//===- FuncOps.cpp - Func Dialect Operations ------------------------------===//
//
// 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 "mlir/Dialect/Func/IR/FuncOps.h"

#include "mlir/Dialect/ControlFlow/IR/ControlFlowOps.h"
#include "mlir/IR/BlockAndValueMapping.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/BuiltinTypes.h"
#include "mlir/IR/Matchers.h"
#include "mlir/IR/OpImplementation.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/IR/Value.h"
#include "mlir/Support/MathExtras.h"
#include "mlir/Transforms/InliningUtils.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/raw_ostream.h"
#include <numeric>

#include "mlir/Dialect/Func/IR/FuncOpsDialect.cpp.inc"

using namespace mlir;
using namespace mlir::func;

//===----------------------------------------------------------------------===//
// FuncDialect Interfaces
//===----------------------------------------------------------------------===//
namespace {
/// This class defines the interface for handling inlining with func operations.
struct FuncInlinerInterface : public DialectInlinerInterface {
  using DialectInlinerInterface::DialectInlinerInterface;

  //===--------------------------------------------------------------------===//
  // Analysis Hooks
  //===--------------------------------------------------------------------===//

  /// All call operations can be inlined.
  bool isLegalToInline(Operation *call, Operation *callable,
                       bool wouldBeCloned) const final {
    return true;
  }

  /// All operations can be inlined.
  bool isLegalToInline(Operation *, Region *, bool,
                       BlockAndValueMapping &) const final {
    return true;
  }

  //===--------------------------------------------------------------------===//
  // Transformation Hooks
  //===--------------------------------------------------------------------===//

  /// Handle the given inlined terminator by replacing it with a new operation
  /// as necessary.
  void handleTerminator(Operation *op, Block *newDest) const final {
    // Only return needs to be handled here.
    auto returnOp = dyn_cast<ReturnOp>(op);
    if (!returnOp)
      return;

    // Replace the return with a branch to the dest.
    OpBuilder builder(op);
    builder.create<cf::BranchOp>(op->getLoc(), newDest, returnOp.getOperands());
    op->erase();
  }

  /// Handle the given inlined terminator by replacing it with a new operation
  /// as necessary.
  void handleTerminator(Operation *op,
                        ArrayRef<Value> valuesToRepl) const final {
    // Only return needs to be handled here.
    auto returnOp = cast<ReturnOp>(op);

    // Replace the values directly with the return operands.
    assert(returnOp.getNumOperands() == valuesToRepl.size());
    for (const auto &it : llvm::enumerate(returnOp.getOperands()))
      valuesToRepl[it.index()].replaceAllUsesWith(it.value());
  }
};
} // namespace

//===----------------------------------------------------------------------===//
// FuncDialect
//===----------------------------------------------------------------------===//

void FuncDialect::initialize() {
  addOperations<
#define GET_OP_LIST
#include "mlir/Dialect/Func/IR/FuncOps.cpp.inc"
      >();
  addInterfaces<FuncInlinerInterface>();
}

/// Materialize a single constant operation from a given attribute value with
/// the desired resultant type.
Operation *FuncDialect::materializeConstant(OpBuilder &builder, Attribute value,
                                            Type type, Location loc) {
  if (ConstantOp::isBuildableWith(value, type))
    return builder.create<ConstantOp>(loc, type,
                                      value.cast<FlatSymbolRefAttr>());
  return nullptr;
}

//===----------------------------------------------------------------------===//
// CallOp
//===----------------------------------------------------------------------===//

LogicalResult CallOp::verifySymbolUses(SymbolTableCollection &symbolTable) {
  // Check that the callee attribute was specified.
  auto fnAttr = (*this)->getAttrOfType<FlatSymbolRefAttr>("callee");
  if (!fnAttr)
    return emitOpError("requires a 'callee' symbol reference attribute");
  FuncOp fn = symbolTable.lookupNearestSymbolFrom<FuncOp>(*this, fnAttr);
  if (!fn)
    return emitOpError() << "'" << fnAttr.getValue()
                         << "' does not reference a valid function";

  // Verify that the operand and result types match the callee.
  auto fnType = fn.getType();
  if (fnType.getNumInputs() != getNumOperands())
    return emitOpError("incorrect number of operands for callee");

  for (unsigned i = 0, e = fnType.getNumInputs(); i != e; ++i)
    if (getOperand(i).getType() != fnType.getInput(i))
      return emitOpError("operand type mismatch: expected operand type ")
             << fnType.getInput(i) << ", but provided "
             << getOperand(i).getType() << " for operand number " << i;

  if (fnType.getNumResults() != getNumResults())
    return emitOpError("incorrect number of results for callee");

  for (unsigned i = 0, e = fnType.getNumResults(); i != e; ++i)
    if (getResult(i).getType() != fnType.getResult(i)) {
      auto diag = emitOpError("result type mismatch at index ") << i;
      diag.attachNote() << "      op result types: " << getResultTypes();
      diag.attachNote() << "function result types: " << fnType.getResults();
      return diag;
    }

  return success();
}

FunctionType CallOp::getCalleeType() {
  return FunctionType::get(getContext(), getOperandTypes(), getResultTypes());
}

//===----------------------------------------------------------------------===//
// CallIndirectOp
//===----------------------------------------------------------------------===//

/// Fold indirect calls that have a constant function as the callee operand.
LogicalResult CallIndirectOp::canonicalize(CallIndirectOp indirectCall,
                                           PatternRewriter &rewriter) {
  // Check that the callee is a constant callee.
  SymbolRefAttr calledFn;
  if (!matchPattern(indirectCall.getCallee(), m_Constant(&calledFn)))
    return failure();

  // Replace with a direct call.
  rewriter.replaceOpWithNewOp<CallOp>(indirectCall, calledFn,
                                      indirectCall.getResultTypes(),
                                      indirectCall.getArgOperands());
  return success();
}

//===----------------------------------------------------------------------===//
// ConstantOp
//===----------------------------------------------------------------------===//

LogicalResult ConstantOp::verify() {
  StringRef fnName = getValue();
  Type type = getType();

  // Try to find the referenced function.
  auto fn = (*this)->getParentOfType<ModuleOp>().lookupSymbol<FuncOp>(fnName);
  if (!fn)
    return emitOpError() << "reference to undefined function '" << fnName
                         << "'";

  // Check that the referenced function has the correct type.
  if (fn.getType() != type)
    return emitOpError("reference to function with mismatched type");

  return success();
}

OpFoldResult ConstantOp::fold(ArrayRef<Attribute> operands) {
  assert(operands.empty() && "constant has no operands");
  return getValueAttr();
}

void ConstantOp::getAsmResultNames(
    function_ref<void(Value, StringRef)> setNameFn) {
  setNameFn(getResult(), "f");
}

bool ConstantOp::isBuildableWith(Attribute value, Type type) {
  return value.isa<FlatSymbolRefAttr>() && type.isa<FunctionType>();
}

//===----------------------------------------------------------------------===//
// ReturnOp
//===----------------------------------------------------------------------===//

LogicalResult ReturnOp::verify() {
  auto function = cast<FuncOp>((*this)->getParentOp());

  // The operand number and types must match the function signature.
  const auto &results = function.getType().getResults();
  if (getNumOperands() != results.size())
    return emitOpError("has ")
           << getNumOperands() << " operands, but enclosing function (@"
           << function.getName() << ") returns " << results.size();

  for (unsigned i = 0, e = results.size(); i != e; ++i)
    if (getOperand(i).getType() != results[i])
      return emitError() << "type of return operand " << i << " ("
                         << getOperand(i).getType()
                         << ") doesn't match function result type ("
                         << results[i] << ")"
                         << " in function @" << function.getName();

  return success();
}

//===----------------------------------------------------------------------===//
// TableGen'd op method definitions
//===----------------------------------------------------------------------===//

#define GET_OP_CLASSES
#include "mlir/Dialect/Func/IR/FuncOps.cpp.inc"