[Flang] Add a Fortran Standards Support doc #132195
There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,119 @@ | ||
| <!--===- docs/FortranStandardsSupport.md | ||
|
|
||
| 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 | ||
|
|
||
| --> | ||
|
|
||
| # Flang Fortran Standards Support | ||
|
|
||
| ```{contents} | ||
| --- | ||
| local: | ||
| --- | ||
| ``` | ||
|
|
||
| This document summarizes Fortran standards support in Flang. The information is only provided as a guideline. The | ||
| TODOs/Not Yet Implemented messages emitted by the compiler for unimplemented features should be treated as authoritative. | ||
|
|
||
| The standards support information is provided as a table with three columns that are self explanatory. No distinction is | ||
| made between the support in the Parser/Semantics and MLIR or Lowering support. The Status column uses | ||
| the letters **P**, **Y**, **N** for the implementation status: | ||
| - **P** : When the implementation is incomplete for a few cases | ||
| - **Y** : When the implementation is complete | ||
| - **N** : When the implementation is absent | ||
|
|
||
| There is no distinction made between support in the Parser/Semantics and the MLIR or Lowering stages. | ||
|
Contributor
There was a problem hiding this comment. This sentence is now repeated (just above the P/Y/N there's an equivalent one).
Contributor
Author
There was a problem hiding this comment. Thanks. Removed the former occurence. |
||
|
|
||
|
Collaborator
There was a problem hiding this comment. Since all the contents in the first three sections are the same, I suggest to consolidate to the
Contributor
Author
There was a problem hiding this comment. I have reorganized in descending order of standards. I do not have entries for 2018 and 2023 now. If it is OK, we can add that in subsequent PRs. |
||
| Note: The two major missing features in Flang at present are coarrays and parameterized derived types (PDTs) with length type parameters. | ||
|
|
||
|
|
||
| ## Fortran 2023 | ||
| See [document](F202X.md) for a brief discussion about the new features in Fortran 2023. The following table summarizes the | ||
| status of all important Fortran 2023 features. The table entries are based on the document [The new features in Fortran 2023](https://wg5-fortran.org/N2201-N2250/N2212.pdf). | ||
|
|
||
| | Feature | Status | Comments | | ||
| |------------------------------------------------------------|--------|---------------------------------------------------------| | ||
| | Allow longer statement lines and overall statement length | Y | | | ||
| | Automatic allocation of lengths of character variables | N | | | ||
| | The specifiers typeof and classof | N | | | ||
| | Conditional expressions and arguments | N | | | ||
| | More use of boz constants | P | All usages other than enum are supported | | ||
| | Intrinsics for extracting tokens from a string | N | | | ||
| | Intrinsics for Trig functions that work in degrees | N | | | ||
| | Intrinsics for Trig functions that work in half revolutions| N | | | ||
| | Changes to system_clock | N | | | ||
| | Changes for conformance with the new IEEE standard | Y | | | ||
| | Additional named constants to specify kinds | Y | | | ||
| | Extensions for c_f_pointer intrinsic | N | | | ||
| | Procedures for converting between fortran and c strings | N | | | ||
| | The at edit descriptor | N | | | ||
| | Control over leading zeros in output of real values | N | | | ||
| | Extensions for Namelist | N | | | ||
| | Allow an object of a type with a coarray ultimate component to be an array or allocatable | N | | | ||
| | Put with Notify | N | | | ||
| | Error conditions in collectives | N | | | ||
| | Simple procedures | N | | | ||
| | Using integer arrays to specify subscripts | N | | | ||
| | Using integer arrays to specify rank and bound of an array | N | | | ||
| | Using an integer constant to specify rank | N | | | ||
| | Reduction specifier for do concurrent | P | Syntax is accepted | | ||
| | Enumerations | N | | | ||
|
|
||
| ## Fortran 2018 | ||
| All features except those listed in the following table are supported. Almost all of the unsupported features are related to | ||
| the multi-image execution. The table entries are based on the document [The new features in Fortran 2018](https://wg5-fortran.org/N2151-N2200/ISO-IECJTC1-SC22-WG5_N2161_The_New_Features_of_Fortran_2018.pdf). | ||
|
|
||
| | Feature | Status | Comments | | ||
| |------------------------------------------------------------|--------|---------------------------------------------------------| | ||
| | Asynchronous communication | P | Syntax is accepted | | ||
| | Teams | N | Multi-image/Coarray feature | | ||
| | Image failure | P | Multi-image/Coarray feature. stat_failed_image is added | | ||
| | Form team statement | N | Multi-image/Coarray feature | | ||
| | Change team construct | N | Multi-image/Coarray feature | | ||
| | Coarrays allocated in teams | N | Multi-image/Coarray feature | | ||
| | Critical construct | N | Multi-image/Coarray feature | | ||
| | Lock and unlock statements | N | Multi-image/Coarray feature | | ||
| | Events | N | Multi-image/Coarray feature | | ||
| | Sync team construct | N | Multi-image/Coarray feature | | ||
| | Image selectors | N | Multi-image/Coarray feature | | ||
| | Intrinsic functions get_team and team_number | N | Multi-image/Coarray feature | | ||
| | Intrinsic function image_index | N | Multi-image/Coarray feature | | ||
| | Intrinsic function num_images | N | Multi-image/Coarray feature | | ||
| | Intrinsic function this_image | N | Multi-image/Coarray feature | | ||
| | Intrinsic move_alloc extensions | P | Multi-image/Coarray feature | | ||
| | Detecting failed and stopped images | N | Multi-image/Coarray feature | | ||
| | Collective subroutines | N | Multi-image/Coarray feature | | ||
| | New and enhanced atomic subroutines | N | Multi-image/Coarray feature | | ||
| | Failed images and stat= specifiers | N | Multi-image/Coarray feature | | ||
| | Intrinsic function coshape | N | Multi-image/Coarray feature | | ||
|
|
||
| ## Fortran 2008 | ||
| All features except those listed in the following table are supported. | ||
|
|
||
| | Feature | Status | Comments | | ||
| |------------------------------------------------------------|--------|---------------------------------------------------------| | ||
| | Coarrays | N | Lowering and runtime support is not implemented | | ||
| | do concurrent | P | Sequential execution works. Parallel support in progress| | ||
| | Internal procedure as an actual argument or pointer target | Y | Current implementation requires stack to be executable. See [Proposal](InternalProcedureTrampolines.md) | | ||
|
|
||
| ## Fortran 2003 | ||
| All features except those listed in the following table are supported. | ||
|
|
||
| | Feature | Status | Comments | | ||
| |------------------------------------------------------------|--------|---------------------------------------------------------| | ||
| | Parameterized Derived Types | P | PDT with length type parameters is not supported. See [Proposal](ParameterizedDerivedTypes.md) | | ||
| | Assignment to allocatable | P | Assignment to whole allocatable in FORALL is not implemented | | ||
| | The VOLATILE attribute | P | VOLATILE in procedure interfaces is not implemented | | ||
| | Asynchronous input/output | P | IO will happen synchronously | | ||
| | MIN/MAX extensions for CHARACTER | P | Some variants are not supported | | ||
|
|
||
| ## Fortran 95 | ||
| All features are supported. | ||
|
|
||
| ## Fortran 90 | ||
| All features are supported. | ||
|
|
||
| ## FORTRAN 77 | ||
| All features are supported. | ||
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Uh oh!
There was an error while loading. Please reload this page.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I still think we should make this easier for readers (explain the letters, order them by degree of completion)
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Done. The following format was used.