commit 3a1513c142f4a1ddb97d882a12c89f90cb2529ac
author Faris Rehman <faris.rehman@arm.com> Tue Jan 26 16:27:30 2021 +0000
committer Faris Rehman <faris.rehman@arm.com> Thu Feb 04 12:24:15 2021 +0000
tree 2dbf85aa6eb404cb2c4fe75e4ba0975eb70c947a
parent fa2cdb81407b9859794e4a47fc65d20a110e338c

[flang][driver] Add forced form flags and -ffixed-line-length

Add support for the following layout options:
* -ffree-form
* -ffixed-form
- -ffixed-line-length=n (alias -ffixed-line-length-n)
Additionally remove options `-fno-free-form` and `-fno-fixed-form` as they were initially added to forward to gfortran but gfortran does not support these flags.

This patch adds the flag FlangOnlyOption to the existing options `-ffixed-form`, `-ffree-form` and `-ffree-line-length-` in Options.td. As of commit 6a75496836ea14bcfd2f4b59d35a1cad4ac58cee, these flags are not currently forwarded to gfortran anyway.

The default fixed line length in FrontendOptions is 72, based off the current default in Fortran::parser::Options. The line length cannot be set to a negative integer, or a positive integer less than 7 excluding 0, consistent with the behaviour of gfortran.

This patch does not add `-ffree-line-length-n` as Fortran::parser::Options does not have a variable for free form columns.
Whilst the `fixedFormColumns` variable is used in f18 for `-ffree-line-length-n`, f18 only allows `-ffree-line-length-none`/`-ffree-line-length-0` and not a user-specified value. `fixedFormcolumns` cannot be used in the new driver as it is ignored in the frontend when dealing with free form files.

Summary of changes:
- Remove -fno-fixed-form and -fno-free-form from Options.td
- Make -ffixed-form, -ffree-form and -ffree-line-length-n FlangOnlyOption in Options.td
- Create AddFortranDialectOptions method in Flang.cpp
- Create FortranForm enum in FrontendOptions.h
- Add fortranForm_ and fixedFormColumns_ to Fortran::frontend::FrontendOptions
- Update fixed-form-test.f so that it guarantees that it fails when forced as a free form file to better facilitate testing.

Differential Revision: https://reviews.llvm.org/D95460

clang/lib/Driver/ToolChains/Flang.cpp

diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 669d911..1b8d034 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -19,6 +19,12 @@
 using namespace clang;
 using namespace llvm::opt;
 
+void Flang::AddFortranDialectOptions(const ArgList &Args,
+                                     ArgStringList &CmdArgs) const {
+  Args.AddAllArgs(CmdArgs, {options::OPT_ffixed_form, options::OPT_ffree_form,
+                            options::OPT_ffixed_line_length_EQ});
+}
+
 void Flang::AddPreprocessingOptions(const ArgList &Args,
                                     ArgStringList &CmdArgs) const {
   Args.AddAllArgs(CmdArgs, {options::OPT_D, options::OPT_U, options::OPT_I});
@@ -79,6 +85,8 @@
   if (types::getPreprocessedType(InputType) != types::TY_INVALID)
     AddPreprocessingOptions(Args, CmdArgs);
 
+  AddFortranDialectOptions(Args, CmdArgs);
+
   if (Output.isFilename()) {
     CmdArgs.push_back("-o");
     CmdArgs.push_back(Output.getFilename());