Revert "[CIR] Initial implementation of CIR-to-LLVM IR lowering pass (llvm#125260)"

This reverts commit 622ee03.

Author: lanza

clang/include/clang/CIR/LowerToLLVM.h

@@ -12,6 +12,8 @@
 #ifndef CLANG_CIR_LOWERTOLLVM_H
 #define CLANG_CIR_LOWERTOLLVM_H
 
+#include "mlir/Pass/Pass.h"
+
 #include <memory>
 
 namespace llvm {

clang/include/clang/CIR/MissingFeatures.h

@@ -3,15 +3,9 @@ set(LLVM_LINK_COMPONENTS
   Support
   )
 
-get_property(dialect_libs GLOBAL PROPERTY MLIR_DIALECT_LIBS)
-
 add_clang_library(clangCIRLoweringDirectToLLVM
   LowerToLLVM.cpp
 
   LINK_LIBS
   MLIRIR
-  ${dialect_libs}
-  MLIRCIR
-  MLIRBuiltinToLLVMIRTranslation
-  MLIRLLVMToLLVMIRTranslation
   )

clang/lib/CIR/Lowering/DirectToLLVM/CMakeLists.txt

@@ -10,22 +10,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "LowerToLLVM.h"
+#include "clang/CIR/LowerToLLVM.h"
 
-#include "mlir/Conversion/LLVMCommon/TypeConverter.h"
-#include "mlir/Dialect/DLTI/DLTI.h"
-#include "mlir/Dialect/Func/IR/FuncOps.h"
-#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
-#include "mlir/IR/BuiltinDialect.h"
 #include "mlir/IR/BuiltinOps.h"
-#include "mlir/Pass/Pass.h"
-#include "mlir/Pass/PassManager.h"
-#include "mlir/Target/LLVMIR/Dialect/Builtin/BuiltinToLLVMIRTranslation.h"
-#include "mlir/Target/LLVMIR/Dialect/LLVMIR/LLVMToLLVMIRTranslation.h"
-#include "mlir/Target/LLVMIR/Export.h"
-#include "mlir/Transforms/DialectConversion.h"
-#include "clang/CIR/Dialect/IR/CIRDialect.h"
-#include "clang/CIR/MissingFeatures.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/TimeProfiler.h"
 
@@ -35,165 +22,16 @@ using namespace llvm;
 namespace cir {
 namespace direct {
 
-// This pass requires the CIR to be in a "flat" state. All blocks in each
-// function must belong to the parent region. Once scopes and control flow
-// are implemented in CIR, a pass will be run before this one to flatten
-// the CIR and get it into the state that this pass requires.
-struct ConvertCIRToLLVMPass
-    : public mlir::PassWrapper<ConvertCIRToLLVMPass,
-                               mlir::OperationPass<mlir::ModuleOp>> {
-  void getDependentDialects(mlir::DialectRegistry &registry) const override {
-    registry.insert<mlir::BuiltinDialect, mlir::DLTIDialect,
-                    mlir::LLVM::LLVMDialect, mlir::func::FuncDialect>();
-  }
-  void runOnOperation() final;
-
-  StringRef getDescription() const override {
-    return "Convert the prepared CIR dialect module to LLVM dialect";
-  }
-
-  StringRef getArgument() const override { return "cir-flat-to-llvm"; }
-};
-
-mlir::LogicalResult CIRToLLVMGlobalOpLowering::matchAndRewrite(
-    cir::GlobalOp op, OpAdaptor adaptor,
-    mlir::ConversionPatternRewriter &rewriter) const {
-
-  // Fetch required values to create LLVM op.
-  const mlir::Type cirSymType = op.getSymType();
-
-  // This is the LLVM dialect type.
-  const mlir::Type llvmType = getTypeConverter()->convertType(cirSymType);
-  // FIXME: These default values are placeholders until the the equivalent
-  //        attributes are available on cir.global ops.
-  assert(!cir::MissingFeatures::opGlobalConstant());
-  const bool isConst = false;
-  assert(!cir::MissingFeatures::addressSpace());
-  const unsigned addrSpace = 0;
-  assert(!cir::MissingFeatures::opGlobalDSOLocal());
-  const bool isDsoLocal = true;
-  assert(!cir::MissingFeatures::opGlobalThreadLocal());
-  const bool isThreadLocal = false;
-  assert(!cir::MissingFeatures::opGlobalAlignment());
-  const uint64_t alignment = 0;
-  assert(!cir::MissingFeatures::opGlobalLinkage());
-  const mlir::LLVM::Linkage linkage = mlir::LLVM::Linkage::External;
-  const StringRef symbol = op.getSymName();
-  std::optional<mlir::Attribute> init = op.getInitialValue();
-
-  SmallVector<mlir::NamedAttribute> attributes;
-
-  if (init.has_value()) {
-    if (const auto fltAttr = mlir::dyn_cast<cir::FPAttr>(init.value())) {
-      // Initializer is a constant floating-point number: convert to MLIR
-      // builtin constant.
-      init = rewriter.getFloatAttr(llvmType, fltAttr.getValue());
-    } else if (const auto intAttr =
-                   mlir::dyn_cast<cir::IntAttr>(init.value())) {
-      // Initializer is a constant array: convert it to a compatible llvm init.
-      init = rewriter.getIntegerAttr(llvmType, intAttr.getValue());
-    } else {
-      op.emitError() << "unsupported initializer '" << init.value() << "'";
-      return mlir::failure();
-    }
-  }
-
-  // Rewrite op.
-  rewriter.replaceOpWithNewOp<mlir::LLVM::GlobalOp>(
-      op, llvmType, isConst, linkage, symbol, init.value_or(mlir::Attribute()),
-      alignment, addrSpace, isDsoLocal, isThreadLocal,
-      /*comdat=*/mlir::SymbolRefAttr(), attributes);
-
-  return mlir::success();
-}
-
-static void prepareTypeConverter(mlir::LLVMTypeConverter &converter,
-                                 mlir::DataLayout &dataLayout) {
-  converter.addConversion([&](cir::IntType type) -> mlir::Type {
-    // LLVM doesn't work with signed types, so we drop the CIR signs here.
-    return mlir::IntegerType::get(type.getContext(), type.getWidth());
-  });
-  converter.addConversion([&](cir::SingleType type) -> mlir::Type {
-    return mlir::Float32Type::get(type.getContext());
-  });
-  converter.addConversion([&](cir::DoubleType type) -> mlir::Type {
-    return mlir::Float64Type::get(type.getContext());
-  });
-  converter.addConversion([&](cir::FP80Type type) -> mlir::Type {
-    return mlir::Float80Type::get(type.getContext());
-  });
-  converter.addConversion([&](cir::FP128Type type) -> mlir::Type {
-    return mlir::Float128Type::get(type.getContext());
-  });
-  converter.addConversion([&](cir::LongDoubleType type) -> mlir::Type {
-    return converter.convertType(type.getUnderlying());
-  });
-  converter.addConversion([&](cir::FP16Type type) -> mlir::Type {
-    return mlir::Float16Type::get(type.getContext());
-  });
-  converter.addConversion([&](cir::BF16Type type) -> mlir::Type {
-    return mlir::BFloat16Type::get(type.getContext());
-  });
-}
-
-void ConvertCIRToLLVMPass::runOnOperation() {
-  llvm::TimeTraceScope scope("Convert CIR to LLVM Pass");
-
-  mlir::ModuleOp module = getOperation();
-  mlir::DataLayout dl(module);
-  mlir::LLVMTypeConverter converter(&getContext());
-  prepareTypeConverter(converter, dl);
-
-  mlir::RewritePatternSet patterns(&getContext());
-
-  patterns.add<CIRToLLVMGlobalOpLowering>(converter, patterns.getContext(), dl);
-
-  mlir::ConversionTarget target(getContext());
-  target.addLegalOp<mlir::ModuleOp>();
-  target.addLegalDialect<mlir::LLVM::LLVMDialect>();
-  target.addIllegalDialect<mlir::BuiltinDialect, cir::CIRDialect,
-                           mlir::func::FuncDialect>();
-
-  if (failed(applyPartialConversion(module, target, std::move(patterns))))
-    signalPassFailure();
-}
-
-static std::unique_ptr<mlir::Pass> createConvertCIRToLLVMPass() {
-  return std::make_unique<ConvertCIRToLLVMPass>();
-}
-
-static void populateCIRToLLVMPasses(mlir::OpPassManager &pm) {
-  pm.addPass(createConvertCIRToLLVMPass());
-}
-
 std::unique_ptr<llvm::Module>
 lowerDirectlyFromCIRToLLVMIR(mlir::ModuleOp mlirModule, LLVMContext &llvmCtx) {
   llvm::TimeTraceScope scope("lower from CIR to LLVM directly");
 
-  mlir::MLIRContext *mlirCtx = mlirModule.getContext();
-
-  mlir::PassManager pm(mlirCtx);
-  populateCIRToLLVMPasses(pm);
-
-  if (mlir::failed(pm.run(mlirModule))) {
-    // FIXME: Handle any errors where they occurs and return a nullptr here.
-    report_fatal_error(
-        "The pass manager failed to lower CIR to LLVMIR dialect!");
-  }
-
-  mlir::registerBuiltinDialectTranslation(*mlirCtx);
-  mlir::registerLLVMDialectTranslation(*mlirCtx);
-
-  llvm::TimeTraceScope translateScope("translateModuleToLLVMIR");
-
-  StringRef moduleName = mlirModule.getName().value_or("CIRToLLVMModule");
-  std::unique_ptr<llvm::Module> llvmModule =
-      mlir::translateModuleToLLVMIR(mlirModule, llvmCtx, moduleName);
+  std::optional<StringRef> moduleName = mlirModule.getName();
+  auto llvmModule = std::make_unique<llvm::Module>(
+      moduleName ? *moduleName : "CIRToLLVMModule", llvmCtx);
 
-  if (!llvmModule) {
-    // FIXME: Handle any errors where they occurs and return a nullptr here.
+  if (!llvmModule)
     report_fatal_error("Lowering from LLVMIR dialect to llvm IR failed!");
-  }
 
   return llvmModule;
 }

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -1,10 +1,8 @@
 // Smoke test for ClangIR-to-LLVM IR code generation
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o -  | FileCheck %s
 
-int a;
+// TODO: Add checks when proper lowering is implemented.
+//       For now, we're just creating an empty module.
+// CHECK: ModuleID
 
-// CHECK: @a = external dso_local global i32
-
-int b = 2;
-
-// CHECK: @b = dso_local global i32 2
+void foo() {}