Automerge: [flang] Adding support of -fcoarray flang and init PRIF (#151675)

In relation to the approval and merge of the
[PRIF](llvm/llvm-project#76088) specification
about multi-image features in Flang, here is a first PR to add support
for the `-fcoarray` compilation flag and the initialization of the PRIF
environment.
Other PRs will follow for adding support of lowering to PRIF.

Author: JDPailleux

clang/include/clang/Driver/Options.td

@@ -6987,7 +6987,6 @@ def static_libgfortran : Flag<["-"], "static-libgfortran">, Group<gfortran_Group
 // "f" options with values for gfortran.
 def fblas_matmul_limit_EQ : Joined<["-"], "fblas-matmul-limit=">, Group<gfortran_Group>;
 def fcheck_EQ : Joined<["-"], "fcheck=">, Group<gfortran_Group>;
-def fcoarray_EQ : Joined<["-"], "fcoarray=">, Group<gfortran_Group>;
 def ffpe_trap_EQ : Joined<["-"], "ffpe-trap=">, Group<gfortran_Group>;
 def ffree_line_length_VALUE : Joined<["-"], "ffree-line-length-">, Group<gfortran_Group>;
 def finit_character_EQ : Joined<["-"], "finit-character=">, Group<gfortran_Group>;
@@ -8695,6 +8694,15 @@ def fopenmp_host_ir_file_path : Separate<["-"], "fopenmp-host-ir-file-path">,
 
 } // let Visibility = [CC1Option, FC1Option]
 
+//===----------------------------------------------------------------------===//
+// Coarray Options
+//===----------------------------------------------------------------------===//
+
+def fcoarray : Flag<["-"], "fcoarray">,
+               Group<f_Group>,
+               Visibility<[FlangOption, FC1Option]>,
+               HelpText<"Enable Coarray features">;
+
 //===----------------------------------------------------------------------===//
 // SYCL Options
 //===----------------------------------------------------------------------===//

clang/lib/Driver/ToolChains/Flang.cpp

@@ -178,6 +178,8 @@ void Flang::addCodegenOptions(const ArgList &Args,
        options::OPT_fstack_repack_arrays, options::OPT_fno_stack_repack_arrays,
        options::OPT_ftime_report, options::OPT_ftime_report_EQ,
        options::OPT_funroll_loops, options::OPT_fno_unroll_loops});
+  if (Args.hasArg(clang::driver::options::OPT_fcoarray))
+    CmdArgs.push_back("-fcoarray");
 }
 
 void Flang::addPicOptions(const ArgList &Args, ArgStringList &CmdArgs) const {

flang/include/flang/Optimizer/Builder/Runtime/Coarray.h

@@ -0,0 +1,41 @@
+//===-- Coarray.h -- generate Coarray intrinsics runtime calls --*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef FORTRAN_OPTIMIZER_BUILDER_RUNTIME_COARRAY_H
+#define FORTRAN_OPTIMIZER_BUILDER_RUNTIME_COARRAY_H
+
+#include "flang/Lower/AbstractConverter.h"
+#include "flang/Optimizer/Support/InternalNames.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+
+namespace fir {
+class ExtendedValue;
+class FirOpBuilder;
+} // namespace fir
+
+namespace fir::runtime {
+
+// Get the function type for a prif subroutine with a variable number of
+// arguments
+#define PRIF_FUNCTYPE(...)                                                     \
+  mlir::FunctionType::get(builder.getContext(), /*inputs*/ {__VA_ARGS__},      \
+                          /*result*/ {})
+
+// Default prefix for subroutines of PRIF compiled with LLVM
+#define PRIFNAME_SUB(fmt)                                                      \
+  []() {                                                                       \
+    std::ostringstream oss;                                                    \
+    oss << "prif_" << fmt;                                                     \
+    return fir::NameUniquer::doProcedure({"prif"}, {}, oss.str());             \
+  }()
+
+/// Generate Call to runtime prif_init
+mlir::Value genInitCoarray(fir::FirOpBuilder &builder, mlir::Location loc);
+
+} // namespace fir::runtime
+#endif // FORTRAN_OPTIMIZER_BUILDER_RUNTIME_COARRAY_H

flang/include/flang/Optimizer/Builder/Runtime/Main.h

@@ -25,7 +25,7 @@ namespace fir::runtime {
 
 void genMain(fir::FirOpBuilder &builder, mlir::Location loc,
              const std::vector<Fortran::lower::EnvironmentDefault> &defs,
-             bool initCuda = false);
+             bool initCuda = false, bool initCoarrayEnv = false);
 }
 
 #endif // FORTRAN_OPTIMIZER_BUILDER_RUNTIME_MAIN_H

flang/include/flang/Support/Fortran-features.h

@@ -56,7 +56,7 @@ ENUM_CLASS(LanguageFeature, BackslashEscapes, OldDebugLines,
     IgnoreIrrelevantAttributes, Unsigned, AmbiguousStructureConstructor,
     ContiguousOkForSeqAssociation, ForwardRefExplicitTypeDummy,
     InaccessibleDeferredOverride, CudaWarpMatchFunction, DoConcurrentOffload,
-    TransferBOZ)
+    TransferBOZ, Coarray)
 
 // Portability and suspicious usage warnings
 ENUM_CLASS(UsageWarning, Portability, PointerToUndefinable,

flang/lib/Frontend/CompilerInvocation.cpp

@@ -1152,6 +1152,17 @@ static bool parseDialectArgs(CompilerInvocation &res, llvm::opt::ArgList &args,
       diags.Report(diagID);
     }
   }
+  // -fcoarray
+  if (args.hasArg(clang::driver::options::OPT_fcoarray)) {
+    res.getFrontendOpts().features.Enable(
+        Fortran::common::LanguageFeature::Coarray);
+    const unsigned diagID =
+        diags.getCustomDiagID(clang::DiagnosticsEngine::Warning,
+                              "Support for multi image Fortran features is "
+                              "still experimental and in development.");
+    diags.Report(diagID);
+  }
+
   return diags.getNumErrors() == numErrorsBefore;
 }
 

flang/lib/Lower/Bridge.cpp

@@ -475,7 +475,9 @@ class FirConverter : public Fortran::lower::AbstractConverter {
         fir::runtime::genMain(*builder, toLocation(),
                               bridge.getEnvironmentDefaults(),
                               getFoldingContext().languageFeatures().IsEnabled(
-                                  Fortran::common::LanguageFeature::CUDA));
+                                  Fortran::common::LanguageFeature::CUDA),
+                              getFoldingContext().languageFeatures().IsEnabled(
+                                  Fortran::common::LanguageFeature::Coarray));
       });
 
     finalizeOpenMPLowering(globalOmpRequiresSymbol);

flang/lib/Optimizer/Builder/CMakeLists.txt

@@ -16,6 +16,7 @@ add_flang_library(FIRBuilder
   Runtime/Allocatable.cpp
   Runtime/ArrayConstructor.cpp
   Runtime/Assign.cpp
+  Runtime/Coarray.cpp
   Runtime/Character.cpp
   Runtime/Command.cpp
   Runtime/CUDA/Descriptor.cpp

flang/lib/Optimizer/Builder/Runtime/Coarray.cpp

@@ -0,0 +1,29 @@
+//===-- Coarray.cpp -- runtime API for coarray intrinsics -----------------===//
+//
+// 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/Optimizer/Builder/Runtime/Coarray.h"
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+
+using namespace Fortran::runtime;
+using namespace Fortran::semantics;
+
+/// Generate Call to runtime prif_init
+mlir::Value fir::runtime::genInitCoarray(fir::FirOpBuilder &builder,
+                                         mlir::Location loc) {
+  mlir::Type i32Ty = builder.getI32Type();
+  mlir::Value result = builder.createTemporary(loc, i32Ty);
+  mlir::FunctionType ftype = PRIF_FUNCTYPE(builder.getRefType(i32Ty));
+  mlir::func::FuncOp funcOp =
+      builder.createFunction(loc, PRIFNAME_SUB("init"), ftype);
+  llvm::SmallVector<mlir::Value> args =
+      fir::runtime::createArguments(builder, loc, ftype, result);
+  builder.create<fir::CallOp>(loc, funcOp, args);
+  return builder.create<fir::LoadOp>(loc, result);
+}

flang/lib/Optimizer/Builder/Runtime/Main.cpp

@@ -10,6 +10,7 @@
 #include "flang/Lower/EnvironmentDefault.h"
 #include "flang/Optimizer/Builder/BoxValue.h"
 #include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Builder/Runtime/Coarray.h"
 #include "flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h"
 #include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
 #include "flang/Optimizer/Dialect/FIROps.h"
@@ -23,8 +24,8 @@ using namespace Fortran::runtime;
 /// Create a `int main(...)` that calls the Fortran entry point
 void fir::runtime::genMain(
     fir::FirOpBuilder &builder, mlir::Location loc,
-    const std::vector<Fortran::lower::EnvironmentDefault> &defs,
-    bool initCuda) {
+    const std::vector<Fortran::lower::EnvironmentDefault> &defs, bool initCuda,
+    bool initCoarrayEnv) {
   auto *context = builder.getContext();
   auto argcTy = builder.getDefaultIntegerType();
   auto ptrTy = mlir::LLVM::LLVMPointerType::get(context);
@@ -69,6 +70,8 @@ void fir::runtime::genMain(
         loc, RTNAME_STRING(CUFInit), mlir::FunctionType::get(context, {}, {}));
     fir::CallOp::create(builder, loc, initFn);
   }
+  if (initCoarrayEnv)
+    fir::runtime::genInitCoarray(builder, loc);
 
   fir::CallOp::create(builder, loc, qqMainFn);
   fir::CallOp::create(builder, loc, stopFn);