Remove -flang-experimental-exec flag

[everythingfunctional]

Summary

This removes the need for the -flang-experimental-exec flag to generate executables.

[awarzynski]

This is in line with the conclusions of https://discourse.llvm.org/t/proposal-rename-flang-new-to-flang/:

We should remove the need for the -flang-experimental-exec flag. There’s no need to hide things to this level given the evolving maturity of LLVM’s flang. This will be an immediate improvement for all flang-new users.

LGTM!

Thanks a ton @everythingfunctional , great to see this flag finally being removed.

[PeteSteinfeld]

All builds and tests correctly and looks good.

@everythingfunctional, can you please post on Discourse about this change when you merge? Since we've discussed this with the community, I think we should let them know that this is happening.

[everythingfunctional]

In D153379#4438419, @PeteSteinfeld wrote:

All builds and tests correctly and looks good.

@everythingfunctional, can you please post on Discourse about this change when you merge? Since we've discussed this with the community, I think we should let them know that this is happening.

Absolutely. Thanks for approving.

[antmo]

Hello,
I think this broke some bots due to remaining references to -flang-experimental-exec in llvm-zorg buildbot config

• clang-aarch64-sve-vla-2stage https://lab.llvm.org/buildbot/#/builders/198/builds/2907
• clang-aarch64-sve-vls-2stage https://lab.llvm.org/buildbot/#/builders/176/builds/2851
• clang-aarch64-sve-vla https://lab.llvm.org/buildbot/#/builders/197/builds/6950
• clang-aarch64-sve-vls https://lab.llvm.org/buildbot/#/builders/184/builds/4485

I proposed a fix here https://reviews.llvm.org/D153501

[h-vetinari]

Does this merit a mention in the release notes?

clang/include/clang/Driver/Options.td

def fsycl : Flag<["-"], "fsycl">, Flags<[NoXarchOption, CoreOption]>,
   Group<sycl_Group>, HelpText<"Enables SYCL kernels compilation for device">;
 def fno_sycl : Flag<["-"], "fno-sycl">, Flags<[NoXarchOption, CoreOption]>,
   Group<sycl_Group>, HelpText<"Disables SYCL kernels compilation for device">;
 
 //===----------------------------------------------------------------------===//
 // FLangOption + NoXarchOption
 //===----------------------------------------------------------------------===//
 
-def flang_experimental_exec : Flag<["-"], "flang-experimental-exec">,
-  Flags<[FlangOption, FlangOnlyOption, NoXarchOption, HelpHidden]>,
-  HelpText<"Enable support for generating executables (experimental)">;
-
 def flang_experimental_hlfir : Flag<["-"], "flang-experimental-hlfir">,
   Flags<[FlangOption, FC1Option, FlangOnlyOption, NoXarchOption, HelpHidden]>,
   HelpText<"Use HLFIR lowering (experimental)">;
 
 //===----------------------------------------------------------------------===//
 // FLangOption + CoreOption + NoXarchOption
 //===----------------------------------------------------------------------===//
 

clang/lib/Driver/ToolChains/CommonArgs.cpp

if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
     CmdArgs.push_back("-lFortranRuntime");
     CmdArgs.push_back("-lFortranDecimal");
   }
 }
 
 void tools::addFortranRuntimeLibraryPath(const ToolChain &TC,
                                          const llvm::opt::ArgList &Args,
                                          ArgStringList &CmdArgs) {
-  // NOTE: Generating executables by Flang is considered an "experimental"
-  // feature and hence this is guarded with a command line option.
-  // TODO: Make this work unconditionally once Flang is mature enough.
-  if (!Args.hasArg(options::OPT_flang_experimental_exec))
-    return;
-
   // Default to the <driver-path>/../lib directory. This works fine on the
   // platforms that we have tested so far. We will probably have to re-fine
   // this in the future. In particular, on some platforms, we may need to use
   // lib64 instead of lib.
   SmallString<256> DefaultLibPath =
       llvm::sys::path::parent_path(TC.getDriver().Dir);
   llvm::sys::path::append(DefaultLibPath, "lib");
   if (TC.getTriple().isKnownWindowsMSVCEnvironment())

flang/docs/FlangDriver.md

 ```bash
 flang-new -ccc-print-phases -c file.f
          +- 0: input, "file.f", f95-cpp-input
       +- 1: preprocessor, {0}, f95
    +- 2: compiler, {1}, ir
 +- 3: backend, {2}, assembler
 4: assembler, {3}, object
 ```
-Note that currently Flang does not support code-generation and `flang-new` will
-fail during the second step above with the following error:
-```bash
-error: code-generation is not available yet
-```
 The other phases are printed nonetheless when using `-ccc-print-phases`, as
 that reflects what `clangDriver`, the library, will try to create and run.
 
 For actions specific to the frontend (e.g. preprocessing or code generation), a
 command to call the frontend driver is generated (more specifically, an
 instance of `clang::driver::Command`). Every command is bound to an instance of
 `clang::driver::Tool`. For Flang we introduced a specialisation of this class:
 `clang::driver::Flang`. This class implements the logic to either translate or

 
 
 # CMake Support
 As of [#7246](https://gitlab.kitware.com/cmake/cmake/-/merge_requests/7246)
 (and soon to be released CMake 3.24.0), `cmake` can detect `flang-new` as a
 supported Fortran compiler. You can configure your CMake projects to use
 `flang-new` as follows:
 ```bash
-cmake -DCMAKE_Fortran_FLAGS="-flang-experimental-exec" -DCMAKE_Fortran_COMPILER=<path/to/flang-new> <src/dir>
+cmake -DCMAKE_Fortran_COMPILER=<path/to/flang-new> <src/dir>
 ```
 You should see the following in the output:
 ```
 -- The Fortran compiler identification is LLVMFlang <version>
 ```
-where `<version>` corresponds to the LLVM Flang version. Note that while
-generating executables remains experimental, you will need to inform CMake to
-use the `-flang-experimental-exec` flag when invoking `flang-new` as in the
-example above.
+where `<version>` corresponds to the LLVM Flang version.
 
 # Testing
 In LIT, we define two variables that you can use to invoke Flang's drivers:
 * `%flang` is expanded as `flang-new` (i.e. the compiler driver)
 * `%flang_fc1` is expanded as `flang-new -fc1` (i.e. the frontend driver)
 
 For most regression tests for the frontend, you will want to use `%flang_fc1`.
 In some cases, the observable behaviour will be identical regardless of whether

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

 ! 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: -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: -flang-experimental-exec
-! CHECK-NEXT:                        Enable support for generating executables (experimental)
 ! CHECK-NEXT: -flang-experimental-hlfir
 ! CHECK-NEXT:                        Use HLFIR lowering (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: -fno-color-diagnostics  Disable colors in diagnostics

flang/test/Driver/linker-flags.f90

 ! Verify that the Fortran runtime libraries are present in the linker
 ! invocation. These libraries are added on top of other standard runtime
 ! libraries that the Clang driver will include.
 
-! RUN: %flang -### -flang-experimental-exec -target ppc64le-linux-gnu %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,GNU
-! RUN: %flang -### -flang-experimental-exec -target aarch64-apple-darwin %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,DARWIN
-! RUN: %flang -### -flang-experimental-exec -target x86_64-windows-gnu %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,MINGW
+! RUN: %flang -### -target ppc64le-linux-gnu %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,GNU
+! RUN: %flang -### -target aarch64-apple-darwin %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,DARWIN
+! RUN: %flang -### -target x86_64-windows-gnu %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,MINGW
 
 ! NOTE: Clang's driver library, clangDriver, usually adds 'libcmt' and
 !       'oldnames' on Windows, but they are not needed when compiling
 !       Fortran code and they might bring in additional dependencies.
 !       Make sure they're not added.
-! RUN: %flang -### -flang-experimental-exec -target aarch64-windows-msvc %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,MSVC --implicit-check-not libcmt --implicit-check-not oldnames
+! RUN: %flang -### -target aarch64-windows-msvc %S/Inputs/hello.f90 2>&1 | FileCheck %s --check-prefixes=CHECK,MSVC --implicit-check-not libcmt --implicit-check-not oldnames
 
 ! Compiler invocation to generate the object file
 ! CHECK-LABEL: {{.*}} "-emit-obj"
 ! CHECK-SAME:  "-o" "[[object_file:.*\.o]]" {{.*}}Inputs/hello.f90
 
 ! Linker invocation to generate the executable
 ! NOTE: Since we are cross-compiling, the host toolchain executables may
 !       run on any other platform, such as Windows that use a .exe