fixup! [CIR] Add option to emit MLIR in LLVM dialect.

Author: Jezurko

clang/include/clang/Driver/Options.td

@@ -3121,14 +3121,14 @@ def emit_cir_flat : Flag<["-"], "emit-cir-flat">, Visibility<[ClangOption, CC1Op
   Group<Action_Group>, HelpText<"Similar to -emit-cir but also lowers structured CFG into basic blocks.">;
 def emit_mlir : Flag<["-"], "emit-mlir">, Visibility<[CC1Option]>, Group<Action_Group>,
   HelpText<"Build ASTs and then lower through ClangIR to MLIR (standard dialects "
-  "or the LLVM dialect), emit the .mlir file.">;
+  "when `-fno-clangir-direct-lowering` is used or the LLVM dialect when "
+  "`-fclangir-direct-lowering` is used), emit the .mlir file.">;
 def emit_mlir_EQ : Joined<["-"], "emit-mlir=">, Visibility<[CC1Option]>, Group<Action_Group>,
   HelpText<"Build ASTs and then lower through ClangIR to the selected MLIR dialect, emit the .mlir file. "
-  "Allowed values are `std` for MLIR standard dialects "
-  "`llvm` for the LLVM dialect and `cir` for the ClangIR dialect.">,
-  Values<"std,llvm,cir">,
+  "Allowed values are `std` for MLIR standard dialects and `llvm` for the LLVM dialect.">,
+  Values<"std,llvm">,
   NormalizedValuesScope<"FrontendOptions">,
-  NormalizedValues<["MLIR_STD", "MLIR_LLVM", "MLIR_CIR"]>,
+  NormalizedValues<["MLIR_STD", "MLIR_LLVM"]>,
   MarshallingInfoEnum<FrontendOpts<"MLIRTargetDialect">, "MLIR_Default">;
 /// ClangIR-specific options - END
 

clang/include/clang/Frontend/FrontendOptions.h

@@ -533,8 +533,7 @@ class FrontendOptions {
   enum {
     MLIR_Default,
     MLIR_STD,
-    MLIR_LLVM,
-    MLIR_CIR
+    MLIR_LLVM
   } MLIRTargetDialect = MLIR_Default;
 
   /// The input kind, either specified via -x argument or deduced from the input

clang/lib/CIR/FrontendAction/CIRGenAction.cpp

@@ -261,7 +261,9 @@ class CIRGenConsumer : public clang::ASTConsumer {
       }
     }
 
-    auto emitCIR = [&]() {
+    switch (action) {
+    case CIRGenAction::OutputType::EmitCIR:
+    case CIRGenAction::OutputType::EmitCIRFlat:
       if (outputStream && mlirMod) {
         // FIXME: we cannot roundtrip prettyForm=true right now.
         mlir::OpPrintingFlags flags;
@@ -270,45 +272,25 @@ class CIRGenConsumer : public clang::ASTConsumer {
           flags.assumeVerified();
         mlirMod->print(*outputStream, flags);
       }
-    };
-
-    switch (action) {
-    case CIRGenAction::OutputType::EmitCIR:
-    case CIRGenAction::OutputType::EmitCIRFlat:
-      emitCIR();
       break;
     case CIRGenAction::OutputType::EmitMLIR: {
       mlir::ModuleOp loweredMlirModule;
-      switch (feOptions.MLIRTargetDialect) {
-      case clang::FrontendOptions::MLIR_Default:
-        loweredMlirModule =
-            feOptions.ClangIRDirectLowering
-                ? direct::lowerDirectlyFromCIRToLLVMDialect(mlirMod)
-                : lowerFromCIRToMLIR(mlirMod, mlirCtx.get());
-
-        break;
-      case clang::FrontendOptions::MLIR_STD:
+      if (feOptions.ClangIRDirectLowering) {
         // Attempting to emit std with direct lowering is already checked by
         // Compiler Invocation
-        loweredMlirModule = lowerFromCIRToMLIR(mlirMod, mlirCtx.get());
-        break;
-      case clang::FrontendOptions::MLIR_LLVM:
-        loweredMlirModule =
-            feOptions.ClangIRDirectLowering
-                ? direct::lowerDirectlyFromCIRToLLVMDialect(mlirMod)
-                : lowerFromCIRToMLIRToLLVMDialect(mlirMod, mlirCtx.get());
-        break;
-      case clang::FrontendOptions::MLIR_CIR:
-        emitCIR();
-        break;
-      }
-      if (loweredMlirModule) {
-        assert(outputStream && "Why are we here without an output stream?");
-        // FIXME: we cannot roundtrip prettyForm=true right now.
-        mlir::OpPrintingFlags flags;
-        flags.enableDebugInfo(/*enable=*/true, /*prettyForm=*/false);
-        loweredMlirModule->print(*outputStream, flags);
+        loweredMlirModule = direct::lowerDirectlyFromCIRToLLVMDialect(mlirMod);
+      } else {
+          if (feOptions.MLIRTargetDialect == clang::FrontendOptions::MLIR_LLVM)
+            loweredMlirModule = lowerFromCIRToMLIRToLLVMDialect(mlirMod, mlirCtx.get());
+          else // STD and Default cases
+            loweredMlirModule = lowerFromCIRToMLIR(mlirMod, mlirCtx.get());
       }
+      assert(loweredMlirModule && "MLIR module does not exist, but lowering did not fail?");
+      assert(outputStream && "Why are we here without an output stream?");
+      // FIXME: we cannot roundtrip prettyForm=true right now.
+      mlir::OpPrintingFlags flags;
+      flags.enableDebugInfo(/*enable=*/true, /*prettyForm=*/false);
+      loweredMlirModule->print(*outputStream, flags);
       break;
     }
     case CIRGenAction::OutputType::EmitLLVM:

clang/test/CIR/emit-mlir.c

@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-mlir %s -o - | FileCheck %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fno-clangir-direct-lowering -emit-mlir %s -o - | FileCheck %s -check-prefix=STD
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-mlir=llvm %s -o - | FileCheck %s -check-prefix=LLVM
+// RUN: not %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-mlir=std %s -o - 2>&1 | FileCheck %s -check-prefix=STD_ERR
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fno-clangir-direct-lowering -emit-mlir=llvm %s -o - | FileCheck %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fno-clangir-direct-lowering -emit-mlir=std %s -o - | FileCheck %s -check-prefix=STD
+
+// RUN: %clang -fclangir -Xclang -emit-mlir %s -o - -### 2>&1 | FileCheck %s -check-prefix=OPTS_NO_VALUE
+// RUN: %clang -fclangir -Xclang -emit-mlir=llvm %s -o - -###  2>&1 | FileCheck %s -check-prefix=OPTS_LLVM
+// RUN: %clang -fno-clangir-direct-lowering -Xclang -emit-mlir=std %s -o - -### 2>&1 | FileCheck %s -check-prefix=OPTS_STD
+
+int foo(int a, int b) {
+    return a + b;
+}
+
+// LLVM: llvm.func @foo
+// STD: func.func @foo
+// STD_ERR: ClangIR direct lowering is incompatible with emitting of MLIR standard dialects
+// OPTS_NO_VALUE: "-emit-mlir"
+// OPTS_LLVM: "-emit-mlir=llvm"
+// OPTS_STD: "-emit-mlir=std"