llvm-project/mlir/lib/IR/Function.cpp

//===- Function.cpp - MLIR Function Classes -------------------------------===//
//
// Copyright 2019 The MLIR Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// =============================================================================

#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/MLIRContext.h"
#include "mlir/IR/Module.h"
#include "mlir/IR/OpImplementation.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 llvm::cast<FuncOp>(Operation::create(state));
}
FuncOp FuncOp::create(Location location, StringRef name, FunctionType type,
                      llvm::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("type", builder->getTypeAttr(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.
static ParseResult
parseArgumentList(OpAsmParser *parser, SmallVectorImpl<Type> &argTypes,
                  SmallVectorImpl<OpAsmParser::OperandType> &argNames,
                  SmallVectorImpl<SmallVector<NamedAttribute, 2>> &argAttrs) {
  if (parser->parseLParen())
    return failure();

  // The argument list either has to consistently have ssa-id's followed by
  // types, or just be a type list.  It isn't ok to sometimes have SSA ID's and
  // sometimes not.
  auto parseArgument = [&]() -> ParseResult {
    llvm::SMLoc loc = parser->getCurrentLocation();

    // Parse argument name if present.
    OpAsmParser::OperandType argument;
    Type argumentType;
    if (succeeded(parser->parseOptionalRegionArgument(argument)) &&
        !argument.name.empty()) {
      // Reject this if the preceding argument was missing a name.
      if (argNames.empty() && !argTypes.empty())
        return parser->emitError(loc,
                                 "expected type instead of SSA identifier");
      argNames.push_back(argument);

      if (parser->parseColonType(argumentType))
        return failure();
    } else if (!argNames.empty()) {
      // Reject this if the preceding argument had a name.
      return parser->emitError(loc, "expected SSA identifier");
    } else if (parser->parseType(argumentType)) {
      return failure();
    }

    // Add the argument type.
    argTypes.push_back(argumentType);

    // Parse any argument attributes.
    SmallVector<NamedAttribute, 2> attrs;
    if (parser->parseOptionalAttributeDict(attrs))
      return failure();
    argAttrs.push_back(attrs);
    return success();
  };

  // Parse the function arguments.
  if (parser->parseOptionalRParen()) {
    do {
      if (parseArgument())
        return failure();
    } while (succeeded(parser->parseOptionalComma()));
    parser->parseRParen();
  }

  return success();
}

/// Parse a function signature, starting with a name and including the
/// parameter list.
static ParseResult parseFunctionSignature(
    OpAsmParser *parser, FunctionType &type,
    SmallVectorImpl<OpAsmParser::OperandType> &argNames,
    SmallVectorImpl<SmallVector<NamedAttribute, 2>> &argAttrs) {
  SmallVector<Type, 4> argTypes;
  if (parseArgumentList(parser, argTypes, argNames, argAttrs))
    return failure();

  // Parse the return types if present.
  SmallVector<Type, 4> results;
  if (parser->parseOptionalArrowTypeList(results))
    return failure();
  type = parser->getBuilder().getFunctionType(argTypes, results);
  return success();
}

ParseResult FuncOp::parse(OpAsmParser *parser, OperationState *result) {
  FunctionType type;
  SmallVector<OpAsmParser::OperandType, 4> entryArgs;
  SmallVector<SmallVector<NamedAttribute, 2>, 4> argAttrs;
  auto &builder = parser->getBuilder();

  // Parse the name as a symbol reference attribute.
  SymbolRefAttr nameAttr;
  if (parser->parseAttribute(nameAttr, SymbolTable::getSymbolAttrName(),
                             result->attributes))
    return failure();
  // Convert the parsed function attr into a string attr.
  result->attributes.back().second = builder.getStringAttr(nameAttr.getValue());

  // Parse the function signature.
  if (parseFunctionSignature(parser, type, entryArgs, argAttrs))
    return failure();
  result->addAttribute("type", builder.getTypeAttr(type));

  // If function attributes are present, parse them.
  if (succeeded(parser->parseOptionalKeyword("attributes")))
    if (parser->parseOptionalAttributeDict(result->attributes))
      return failure();

  // Add the attributes to the function arguments.
  SmallString<8> argAttrName;
  for (unsigned i = 0, e = type.getNumInputs(); i != e; ++i)
    if (!argAttrs[i].empty())
      result->addAttribute(getArgAttrName(i, argAttrName),
                           builder.getDictionaryAttr(argAttrs[i]));

  // Parse the optional function body.
  auto *body = result->addRegion();
  if (parser->parseOptionalRegion(
          *body, entryArgs, entryArgs.empty() ? llvm::None : type.getInputs()))
    return failure();

  return success();
}

static void printFunctionSignature(OpAsmPrinter *p, FuncOp op) {
  *p << '(';

  auto fnType = op.getType();
  bool isExternal = op.isExternal();
  for (unsigned i = 0, e = op.getNumArguments(); i != e; ++i) {
    if (i > 0)
      *p << ", ";

    // If this is an external function, don't print argument labels.
    if (!isExternal) {
      p->printOperand(op.getArgument(i));
      *p << ": ";
    }

    // Print the type followed by any argument attributes.
    p->printType(fnType.getInput(i));
    p->printOptionalAttrDict(op.getArgAttrs(i));
  }
  *p << ')';
  p->printOptionalArrowTypeList(fnType.getResults());
}

void FuncOp::print(OpAsmPrinter *p) {
  *p << "func @" << getName();

  // Print the signature.
  printFunctionSignature(p, *this);

  // Print out function attributes, if present.
  SmallVector<StringRef, 2> ignoredAttrs = {SymbolTable::getSymbolAttrName(),
                                            "type"};

  // Ignore any argument attributes.
  std::vector<SmallString<8>> argAttrStorage;
  SmallString<8> argAttrName;
  for (unsigned i = 0, e = getNumArguments(); i != e; ++i)
    if (getAttr(getArgAttrName(i, argAttrName)))
      argAttrStorage.emplace_back(argAttrName);
  ignoredAttrs.append(argAttrStorage.begin(), argAttrStorage.end());

  auto attrs = getAttrs();
  if (attrs.size() > ignoredAttrs.size()) {
    *p << "\n  attributes ";
    p->printOptionalAttrDict(attrs, ignoredAttrs);
  }

  // Print the body if this is not an external function.
  if (!isExternal())
    p->printRegion(getBody(), /*printEntryBlockArgs=*/false,
                   /*printBlockTerminators=*/true);
}

LogicalResult FuncOp::verify() {
  auto fnInputTypes = getType().getInputs();

  /// Verify that all of the argument attributes are dialect attributes.
  for (unsigned i = 0, e = fnInputTypes.size(); i != e; ++i) {
    for (auto attr : getArgAttrs(i)) {
      if (!attr.first.strref().contains('.'))
        return emitOpError("arguments may only have dialect attributes");
      auto dialectNamePair = attr.first.strref().split('.');
      if (auto *dialect =
              getContext()->getRegisteredDialect(dialectNamePair.first)) {
        if (failed(dialect->verifyFunctionArgAttribute(*this, i, attr)))
          return failure();
      }
    }
  }

  // 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.
  Block &entryBlock = front();
  if (fnInputTypes.size() != entryBlock.getNumArguments())
    return emitOpError("entry block must have ")
           << fnInputTypes.size() << " arguments to match function signature";

  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();
}

/// Returns the name of this function.
StringRef FuncOp::getName() {
  return getAttrOfType<StringAttr>(SymbolTable::getSymbolAttrName()).getValue();
}

/// Set the name of this function.
void FuncOp::setName(StringRef name) {
  return setAttr(SymbolTable::getSymbolAttrName(),
                 StringAttr::get(name, getContext()));
}

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

/// 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);
}

/// Delete all blocks from this function.
void FuncOp::eraseBody() {
  // First, drop all references in the blocks because they may point to values
  // defined in the dominating blocks.
  getBody().dropAllReferences();
  getBody().getBlocks().clear();
}

/// 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 = llvm::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);
}

//===----------------------------------------------------------------------===//
// Function Argument Attribute.
//===----------------------------------------------------------------------===//

/// Set the attributes held by the argument at 'index'.
void FuncOp::setArgAttrs(unsigned index, ArrayRef<NamedAttribute> attributes) {
  assert(index < getNumArguments() && "invalid argument number");
  SmallString<8> nameOut;
  getArgAttrName(index, nameOut);

  if (attributes.empty())
    return (void)removeAttr(nameOut);
  setAttr(nameOut, DictionaryAttr::get(attributes, getContext()));
}

void FuncOp::setArgAttrs(unsigned index, NamedAttributeList attributes) {
  assert(index < getNumArguments() && "invalid argument number");
  SmallString<8> nameOut;
  if (auto newAttr = attributes.getDictionary())
    return setAttr(getArgAttrName(index, nameOut), newAttr);
  removeAttr(getArgAttrName(index, nameOut));
}

/// If the an attribute exists with the specified name, change it to the new
/// value. Otherwise, add a new attribute with the specified name/value.
void FuncOp::setArgAttr(unsigned index, Identifier name, Attribute value) {
  auto curAttr = getArgAttrDict(index);
  NamedAttributeList attrList(curAttr);
  attrList.set(name, value);

  // If the attribute changed, then set the new arg attribute list.
  if (curAttr != attrList.getDictionary())
    setArgAttrs(index, attrList);
}

/// Remove the attribute 'name' from the argument at 'index'.
NamedAttributeList::RemoveResult FuncOp::removeArgAttr(unsigned index,
                                                       Identifier name) {
  // Build an attribute list and remove the attribute at 'name'.
  NamedAttributeList attrList(getArgAttrDict(index));
  auto result = attrList.remove(name);

  // If the attribute was removed, then update the argument dictionary.
  if (result == NamedAttributeList::RemoveResult::Removed)
    setArgAttrs(index, attrList);
  return result;
}

/// Returns the attribute entry name for the set of argument attributes at index
/// 'arg'.
StringRef FuncOp::getArgAttrName(unsigned arg, SmallVectorImpl<char> &out) {
  out.clear();
  return ("arg" + Twine(arg)).toStringRef(out);
}