[flang][examples] Add missing CMake dependencies

[awarzynski]

Summary

Currently everything that includes "flang/Parser/parse-tree.h" in Flang
depends on the gen_acc CMake target (it generates one of the include
files that are used in "parse-tree.h"). The examples in Flang do use
this header file and hence also depend on gen_acc. This patch updates
relevant CMake scripts accordingly.

I've also taken the liberty to rename some of the example files so that
their names follow LLVM's coding guidelines.

[kiranchandramohan]

@awarzynski What about omp_gen? Do you know why it is not explicitly required?

[awarzynski]

In D117016#3234201, @kiranchandramohan wrote:

@awarzynski What about omp_gen? Do you know why it is not explicitly required?

The dependency on acc_gen comes from this include: https://github.com/llvm/llvm-project/blob/main/flang/include/flang/Parser/parse-tree.h#L28

#include "llvm/Frontend/OpenACC/ACC.h.inc"

There are no TableGen-generated OpenMP headers here. Are there any in other places? I might have missed something!

[kiranchandramohan]

In D117016#3234219, @awarzynski wrote:

In D117016#3234201, @kiranchandramohan wrote:

@awarzynski What about omp_gen? Do you know why it is not explicitly required?

The dependency on acc_gen comes from this include: https://github.com/llvm/llvm-project/blob/main/flang/include/flang/Parser/parse-tree.h#L28

#include "llvm/Frontend/OpenACC/ACC.h.inc"

There are no TableGen-generated OpenMP headers here. Are there any in other places? I might have missed something!

I don't remember the difference. Usually, OpenMP and OpenACC have similar handling. Anyway, further below there are includes for ACC.inc and OMP.inc. Are these includes not affected?

[awarzynski]

In D117016#3234228, @kiranchandramohan wrote:

There are no TableGen-generated OpenMP headers here. Are there any in other places? I might have missed something!

I don't remember the difference. Usually, OpenMP and OpenACC have similar handling. Anyway, further below there are includes for ACC.inc and OMP.inc. Are these includes not affected?

Ah, I was looking for "OpenMP.h.inc" rather than "OMP.inc", so didn't find that. Both files are generated by the omp_gen target. It does look identical to acc_gen, so I should probably add it as a dependency too. Any thoughts?

[awarzynski]

Add omp_gen to the list of dependencies

[kiranchandramohan]

Ideally, we should avoid depending on these targets directly. For now, this LGTM.

[awarzynski]

In D117016#3243314, @kiranchandramohan wrote:

Ideally, we should avoid depending on these targets directly.

I agree. We'd probably have to remove these *.inc files from all header files. I can't think of any other way.

[clementval]

In D117016#3243835, @awarzynski wrote:

In D117016#3243314, @kiranchandramohan wrote:

Ideally, we should avoid depending on these targets directly.

I agree. We'd probably have to remove these *.inc files from all header files. I can't think of any other way.

Why would you remove them? They are necessary. MLIR works on the same principle without any issue.

[awarzynski]

In D117016#3243872, @clementval wrote:

I agree. We'd probably have to remove these *.inc files from all header files. I can't think of any other way.

Why would you remove them?

So that various CMake targets don't depend on acc_gen or omp_gen. To me it's rather counter-intuitive that everything that includes parse-tree.h depends on acc_gen and omp_gen. But perhaps that's by design?

Anyway, @clementval , are you OK with this change?

[clementval]

In D117016#3243970, @awarzynski wrote:

In D117016#3243872, @clementval wrote:

I agree. We'd probably have to remove these *.inc files from all header files. I can't think of any other way.

Why would you remove them?

So that various CMake targets don't depend on acc_gen or omp_gen. To me it's rather counter-intuitive that everything that includes parse-tree.h depends on acc_gen and omp_gen. But perhaps that's by design?

Anyway, @clementval , are you OK with this change?

I'm ok with the change. The only solution would be to extract OpenMP and OpenACC specific parts to their own include files but in your example you would need the omp_gen dependency.

[awarzynski]

Thanks for the comments, @clementval !

In D117016#3248081, @clementval wrote:

I'm ok with the change.

Ta!

The only solution would be to extract OpenMP and OpenACC specific parts to their own include files (...)

Sounds like a good idea.

(...) but in your example you would need the omp_gen dependency.

Only in one of them - FlangOmpReport. But that makes sense - it's for finding OpenMP construct/clauses anyway. The other one, PrintFlangFunctionNames, doesn't need it. And neither of the examples requires OpenACC.

flang/examples/CMakeLists.txt

 if(NOT FLANG_BUILD_EXAMPLES)
   set(EXCLUDE_FROM_ALL ON)
 endif()
 
 # This test is not run by default as it requires input.
 add_executable(external-hello-world
   external-hello.cpp
 )
 
 target_link_libraries(external-hello-world
   FortranRuntime
 )
 
 add_subdirectory(PrintFlangFunctionNames)
-add_subdirectory(flang-omp-report-plugin)
+add_subdirectory(FlangOmpReport)

flang/examples/FlangOmpReport/CMakeLists.txt

+add_llvm_library(flangOmpReport
+  MODULE
+  FlangOmpReport.cpp
+  FlangOmpReportVisitor.cpp
+
+  DEPENDS
+  acc_gen
+  omp_gen
+)

flang/examples/FlangOmpReport/FlangOmpReport.cpp

 // line they're located on.
 //
 // The plugin may be invoked as:
 // ./bin/flang-new -fc1 -load lib/flangOmpReport.so -plugin
 // flang-omp-report -fopenmp -o - <source_file.f90>
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-omp-report-visitor.h"
+#include "FlangOmpReportVisitor.h"
 
 #include "flang/Frontend/CompilerInstance.h"
 #include "flang/Frontend/FrontendActions.h"
 #include "flang/Frontend/FrontendPluginRegistry.h"
 #include "flang/Parser/dump-parse-tree.h"
 #include "llvm/Support/YAMLParser.h"
 #include "llvm/Support/YAMLTraits.h"
 

flang/examples/FlangOmpReport/FlangOmpReportVisitor.cpp

 //===-- examples/flang-omp-report-plugin/flang-omp-report-visitor.cpp -----===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
-#include "flang-omp-report-visitor.h"
+#include "FlangOmpReportVisitor.h"
 #include "llvm/ADT/StringExtras.h"
 
 namespace Fortran {
 namespace parser {
 bool operator<(const ClauseInfo &a, const ClauseInfo &b) {
   return a.clause < b.clause;
 }
 bool operator==(const ClauseInfo &a, const ClauseInfo &b) {

flang/examples/PrintFlangFunctionNames/CMakeLists.txt

 # TODO: Note that this is currently only available on Linux.
 # On Windows, we would also have to specify e.g. `PLUGIN_TOOL`.
-add_llvm_library(
-    flangPrintFunctionNames
+add_llvm_library(flangPrintFunctionNames
     MODULE
     PrintFlangFunctionNames.cpp
+
+    DEPENDS
+    acc_gen
+    omp_gen
 )

flang/examples/flang-omp-report-plugin/CMakeLists.txt

-add_llvm_library(
-  flangOmpReport
-  MODULE
-  flang-omp-report.cpp
-  flang-omp-report-visitor.cpp
-)