add initial set of lowerings for MPI dialect

flake.nix

@@ -0,0 +1,30 @@
+{
+  inputs = {
+    flake-utils.follows = "nix-vscode-extensions/flake-utils";
+    nixpkgs.follows = "nix-vscode-extensions/nixpkgs";
+  };
+
+  outputs = inputs:
+    inputs.flake-utils.lib.eachDefaultSystem
+      (system:
+        let
+          pkgs = inputs.nixpkgs.legacyPackages.${system};
+
+          devShells.default = pkgs.mkShell {
+            buildInputs = [ 
+              packages.default 
+              pkgs.git pkgs.ripgrep pkgs.gdb pkgs.clang-tools
+              pkgs.cmake pkgs.ninja pkgs.clang pkgs.lld pkgs.chrpath
+              pkgs.fish pkgs.neovim pkgs.git pkgs.libclang
+              pkgs.ccache
+            ] ;
+            shellHook = ''
+              export CC=clang
+              export CXX=clang++
+            '';
+          };
+        in
+        {
+          inherit packages devShells;
+        });
+}

mlir/include/mlir/Conversion/MPIToLLVM/MPIToLLVM.h

@@ -0,0 +1,30 @@
+//
+// 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 MLIR_CONVERSION_MPITOLLVM_H
+#define MLIR_CONVERSION_MPITOLLVM_H
+
+#include "mlir/IR/DialectRegistry.h"
+
+namespace mlir {
+
+class LLVMTypeConverter;
+class RewritePatternSet;
+
+#define GEN_PASS_DECL_MPITOLLVMCONVERSIONPASS
+#include "mlir/Conversion/Passes.h.inc"
+
+namespace mpi {
+void populateMPIToLLVMConversionPatterns(LLVMTypeConverter &converter,
+                                         RewritePatternSet &patterns);
+
+void registerConvertMPIToLLVMInterface(DialectRegistry &registry);
+
+} // namespace mpi
+} // namespace mlir
+
+#endif // MLIR_CONVERSION_MPITOLLVM_H

mlir/include/mlir/Dialect/MPI/IR/MPITypes.td

@@ -30,7 +30,7 @@ class MPI_Type<string name, string typeMnemonic, list<Trait> traits = []>
 //===----------------------------------------------------------------------===//
 
 def MPI_Retval : MPI_Type<"Retval", "retval"> {
-  let summary = "MPI function call return value";
+  let summary = "MPI function call return value (!mpi.retval)";
   let description = [{
     This type represents a return value from an MPI function call.
     This value can be MPI_SUCCESS, MPI_ERR_IN_STATUS, or any error code.

mlir/include/mlir/InitAllExtensions.h

@@ -14,6 +14,7 @@
 #ifndef MLIR_INITALLEXTENSIONS_H_
 #define MLIR_INITALLEXTENSIONS_H_
 
+#include "Conversion/MPIToLLVM/MPIToLLVM.h"
 #include "mlir/Conversion/ArithToLLVM/ArithToLLVM.h"
 #include "mlir/Conversion/ComplexToLLVM/ComplexToLLVM.h"
 #include "mlir/Conversion/ControlFlowToLLVM/ControlFlowToLLVM.h"
@@ -62,6 +63,7 @@ inline void registerAllExtensions(DialectRegistry &registry) {
   registerConvertFuncToLLVMInterface(registry);
   index::registerConvertIndexToLLVMInterface(registry);
   registerConvertMathToLLVMInterface(registry);
+  mpi::registerConvertMPIToLLVMInterface(registry);
   registerConvertMemRefToLLVMInterface(registry);
   registerConvertNVVMToLLVMInterface(registry);
   ub::registerConvertUBToLLVMInterface(registry);

mlir/lib/Conversion/CMakeLists.txt

@@ -39,6 +39,7 @@ add_subdirectory(MathToSPIRV)
 add_subdirectory(MemRefToEmitC)
 add_subdirectory(MemRefToLLVM)
 add_subdirectory(MemRefToSPIRV)
+add_subdirectory(MPIToLLVM)
 add_subdirectory(NVGPUToNVVM)
 add_subdirectory(NVVMToLLVM)
 add_subdirectory(OpenACCToSCF)

mlir/lib/Conversion/MPIToLLVM/CMakeLists.txt

@@ -0,0 +1,17 @@
+add_mlir_conversion_library(MLIRMPIToLLVM
+  MPIToLLVM.cpp
+
+  ADDITIONAL_HEADER_DIRS
+  ${MLIR_MAIN_INCLUDE_DIR}/mlir/Conversion/MPIToLLVM
+
+  DEPENDS
+  MLIRConversionPassIncGen
+
+  LINK_COMPONENTS
+  Core
+
+  LINK_LIBS PUBLIC
+  MLIRLLVMCommonConversion
+  MLIRLLVMDialect
+  MLIRMPIDialect
+  )