HWAttributes.cpp

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//===- HWAttributes.cpp - Implement HW attributes -------------------------===//
//
// 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 "circt/Dialect/HW/HWAttributes.h"
#include "circt/Dialect/HW/HWDialect.h"
#include "circt/Dialect/HW/HWOps.h"
#include "circt/Dialect/HW/HWTypes.h"
#include "circt/Support/LLVM.h"
#include "mlir/IR/Diagnostics.h"
#include "mlir/IR/DialectImplementation.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
 
using namespace circt;
using namespace circt::hw;
using mlir::TypedAttr;
 
// Internal method used for .mlir file parsing, defined below.
static Attribute parseParamExprWithOpcode(StringRef opcode, DialectAsmParser &p,
                                          Type type);
 
//===----------------------------------------------------------------------===//
// ODS Boilerplate
//===----------------------------------------------------------------------===//
 
#define GET_ATTRDEF_CLASSES
#include "circt/Dialect/HW/HWAttributes.cpp.inc"
 
void HWDialect::registerAttributes() {
  addAttributes<
#define GET_ATTRDEF_LIST
#include "circt/Dialect/HW/HWAttributes.cpp.inc"
      >();
}
 
Attribute HWDialect::parseAttribute(DialectAsmParser &p, Type type) const {
  StringRef attrName;
  Attribute attr;
  auto parseResult = generatedAttributeParser(p, &attrName, type, attr);
  if (parseResult.has_value())
    return attr;
 
  // Parse "#hw.param.expr.add" as ParamExprAttr.
  if (attrName.starts_with(ParamExprAttr::getMnemonic())) {
    auto string = attrName.drop_front(ParamExprAttr::getMnemonic().size());
    if (string.front() == '.')
      return parseParamExprWithOpcode(string.drop_front(), p, type);
  }
 
  p.emitError(p.getNameLoc(), "Unexpected hw attribute '" + attrName + "'");
  return {};
}
 
void HWDialect::printAttribute(Attribute attr, DialectAsmPrinter &p) const {
  if (succeeded(generatedAttributePrinter(attr, p)))
    return;
  llvm_unreachable("Unexpected attribute");
}
 
//===----------------------------------------------------------------------===//
// OutputFileAttr
//===----------------------------------------------------------------------===//
 
static std::string canonicalizeFilename(const Twine &directory,
                                        const Twine &filename) {
 
  // Convert the filename to a native style path.
  SmallString<128> nativeFilename;
  llvm::sys::path::native(filename, nativeFilename);
 
  // If the filename is an absolute path, ignore the directory.
  // e.g. `directory/` + `/etc/filename` -> `/etc/filename`.
  if (llvm::sys::path::is_absolute(nativeFilename))
    return std::string(nativeFilename);
 
  // Convert the directory to a native style path.
  SmallString<128> nativeDirectory;
  llvm::sys::path::native(directory, nativeDirectory);
 
  // If the filename component is empty, then ensure that the path ends in a
  // separator and return it.
  // e.g. `directory` + `` -> `directory/`.
  auto separator = llvm::sys::path::get_separator();
  if (nativeFilename.empty() && !nativeDirectory.ends_with(separator)) {
    nativeDirectory += separator;
    return std::string(nativeDirectory);
  }
 
  // Append the directory and filename together.
  // e.g. `/tmp/` + `out/filename` -> `/tmp/out/filename`.
  SmallString<128> fullPath;
  llvm::sys::path::append(fullPath, nativeDirectory, nativeFilename);
  return std::string(fullPath);
}
 
OutputFileAttr OutputFileAttr::getFromFilename(MLIRContext *context,
                                               const Twine &filename,
                                               bool excludeFromFileList,
                                               bool includeReplicatedOps) {
  return OutputFileAttr::getFromDirectoryAndFilename(
      context, "", filename, excludeFromFileList, includeReplicatedOps);
}
 
OutputFileAttr OutputFileAttr::getFromDirectoryAndFilename(
    MLIRContext *context, const Twine &directory, const Twine &filename,
    bool excludeFromFileList, bool includeReplicatedOps) {
  auto canonicalized = canonicalizeFilename(directory, filename);
  return OutputFileAttr::get(StringAttr::get(context, canonicalized),
                             BoolAttr::get(context, excludeFromFileList),
                             BoolAttr::get(context, includeReplicatedOps));
}
 
OutputFileAttr OutputFileAttr::getAsDirectory(MLIRContext *context,
                                              const Twine &directory,
                                              bool excludeFromFileList,
                                              bool includeReplicatedOps) {
  return getFromDirectoryAndFilename(context, directory, "",
                                     excludeFromFileList, includeReplicatedOps);
}
 
bool OutputFileAttr::isDirectory() {
  return getFilename().getValue().ends_with(llvm::sys::path::get_separator());
}
 
StringRef OutputFileAttr::getDirectory() {
  auto dir = getFilename().getValue();
  for (unsigned i = 0, e = dir.size(); i < e; ++i) {
    if (dir.ends_with(llvm::sys::path::get_separator()))
      break;
    dir = dir.drop_back();
  }
  return dir;
}
 
/// Option         ::= 'excludeFromFileList' | 'includeReplicatedOp'
/// OutputFileAttr ::= 'output_file<' directory ',' name (',' Option)* '>'
Attribute OutputFileAttr::parse(AsmParser &p, Type type) {
  StringAttr filename;
  if (p.parseLess() || p.parseAttribute<StringAttr>(filename))
    return Attribute();
 
  // Parse the additional keyword attributes.  Its easier to let people specify
  // these more than once than to detect the problem and do something about it.
  bool excludeFromFileList = false;
  bool includeReplicatedOps = false;
  while (true) {
    if (p.parseOptionalComma())
      break;
    if (!p.parseOptionalKeyword("excludeFromFileList"))
      excludeFromFileList = true;
    else if (!p.parseKeyword("includeReplicatedOps",
                             "or 'excludeFromFileList'"))
      includeReplicatedOps = true;
    else
      return Attribute();
  }
 
  if (p.parseGreater())
    return Attribute();
 
  return OutputFileAttr::getFromFilename(p.getContext(), filename.getValue(),
                                         excludeFromFileList,
                                         includeReplicatedOps);
}
 
void OutputFileAttr::print(AsmPrinter &p) const {
  p << "<" << getFilename();
  if (getExcludeFromFilelist().getValue())
    p << ", excludeFromFileList";
  if (getIncludeReplicatedOps().getValue())
    p << ", includeReplicatedOps";
  p << ">";
}
 
//===----------------------------------------------------------------------===//
// EnumFieldAttr
//===----------------------------------------------------------------------===//
 
Attribute EnumFieldAttr::parse(AsmParser &p, Type) {
  StringRef field;
  Type type;
  if (p.parseLess() || p.parseKeyword(&field) || p.parseComma() ||
      p.parseType(type) || p.parseGreater())
    return Attribute();
  return EnumFieldAttr::get(p.getEncodedSourceLoc(p.getCurrentLocation()),
                            StringAttr::get(p.getContext(), field), type);
}
 
void EnumFieldAttr::print(AsmPrinter &p) const {
  p << "<" << getField().getValue() << ", ";
  p.printType(getType().getValue());
  p << ">";
}
 
EnumFieldAttr EnumFieldAttr::get(Location loc, StringAttr value,
                                 mlir::Type type) {
  if (!hw::isHWEnumType(type))
    emitError(loc) << "expected enum type";
 
  // Check whether the provided value is a member of the enum type.
  EnumType enumType = llvm::cast<EnumType>(getCanonicalType(type));
  if (!enumType.contains(value.getValue())) {
    emitError(loc) << "enum value '" << value.getValue()
                   << "' is not a member of enum type " << enumType;
    return nullptr;
  }
 
  return Base::get(value.getContext(), value, TypeAttr::get(type));
}
 
//===----------------------------------------------------------------------===//
// InnerRefAttr
//===----------------------------------------------------------------------===//
 
Attribute InnerRefAttr::parse(AsmParser &p, Type type) {
  SymbolRefAttr attr;
  if (p.parseLess() || p.parseAttribute<SymbolRefAttr>(attr) ||
      p.parseGreater())
    return Attribute();
  if (attr.getNestedReferences().size() != 1) {
    p.emitError(p.getNameLoc(),
                "inner reference must have exactly one nested reference");
    return Attribute();
  }
  return InnerRefAttr::get(attr.getRootReference(), attr.getLeafReference());
}
 
static void printSymbolName(AsmPrinter &p, StringAttr sym) {
  if (sym)
    p.printSymbolName(sym.getValue());
  else
    p.printSymbolName({});
}
 
void InnerRefAttr::print(AsmPrinter &p) const {
  p << "<";
  printSymbolName(p, getModule());
  p << "::";
  printSymbolName(p, getName());
  p << ">";
}
 
//===----------------------------------------------------------------------===//
// InnerSymAttr and InnerSymPropertiesAttr
//===----------------------------------------------------------------------===//
 
Attribute InnerSymPropertiesAttr::parse(AsmParser &parser, Type type) {
  StringAttr name;
  NamedAttrList dummyList;
  int64_t fieldId = 0;
  if (parser.parseLess() || parser.parseSymbolName(name, "name", dummyList) ||
      parser.parseComma() || parser.parseInteger(fieldId) ||
      parser.parseComma())
    return Attribute();
 
  StringRef visibility;
  auto loc = parser.getCurrentLocation();
  if (parser.parseOptionalKeyword(&visibility,
                                  {"public", "private", "nested"})) {
    parser.emitError(loc, "expected 'public', 'private', or 'nested'");
    return Attribute();
  }
  auto visibilityAttr = parser.getBuilder().getStringAttr(visibility);
 
  if (parser.parseGreater())
    return Attribute();
 
  return parser.getChecked<InnerSymPropertiesAttr>(parser.getContext(), name,
                                                   fieldId, visibilityAttr);
}
 
void InnerSymPropertiesAttr::print(AsmPrinter &odsPrinter) const {
  odsPrinter << "<@" << getName().getValue() << "," << getFieldID() << ","
             << getSymVisibility().getValue() << ">";
}
 
LogicalResult InnerSymPropertiesAttr::verify(
    ::llvm::function_ref<::mlir::InFlightDiagnostic()> emitError,
    ::mlir::StringAttr name, uint64_t fieldID,
    ::mlir::StringAttr symVisibility) {
  if (!name || name.getValue().empty())
    return emitError() << "inner symbol cannot have empty name";
  return success();
}
 
StringAttr InnerSymAttr::getSymIfExists(uint64_t fieldId) const {
  const auto *it =
      llvm::find_if(getImpl()->props, [&](const InnerSymPropertiesAttr &p) {
        return p.getFieldID() == fieldId;
      });
  if (it != getProps().end())
    return it->getName();
  return {};
}
 
InnerSymAttr InnerSymAttr::erase(uint64_t fieldID) const {
  SmallVector<InnerSymPropertiesAttr> syms(getProps());
  const auto *it = llvm::find_if(syms, [fieldID](InnerSymPropertiesAttr p) {
    return p.getFieldID() == fieldID;
  });
  assert(it != syms.end());
  syms.erase(it);
  return InnerSymAttr::get(getContext(), syms);
}
 
LogicalResult InnerSymAttr::walkSymbols(
    llvm::function_ref<LogicalResult(StringAttr)> callback) const {
  for (auto p : getImpl()->props)
    if (callback(p.getName()).failed())
      return failure();
  return success();
}
 
Attribute InnerSymAttr::parse(AsmParser &parser, Type type) {
  StringAttr sym;
  NamedAttrList dummyList;
  SmallVector<InnerSymPropertiesAttr, 4> names;
  if (!parser.parseOptionalSymbolName(sym, "dummy", dummyList)) {
    auto prop = parser.getChecked<InnerSymPropertiesAttr>(
        parser.getContext(), sym, 0,
        StringAttr::get(parser.getContext(), "public"));
    if (!prop)
      return {};
    names.push_back(prop);
  } else if (parser.parseCommaSeparatedList(
                 OpAsmParser::Delimiter::Square, [&]() -> ParseResult {
                   InnerSymPropertiesAttr prop;
                   if (parser.parseCustomAttributeWithFallback(
                           prop, mlir::Type{}, "dummy", dummyList))
                     return failure();
 
                   names.push_back(prop);
 
                   return success();
                 }))
    return Attribute();
 
  std::sort(names.begin(), names.end(),
            [&](InnerSymPropertiesAttr a, InnerSymPropertiesAttr b) {
              return a.getFieldID() < b.getFieldID();
            });
 
  return InnerSymAttr::get(parser.getContext(), names);
}
 
void InnerSymAttr::print(AsmPrinter &odsPrinter) const {
 
  auto props = getProps();
  if (props.size() == 1 && props[0].getSymVisibility().getValue() == "public" &&
      props[0].getFieldID() == 0) {
    odsPrinter.printSymbolName(props[0].getName().getValue());
    return;
  }
  auto names = props.vec();
 
  std::sort(names.begin(), names.end(),
            [&](InnerSymPropertiesAttr a, InnerSymPropertiesAttr b) {
              return a.getFieldID() < b.getFieldID();
            });
  odsPrinter << "[";
  llvm::interleaveComma(names, odsPrinter, [&](InnerSymPropertiesAttr attr) {
    attr.print(odsPrinter);
  });
  odsPrinter << "]";
}
 
//===----------------------------------------------------------------------===//
// ParamDeclAttr
//===----------------------------------------------------------------------===//
 
Attribute ParamDeclAttr::parse(AsmParser &p, Type trailing) {
  std::string name;
  Type type;
  Attribute value;
  // < "FOO" : i32 > : i32
  // < "FOO" : i32 = 0 > : i32
  // < "FOO" : none >
  if (p.parseLess() || p.parseString(&name) || p.parseColonType(type))
    return Attribute();
 
  if (succeeded(p.parseOptionalEqual())) {
    if (p.parseAttribute(value, type))
      return Attribute();
  }
 
  if (p.parseGreater())
    return Attribute();
 
  if (value)
    return ParamDeclAttr::get(p.getContext(),
                              p.getBuilder().getStringAttr(name), type, value);
  return ParamDeclAttr::get(name, type);
}
 
void ParamDeclAttr::print(AsmPrinter &p) const {
  p << "<" << getName() << ": " << getType();
  if (getValue()) {
    p << " = ";
    p.printAttributeWithoutType(getValue());
  }
  p << ">";
}
 
//===----------------------------------------------------------------------===//
// ParamDeclRefAttr
//===----------------------------------------------------------------------===//
 
Attribute ParamDeclRefAttr::parse(AsmParser &p, Type type) {
  StringAttr name;
  if (p.parseLess() || p.parseAttribute(name) || p.parseGreater() ||
      (!type && (p.parseColon() || p.parseType(type))))
    return Attribute();
 
  return ParamDeclRefAttr::get(name, type);
}
 
void ParamDeclRefAttr::print(AsmPrinter &p) const {
  p << "<" << getName() << ">";
}
 
//===----------------------------------------------------------------------===//
// ParamVerbatimAttr
//===----------------------------------------------------------------------===//
 
Attribute ParamVerbatimAttr::parse(AsmParser &p, Type type) {
  StringAttr text;
  if (p.parseLess() || p.parseAttribute(text) || p.parseGreater() ||
      (!type && (p.parseColon() || p.parseType(type))))
    return Attribute();
 
  return ParamVerbatimAttr::get(p.getContext(), text, type);
}
 
void ParamVerbatimAttr::print(AsmPrinter &p) const {
  p << "<" << getValue() << ">";
}
 
//===----------------------------------------------------------------------===//
// ParamExprAttr
//===----------------------------------------------------------------------===//
 
/// Given a binary function, if the two operands are known constant integers,
/// use the specified fold function to compute the result.
static TypedAttr foldBinaryOp(
    ArrayRef<TypedAttr> operands,
    llvm::function_ref<APInt(const APInt &, const APInt &)> calculate) {
  assert(operands.size() == 2 && "binary operator always has two operands");
  if (auto lhs = dyn_cast<IntegerAttr>(operands[0]))
    if (auto rhs = dyn_cast<IntegerAttr>(operands[1]))
      return IntegerAttr::get(lhs.getType(),
                              calculate(lhs.getValue(), rhs.getValue()));
  return {};
}
 
/// Given a unary function, if the operand is a known constant integer,
/// use the specified fold function to compute the result.
static TypedAttr
foldUnaryOp(ArrayRef<TypedAttr> operands,
            llvm::function_ref<APInt(const APInt &)> calculate) {
  assert(operands.size() == 1 && "unary operator always has one operand");
  if (auto intAttr = dyn_cast<IntegerAttr>(operands[0]))
    return IntegerAttr::get(intAttr.getType(), calculate(intAttr.getValue()));
  return {};
}
 
/// If the specified attribute is a ParamExprAttr with the specified opcode,
/// return it.  Otherwise return null.
static ParamExprAttr dyn_castPE(PEO opcode, Attribute value) {
  if (auto expr = dyn_cast<ParamExprAttr>(value))
    if (expr.getOpcode() == opcode)
      return expr;
  return {};
}
 
/// This implements a < comparison for two operands to an associative operation
/// imposing an ordering upon them.
///
/// The ordering provided puts more complex things to the start of the list,
/// from left to right:
///    expressions :: verbatims :: decl.refs :: constant
///
static bool paramExprOperandSortPredicate(Attribute lhs, Attribute rhs) {
  // Simplify the code below - we never have to care about exactly equal values.
  if (lhs == rhs)
    return false;
 
  // All expressions are "less than" a constant, since they appear on the right.
  if (isa<IntegerAttr>(rhs)) {
    // We don't bother to order constants w.r.t. each other since they will be
    // folded - they can all compare equal.
    return !isa<IntegerAttr>(lhs);
  }
  if (isa<IntegerAttr>(lhs))
    return false;
 
  // Next up are named parameters.
  if (auto rhsParam = dyn_cast<ParamDeclRefAttr>(rhs)) {
    // Parameters are sorted lexically w.r.t. each other.
    if (auto lhsParam = dyn_cast<ParamDeclRefAttr>(lhs))
      return lhsParam.getName().getValue() < rhsParam.getName().getValue();
    // They otherwise appear on the right of other things.
    return true;
  }
  if (isa<ParamDeclRefAttr>(lhs))
    return false;
 
  // Next up are verbatim parameters.
  if (auto rhsParam = dyn_cast<ParamVerbatimAttr>(rhs)) {
    // Verbatims are sorted lexically w.r.t. each other.
    if (auto lhsParam = dyn_cast<ParamVerbatimAttr>(lhs))
      return lhsParam.getValue().getValue() < rhsParam.getValue().getValue();
    // They otherwise appear on the right of other things.
    return true;
  }
  if (isa<ParamVerbatimAttr>(lhs))
    return false;
 
  // The only thing left are nested expressions.
  auto lhsExpr = cast<ParamExprAttr>(lhs), rhsExpr = cast<ParamExprAttr>(rhs);
  // Sort by the string form of the opcode, e.g. add, .. mul,... then xor.
  if (lhsExpr.getOpcode() != rhsExpr.getOpcode())
    return stringifyPEO(lhsExpr.getOpcode()) <
           stringifyPEO(rhsExpr.getOpcode());
 
  // If they are the same opcode, then sort by arity: more complex to the left.
  ArrayRef<TypedAttr> lhsOperands = lhsExpr.getOperands(),
                      rhsOperands = rhsExpr.getOperands();
  if (lhsOperands.size() != rhsOperands.size())
    return lhsOperands.size() > rhsOperands.size();
 
  // We know the two subexpressions are different (they'd otherwise be pointer
  // equivalent) so just go compare all of the elements.
  for (size_t i = 0, e = lhsOperands.size(); i != e; ++i) {
    if (paramExprOperandSortPredicate(lhsOperands[i], rhsOperands[i]))
      return true;
    if (paramExprOperandSortPredicate(rhsOperands[i], lhsOperands[i]))
      return false;
  }
 
  llvm_unreachable("expressions should never be equivalent");
  return false;
}
 
/// Given a fully associative variadic integer operation, constant fold any
/// constant operands and move them to the right.  If the whole expression is
/// constant, then return that, otherwise update the operands list.
static TypedAttr simplifyAssocOp(
    PEO opcode, SmallVector<TypedAttr, 4> &operands,
    llvm::function_ref<APInt(const APInt &, const APInt &)> calculateFn,
    llvm::function_ref<bool(const APInt &)> identityConstantFn,
    llvm::function_ref<bool(const APInt &)> destructiveConstantFn = {}) {
  auto type = operands[0].getType();
  assert(isHWIntegerType(type));
  if (operands.size() == 1)
    return operands[0];
 
  // Flatten any of the same operation into the operand list:
  // `(add x, (add y, z))` => `(add x, y, z)`.
  for (size_t i = 0, e = operands.size(); i != e; ++i) {
    if (auto subexpr = dyn_castPE(opcode, operands[i])) {
      std::swap(operands[i], operands.back());
      operands.pop_back();
      --e;
      --i;
      operands.append(subexpr.getOperands().begin(),
                      subexpr.getOperands().end());
    }
  }
 
  // Impose an ordering on the operands, pushing subexpressions to the left and
  // constants to the right, with verbatims and parameters in the middle - but
  // predictably ordered w.r.t. each other.
  llvm::stable_sort(operands, paramExprOperandSortPredicate);
 
  // Merge any constants, they will appear at the back of the operand list now.
  if (isa<IntegerAttr>(operands.back())) {
    while (operands.size() >= 2 &&
           isa<IntegerAttr>(operands[operands.size() - 2])) {
      APInt c1 = cast<IntegerAttr>(operands.pop_back_val()).getValue();
      APInt c2 = cast<IntegerAttr>(operands.pop_back_val()).getValue();
      auto resultConstant = IntegerAttr::get(type, calculateFn(c1, c2));
      operands.push_back(resultConstant);
    }
 
    auto resultCst = cast<IntegerAttr>(operands.back());
 
    // If the resulting constant is the destructive constant (e.g. `x*0`), then
    // return it.
    if (destructiveConstantFn && destructiveConstantFn(resultCst.getValue()))
      return resultCst;
 
    // Remove the constant back to our operand list if it is the identity
    // constant for this operator (e.g. `x*1`) and there are other operands.
    if (identityConstantFn(resultCst.getValue()) && operands.size() != 1)
      operands.pop_back();
  }
 
  return operands.size() == 1 ? operands[0] : TypedAttr();
}
 
/// Analyze an operand to an add.  If it is a multiplication by a constant (e.g.
/// `(a*b*42)` then split it into the non-constant and the constant portions
/// (e.g. `a*b` and `42`).  Otherwise return the operand as the first value and
/// null as the second (standin for "multiplication by 1").
static std::pair<TypedAttr, TypedAttr> decomposeAddend(TypedAttr operand) {
  if (auto mul = dyn_castPE(PEO::Mul, operand))
    if (auto cst = dyn_cast<IntegerAttr>(mul.getOperands().back())) {
      auto nonCst = ParamExprAttr::get(PEO::Mul, mul.getOperands().drop_back());
      return {nonCst, cst};
    }
  return {operand, TypedAttr()};
}
 
static TypedAttr getOneOfType(Type type) {
  return IntegerAttr::get(type, APInt(type.getIntOrFloatBitWidth(), 1));
}
 
static TypedAttr simplifyAdd(SmallVector<TypedAttr, 4> &operands) {
  if (auto result = simplifyAssocOp(
          PEO::Add, operands, [](auto a, auto b) { return a + b; },
          /*identityCst*/ [](auto cst) { return cst.isZero(); }))
    return result;
 
  // Canonicalize the add by splitting all addends into their variable and
  // constant factors.
  SmallVector<std::pair<TypedAttr, TypedAttr>> decomposedOperands;
  llvm::SmallDenseSet<TypedAttr> nonConstantParts;
  for (auto &op : operands) {
    decomposedOperands.push_back(decomposeAddend(op));
 
    // Keep track of non-constant parts we've already seen.  If we see multiple
    // uses of the same value, then we can fold them together with a multiply.
    // This handles things like `(a+b+a)` => `(a*2 + b)` and `(a*2 + b + a)` =>
    // `(a*3 + b)`.
    if (!nonConstantParts.insert(decomposedOperands.back().first).second) {
      // The thing we multiply will be the common expression.
      TypedAttr mulOperand = decomposedOperands.back().first;
 
      // Find the index of the first occurrence.
      size_t i = 0;
      while (decomposedOperands[i].first != mulOperand)
        ++i;
      // Remove both occurrences from the operand list.
      operands.erase(operands.begin() + (&op - &operands[0]));
      operands.erase(operands.begin() + i);
 
      auto type = mulOperand.getType();
      auto c1 = decomposedOperands[i].second,
           c2 = decomposedOperands.back().second;
      // Fill in missing constant multiplicands with 1.
      if (!c1)
        c1 = getOneOfType(type);
      if (!c2)
        c2 = getOneOfType(type);
      // Re-add the "a"*(c1+c2) expression to the operand list and
      // re-canonicalize.
      auto constant = ParamExprAttr::get(PEO::Add, c1, c2);
      auto mulCst = ParamExprAttr::get(PEO::Mul, mulOperand, constant);
      operands.push_back(mulCst);
      return ParamExprAttr::get(PEO::Add, operands);
    }
  }
 
  return {};
}
 
static TypedAttr simplifyMul(SmallVector<TypedAttr, 4> &operands) {
  if (auto result = simplifyAssocOp(
          PEO::Mul, operands, [](auto a, auto b) { return a * b; },
          /*identityCst*/ [](auto cst) { return cst.isOne(); },
          /*destructiveCst*/ [](auto cst) { return cst.isZero(); }))
    return result;
 
  // We always build a sum-of-products representation, so if we see an addition
  // as a subexpr, we need to pull it out: (a+b)*c*d ==> (a*c*d + b*c*d).
  for (size_t i = 0, e = operands.size(); i != e; ++i) {
    if (auto subexpr = dyn_castPE(PEO::Add, operands[i])) {
      // Pull the `c*d` operands out - it is whatever operands remain after
      // removing the `(a+b)` term.
      SmallVector<TypedAttr> mulOperands(operands.begin(), operands.end());
      mulOperands.erase(mulOperands.begin() + i);
 
      // Build each add operand.
      SmallVector<TypedAttr> addOperands;
      for (auto addOperand : subexpr.getOperands()) {
        mulOperands.push_back(addOperand);
        addOperands.push_back(ParamExprAttr::get(PEO::Mul, mulOperands));
        mulOperands.pop_back();
      }
      // Canonicalize and form the add expression.
      return ParamExprAttr::get(PEO::Add, addOperands);
    }
  }
 
  return {};
}
static TypedAttr simplifyAnd(SmallVector<TypedAttr, 4> &operands) {
  return simplifyAssocOp(
      PEO::And, operands, [](auto a, auto b) { return a & b; },
      /*identityCst*/ [](auto cst) { return cst.isAllOnes(); },
      /*destructiveCst*/ [](auto cst) { return cst.isZero(); });
}
 
static TypedAttr simplifyOr(SmallVector<TypedAttr, 4> &operands) {
  return simplifyAssocOp(
      PEO::Or, operands, [](auto a, auto b) { return a | b; },
      /*identityCst*/ [](auto cst) { return cst.isZero(); },
      /*destructiveCst*/ [](auto cst) { return cst.isAllOnes(); });
}
 
static TypedAttr simplifyXor(SmallVector<TypedAttr, 4> &operands) {
  return simplifyAssocOp(
      PEO::Xor, operands, [](auto a, auto b) { return a ^ b; },
      /*identityCst*/ [](auto cst) { return cst.isZero(); });
}
 
static TypedAttr simplifyShl(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
 
  if (auto rhs = dyn_cast<IntegerAttr>(operands[1])) {
    // Constant fold simple integers.
    if (auto lhs = dyn_cast<IntegerAttr>(operands[0]))
      return IntegerAttr::get(lhs.getType(),
                              lhs.getValue().shl(rhs.getValue()));
 
    // Canonicalize `x << cst` => `x * (1<<cst)` to compose correctly with
    // add/mul canonicalization.
    auto rhsCst = APInt::getOneBitSet(rhs.getValue().getBitWidth(),
                                      rhs.getValue().getZExtValue());
    return ParamExprAttr::get(PEO::Mul, operands[0],
                              IntegerAttr::get(rhs.getType(), rhsCst));
  }
  return {};
}
 
static TypedAttr simplifyShrU(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
  // Implement support for identities like `x >> 0`.
  if (auto rhs = dyn_cast<IntegerAttr>(operands[1]))
    if (rhs.getValue().isZero())
      return operands[0];
 
  return foldBinaryOp(operands, [](auto a, auto b) { return a.lshr(b); });
}
 
static TypedAttr simplifyShrS(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
  // Implement support for identities like `x >> 0`.
  if (auto rhs = dyn_cast<IntegerAttr>(operands[1]))
    if (rhs.getValue().isZero())
      return operands[0];
 
  return foldBinaryOp(operands, [](auto a, auto b) { return a.ashr(b); });
}
 
static TypedAttr simplifyDivU(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
  // Implement support for identities like `x/1`.
  if (auto rhs = dyn_cast<IntegerAttr>(operands[1]))
    if (rhs.getValue().isOne())
      return operands[0];
 
  return foldBinaryOp(operands, [](auto a, auto b) { return a.udiv(b); });
}
 
static TypedAttr simplifyDivS(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
  // Implement support for identities like `x/1`.
  if (auto rhs = dyn_cast<IntegerAttr>(operands[1]))
    if (rhs.getValue().isOne())
      return operands[0];
 
  return foldBinaryOp(operands, [](auto a, auto b) { return a.sdiv(b); });
}
 
static TypedAttr simplifyModU(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
  // Implement support for identities like `x%1`.
  if (auto rhs = dyn_cast<IntegerAttr>(operands[1]))
    if (rhs.getValue().isOne())
      return IntegerAttr::get(rhs.getType(), 0);
 
  return foldBinaryOp(operands, [](auto a, auto b) { return a.urem(b); });
}
 
static TypedAttr simplifyModS(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
  // Implement support for identities like `x%1`.
  if (auto rhs = dyn_cast<IntegerAttr>(operands[1]))
    if (rhs.getValue().isOne())
      return IntegerAttr::get(rhs.getType(), 0);
 
  return foldBinaryOp(operands, [](auto a, auto b) { return a.srem(b); });
}
 
static TypedAttr simplifyCLog2(SmallVector<TypedAttr, 4> &operands) {
  assert(isHWIntegerType(operands[0].getType()));
  return foldUnaryOp(operands, [](auto a) {
    // Following the Verilog spec, clog2(0) is 0
    return APInt(a.getBitWidth(), a == 0 ? 0 : a.ceilLogBase2());
  });
}
 
static TypedAttr simplifyStrConcat(SmallVector<TypedAttr, 4> &operands) {
  // Combine all adjacent strings.
  SmallVector<TypedAttr> newOperands;
  SmallVector<StringAttr> stringsToCombine;
  auto combineAndPush = [&]() {
    if (stringsToCombine.empty())
      return;
    // Concatenate buffered strings, push to ops.
    SmallString<32> newString;
    for (auto part : stringsToCombine)
      newString.append(part.getValue());
    newOperands.push_back(
        StringAttr::get(stringsToCombine[0].getContext(), newString));
    stringsToCombine.clear();
  };
 
  for (TypedAttr op : operands) {
    if (auto strOp = dyn_cast<StringAttr>(op)) {
      // Queue up adjacent strings.
      stringsToCombine.push_back(strOp);
    } else {
      combineAndPush();
      newOperands.push_back(op);
    }
  }
  combineAndPush();
 
  assert(!newOperands.empty());
  if (newOperands.size() == 1)
    return newOperands[0];
  if (newOperands.size() < operands.size())
    return ParamExprAttr::get(PEO::StrConcat, newOperands);
  return {};
}
 
/// Build a parameter expression.  This automatically canonicalizes and
/// folds, so it may not necessarily return a ParamExprAttr.
TypedAttr ParamExprAttr::get(PEO opcode, ArrayRef<TypedAttr> operandsIn) {
  assert(!operandsIn.empty() && "Cannot have expr with no operands");
  // All operands must have the same type, which is the type of the result.
  auto type = operandsIn.front().getType();
  assert(llvm::all_of(operandsIn.drop_front(),
                      [&](auto op) { return op.getType() == type; }));
 
  SmallVector<TypedAttr, 4> operands(operandsIn.begin(), operandsIn.end());
 
  // Verify and canonicalize parameter expressions.
  TypedAttr result;
  switch (opcode) {
  case PEO::Add:
    result = simplifyAdd(operands);
    break;
  case PEO::Mul:
    result = simplifyMul(operands);
    break;
  case PEO::And:
    result = simplifyAnd(operands);
    break;
  case PEO::Or:
    result = simplifyOr(operands);
    break;
  case PEO::Xor:
    result = simplifyXor(operands);
    break;
  case PEO::Shl:
    result = simplifyShl(operands);
    break;
  case PEO::ShrU:
    result = simplifyShrU(operands);
    break;
  case PEO::ShrS:
    result = simplifyShrS(operands);
    break;
  case PEO::DivU:
    result = simplifyDivU(operands);
    break;
  case PEO::DivS:
    result = simplifyDivS(operands);
    break;
  case PEO::ModU:
    result = simplifyModU(operands);
    break;
  case PEO::ModS:
    result = simplifyModS(operands);
    break;
  case PEO::CLog2:
    result = simplifyCLog2(operands);
    break;
  case PEO::StrConcat:
    result = simplifyStrConcat(operands);
    break;
  }
 
  // If we folded to an operand, return it.
  if (result)
    return result;
 
  return Base::get(operands[0].getContext(), opcode, operands, type);
}
 
Attribute ParamExprAttr::parse(AsmParser &p, Type type) {
  // We require an opcode suffix like `#hw.param.expr.add`, we don't allow
  // parsing a plain `#hw.param.expr` on its own.
  p.emitError(p.getNameLoc(), "#hw.param.expr should have opcode suffix");
  return {};
}
 
/// Internal method used for .mlir file parsing when parsing the
/// "#hw.param.expr.mul" form of the attribute.
static Attribute parseParamExprWithOpcode(StringRef opcodeStr,
                                          DialectAsmParser &p, Type type) {
  SmallVector<TypedAttr> operands;
  if (p.parseCommaSeparatedList(
          mlir::AsmParser::Delimiter::LessGreater, [&]() -> ParseResult {
            operands.push_back({});
            return p.parseAttribute(operands.back(), type);
          }))
    return {};
 
  std::optional<PEO> opcode = symbolizePEO(opcodeStr);
  if (!opcode.has_value()) {
    p.emitError(p.getNameLoc(), "unknown parameter expr operator name");
    return {};
  }
 
  return ParamExprAttr::get(*opcode, operands);
}
 
void ParamExprAttr::print(AsmPrinter &p) const {
  p << "." << stringifyPEO(getOpcode()) << '<';
  llvm::interleaveComma(getOperands(), p.getStream(),
                        [&](Attribute op) { p.printAttributeWithoutType(op); });
  p << '>';
}
 
// Replaces any ParamDeclRefAttr within a parametric expression with its
// corresponding value from the map of provided parameters.
static FailureOr<Attribute>
replaceDeclRefInExpr(Location loc,
                     const std::map<std::string, Attribute> &parameters,
                     Attribute paramAttr, bool emitErrors) {
  if (dyn_cast<IntegerAttr>(paramAttr)) {
    // Nothing to do, constant value.
    return paramAttr;
  }
  if (auto paramRefAttr = dyn_cast<hw::ParamDeclRefAttr>(paramAttr)) {
    // Get the value from the provided parameters.
    auto it = parameters.find(paramRefAttr.getName().str());
    if (it == parameters.end()) {
      if (emitErrors)
        return emitError(loc)
               << "Could not find parameter " << paramRefAttr.getName().str()
               << " in the provided parameters for the expression!";
      return failure();
    }
    return it->second;
  }
  if (auto paramExprAttr = dyn_cast<hw::ParamExprAttr>(paramAttr)) {
    // Recurse into all operands of the expression.
    llvm::SmallVector<TypedAttr, 4> replacedOperands;
    for (auto operand : paramExprAttr.getOperands()) {
      auto res = replaceDeclRefInExpr(loc, parameters, operand, emitErrors);
      if (failed(res))
        return {failure()};
      replacedOperands.push_back(cast<TypedAttr>(*res));
    }
    return {
        hw::ParamExprAttr::get(paramExprAttr.getOpcode(), replacedOperands)};
  }
  llvm_unreachable("Unhandled parametric attribute");
  return {};
}
 
FailureOr<TypedAttr> hw::evaluateParametricAttr(Location loc,
                                                ArrayAttr parameters,
                                                Attribute paramAttr,
                                                bool emitErrors) {
  // Create a map of the provided parameters for faster lookup.
  std::map<std::string, Attribute> parameterMap;
  for (auto param : parameters) {
    auto paramDecl = cast<ParamDeclAttr>(param);
    parameterMap[paramDecl.getName().str()] = paramDecl.getValue();
  }
 
  // First, replace any ParamDeclRefAttr in the expression with its
  // corresponding value in 'parameters'.
  auto paramAttrRes =
      replaceDeclRefInExpr(loc, parameterMap, paramAttr, emitErrors);
  if (failed(paramAttrRes))
    return {failure()};
  paramAttr = *paramAttrRes;
 
  // Then, evaluate the parametric attribute.
  if (isa<IntegerAttr, hw::ParamDeclRefAttr>(paramAttr))
    return cast<TypedAttr>(paramAttr);
  if (auto paramExprAttr = dyn_cast<hw::ParamExprAttr>(paramAttr)) {
    // Since any ParamDeclRefAttr was replaced within the expression,
    // we re-evaluate the expression through the existing ParamExprAttr
    // canonicalizer.
    return ParamExprAttr::get(paramExprAttr.getOpcode(),
                              paramExprAttr.getOperands());
  }
 
  llvm_unreachable("Unhandled parametric attribute");
  return TypedAttr();
}
 
template <typename TArray>
FailureOr<Type> evaluateParametricArrayType(Location loc, ArrayAttr parameters,
                                            TArray arrayType, bool emitErrors) {
  auto size = evaluateParametricAttr(loc, parameters, arrayType.getSizeAttr(),
                                     emitErrors);
  if (failed(size))
    return failure();
  auto elementType = evaluateParametricType(
      loc, parameters, arrayType.getElementType(), emitErrors);
  if (failed(elementType))
    return failure();
 
  // If the size was evaluated to a constant, use a 64-bit integer
  // attribute version of it
  if (auto intAttr = dyn_cast<IntegerAttr>(*size))
    return TArray::get(
        arrayType.getContext(), *elementType,
        IntegerAttr::get(IntegerType::get(arrayType.getContext(), 64),
                         intAttr.getValue().getSExtValue()));
 
  // Otherwise parameter references are still involved
  return TArray::get(arrayType.getContext(), *elementType, *size);
}
 
FailureOr<Type> hw::evaluateParametricType(Location loc, ArrayAttr parameters,
                                           Type type, bool emitErrors) {
  return llvm::TypeSwitch<Type, FailureOr<Type>>(type)
      .Case<hw::IntType>([&](hw::IntType t) -> FailureOr<Type> {
        auto evaluatedWidth =
            evaluateParametricAttr(loc, parameters, t.getWidth(), emitErrors);
        if (failed(evaluatedWidth))
          return {failure()};
 
        // If the width was evaluated to a constant, return an `IntegerType`
        if (auto intAttr = dyn_cast<IntegerAttr>(*evaluatedWidth))
          return {IntegerType::get(type.getContext(),
                                   intAttr.getValue().getSExtValue())};
 
        // Otherwise parameter references are still involved
        return hw::IntType::get(cast<TypedAttr>(*evaluatedWidth));
      })
      .Case<hw::ArrayType, hw::UnpackedArrayType>(
          [&](auto arrayType) -> FailureOr<Type> {
            return evaluateParametricArrayType(loc, parameters, arrayType,
                                               emitErrors);
          })
      .Default([&](auto) { return type; });
}
 
// Returns true if any part of this parametric attribute contains a reference
// to a parameter declaration.
static bool isParamAttrWithParamRef(Attribute expr) {
  return llvm::TypeSwitch<Attribute, bool>(expr)
      .Case([](ParamExprAttr attr) {
        return llvm::any_of(attr.getOperands(), isParamAttrWithParamRef);
      })
      .Case([](ParamDeclRefAttr) { return true; })
      .Default([](auto) { return false; });
}
 
bool hw::isParametricType(mlir::Type t) {
  return llvm::TypeSwitch<Type, bool>(t)
      .Case<hw::IntType>(
          [&](hw::IntType t) { return isParamAttrWithParamRef(t.getWidth()); })
      .Case<hw::ArrayType, hw::UnpackedArrayType>([&](auto arrayType) {
        return isParametricType(arrayType.getElementType()) ||
               isParamAttrWithParamRef(arrayType.getSizeAttr());
      })
      .Default([](auto) { return false; });
}