ConvertToLLVM.cpp

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//===- ConvertToLLVM.cpp - ConvertToLLVM Pass ----------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the ConvertToLLVM pass.
//
//===----------------------------------------------------------------------===//
 
#include "circt/Conversion/ConvertToLLVM.h"
#include "circt/Conversion/CombToArith.h"
#include "circt/Conversion/CombToLLVM.h"
#include "circt/Conversion/HWToLLVM.h"
#include "circt/Dialect/Comb/CombOps.h"
#include "circt/Dialect/SV/SVOps.h"
#include "mlir/Conversion/ArithToLLVM/ArithToLLVM.h"
#include "mlir/Conversion/ControlFlowToLLVM/ControlFlowToLLVM.h"
#include "mlir/Conversion/FuncToLLVM/ConvertFuncToLLVM.h"
#include "mlir/Conversion/IndexToLLVM/IndexToLLVM.h"
#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
#include "mlir/Conversion/LLVMCommon/Pattern.h"
#include "mlir/Conversion/SCFToControlFlow/SCFToControlFlow.h"
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Transforms/DialectConversion.h"
 
using namespace mlir;
using namespace circt;
 
namespace circt {
#define GEN_PASS_DEF_CONVERTTOLLVM
#include "circt/Conversion/Passes.h.inc"
 
namespace impl {
 
//===----------------------------------------------------------------------===//
// Pass Implementation
//===----------------------------------------------------------------------===//
 
struct ConvertToLLVMPass : public ConvertToLLVMBase<ConvertToLLVMPass> {
  void runOnOperation() override;
 
private:
  void convertFuncOp(func::FuncOp funcOp);
};
 
void ConvertToLLVMPass::runOnOperation() {
  // Iterate over all func.func operations in the module and convert them
  for (auto funcOp :
       llvm::make_early_inc_range(getOperation().getOps<func::FuncOp>())) {
    convertFuncOp(funcOp);
  }
}
 
void ConvertToLLVMPass::convertFuncOp(func::FuncOp funcOp) {
  MLIRContext *context = &getContext();
  RewritePatternSet patterns(context);
  auto converter = mlir::LLVMTypeConverter(context);
 
  // Add HW to LLVM type conversions
  populateHWToLLVMTypeConversions(converter);
 
  LLVMConversionTarget target(*context);
  target.addIllegalDialect<comb::CombDialect>();
  target.addIllegalDialect<arith::ArithDialect>();
 
  // Mark HW and SV dialects as legal - we only convert operations inside
  // func.func
  target.addLegalDialect<hw::HWDialect>();
  target.addLegalDialect<sv::SVDialect>();
 
  // Mark hw.constant as illegal so it gets converted to arith.constant
  // (via CombToArith) and then to llvm.mlir.constant
  target.addIllegalOp<hw::ConstantOp>();
 
  // Setup the conversion patterns in the correct order:
  // 1. SCF to ControlFlow (for structured control flow)
  populateSCFToControlFlowConversionPatterns(patterns);
 
  // 2. Func to LLVM (for function operations)
  populateFuncToLLVMConversionPatterns(converter, patterns);
 
  // 3. ControlFlow to LLVM (for control flow operations)
  cf::populateControlFlowToLLVMConversionPatterns(converter, patterns);
 
  // 4. Comb to Arith (for most combinational operations)
  populateCombToArithConversionPatterns(converter, patterns);
 
  // 5. Arith to LLVM (for arithmetic operations)
  arith::populateArithToLLVMConversionPatterns(converter, patterns);
 
  // 6. Index to LLVM (for index operations)
  index::populateIndexToLLVMConversionPatterns(converter, patterns);
 
  // 7. Any function op interface type conversion
  populateAnyFunctionOpInterfaceTypeConversionPattern(patterns, converter);
 
  // 8. Comb to LLVM (for operations without Comb-to-Arith patterns, like
  // parity)
  populateCombToLLVMConversionPatterns(converter, patterns);
 
  // Apply the partial conversion only to this func.func operation
  if (failed(applyPartialConversion(funcOp, target, std::move(patterns))))
    signalPassFailure();
}
 
} // namespace impl
} // namespace circt