SimOps.cpp

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//===- SimOps.cpp - Implement the Sim 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
//
//===----------------------------------------------------------------------===//
//
// This file implements `sim` dialect ops.
//
//===----------------------------------------------------------------------===//
 
#include "circt/Dialect/Sim/SimOps.h"
#include "circt/Dialect/HW/HWOps.h"
#include "circt/Dialect/HW/HWTypes.h"
#include "circt/Dialect/SV/SVOps.h"
#include "circt/Support/CustomDirectiveImpl.h"
#include "circt/Support/FormatInteger.h"
#include "circt/Support/ProceduralRegionTrait.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/LLVMIR/LLVMTypes.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/Interfaces/FunctionImplementation.h"
#include "llvm/ADT/MapVector.h"
 
using namespace mlir;
using namespace circt;
using namespace sim;
 
//===----------------------------------------------------------------------===//
// DPIFuncOp
//===----------------------------------------------------------------------===//
 
void DPIFuncOp::build(OpBuilder &odsBuilder, OperationState &odsState,
                      StringAttr symName, ArrayRef<StringAttr> argNames,
                      ArrayRef<Type> argTypes,
                      ArrayRef<DPIDirection> argDirections, ArrayAttr argLocs,
                      StringAttr verilogName) {
  // Build DPIFunctionType from argument info.
  SmallVector<DPIArgument> args;
  args.reserve(argNames.size());
  for (auto [name, type, dir] : llvm::zip(argNames, argTypes, argDirections))
    args.push_back({name, type, dir});
  auto dpiType = DPIFunctionType::get(odsBuilder.getContext(), args);
  build(odsBuilder, odsState, symName, dpiType, argLocs, verilogName);
}
 
void DPIFuncOp::build(OpBuilder &odsBuilder, OperationState &odsState,
                      StringAttr symName, DPIFunctionType dpiFunctionType,
                      ArrayAttr argLocs, StringAttr verilogName) {
  odsState.addAttribute(getSymNameAttrName(odsState.name), symName);
  odsState.addAttribute(getDpiFunctionTypeAttrName(odsState.name),
                        TypeAttr::get(dpiFunctionType));
  if (argLocs)
    odsState.addAttribute(getArgumentLocsAttrName(odsState.name), argLocs);
  if (verilogName)
    odsState.addAttribute(getVerilogNameAttrName(odsState.name), verilogName);
  odsState.addRegion();
}
 
::mlir::Type DPIFuncOp::getFunctionType() {
  return getDpiFunctionType().getFunctionType();
}
 
void DPIFuncOp::setFunctionTypeAttr(::mlir::TypeAttr type) {
  // function_type is always derived from dpi_function_type.
  auto dpiType = llvm::dyn_cast<DPIFunctionType>(type.getValue());
  assert(dpiType && "DPIFuncOp function type can only be set via "
                    "DPIFunctionType, not a plain FunctionType");
  setDpiFunctionType(dpiType);
}
 
::mlir::Type DPIFuncOp::cloneTypeWith(::mlir::TypeRange inputs,
                                      ::mlir::TypeRange results) {
  return FunctionType::get(getContext(), inputs, results);
}
 
ParseResult DPIFuncOp::parse(OpAsmParser &parser, OperationState &result) {
  auto builder = parser.getBuilder();
  auto ctx = builder.getContext();
 
  (void)mlir::impl::parseOptionalVisibilityKeyword(parser, result.attributes);
 
  StringAttr nameAttr;
  if (parser.parseSymbolName(nameAttr,
                             DPIFuncOp::getSymNameAttrName(result.name),
                             result.attributes))
    return failure();
 
  SmallVector<DPIArgument> args;
  SmallVector<Attribute> argLocs;
  auto unknownLoc = builder.getUnknownLoc();
  bool hasLocs = false;
 
  auto parseOneArg = [&]() -> ParseResult {
    StringRef dirKeyword;
    auto keyLoc = parser.getCurrentLocation();
    if (parser.parseKeyword(&dirKeyword))
      return failure();
    auto dir = parseDPIDirectionKeyword(dirKeyword);
    if (!dir)
      return parser.emitError(keyLoc,
                              "expected DPI argument direction keyword");
 
    // For input/inout/ref args, parse SSA name; for output/return, bare name.
    bool hasSSA = isCallOperandDir(*dir);
    std::string argName;
    if (hasSSA) {
      OpAsmParser::UnresolvedOperand ssaName;
      if (parser.parseOperand(ssaName, /*allowResultNumber=*/false))
        return failure();
      argName = ssaName.name.substr(1).str();
    } else {
      if (parser.parseKeywordOrString(&argName))
        return failure();
    }
 
    Type argType;
    if (parser.parseColonType(argType))
      return failure();
    args.push_back({StringAttr::get(ctx, argName), argType, *dir});
 
    std::optional<Location> maybeLoc;
    if (failed(parser.parseOptionalLocationSpecifier(maybeLoc)))
      return failure();
    if (maybeLoc) {
      argLocs.push_back(*maybeLoc);
      hasLocs = true;
    } else {
      argLocs.push_back(unknownLoc);
    }
    return success();
  };
 
  if (parser.parseCommaSeparatedList(OpAsmParser::Delimiter::Paren, parseOneArg,
                                     " in DPI argument list"))
    return failure();
 
  auto dpiType = DPIFunctionType::get(ctx, args);
 
  result.addAttribute(DPIFuncOp::getDpiFunctionTypeAttrName(result.name),
                      TypeAttr::get(dpiType));
  if (hasLocs)
    result.addAttribute(DPIFuncOp::getArgumentLocsAttrName(result.name),
                        builder.getArrayAttr(argLocs));
  result.addRegion();
 
  if (failed(parser.parseOptionalAttrDictWithKeyword(result.attributes)))
    return failure();
  return success();
}
 
void DPIFuncOp::print(OpAsmPrinter &p) {
  p << ' ';
 
  StringRef visibilityAttrName =
      mlir::SymbolOpInterface::getDefaultVisibilityAttrName();
  if (auto visibility = (*this)->getAttrOfType<StringAttr>(visibilityAttrName))
    p << visibility.getValue() << ' ';
  p.printSymbolName(getSymName());
 
  auto dpiType = getDpiFunctionType();
  auto dpiArgs = dpiType.getArguments();
 
  p << '(';
  llvm::interleaveComma(llvm::enumerate(dpiArgs), p, [&](auto it) {
    auto &arg = it.value();
    auto i = it.index();
 
    p << stringifyDPIDirectionKeyword(arg.dir) << ' ';
 
    if (isCallOperandDir(arg.dir))
      p << '%';
    p.printKeywordOrString(arg.name.getValue());
    p << " : ";
    p.printType(arg.type);
 
    if (getArgumentLocs()) {
      auto loc = cast<Location>(getArgumentLocsAttr()[i]);
      if (loc != UnknownLoc::get(getContext()))
        p.printOptionalLocationSpecifier(loc);
    }
  });
  p << ')';
 
  mlir::function_interface_impl::printFunctionAttributes(
      p, *this,
      {visibilityAttrName, getDpiFunctionTypeAttrName(),
       getArgumentLocsAttrName()});
}
 
LogicalResult DPIFuncOp::verify() {
  auto dpiType = getDpiFunctionType();
 
  // Structural constraints shared with all DPIFunctionType users.
  if (failed(dpiType.verify([&]() { return emitOpError(); })))
    return failure();
 
  // Sim-specific constraints.
  for (auto &arg : dpiType.getArguments()) {
    if (arg.dir == DPIDirection::Ref) {
      if (!isa<LLVM::LLVMPointerType>(arg.type))
        return emitOpError("'ref' arguments must use !llvm.ptr type");
    }
  }
 
  return success();
}
 
LogicalResult
sim::DPICallOp::verifySymbolUses(SymbolTableCollection &symbolTable) {
  auto referencedOp =
      symbolTable.lookupNearestSymbolFrom(*this, getCalleeAttr());
  if (!referencedOp)
    return emitError("cannot find function declaration '")
           << getCallee() << "'";
  if (auto dpiFunc = dyn_cast<sim::DPIFuncOp>(referencedOp)) {
    auto expectedFuncType = cast<FunctionType>(dpiFunc.getFunctionType());
    auto expectedInputs = expectedFuncType.getInputs();
    auto expectedResults = expectedFuncType.getResults();
    if (getInputs().size() != expectedInputs.size())
      return emitError("expects ")
             << expectedInputs.size() << " DPI operands, but got "
             << getInputs().size();
    if (getResults().size() != expectedResults.size())
      return emitError("expects ")
             << expectedResults.size() << " DPI results, but got "
             << getResults().size();
    for (auto [operand, expectedType] : llvm::zip(getInputs(), expectedInputs))
      if (operand.getType() != expectedType)
        return emitError("operand type mismatch: expected ")
               << expectedType << ", but got " << operand.getType();
    for (auto [result, expectedType] : llvm::zip(getResults(), expectedResults))
      if (result.getType() != expectedType)
        return emitError("result type mismatch: expected ")
               << expectedType << ", but got " << result.getType();
    return success();
  }
  if (isa<func::FuncOp>(referencedOp))
    return success();
  return emitError("callee must be 'sim.func.dpi' or 'func.func' but got '")
         << referencedOp->getName() << "'";
}
 
// Render `value` in the given `radix` and pad it to a field width, returning
// the result as a `StringAttr`. The field width and padding semantics are
// shared with the Arc runtime through `circt::formatInteger` (see
// FormatInteger.h). Zero-width values produce the empty string.
static StringAttr formatIntegersByRadix(MLIRContext *ctx, unsigned radix,
                                        const Attribute &value,
                                        bool isUpperCase, bool isLeftAligned,
                                        char paddingChar,
                                        std::optional<int32_t> specifierWidth,
                                        bool isSigned = false) {
  auto intAttr = llvm::dyn_cast_or_null<IntegerAttr>(value);
  if (!intAttr)
    return {};
  if (intAttr.getType().getIntOrFloatBitWidth() == 0)
    return StringAttr::get(ctx, "");
 
  SmallString<32> str;
  llvm::raw_svector_ostream os(str);
  formatInteger(os, intAttr.getValue(), radix, isUpperCase, isLeftAligned,
                paddingChar, specifierWidth, isSigned);
  return StringAttr::get(ctx, str);
}
 
static StringAttr formatFloatsBySpecifier(MLIRContext *ctx, Attribute value,
                                          bool isLeftAligned,
                                          std::optional<unsigned> fieldWidth,
                                          std::optional<unsigned> fracDigits,
                                          std::string formatSpecifier) {
  if (auto floatAttr = llvm::dyn_cast_or_null<FloatAttr>(value)) {
    std::string widthString = isLeftAligned ? "-" : "";
    if (fieldWidth.has_value()) {
      widthString += std::to_string(fieldWidth.value());
    }
    std::string fmtSpecifier = "%" + widthString + "." +
                               std::to_string(fracDigits.value()) +
                               formatSpecifier;
 
    // Calculates number of bytes needed to store the format string
    // excluding the null terminator
    int bufferSize = std::snprintf(nullptr, 0, fmtSpecifier.c_str(),
                                   floatAttr.getValue().convertToDouble());
    std::string floatFmtBuffer(bufferSize, '\0');
    snprintf(floatFmtBuffer.data(), bufferSize + 1, fmtSpecifier.c_str(),
             floatAttr.getValue().convertToDouble());
    return StringAttr::get(ctx, floatFmtBuffer);
  }
  return {};
}
 
// (DPIFuncOp parse/print/verify are now defined above, near the top of the
// file)
 
OpFoldResult FormatLiteralOp::fold(FoldAdaptor adaptor) {
  return getLiteralAttr();
}
 
// --- FormatStringOp ---
 
StringAttr FormatStringOp::formatConstant(Attribute constVal) {
  auto strAttr = llvm::dyn_cast<StringAttr>(constVal);
  if (!strAttr)
    return {};
 
  SmallString<128> strBuf(strAttr.getValue());
  if (getSpecifierWidth().has_value()) {
    auto padChar = static_cast<char>(getPaddingChar());
    unsigned padWidth = getSpecifierWidth().value();
    padWidth = padWidth > strBuf.size() ? padWidth - strBuf.size() : 0;
    if (getIsLeftAligned())
      strBuf.append(padWidth, padChar);
    else
      strBuf.insert(strBuf.begin(), padWidth, padChar);
  }
  return StringAttr::get(getContext(), strBuf);
}
 
// --- FormatDecOp ---
 
StringAttr FormatDecOp::formatConstant(Attribute constVal) {
  auto intAttr = llvm::dyn_cast<IntegerAttr>(constVal);
  if (!intAttr)
    return {};
  SmallString<16> str;
  llvm::raw_svector_ostream os(str);
  formatInteger(os, intAttr.getValue(), /*radix=*/10, /*isUpperCase=*/false,
                getIsLeftAligned(), getPaddingChar(), getSpecifierWidth(),
                getIsSigned());
  return StringAttr::get(getContext(), str);
}
 
OpFoldResult FormatDecOp::fold(FoldAdaptor adaptor) {
  if (getValue().getType().getIntOrFloatBitWidth() == 0)
    return StringAttr::get(getContext(), "0");
  return {};
}
 
// --- FormatHexOp ---
 
StringAttr FormatHexOp::formatConstant(Attribute constVal) {
  return formatIntegersByRadix(constVal.getContext(), 16, constVal,
                               getIsHexUppercase(), getIsLeftAligned(),
                               getPaddingChar(), getSpecifierWidth());
}
 
OpFoldResult FormatHexOp::fold(FoldAdaptor adaptor) {
  if (getValue().getType().getIntOrFloatBitWidth() == 0)
    return formatIntegersByRadix(
        getContext(), 16, IntegerAttr::get(getValue().getType(), 0), false,
        getIsLeftAligned(), getPaddingChar(), getSpecifierWidth());
  return {};
}
 
// --- FormatOctOp ---
 
StringAttr FormatOctOp::formatConstant(Attribute constVal) {
  return formatIntegersByRadix(constVal.getContext(), 8, constVal, false,
                               getIsLeftAligned(), getPaddingChar(),
                               getSpecifierWidth());
}
 
OpFoldResult FormatOctOp::fold(FoldAdaptor adaptor) {
  if (getValue().getType().getIntOrFloatBitWidth() == 0)
    return formatIntegersByRadix(
        getContext(), 8, IntegerAttr::get(getValue().getType(), 0), false,
        getIsLeftAligned(), getPaddingChar(), getSpecifierWidth());
  return {};
}
 
// --- FormatBinOp ---
 
StringAttr FormatBinOp::formatConstant(Attribute constVal) {
  return formatIntegersByRadix(constVal.getContext(), 2, constVal, false,
                               getIsLeftAligned(), getPaddingChar(),
                               getSpecifierWidth());
}
 
OpFoldResult FormatBinOp::fold(FoldAdaptor adaptor) {
  if (getValue().getType().getIntOrFloatBitWidth() == 0)
    return formatIntegersByRadix(
        getContext(), 2, IntegerAttr::get(getValue().getType(), 0), false,
        getIsLeftAligned(), getPaddingChar(), getSpecifierWidth());
  return {};
}
 
// --- FormatScientificOp ---
 
StringAttr FormatScientificOp::formatConstant(Attribute constVal) {
  return formatFloatsBySpecifier(getContext(), constVal, getIsLeftAligned(),
                                 getFieldWidth(), getFracDigits(), "e");
}
 
// --- FormatFloatOp ---
 
StringAttr FormatFloatOp::formatConstant(Attribute constVal) {
  return formatFloatsBySpecifier(getContext(), constVal, getIsLeftAligned(),
                                 getFieldWidth(), getFracDigits(), "f");
}
 
// --- FormatGeneralOp ---
 
StringAttr FormatGeneralOp::formatConstant(Attribute constVal) {
  return formatFloatsBySpecifier(getContext(), constVal, getIsLeftAligned(),
                                 getFieldWidth(), getFracDigits(), "g");
}
 
// --- FormatCharOp ---
 
StringAttr FormatCharOp::formatConstant(Attribute constVal) {
  auto intCst = dyn_cast<IntegerAttr>(constVal);
  if (!intCst)
    return {};
  if (intCst.getType().getIntOrFloatBitWidth() == 0)
    return StringAttr::get(getContext(), Twine(static_cast<char>(0)));
  if (intCst.getType().getIntOrFloatBitWidth() > 8)
    return {};
  auto intValue = intCst.getValue().getZExtValue();
  return StringAttr::get(getContext(), Twine(static_cast<char>(intValue)));
}
 
OpFoldResult FormatCharOp::fold(FoldAdaptor adaptor) {
  if (getValue().getType().getIntOrFloatBitWidth() == 0)
    return StringAttr::get(getContext(), Twine(static_cast<char>(0)));
  return {};
}
 
static StringAttr concatLiterals(MLIRContext *ctxt, ArrayRef<StringRef> lits) {
  assert(!lits.empty() && "No literals to concatenate");
  if (lits.size() == 1)
    return StringAttr::get(ctxt, lits.front());
  SmallString<64> newLit;
  for (auto lit : lits)
    newLit += lit;
  return StringAttr::get(ctxt, newLit);
}
 
OpFoldResult FormatStringConcatOp::fold(FoldAdaptor adaptor) {
  if (getNumOperands() == 0)
    return StringAttr::get(getContext(), "");
  if (getNumOperands() == 1) {
    // Don't fold to our own result to avoid an infinte loop.
    if (getResult() == getOperand(0))
      return {};
    return getOperand(0);
  }
 
  // Fold if all operands are literals.
  SmallVector<StringRef> lits;
  for (auto attr : adaptor.getInputs()) {
    auto lit = dyn_cast_or_null<StringAttr>(attr);
    if (!lit)
      return {};
    lits.push_back(lit);
  }
  return concatLiterals(getContext(), lits);
}
 
LogicalResult FormatStringConcatOp::getFlattenedInputs(
    llvm::SmallVectorImpl<Value> &flatOperands) {
  llvm::SmallMapVector<FormatStringConcatOp, unsigned, 4> concatStack;
  bool isCyclic = false;
 
  // Perform a DFS on this operation's concatenated operands,
  // collect the leaf format string fragments.
  concatStack.insert({*this, 0});
  while (!concatStack.empty()) {
    auto &top = concatStack.back();
    auto currentConcat = top.first;
    unsigned operandIndex = top.second;
 
    // Iterate over concatenated operands
    while (operandIndex < currentConcat.getNumOperands()) {
      auto currentOperand = currentConcat.getOperand(operandIndex);
 
      if (auto nextConcat =
              currentOperand.getDefiningOp<FormatStringConcatOp>()) {
        // Concat of a concat
        if (!concatStack.contains(nextConcat)) {
          // Save the next operand index to visit on the
          // stack and put the new concat on top.
          top.second = operandIndex + 1;
          concatStack.insert({nextConcat, 0});
          break;
        }
        // Cyclic concatenation encountered. Don't recurse.
        isCyclic = true;
      }
 
      flatOperands.push_back(currentOperand);
      operandIndex++;
    }
 
    // Pop the concat off of the stack if we have visited all operands.
    if (operandIndex >= currentConcat.getNumOperands())
      concatStack.pop_back();
  }
 
  return success(!isCyclic);
}
 
LogicalResult FormatStringConcatOp::verify() {
  if (llvm::any_of(getOperands(),
                   [&](Value operand) { return operand == getResult(); }))
    return emitOpError("is infinitely recursive.");
  return success();
}
 
LogicalResult FormatStringConcatOp::canonicalize(FormatStringConcatOp op,
                                                 PatternRewriter &rewriter) {
  // Any helper literals created during canonicalization must dominate `op`.
  rewriter.setInsertionPoint(op);
 
  auto fmtStrType = FormatStringType::get(op.getContext());
 
  // Check if we can flatten concats of concats
  bool hasBeenFlattened = false;
  SmallVector<Value, 0> flatOperands;
  if (!op.isFlat()) {
    // Get a new, flattened list of operands
    flatOperands.reserve(op.getNumOperands() + 4);
    auto isAcyclic = op.getFlattenedInputs(flatOperands);
 
    if (failed(isAcyclic)) {
      // Infinite recursion, but we cannot fail compilation right here (can we?)
      // so just emit a warning and bail out.
      op.emitWarning("Cyclic concatenation detected.");
      return failure();
    }
 
    hasBeenFlattened = true;
  }
 
  if (!hasBeenFlattened && op.getNumOperands() < 2)
    return failure(); // Should be handled by the folder
 
  // Check if there are adjacent literals we can merge or empty literals to
  // remove
  SmallVector<StringRef> litSequence;
  SmallVector<Value> newOperands;
  newOperands.reserve(op.getNumOperands());
  FormatLiteralOp prevLitOp;
 
  auto oldOperands = hasBeenFlattened ? flatOperands : op.getOperands();
  for (auto operand : oldOperands) {
    if (auto litOp = operand.getDefiningOp<FormatLiteralOp>()) {
      if (!litOp.getLiteral().empty()) {
        prevLitOp = litOp;
        litSequence.push_back(litOp.getLiteral());
      }
    } else {
      if (!litSequence.empty()) {
        if (litSequence.size() > 1) {
          // Create a fused literal.
          auto newLit = rewriter.createOrFold<FormatLiteralOp>(
              op.getLoc(), fmtStrType,
              concatLiterals(op.getContext(), litSequence));
          newOperands.push_back(newLit);
        } else {
          // Reuse the existing literal.
          newOperands.push_back(prevLitOp.getResult());
        }
        litSequence.clear();
      }
      newOperands.push_back(operand);
    }
  }
 
  // Push trailing literals into the new operand list
  if (!litSequence.empty()) {
    if (litSequence.size() > 1) {
      // Create a fused literal.
      auto newLit = rewriter.createOrFold<FormatLiteralOp>(
          op.getLoc(), fmtStrType,
          concatLiterals(op.getContext(), litSequence));
      newOperands.push_back(newLit);
    } else {
      // Reuse the existing literal.
      newOperands.push_back(prevLitOp.getResult());
    }
  }
 
  if (!hasBeenFlattened && newOperands.size() == op.getNumOperands())
    return failure(); // Nothing changed
 
  if (newOperands.empty())
    rewriter.replaceOpWithNewOp<FormatLiteralOp>(op, fmtStrType,
                                                 rewriter.getStringAttr(""));
  else if (newOperands.size() == 1)
    rewriter.replaceOp(op, newOperands);
  else
    rewriter.modifyOpInPlace(op, [&]() { op->setOperands(newOperands); });
 
  return success();
}
 
LogicalResult PrintFormattedOp::canonicalize(PrintFormattedOp op,
                                             PatternRewriter &rewriter) {
  // Remove ops with constant false condition.
  if (auto cstCond = op.getCondition().getDefiningOp<hw::ConstantOp>()) {
    if (cstCond.getValue().isZero()) {
      rewriter.eraseOp(op);
      return success();
    }
  }
  return failure();
}
 
LogicalResult PrintFormattedProcOp::canonicalize(PrintFormattedProcOp op,
                                                 PatternRewriter &rewriter) {
  // Remove empty prints.
  if (auto litInput = op.getInput().getDefiningOp<FormatLiteralOp>()) {
    if (litInput.getLiteral().empty()) {
      rewriter.eraseOp(op);
      return success();
    }
  }
  return failure();
}
 
OpFoldResult StringConstantOp::fold(FoldAdaptor adaptor) {
  return adaptor.getLiteralAttr();
}
 
OpFoldResult StringConcatOp::fold(FoldAdaptor adaptor) {
  auto operands = adaptor.getInputs();
  if (operands.empty())
    return StringAttr::get(getContext(), "");
 
  SmallString<128> result;
  for (auto &operand : operands) {
    auto strAttr = cast_if_present<StringAttr>(operand);
    if (!strAttr)
      return {};
    result += strAttr.getValue();
  }
 
  return StringAttr::get(getContext(), result);
}
 
OpFoldResult StringLengthOp::fold(FoldAdaptor adaptor) {
  auto inputAttr = adaptor.getInput();
  if (!inputAttr)
    return {};
 
  if (auto strAttr = cast<StringAttr>(inputAttr))
    return IntegerAttr::get(getType(), strAttr.getValue().size());
 
  return {};
}
 
OpFoldResult IntToStringOp::fold(FoldAdaptor adaptor) {
  auto intAttr = cast_or_null<IntegerAttr>(adaptor.getInput());
  if (!intAttr)
    return {};
 
  SmallString<128> result;
  auto width = intAttr.getType().getIntOrFloatBitWidth();
  // Starting from the LSB, we extract the values byte-by-byte,
  // and convert each non-null byte to a char
 
  // For example 0x00_00_00_48_00_00_6C_6F would look like "Hlo"
  for (unsigned int i = 0; i < width; i += 8) {
    auto byte =
        intAttr.getValue().extractBitsAsZExtValue(std::min(width - i, 8U), i);
    if (byte)
      result.push_back(static_cast<char>(byte));
  }
  std::reverse(result.begin(), result.end());
  return StringAttr::get(getContext(), result);
  return {};
}
 
//===----------------------------------------------------------------------===//
// StringGetOp
//===----------------------------------------------------------------------===//
 
OpFoldResult StringGetOp::fold(FoldAdaptor adaptor) {
  auto strAttr = cast_or_null<StringAttr>(adaptor.getStr());
  auto indexAttr = cast_or_null<IntegerAttr>(adaptor.getIndex());
  if (!strAttr || !indexAttr)
    return {};
 
  auto str = strAttr.getValue();
  int64_t index = indexAttr.getValue().getSExtValue();
 
  // Out-of-bounds access returns 0 (null character) per IEEE 1800-2023 § 6.16
  if (index < 0 || index >= static_cast<int64_t>(str.size()))
    return IntegerAttr::get(getType(), 0);
 
  // Return the character at the specified index
  uint8_t ch = static_cast<uint8_t>(str[index]);
  return IntegerAttr::get(getType(), ch);
}
 
//===----------------------------------------------------------------------===//
// QueueResizeOp
//===----------------------------------------------------------------------===//
 
LogicalResult QueueResizeOp::verify() {
  if (cast<QueueType>(getInput().getType()).getElementType() !=
      cast<QueueType>(getResult().getType()).getElementType())
    return failure();
  return success();
}
 
LogicalResult QueueFromArrayOp::verify() {
  auto queueElementType =
      cast<QueueType>(getResult().getType()).getElementType();
 
  auto arrayElementType =
      cast<hw::ArrayType>(getInput().getType()).getElementType();
 
  if (queueElementType != arrayElementType) {
    return emitOpError() << "sim::Queue element type " << queueElementType
                         << " doesn't match hw::ArrayType element type "
                         << arrayElementType;
  }
 
  return success();
}
 
LogicalResult QueueConcatOp::verify() {
  // Verify the element types of all concatenated queues equal that of the
  // result queue. (but not the bounds)
  auto resultElType = cast<QueueType>(getResult().getType()).getElementType();
 
  for (Value input : getInputs()) {
    auto inpElType = cast<QueueType>(input.getType()).getElementType();
    if (inpElType != resultElType) {
      return emitOpError() << "sim::Queue element type " << inpElType
                           << " doesn't match result sim::Queue element type "
                           << resultElType;
    }
  }
 
  return success();
}
 
//===----------------------------------------------------------------------===//
// TriggeredOp
//===----------------------------------------------------------------------===//
 
void TriggeredOp::build(OpBuilder &builder, OperationState &odsState,
                        Value clock, Value condition) {
  odsState.addOperands(clock);
  if (condition)
    odsState.addOperands(condition);
 
  auto *region = odsState.addRegion();
  region->push_back(new Block());
}
 
void TriggeredOp::build(OpBuilder &builder, OperationState &odsState,
                        Value clock, Value condition,
                        llvm::function_ref<void()> bodyCtor) {
  OpBuilder::InsertionGuard guard(builder);
 
  odsState.addOperands(clock);
  if (condition)
    odsState.addOperands(condition);
 
  builder.createBlock(odsState.addRegion());
  if (bodyCtor)
    bodyCtor();
}
 
//===----------------------------------------------------------------------===//
// SVReadMemOp
//===----------------------------------------------------------------------===//
 
LogicalResult SVReadMemOp::verify() {
  if (getFinishAddr() && !getStartAddr())
    return emitOpError("'finishAddr' requires 'startAddr' to be present");
  if (getSliceLeft() && !getSliceRight())
    return emitOpError("'sliceLeft' requires 'sliceRight' to be present");
  if (getSliceRight() && !getSliceLeft())
    return emitOpError("'sliceRight' requires 'sliceLeft' to be present");
  if (getDimLows().empty() || getDimLows().size() != getDimDescending().size())
    return emitOpError("'dimLows' and 'dimDescending' must have one entry per "
                       "unpacked dimension");
  return success();
}
 
//===----------------------------------------------------------------------===//
// TableGen generated logic.
//===----------------------------------------------------------------------===//
 
#include "circt/Dialect/Sim/SimOpInterfaces.cpp.inc"
 
// Provide the autogenerated implementation guts for the Op classes.
#define GET_OP_CLASSES
#include "circt/Dialect/Sim/Sim.cpp.inc"
#include "circt/Dialect/Sim/SimEnums.cpp.inc"