//===- Function.cpp - MLIR Function Classes -------------------------------===//
//
// Part of the MLIR 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/IR/Function.h"
#include "mlir/IR/BlockAndValueMapping.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/Diagnostics.h"
#include "mlir/IR/Dialect.h"
#include "mlir/IR/FunctionImplementation.h"
#include "mlir/IR/MLIRContext.h"
#include "mlir/IR/Module.h"
#include "mlir/IR/OpImplementation.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Twine.h"

using namespace mlir;

//===----------------------------------------------------------------------===//
// Function Operation.
//===----------------------------------------------------------------------===//

FuncOp FuncOp::create(Location location, StringRef name, FunctionType type,
                      ArrayRef<NamedAttribute> attrs) {
  OperationState state(location, "func");
  Builder builder(location->getContext());
  FuncOp::build(&builder, state, name, type, attrs);
  return cast<FuncOp>(Operation::create(state));
}
FuncOp FuncOp::create(Location location, StringRef name, FunctionType type,
                      iterator_range<dialect_attr_iterator> attrs) {
  SmallVector<NamedAttribute, 8> attrRef(attrs);
  return create(location, name, type, llvm::makeArrayRef(attrRef));
}
FuncOp FuncOp::create(Location location, StringRef name, FunctionType type,
                      ArrayRef<NamedAttribute> attrs,
                      ArrayRef<NamedAttributeList> argAttrs) {
  FuncOp func = create(location, name, type, attrs);
  func.setAllArgAttrs(argAttrs);
  return func;
}

void FuncOp::build(Builder *builder, OperationState &result, StringRef name,
                   FunctionType type, ArrayRef<NamedAttribute> attrs) {
  result.addAttribute(SymbolTable::getSymbolAttrName(),
                      builder->getStringAttr(name));
  result.addAttribute(getTypeAttrName(), TypeAttr::get(type));
  result.attributes.append(attrs.begin(), attrs.end());
  result.addRegion();
}

void FuncOp::build(Builder *builder, OperationState &result, StringRef name,
                   FunctionType type, ArrayRef<NamedAttribute> attrs,
                   ArrayRef<NamedAttributeList> argAttrs) {
  build(builder, result, name, type, attrs);
  assert(type.getNumInputs() == argAttrs.size());
  SmallString<8> argAttrName;
  for (unsigned i = 0, e = type.getNumInputs(); i != e; ++i)
    if (auto argDict = argAttrs[i].getDictionary())
      result.addAttribute(getArgAttrName(i, argAttrName), argDict);
}

/// Parsing/Printing methods.

ParseResult FuncOp::parse(OpAsmParser &parser, OperationState &result) {
  auto buildFuncType = [](Builder &builder, ArrayRef<Type> argTypes,
                          ArrayRef<Type> results, impl::VariadicFlag,
                          std::string &) {
    return builder.getFunctionType(argTypes, results);
  };

  return impl::parseFunctionLikeOp(parser, result, /*allowVariadic=*/false,
                                   buildFuncType);
}

void FuncOp::print(OpAsmPrinter &p) {
  FunctionType fnType = getType();
  impl::printFunctionLikeOp(p, *this, fnType.getInputs(), /*isVariadic=*/false,
                            fnType.getResults());
}

LogicalResult FuncOp::verify() {
  // If this function is external there is nothing to do.
  if (isExternal())
    return success();

  // Verify that the argument list of the function and the arg list of the entry
  // block line up.  The trait already verified that the number of arguments is
  // the same between the signature and the block.
  auto fnInputTypes = getType().getInputs();
  Block &entryBlock = front();
  for (unsigned i = 0, e = entryBlock.getNumArguments(); i != e; ++i)
    if (fnInputTypes[i] != entryBlock.getArgument(i).getType())
      return emitOpError("type of entry block argument #")
             << i << '(' << entryBlock.getArgument(i).getType()
             << ") must match the type of the corresponding argument in "
             << "function signature(" << fnInputTypes[i] << ')';

  return success();
}

void FuncOp::eraseArguments(ArrayRef<unsigned> argIndices) {
  auto oldType = getType();
  int originalNumArgs = oldType.getNumInputs();
  llvm::BitVector eraseIndices(originalNumArgs);
  for (auto index : argIndices)
    eraseIndices.set(index);
  auto shouldEraseArg = [&](int i) { return eraseIndices.test(i); };

  // There are 3 things that need to be updated:
  // - Function type.
  // - Arg attrs.
  // - Block arguments of entry block.

  // Update the function type and arg attrs.
  SmallVector<Type, 4> newInputTypes;
  SmallVector<NamedAttributeList, 4> newArgAttrs;
  for (int i = 0; i < originalNumArgs; i++) {
    if (shouldEraseArg(i))
      continue;
    newInputTypes.emplace_back(oldType.getInput(i));
    newArgAttrs.emplace_back(getArgAttrDict(i));
  }
  setType(FunctionType::get(newInputTypes, oldType.getResults(), getContext()));
  setAllArgAttrs(newArgAttrs);

  // Update the entry block's arguments.
  // We do this in reverse so that we erase later indices before earlier
  // indices, to avoid shifting the later indices.
  Block &entry = front();
  for (int i = 0; i < originalNumArgs; i++)
    if (shouldEraseArg(originalNumArgs - i - 1))
      entry.eraseArgument(originalNumArgs - i - 1);
}

/// Add an entry block to an empty function, and set up the block arguments
/// to match the signature of the function.
Block *FuncOp::addEntryBlock() {
  assert(empty() && "function already has an entry block");
  auto *entry = new Block();
  push_back(entry);
  entry->addArguments(getType().getInputs());
  return entry;
}

/// Add a normal block to the end of the function's block list. The function
/// should at least already have an entry block.
Block *FuncOp::addBlock() {
  assert(!empty() && "function should at least have an entry block");
  push_back(new Block());
  return &back();
}

/// Clone the internal blocks from this function into dest and all attributes
/// from this function to dest.
void FuncOp::cloneInto(FuncOp dest, BlockAndValueMapping &mapper) {
  // Add the attributes of this function to dest.
  llvm::MapVector<Identifier, Attribute> newAttrs;
  for (auto &attr : dest.getAttrs())
    newAttrs.insert(attr);
  for (auto &attr : getAttrs())
    newAttrs.insert(attr);
  dest.getOperation()->setAttrs(
      DictionaryAttr::get(newAttrs.takeVector(), getContext()));

  // Clone the body.
  getBody().cloneInto(&dest.getBody(), mapper);
}

/// Create a deep copy of this function and all of its blocks, remapping
/// any operands that use values outside of the function using the map that is
/// provided (leaving them alone if no entry is present). Replaces references
/// to cloned sub-values with the corresponding value that is copied, and adds
/// those mappings to the mapper.
FuncOp FuncOp::clone(BlockAndValueMapping &mapper) {
  FunctionType newType = getType();

  // If the function has a body, then the user might be deleting arguments to
  // the function by specifying them in the mapper. If so, we don't add the
  // argument to the input type vector.
  bool isExternalFn = isExternal();
  if (!isExternalFn) {
    SmallVector<Type, 4> inputTypes;
    inputTypes.reserve(newType.getNumInputs());
    for (unsigned i = 0, e = getNumArguments(); i != e; ++i)
      if (!mapper.contains(getArgument(i)))
        inputTypes.push_back(newType.getInput(i));
    newType = FunctionType::get(inputTypes, newType.getResults(), getContext());
  }

  // Create the new function.
  FuncOp newFunc = cast<FuncOp>(getOperation()->cloneWithoutRegions());
  newFunc.setType(newType);

  /// Set the argument attributes for arguments that aren't being replaced.
  for (unsigned i = 0, e = getNumArguments(), destI = 0; i != e; ++i)
    if (isExternalFn || !mapper.contains(getArgument(i)))
      newFunc.setArgAttrs(destI++, getArgAttrs(i));

  /// Clone the current function into the new one and return it.
  cloneInto(newFunc, mapper);
  return newFunc;
}
FuncOp FuncOp::clone() {
  BlockAndValueMapping mapper;
  return clone(mapper);
}