT: -ffree-form            Process source files in free form
-! HELP-NEXT: -fimplicit-none        No implicit typing allowed unless overridden by IMPLICIT statements
+! HELP-NEXT:                         Use <value> as character line width in fixed mode
+! HELP-NEXT: -ffp-contract=<value>   Form fused FP ops (e.g. FMAs)
+! HELP-NEXT: -ffree-form             Process source files in free form
+! HELP-NEXT: -fimplicit-none         No implicit typing allowed unless overridden by IMPLICIT statements
 ! HELP-NEXT: -finput-charset=<value> Specify the default character set for source files
 ! HELP-NEXT: -fintrinsic-modules-path <dir>
-! HELP-NEXT:                        Specify where to find the compiled intrinsic modules
-! HELP-NEXT: -flarge-sizes          Use INTEGER(KIND=8) for the result type in size-related intrinsics
+! HELP-NEXT:                         Specify where to find the compiled intrinsic modules
+! HELP-NEXT: -flarge-sizes           Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! HELP-NEXT: -flogical-abbreviations Enable logical abbreviations
-! HELP-NEXT: -flto=<value> Set LTO mode
-! HELP-NEXT: -flto Enable LTO in 'full' mode
-! HELP-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
+! HELP-NEXT: -flto=<value>           Set LTO mode
+! HELP-NEXT: -flto                   Enable LTO in 'full' mode
+! HELP-NEXT: -fno-automatic          Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
+! HELP-NEXT: -fno-backslash
 ! HELP-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
+! HELP-NEXT: -fno-implicit-none
 ! HELP-NEXT: -fno-integrated-as      Disable the integrated assembler
-! HELP-NEXT: -fno-signed-zeros      Allow optimizations that ignore the sign of floating point zeros
-! HELP-NEXT: -fno-stack-arrays      Allocate array temporaries on the heap (default)
+! HELP-NEXT: -fno-logical-abbreviations
+! HELP-NEXT: -fno-signed-zeros       Allow optimizations that ignore the sign of floating point zeros
+! HELP-NEXT: -fno-stack-arrays       Allocate array temporaries on the heap (default)
+! HELP-NEXT: -fno-underscoring
 ! HELP-NEXT: -fno-version-loops-for-stride
-! HELP-NEXT:                        Do not create unit-strided loops (default)
-! HELP-NEXT: -fopenacc              Enable OpenACC
+! HELP-NEXT:                         Do not create unit-strided loops (default)
+! HELP-NEXT: -fno-xor-operator
+! HELP-NEXT: -fopenacc               Enable OpenACC
 ! HELP-NEXT: -fopenmp-version=<value>
-! HELP-NEXT:                        Set OpenMP version (e.g. 45 for OpenMP 4.5, 50 for OpenMP 5.0). Default value is 50 for Clang and 11 for Flang
-! HELP-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
+! HELP-NEXT:                         Set OpenMP version (e.g. 45 for OpenMP 4.5, 50 for OpenMP 5.0). Default value is 50 for Clang and 11 for Flang
+! HELP-NEXT: -fopenmp                Parse OpenMP pragmas and generate parallel code.
 ! HELP-NEXT: -fpass-plugin=<dsopath> Load pass plugin from a dynamic shared object file (only with new pass manager).
-! HELP-NEXT: -freciprocal-math      Allow division operations to be reassociated
-! HELP-NEXT: -fstack-arrays         Attempt to allocate array temporaries on the stack, no matter their size
-! HELP-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
-! HELP-NEXT: -funderscoring         Appends one trailing underscore to external names
+! HELP-NEXT: -freciprocal-math       Allow division operations to be reassociated
+! HELP-NEXT: -fstack-arrays          Attempt to allocate array temporaries on the stack, no matter their size
+! HELP-NEXT: -fsyntax-only           Run the preprocessor, parser and semantic analysis stages
+! HELP-NEXT: -funderscoring          Appends one trailing underscore to external names
 ! HELP-NEXT: -fversion-loops-for-stride
-! HELP-NEXT:                        Create unit-strided versions of loops
-! HELP-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
-! HELP-NEXT: -gline-tables-only     Emit debug line number tables only
-! HELP-NEXT: -g                     Generate source-level debug information
-! HELP-NEXT: -help                  Display available options
-! HELP-NEXT: -I <dir>               Add directory to the end of the list of include search paths
-! HELP-NEXT: -mllvm=<arg>           Alias for -mllvm
-! HELP-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing
-! HELP-NEXT: -mmlir <value>         Additional arguments to forward to MLIR's option processing
-! HELP-NEXT: -module-dir <dir>      Put MODULE files in <dir>
-! HELP-NEXT: -nocpp                 Disable predefined and command line preprocessor macros
+! HELP-NEXT:                         Create unit-strided versions of loops
+! HELP-NEXT: -fxor-operator          Enable .XOR. as a synonym of .NEQV.
+! HELP-NEXT: -gline-tables-only      Emit debug line number tables only
+! HELP-NEXT: -g                      Generate source-level debug information
+! HELP-NEXT: -help                   Display available options
+! HELP-NEXT: -I <dir>                Add directory to the end of the list of include search paths
+! HELP-NEXT: -mllvm=<arg>            Alias for -mllvm
+! HELP-NEXT: -mllvm <value>          Additional arguments to forward to LLVM's option processing
+! HELP-NEXT: -mmlir <value>          Additional arguments to forward to MLIR's option processing
+! HELP-NEXT: -module-dir <dir>       Put MODULE files in <dir>
+! HELP-NEXT: -nocpp                  Disable predefined and command line preprocessor macros
+! HELP-NEXT: -Ofast<value>
 ! HELP-NEXT: --offload-device-only   Only compile for the offloading device.
 ! HELP-NEXT: --offload-host-device   Only compile for the offloading host.
 ! HELP-NEXT: --offload-host-only     Only compile for the offloading host.
-! HELP-NEXT: -o <file>              Write output to <file>
-! HELP-NEXT: -pedantic              Warn on language extensions
+! 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: -save-temps=<value>    Save intermediate compilation results.
-! HELP-NEXT: -save-temps            Save intermediate compilation results
-! HELP-NEXT: -std=<value>           Language standard to compile for
-! HELP-NEXT: -S                     Only run preprocess and compilation steps
-! 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
+! HELP-NEXT: -P                      Disable linemarker output in -E mode
+! HELP-NEXT: -save-temps=<value>     Save intermediate compilation results.
+! HELP-NEXT: -save-temps             Save intermediate compilation results
+! HELP-NEXT: -std=<value>            Language standard to compile for
+! HELP-NEXT: -S                      Only run preprocess and compilation steps
+! 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
+! HELP-NEXT: -x <language>           Treat subsequent input files as having type <language>
+! HELP-EMPTY:
 
 ! HELP-FC1:USAGE: flang
 ! HELP-FC1-EMPTY:
 ! HELP-FC1-NEXT:OPTIONS:
-! HELP-FC1-NEXT: -cpp                   Enable predefined and command line preprocessor macros
-! HELP-FC1-NEXT: -D <macro>=<value>     Define <macro> to <value> (or 1 if <value> omitted)
-! HELP-FC1-NEXT: -emit-fir              Build the parse tree, then lower it to FIR
-! HELP-FC1-NEXT: -emit-hlfir            Build the parse tree, then lower it to HLFIR
-! HELP-FC1-NEXT: -emit-llvm-bc          Build ASTs then convert to LLVM, emit .bc file
-! HELP-FC1-NEXT: -emit-llvm Use the LLVM representation for assembler and object files
-! HELP-FC1-NEXT: -emit-obj Emit native object files
-! HELP-FC1-NEXT: -E                     Only run the preprocessor
+! HELP-FC1-NEXT: -cpp                    Enable predefined and command line preprocessor macros
+! HELP-FC1-NEXT: -debug-info-kind=<value>
+! HELP-FC1-NEXT: -D <macro>=<value>      Define <macro> to <value> (or 1 if <value> omitted)
+! HELP-FC1-NEXT: -emit-fir               Build the parse tree, then lower it to FIR
+! HELP-FC1-NEXT: -emit-hlfir             Build the parse tree, then lower it to HLFIR
+! HELP-FC1-NEXT: -emit-llvm-bc           Build ASTs then convert to LLVM, emit .bc file
+! HELP-FC1-NEXT: -emit-llvm              Use the LLVM representation for assembler and object files
+! HELP-FC1-NEXT: -emit-obj               Emit native object files
+! HELP-FC1-NEXT: -E                      Only run the preprocessor
 ! HELP-FC1-NEXT: -falternative-parameter-statement
-! HELP-FC1-NEXT: Enable the old style PARAMETER statement
-! HELP-FC1-NEXT: -fapprox-func          Allow certain math function calls to be replaced with an approximately equivalent calculation
-! HELP-FC1-NEXT: -fbackslash            Specify that backslash in string introduces an escape character
+! HELP-FC1-NEXT:                         Enable the old style PARAMETER statement
+! HELP-FC1-NEXT: -fanalyzed-objects-for-unparse
+! HELP-FC1-NEXT: -fapprox-func           Allow certain math function calls to be replaced with an approximately equivalent calculation
+! HELP-FC1-NEXT: -fbackslash             Specify that backslash in string introduces an escape character
 ! HELP-FC1-NEXT: -fcolor-diagnostics     Enable colors in diagnostics
-! HELP-FC1-NEXT: -fconvert=<value>      Set endian conversion of data for unformatted files
-! HELP-FC1-NEXT: -fdebug-dump-all       Dump symbols and the parse tree after the semantic checks
+! HELP-FC1-NEXT: -fconvert=<value>       Set endian conversion of data for unformatted files
+! HELP-FC1-NEXT: -fdebug-dump-all        Dump symbols and the parse tree after the semantic checks
 ! HELP-FC1-NEXT: -fdebug-dump-parse-tree-no-sema
-! HELP-FC1-NEXT:                        Dump the parse tree (skips the semantic checks)
+! HELP-FC1-NEXT:                         Dump the parse tree (skips the semantic checks)
 ! HELP-FC1-NEXT: -fdebug-dump-parse-tree Dump the parse tree
 ! HELP-FC1-NEXT: -fdebug-dump-parsing-log
-! HELP-FC1-NEXT:                   Run instrumented parse and dump the parsing log
+! HELP-FC1-NEXT:                         Run instrumented parse and dump the parsing log
 ! HELP-FC1-NEXT: -fdebug-dump-pft        Dump the pre-fir parse tree
 ! HELP-FC1-NEXT: -fdebug-dump-provenance Dump provenance
 ! HELP-FC1-NEXT: -fdebug-dump-symbols    Dump symbols after the semantic analysis
 ! HELP-FC1-NEXT: -fdebug-measure-parse-tree
 ! HELP-FC1-NEXT:                         Measure the parse tree
 ! HELP-FC1-NEXT: -fdebug-module-writer   Enable debug messages while writing module files
-! HELP-FC1-NEXT: -fdebug-pass-manager    Prints debug information for the new pass manage
+! HELP-FC1-NEXT: -fdebug-pass-manager    Prints debug information for the new pass manager
 ! HELP-FC1-NEXT: -fdebug-pre-fir-tree    Dump the pre-FIR tree
 ! HELP-FC1-NEXT: -fdebug-unparse-no-sema Unparse and stop (skips the semantic checks)
 ! HELP-FC1-NEXT: -fdebug-unparse-with-symbols
-! HELP-FC1-NEXT:                        Unparse and stop.
-! HELP-FC1-NEXT: -fdebug-unparse        Unparse and stop.
-! HELP-FC1-NEXT: -fdefault-double-8  Set the default double precision kind to an 8 byte wide type
-! HELP-FC1-NEXT: -fdefault-integer-8 Set the default integer and logical kind to an 8 byte wide type
-! HELP-FC1-NEXT: -fdefault-real-8    Set the default real kind to an 8 byte wide type
+! HELP-FC1-NEXT:                         Unparse and stop.
+! HELP-FC1-NEXT: -fdebug-unparse         Unparse and stop.
+! HELP-FC1-NEXT: -fdefault-double-8      Set the default double precision kind to an 8 byte wide type
+! HELP-FC1-NEXT: -fdefault-integer-8     Set the default integer and logical kind to an 8 byte wide type
+! HELP-FC1-NEXT: -fdefault-real-8        Set the default real kind to an 8 byte wide type
 ! HELP-FC1-NEXT: -fembed-offload-object=<value>
-! HELP-FC1-NEXT:                        Embed Offloading device-side binary into host object file as a section.
-! HELP-FC1-NEXT: -ffast-math            Allow aggressive, lossy floating-point optimizations
-! HELP-FC1-NEXT: -ffixed-form           Process source files in fixed form
+! HELP-FC1-NEXT:                         Embed Offloading device-side binary into host object file as a section.
+! HELP-FC1-NEXT: -ffast-math             Allow aggressive, lossy floating-point optimizations
+! HELP-FC1-NEXT: -ffixed-form            Process source files in fixed form
 ! HELP-FC1-NEXT: -ffixed-line-length=<value>
-! HELP-FC1-NEXT: Use <value> as character line width in fixed mode
-! HELP-FC1-NEXT: -ffp-contract=<value> Form fused FP ops (e.g. FMAs)
-! HELP-FC1-NEXT: -ffree-form            Process source files in free form
+! HELP-FC1-NEXT:                         Use <value> as character line width in fixed mode
+! HELP-FC1-NEXT: -ffp-contract=<value>   Form fused FP ops (e.g. FMAs)
+! HELP-FC1-NEXT: -ffree-form             Process source files in free form
 ! HELP-FC1-NEXT: -fget-definition <value> <value> <value>
-! HELP-FC1-NEXT:                        Get the symbol definition from <line> <start-column> <end-column>
+! HELP-FC1-NEXT:                         Get the symbol definition from <line> <start-column> <end-column>
 ! HELP-FC1-NEXT: -fget-symbols-sources   Dump symbols and their source code locations
-! HELP-FC1-NEXT: -fimplicit-none        No implicit typing allowed unless overridden by IMPLICIT statements
+! HELP-FC1-NEXT: -fimplicit-none         No implicit typing allowed unless overridden by IMPLICIT statements
 ! HELP-FC1-NEXT: -finput-charset=<value> Specify the default character set for source files
 ! HELP-FC1-NEXT: -fintrinsic-modules-path <dir>
-! HELP-FC1-NEXT:                        Specify where to find the compiled intrinsic modules
-! HELP-FC1-NEXT: -flarge-sizes          Use INTEGER(KIND=8) for the result type in size-related intrinsics
+! HELP-FC1-NEXT:                         Specify where to find the compiled intrinsic modules
+! HELP-FC1-NEXT: -flarge-sizes           Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! HELP-FC1-NEXT: -flogical-abbreviations Enable logical abbreviations
 ! HELP-FC1-NEXT: -flto=<value>           Set LTO mode
 ! HELP-FC1-NEXT: -flto                   Enable LTO in 'full' mode
 ! HELP-FC1-NEXT: -fno-analyzed-objects-for-unparse
-! HELP-FC1-NEXT:                        Do not use the analyzed objects when unparsing
-! HELP-FC1-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
+! HELP-FC1-NEXT:                         Do not use the analyzed objects when unparsing
+! HELP-FC1-NEXT: -fno-automatic          Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
+! HELP-FC1-NEXT: -fno-backslash
 ! HELP-FC1-NEXT: -fno-debug-pass-manager Disables debug printing for the new pass manager
-! HELP-FC1-NEXT: -fno-reformat          Dump the cooked character stream in -E mode
-! HELP-FC1-NEXT: -fno-signed-zeros      Allow optimizations that ignore the sign of floating point zeros
-! HELP-FC1-NEXT: -fno-stack-arrays      Allocate array temporaries on the heap (default)
+! HELP-FC1-NEXT: -fno-implicit-none
+! HELP-FC1-NEXT: -fno-logical-abbreviations
+! HELP-FC1-NEXT: -fno-openmp-target-debug
+! HELP-FC1-NEXT: -fno-reformat           Dump the cooked character stream in -E mode
+! HELP-FC1-NEXT: -fno-signed-zeros       Allow optimizations that ignore the sign of floating point zeros
+! HELP-FC1-NEXT: -fno-stack-arrays       Allocate array temporaries on the heap (default)
+! HELP-FC1-NEXT: -fno-underscoring
 ! HELP-FC1-NEXT: -fno-version-loops-for-stride
-! HELP-FC1-NEXT:                        Do not create unit-strided loops (default)
-! HELP-FC1-NEXT: -fopenacc              Enable OpenACC
-! HELP-FC1-NEXT: -fopenmp-host-ir-file-path <value> 
-! HELP-FC1-NEXT:                        Path to the IR file produced by the frontend for the host.
+! HELP-FC1-NEXT:                         Do not create unit-strided loops (default)
+! HELP-FC1-NEXT: -fno-xor-operator
+! HELP-FC1-NEXT: -fopenacc               Enable OpenACC
+! HELP-FC1-NEXT: -fopenmp-host-ir-file-path <value>
+! HELP-FC1-NEXT:                         Path to the IR file produced by the frontend for the host.
 ! HELP-FC1-NEXT: -fopenmp-is-target-device
-! HELP-FC1-NEXT:                        Generate code only for an OpenMP target device.
-! HELP-FC1-NEXT: -fopenmp-target-debug  Enable debugging in the OpenMP offloading device RTL
+! HELP-FC1-NEXT:                         Generate code only for an OpenMP target device.
+! HELP-FC1-NEXT: -fopenmp-target-debug   Enable debugging in the OpenMP offloading device RTL
 ! HELP-FC1-NEXT: -fopenmp-version=<value>
-! HELP-FC1-NEXT:                        Set OpenMP version (e.g. 45 for OpenMP 4.5, 50 for OpenMP 5.0). Default value is 50 for Clang and 11 for Flang
-! HELP-FC1-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
+! HELP-FC1-NEXT:                         Set OpenMP version (e.g. 45 for OpenMP 4.5, 50 for OpenMP 5.0). Default value is 50 for Clang and 11 for Flang
+! HELP-FC1-NEXT: -fopenmp                Parse OpenMP pragmas and generate parallel code.
 ! HELP-FC1-NEXT: -fpass-plugin=<dsopath> Load pass plugin from a dynamic shared object file (only with new pass manager).
-! HELP-FC1-NEXT: -freciprocal-math      Allow division operations to be reassociated
-! HELP-FC1-NEXT: -fstack-arrays         Attempt to allocate array temporaries on the stack, no matter their size
-! HELP-FC1-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
-! HELP-FC1-NEXT: -funderscoring         Appends one trailing underscore to external names
+! HELP-FC1-NEXT: -freciprocal-math       Allow division operations to be reassociated
+! HELP-FC1-NEXT: -fstack-arrays          Attempt to allocate array temporaries on the stack, no matter their size
+! HELP-FC1-NEXT: -fsyntax-only           Run the preprocessor, parser and semantic analysis stages
+! HELP-FC1-NEXT: -funderscoring          Appends one trailing underscore to external names
 ! HELP-FC1-NEXT: -fversion-loops-for-stride
-! HELP-FC1-NEXT:                        Create unit-strided versions of loops
-! HELP-FC1-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
-! HELP-FC1-NEXT: -help                  Display available options
-! HELP-FC1-NEXT: -init-only             Only execute frontend initialization
-! HELP-FC1-NEXT: -I <dir>               Add directory to the end of the list of include search paths
-! HELP-FC1-NEXT: -load <dsopath>        Load the named plugin (dynamic shared object)
-! HELP-FC1-NEXT: -menable-no-infs       Allow optimization to assume there are no infinities.
-! HELP-FC1-NEXT: -menable-no-nans       Allow optimization to assume there are no NaNs.
-! HELP-FC1-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing
-! HELP-FC1-NEXT: -mmlir <value>         Additional arguments to forward to MLIR's option processing
-! HELP-FC1-NEXT: -module-dir <dir>      Put MODULE files in <dir>
+! HELP-FC1-NEXT:                         Create unit-strided versions of loops
+! HELP-FC1-NEXT: -fxor-operator          Enable .XOR. as a synonym of .NEQV.
+! HELP-FC1-NEXT: -help                   Display available options
+! HELP-FC1-NEXT: -init-only              Only execute frontend initialization
+! HELP-FC1-NEXT: -I <dir>                Add directory to the end of the list of include search paths
+! HELP-FC1-NEXT: -load <dsopath>         Load the named plugin (dynamic shared object)
+! HELP-FC1-NEXT: -menable-no-infs        Allow optimization to assume there are no infinities.
+! HELP-FC1-NEXT: -menable-no-nans        Allow optimization to assume there are no NaNs.
+! HELP-FC1-NEXT: -mllvm <value>          Additional arguments to forward to LLVM's option processing
+! HELP-FC1-NEXT: -mmlir <value>          Additional arguments to forward to MLIR's option processing
+! HELP-FC1-NEXT: -module-dir <dir>       Put MODULE files in <dir>
 ! HELP-FC1-NEXT: -module-suffix <suffix> Use <suffix> as the suffix for module files (the default value is `.mod`)
-! HELP-FC1-NEXT: -mreassociate          Allow reassociation transformations for floating-point instructions
+! HELP-FC1-NEXT: -mreassociate           Allow reassociation transformations for floating-point instructions
 ! HELP-FC1-NEXT: -mrelocation-model <value>
-! HELP-FC1-NEXT:                        The relocation model to use
-! 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:                         The relocation model to use
+! HELP-FC1-NEXT: -nocpp                  Disable predefined and command line preprocessor macros
+! HELP-FC1-NEXT: -O<value>
+! 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: -save-temps=<value>    Save intermediate compilation results.
-! HELP-FC1-NEXT: -save-temps            Save intermediate compilation results
-! 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: -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: -save-temps=<value>     Save intermediate compilation results.
+! HELP-FC1-NEXT: -save-temps             Save intermediate compilation results
+! 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
+! 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
+! HELP-FC1-NEXT: -x <language>           Treat subsequent input files as having type <language>
+! HELP-FC1-EMPTY:
 
 ! ERROR: error: unknown argument '-helps'; did you mean '-help'

llvm/include/llvm/Option/OptTable.h

public:
   /// \param ErrorFn - Called on a formatted error message for missing arguments
   /// or unknown options.
   /// \return An InputArgList; on error this will contain all the options which
   /// could be parsed.
   InputArgList parseArgs(int Argc, char *const *Argv, OptSpecifier Unknown,
                          StringSaver &Saver,
                          function_ref<void(StringRef)> ErrorFn) const;
 
-  /// Render the help text for an option table.
+  /// Render the help text for an option table. Render options with and without
+  /// help texts.
   ///
   /// \param OS - The stream to write the help text to.
   /// \param Usage - USAGE: Usage
   /// \param Title - OVERVIEW: Title
   /// \param FlagsToInclude - If non-zero, only include options with any
   ///                         of these flags set.
   /// \param FlagsToExclude - Exclude options with any of these flags set.
-  /// \param ShowAllAliases - If true, display all options including aliases
-  ///                         that don't have help texts. By default, we display
-  ///                         only options that are not hidden and have help
-  ///                         texts.
+  /// \param ShowAllAliases - If false, hide aliases that do not have their
+  ///                         own help text.
   void printHelp(raw_ostream &OS, const char *Usage, const char *Title,
                  unsigned FlagsToInclude, unsigned FlagsToExclude,
                  bool ShowAllAliases) const;
 
   void printHelp(raw_ostream &OS, const char *Usage, const char *Title,
                  bool ShowHidden = false, bool ShowAllAliases = false) const;
 };
 

llvm/lib/Option/OptTable.cpp

static void PrintHelpOptionList(raw_ostream &OS, StringRef Title,
   }
 
   const unsigned InitialPad = 2;
   for (const OptionInfo &Opt : OptionHelp) {
     const std::string &Option = Opt.Name;
     int Pad = OptionFieldWidth - int(Option.size());
     OS.indent(InitialPad) << Option;
 
+    if (Opt.HelpText.empty()) {
+      OS << '\n';
+      continue;
+    }
+
     // Break on long option names.
     if (Pad < 0) {
       OS << "\n";
       Pad = OptionFieldWidth + InitialPad;
     }
     OS.indent(Pad + 1) << Opt.HelpText << '\n';
   }
 }
void OptTable::printHelp(raw_ostream &OS, const char *Usage, const char *Title,
   OS << "USAGE: " << Usage << "\n\n";
 
   // Render help text into a map of group-name to a list of (option, help)
   // pairs.
   std::map<std::string, std::vector<OptionInfo>> GroupedOptionHelp;
 
   for (unsigned Id = 1, e = getNumOptions() + 1; Id != e; ++Id) {
     // FIXME: Split out option groups.
-    if (getOptionKind(Id) == Option::GroupClass)
+    auto Kind = getOptionKind(Id);
+    if (Kind == Option::GroupClass || Kind == Option::InputClass ||
+        Kind == Option::UnknownClass)
       continue;
 
     unsigned Flags = getInfo(Id).Flags;
     if (FlagsToInclude && !(Flags & FlagsToInclude))
       continue;
     if (Flags & FlagsToExclude)
       continue;
 
     // If an alias doesn't have a help text, show a help text for the aliased
     // option instead.
     const char *HelpText = getOptionHelpText(Id);
-    if (!HelpText && ShowAllAliases) {
+    if (!HelpText) {
       const Option Alias = getOption(Id).getAlias();
-      if (Alias.isValid())
+      if (Alias.isValid()) {
+        if (!ShowAllAliases)
+          continue;
         HelpText = getOptionHelpText(Alias.getID());
       }
+    }
 
-    if (HelpText && (strlen(HelpText) != 0)) {
-      const char *HelpGroup = getOptionHelpGroup(*this, Id);
-      const std::string &OptName = getOptionHelpName(*this, Id);
-      GroupedOptionHelp[HelpGroup].push_back({OptName, HelpText});
-    }
-  }
 
   for (auto& OptionGroup : GroupedOptionHelp) {
     if (OptionGroup.first != GroupedOptionHelp.begin()->first)
       OS << "\n";
     PrintHelpOptionList(OS, OptionGroup.first, OptionGroup.second);
   }
 
   OS.flush();