[flang][cuda] Remove the need of special compile definition for CUFInit

[clementval]

This patch addresses post commit review comments from #124859.

The extra compile definition is not necessary and goes against the effort to separate the runtimes from the flang compiler itself. The function declaration for CUFInit can be accessed anyway since the header are always present. The insertion of the call is only based on the language feature options from the folding context.

A program compiled with cuda enabled but no cufruntime would just fail at link time as expected.

[llvmbot]

@llvm/pr-subscribers-flang-fir-hlfir

Author: Valentin Clement (バレンタイン クレメン) (clementval)

Changes

This patch addresses post commit review comments from #124859.

The extra compile definition is not necessary and goes against the effort to separate the runtimes from the flang compiler itself. The function declaration for CUFInit can be accessed anyway since the header are always present.

A program compiled with cuda enabled but no cufruntime would just fail at link time as expected.

---

Full diff: https://github.com/llvm/llvm-project/pull/124965.diff

4 Files Affected:

• (modified) flang/CMakeLists.txt (-1)
• (modified) flang/include/flang/Runtime/CUDA/init.h (-1)
• (modified) flang/lib/Optimizer/Builder/Runtime/Main.cpp (+1-5)
• (added) flang/test/Lower/CUDA/cuda-init.cuf (+11)

diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
index fb7ab4759ad37e..2e27bc2279ac47 100644
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -475,7 +475,6 @@ option(FLANG_CUF_RUNTIME
   "Compile CUDA Fortran runtime sources" OFF)
 if (FLANG_CUF_RUNTIME)
   find_package(CUDAToolkit REQUIRED)
-  add_compile_definitions(FLANG_CUDA_SUPPORT=1)
 endif()
 
 add_subdirectory(include)
diff --git a/flang/include/flang/Runtime/CUDA/init.h b/flang/include/flang/Runtime/CUDA/init.h
index 24bc6838227208..d1c8fcbf7d5875 100644
--- a/flang/include/flang/Runtime/CUDA/init.h
+++ b/flang/include/flang/Runtime/CUDA/init.h
@@ -9,7 +9,6 @@
 #ifndef FORTRAN_RUNTIME_CUDA_INIT_H_
 #define FORTRAN_RUNTIME_CUDA_INIT_H_
 
-#include "common.h"
 #include "flang/Runtime/entry-names.h"
 
 extern "C" {
diff --git a/flang/lib/Optimizer/Builder/Runtime/Main.cpp b/flang/lib/Optimizer/Builder/Runtime/Main.cpp
index 5156fd54020777..973744837d378a 100644
--- a/flang/lib/Optimizer/Builder/Runtime/Main.cpp
+++ b/flang/lib/Optimizer/Builder/Runtime/Main.cpp
@@ -14,11 +14,9 @@
 #include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
 #include "flang/Optimizer/Dialect/FIROps.h"
 #include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Runtime/CUDA/init.h"
 #include "flang/Runtime/main.h"
 #include "flang/Runtime/stop.h"
-#ifdef FLANG_CUDA_SUPPORT
-#include "flang/Runtime/CUDA/init.h"
-#endif
 
 using namespace Fortran::runtime;
 
@@ -66,13 +64,11 @@ void fir::runtime::genMain(
 
   builder.create<fir::CallOp>(loc, startFn, args);
 
-#ifdef FLANG_CUDA_SUPPORT
   if (initCuda) {
     auto initFn = builder.createFunction(
         loc, RTNAME_STRING(CUFInit), mlir::FunctionType::get(context, {}, {}));
     builder.create<fir::CallOp>(loc, initFn);
   }
-#endif
 
   builder.create<fir::CallOp>(loc, qqMainFn);
   builder.create<fir::CallOp>(loc, stopFn);
diff --git a/flang/test/Lower/CUDA/cuda-init.cuf b/flang/test/Lower/CUDA/cuda-init.cuf
new file mode 100644
index 00000000000000..71ec1e3f9df56d
--- /dev/null
+++ b/flang/test/Lower/CUDA/cuda-init.cuf
@@ -0,0 +1,11 @@
+! RUN: bbc -emit-fir -hlfir -fcuda %s -o - | FileCheck %s --check-prefixes=ALL,CUDA
+! RUN: bbc -emit-fir -hlfir %s -o - | FileCheck %s --check-prefixes=ALL,NOCUDA
+
+program test_init
+
+end 
+
+! ALL-LABEL: func.func @main
+! ALL: fir.call @_FortranAProgramStart
+! CUDA: fir.call @_FortranACUFInit() fastmath<contract> : () -> ()
+! NOCUDA-NOT: fir.call @_FortranACUFInit() fastmath<contract> : () -> ()

[Meinersbur]

Please allow for the reviewers that had concerns to confirm whether they have been addressed.

[clementval]

Please allow for the reviewers that had concerns to confirm whether they have been addressed.

Is it addressed?

[Meinersbur]

Yes. I still think it would have been cleaner to revert first. Now

if (FLANG_CUF_RUNTIME)
  find_package(CUDAToolkit REQUIRED)
endif()

has moved from line 484 to line 476 for no reason.

[clementval]

Yes. I still think it would have been cleaner to revert first. Now

if (FLANG_CUF_RUNTIME)
  find_package(CUDAToolkit REQUIRED)
endif()

has moved from line 484 to line 476 for no reason.

I can move it back with an NFC if you prefer it to stay at the same place.

[Meinersbur]

Up to you, I already fixed the merge conflict.