Deserializer.cpp

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//===- Deserializer.cpp - MLIR SPIR-V Deserializer ------------------------===//
//
// 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 defines the SPIR-V binary to MLIR SPIR-V module deserializer.
//
//===----------------------------------------------------------------------===//
 
#include "Deserializer.h"
 
#include "mlir/Dialect/SPIRV/IR/SPIRVAttributes.h"
#include "mlir/Dialect/SPIRV/IR/SPIRVEnums.h"
#include "mlir/Dialect/SPIRV/IR/SPIRVOps.h"
#include "mlir/Dialect/SPIRV/IR/SPIRVTypes.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/IRMapping.h"
#include "mlir/IR/Location.h"
#include "mlir/Target/SPIRV/SPIRVBinaryUtils.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Sequence.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/bit.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
#include <optional>
 
using namespace mlir;
 
#define DEBUG_TYPE "spirv-deserialization"
 
//===----------------------------------------------------------------------===//
// Utility Functions
//===----------------------------------------------------------------------===//
 
/// Returns true if the given `block` is a function entry block.
static inline bool isFnEntryBlock(Block *block) {
  return block->isEntryBlock() &&
         isa_and_nonnull<spirv::FuncOp>(block->getParentOp());
}
 
//===----------------------------------------------------------------------===//
// Deserializer Method Definitions
//===----------------------------------------------------------------------===//
 
spirv::Deserializer::Deserializer(ArrayRef<uint32_t> binary,
                                  MLIRContext *context,
                                  const spirv::DeserializationOptions &options)
    : binary(binary), context(context), unknownLoc(UnknownLoc::get(context)),
      module(createModuleOp()), opBuilder(module->getRegion()), options(options)
#ifndef NDEBUG
      ,
      logger(llvm::dbgs())
#endif
{
}
 
LogicalResult spirv::Deserializer::deserialize() {
  LLVM_DEBUG({
    logger.resetIndent();
    logger.startLine()
        << "//+++---------- start deserialization ----------+++//\n";
  });
 
  if (failed(processHeader()))
    return failure();
 
  spirv::Opcode opcode = spirv::Opcode::OpNop;
  ArrayRef<uint32_t> operands;
  auto binarySize = binary.size();
  while (curOffset < binarySize) {
    // Slice the next instruction out and populate `opcode` and `operands`.
    // Internally this also updates `curOffset`.
    if (failed(sliceInstruction(opcode, operands)))
      return failure();
 
    if (failed(processInstruction(opcode, operands)))
      return failure();
  }
 
  assert(curOffset == binarySize &&
         "deserializer should never index beyond the binary end");
 
  for (auto &deferred : deferredInstructions) {
    if (failed(processInstruction(deferred.first, deferred.second, false))) {
      return failure();
    }
  }
 
  attachVCETriple();
 
  LLVM_DEBUG(logger.startLine()
             << "//+++-------- completed deserialization --------+++//\n");
  return success();
}
 
OwningOpRef<spirv::ModuleOp> spirv::Deserializer::collect() {
  return std::move(module);
}
 
//===----------------------------------------------------------------------===//
// Module structure
//===----------------------------------------------------------------------===//
 
OwningOpRef<spirv::ModuleOp> spirv::Deserializer::createModuleOp() {
  OpBuilder builder(context);
  OperationState state(unknownLoc, spirv::ModuleOp::getOperationName());
  spirv::ModuleOp::build(builder, state);
  return cast<spirv::ModuleOp>(Operation::create(state));
}
 
LogicalResult spirv::Deserializer::processHeader() {
  if (binary.size() < spirv::kHeaderWordCount)
    return emitError(unknownLoc,
                     "SPIR-V binary module must have a 5-word header");
 
  if (binary[0] != spirv::kMagicNumber)
    return emitError(unknownLoc, "incorrect magic number");
 
  // Version number bytes: 0 | major number | minor number | 0
  uint32_t majorVersion = (binary[1] << 8) >> 24;
  uint32_t minorVersion = (binary[1] << 16) >> 24;
  if (majorVersion == 1) {
    switch (minorVersion) {
#define MIN_VERSION_CASE(v)                                                    \
  case v:                                                                      \
    version = spirv::Version::V_1_##v;                                         \
    break
 
      MIN_VERSION_CASE(0);
      MIN_VERSION_CASE(1);
      MIN_VERSION_CASE(2);
      MIN_VERSION_CASE(3);
      MIN_VERSION_CASE(4);
      MIN_VERSION_CASE(5);
      MIN_VERSION_CASE(6);
#undef MIN_VERSION_CASE
    default:
      return emitError(unknownLoc, "unsupported SPIR-V minor version: ")
             << minorVersion;
    }
  } else {
    return emitError(unknownLoc, "unsupported SPIR-V major version: ")
           << majorVersion;
  }
 
  // TODO: generator number, bound, schema
  curOffset = spirv::kHeaderWordCount;
  return success();
}
 
LogicalResult
spirv::Deserializer::processCapability(ArrayRef<uint32_t> operands) {
  if (operands.size() != 1)
    return emitError(unknownLoc, "OpCapability must have one parameter");
 
  auto cap = spirv::symbolizeCapability(operands[0]);
  if (!cap)
    return emitError(unknownLoc, "unknown capability: ") << operands[0];
 
  capabilities.insert(*cap);
  return success();
}
 
LogicalResult spirv::Deserializer::processExtension(ArrayRef<uint32_t> words) {
  if (words.empty()) {
    return emitError(
        unknownLoc,
        "OpExtension must have a literal string for the extension name");
  }
 
  unsigned wordIndex = 0;
  StringRef extName = decodeStringLiteral(words, wordIndex);
  if (wordIndex != words.size())
    return emitError(unknownLoc,
                     "unexpected trailing words in OpExtension instruction");
  auto ext = spirv::symbolizeExtension(extName);
  if (!ext)
    return emitError(unknownLoc, "unknown extension: ") << extName;
 
  extensions.insert(*ext);
  return success();
}
 
LogicalResult
spirv::Deserializer::processExtInstImport(ArrayRef<uint32_t> words) {
  if (words.size() < 2) {
    return emitError(unknownLoc,
                     "OpExtInstImport must have a result <id> and a literal "
                     "string for the extended instruction set name");
  }
 
  unsigned wordIndex = 1;
  extendedInstSets[words[0]] = decodeStringLiteral(words, wordIndex);
  if (wordIndex != words.size()) {
    return emitError(unknownLoc,
                     "unexpected trailing words in OpExtInstImport");
  }
  return success();
}
 
void spirv::Deserializer::attachVCETriple() {
  (*module)->setAttr(
      spirv::ModuleOp::getVCETripleAttrName(),
      spirv::VerCapExtAttr::get(version, capabilities.getArrayRef(),
                                extensions.getArrayRef(), context));
}
 
LogicalResult
spirv::Deserializer::processMemoryModel(ArrayRef<uint32_t> operands) {
  if (operands.size() != 2)
    return emitError(unknownLoc, "OpMemoryModel must have two operands");
 
  (*module)->setAttr(
      module->getAddressingModelAttrName(),
      opBuilder.getAttr<spirv::AddressingModelAttr>(
          static_cast<spirv::AddressingModel>(operands.front())));
 
  (*module)->setAttr(module->getMemoryModelAttrName(),
                     opBuilder.getAttr<spirv::MemoryModelAttr>(
                         static_cast<spirv::MemoryModel>(operands.back())));
 
  return success();
}
 
template <typename AttrTy, typename EnumAttrTy, typename EnumTy>
LogicalResult deserializeCacheControlDecoration(
    Location loc, OpBuilder &opBuilder,
    DenseMap<uint32_t, NamedAttrList> &decorations, ArrayRef<uint32_t> words,
    StringAttr symbol, StringRef decorationName, StringRef cacheControlKind) {
  if (words.size() != 4) {
    return emitError(loc, "OpDecoration with ")
           << decorationName << "needs a cache control integer literal and a "
           << cacheControlKind << " cache control literal";
  }
  unsigned cacheLevel = words[2];
  auto cacheControlAttr = static_cast<EnumTy>(words[3]);
  auto value = opBuilder.getAttr<AttrTy>(cacheLevel, cacheControlAttr);
  SmallVector<Attribute> attrs;
  if (auto attrList =
          llvm::dyn_cast_or_null<ArrayAttr>(decorations[words[0]].get(symbol)))
    llvm::append_range(attrs, attrList);
  attrs.push_back(value);
  decorations[words[0]].set(symbol, opBuilder.getArrayAttr(attrs));
  return success();
}
 
LogicalResult spirv::Deserializer::processDecoration(ArrayRef<uint32_t> words) {
  // TODO: This function should also be auto-generated. For now, since only a
  // few decorations are processed/handled in a meaningful manner, going with a
  // manual implementation.
  if (words.size() < 2) {
    return emitError(
        unknownLoc, "OpDecorate must have at least result <id> and Decoration");
  }
  auto decorationName =
      stringifyDecoration(static_cast<spirv::Decoration>(words[1]));
  if (decorationName.empty()) {
    return emitError(unknownLoc, "invalid Decoration code : ") << words[1];
  }
  auto symbol = getSymbolDecoration(decorationName);
  switch (static_cast<spirv::Decoration>(words[1])) {
  case spirv::Decoration::FPFastMathMode:
    if (words.size() != 3) {
      return emitError(unknownLoc, "OpDecorate with ")
             << decorationName << " needs a single integer literal";
    }
    decorations[words[0]].set(
        symbol, FPFastMathModeAttr::get(opBuilder.getContext(),
                                        static_cast<FPFastMathMode>(words[2])));
    break;
  case spirv::Decoration::FPRoundingMode:
    if (words.size() != 3) {
      return emitError(unknownLoc, "OpDecorate with ")
             << decorationName << " needs a single integer literal";
    }
    decorations[words[0]].set(
        symbol, FPRoundingModeAttr::get(opBuilder.getContext(),
                                        static_cast<FPRoundingMode>(words[2])));
    break;
  case spirv::Decoration::DescriptorSet:
  case spirv::Decoration::Binding:
    if (words.size() != 3) {
      return emitError(unknownLoc, "OpDecorate with ")
             << decorationName << " needs a single integer literal";
    }
    decorations[words[0]].set(
        symbol, opBuilder.getI32IntegerAttr(static_cast<int32_t>(words[2])));
    break;
  case spirv::Decoration::BuiltIn:
    if (words.size() != 3) {
      return emitError(unknownLoc, "OpDecorate with ")
             << decorationName << " needs a single integer literal";
    }
    decorations[words[0]].set(
        symbol, opBuilder.getStringAttr(
                    stringifyBuiltIn(static_cast<spirv::BuiltIn>(words[2]))));
    break;
  case spirv::Decoration::ArrayStride:
    if (words.size() != 3) {
      return emitError(unknownLoc, "OpDecorate with ")
             << decorationName << " needs a single integer literal";
    }
    typeDecorations[words[0]] = words[2];
    break;
  case spirv::Decoration::LinkageAttributes: {
    if (words.size() < 4) {
      return emitError(unknownLoc, "OpDecorate with ")
             << decorationName
             << " needs at least 1 string and 1 integer literal";
    }
    // LinkageAttributes has two parameters ["linkageName", linkageType]
    // e.g., OpDecorate %imported_func LinkageAttributes "outside.func" Import
    // "linkageName" is a stringliteral encoded as uint32_t,
    // hence the size of name is variable length which results in words.size()
    // being variable length, words.size() = 3 + strlen(name)/4 + 1 or
    // 3 + ceildiv(strlen(name), 4).
    unsigned wordIndex = 2;
    auto linkageName = spirv::decodeStringLiteral(words, wordIndex).str();
    auto linkageTypeAttr = opBuilder.getAttr<::mlir::spirv::LinkageTypeAttr>(
        static_cast<::mlir::spirv::LinkageType>(words[wordIndex++]));
    auto linkageAttr = opBuilder.getAttr<::mlir::spirv::LinkageAttributesAttr>(
        StringAttr::get(context, linkageName), linkageTypeAttr);
    decorations[words[0]].set(symbol, llvm::dyn_cast<Attribute>(linkageAttr));
    break;
  }
  case spirv::Decoration::Aliased:
  case spirv::Decoration::AliasedPointer:
  case spirv::Decoration::Block:
  case spirv::Decoration::BufferBlock:
  case spirv::Decoration::Flat:
  case spirv::Decoration::NonReadable:
  case spirv::Decoration::NonWritable:
  case spirv::Decoration::NoPerspective:
  case spirv::Decoration::NoSignedWrap:
  case spirv::Decoration::NoUnsignedWrap:
  case spirv::Decoration::RelaxedPrecision:
  case spirv::Decoration::Restrict:
  case spirv::Decoration::RestrictPointer:
  case spirv::Decoration::NoContraction:
  case spirv::Decoration::Constant:
  case spirv::Decoration::Invariant:
  case spirv::Decoration::Patch:
    if (words.size() != 2) {
      return emitError(unknownLoc, "OpDecoration with ")
             << decorationName << "needs a single target <id>";
    }
    decorations[words[0]].set(symbol, opBuilder.getUnitAttr());
    break;
  case spirv::Decoration::Location:
  case spirv::Decoration::SpecId:
    if (words.size() != 3) {
      return emitError(unknownLoc, "OpDecoration with ")
             << decorationName << "needs a single integer literal";
    }
    decorations[words[0]].set(
        symbol, opBuilder.getI32IntegerAttr(static_cast<int32_t>(words[2])));
    break;
  case spirv::Decoration::CacheControlLoadINTEL: {
    LogicalResult res = deserializeCacheControlDecoration<
        CacheControlLoadINTELAttr, LoadCacheControlAttr, LoadCacheControl>(
        unknownLoc, opBuilder, decorations, words, symbol, decorationName,
        "load");
    if (failed(res))
      return res;
    break;
  }
  case spirv::Decoration::CacheControlStoreINTEL: {
    LogicalResult res = deserializeCacheControlDecoration<
        CacheControlStoreINTELAttr, StoreCacheControlAttr, StoreCacheControl>(
        unknownLoc, opBuilder, decorations, words, symbol, decorationName,
        "store");
    if (failed(res))
      return res;
    break;
  }
  default:
    return emitError(unknownLoc, "unhandled Decoration : '") << decorationName;
  }
  return success();
}
 
LogicalResult
spirv::Deserializer::processMemberDecoration(ArrayRef<uint32_t> words) {
  // The binary layout of OpMemberDecorate is different comparing to OpDecorate
  if (words.size() < 3) {
    return emitError(unknownLoc,
                     "OpMemberDecorate must have at least 3 operands");
  }
 
  auto decoration = static_cast<spirv::Decoration>(words[2]);
  if (decoration == spirv::Decoration::Offset && words.size() != 4) {
    return emitError(unknownLoc,
                     " missing offset specification in OpMemberDecorate with "
                     "Offset decoration");
  }
  ArrayRef<uint32_t> decorationOperands;
  if (words.size() > 3) {
    decorationOperands = words.slice(3);
  }
  memberDecorationMap[words[0]][words[1]][decoration] = decorationOperands;
  return success();
}
 
LogicalResult spirv::Deserializer::processMemberName(ArrayRef<uint32_t> words) {
  if (words.size() < 3) {
    return emitError(unknownLoc, "OpMemberName must have at least 3 operands");
  }
  unsigned wordIndex = 2;
  auto name = decodeStringLiteral(words, wordIndex);
  if (wordIndex != words.size()) {
    return emitError(unknownLoc,
                     "unexpected trailing words in OpMemberName instruction");
  }
  memberNameMap[words[0]][words[1]] = name;
  return success();
}
 
LogicalResult spirv::Deserializer::setFunctionArgAttrs(
    uint32_t argID, SmallVectorImpl<Attribute> &argAttrs, size_t argIndex) {
  if (!decorations.contains(argID)) {
    argAttrs[argIndex] = DictionaryAttr::get(context, {});
    return success();
  }
 
  spirv::DecorationAttr foundDecorationAttr;
  for (NamedAttribute decAttr : decorations[argID]) {
    for (auto decoration :
         {spirv::Decoration::Aliased, spirv::Decoration::Restrict,
          spirv::Decoration::AliasedPointer,
          spirv::Decoration::RestrictPointer}) {
 
      if (decAttr.getName() !=
          getSymbolDecoration(stringifyDecoration(decoration)))
        continue;
 
      if (foundDecorationAttr)
        return emitError(unknownLoc,
                         "more than one Aliased/Restrict decorations for "
                         "function argument with result <id> ")
               << argID;
 
      foundDecorationAttr = spirv::DecorationAttr::get(context, decoration);
      break;
    }
 
    if (decAttr.getName() == getSymbolDecoration(stringifyDecoration(
                                 spirv::Decoration::RelaxedPrecision))) {
      // TODO: Current implementation supports only one decoration per function
      // parameter so RelaxedPrecision cannot be applied at the same time as,
      // for example, Aliased/Restrict/etc. This should be relaxed to allow any
      // combination of decoration allowed by the spec to be supported.
      if (foundDecorationAttr)
        return emitError(unknownLoc, "already found a decoration for function "
                                     "argument with result <id> ")
               << argID;
 
      foundDecorationAttr = spirv::DecorationAttr::get(
          context, spirv::Decoration::RelaxedPrecision);
    }
  }
 
  if (!foundDecorationAttr)
    return emitError(unknownLoc, "unimplemented decoration support for "
                                 "function argument with result <id> ")
           << argID;
 
  NamedAttribute attr(StringAttr::get(context, spirv::DecorationAttr::name),
                      foundDecorationAttr);
  argAttrs[argIndex] = DictionaryAttr::get(context, attr);
  return success();
}
 
LogicalResult
spirv::Deserializer::processFunction(ArrayRef<uint32_t> operands) {
  if (curFunction) {
    return emitError(unknownLoc, "found function inside function");
  }
 
  // Get the result type
  if (operands.size() != 4) {
    return emitError(unknownLoc, "OpFunction must have 4 parameters");
  }
  Type resultType = getType(operands[0]);
  if (!resultType) {
    return emitError(unknownLoc, "undefined result type from <id> ")
           << operands[0];
  }
 
  uint32_t fnID = operands[1];
  if (funcMap.count(fnID)) {
    return emitError(unknownLoc, "duplicate function definition/declaration");
  }
 
  auto fnControl = spirv::symbolizeFunctionControl(operands[2]);
  if (!fnControl) {
    return emitError(unknownLoc, "unknown Function Control: ") << operands[2];
  }
 
  Type fnType = getType(operands[3]);
  if (!fnType || !isa<FunctionType>(fnType)) {
    return emitError(unknownLoc, "unknown function type from <id> ")
           << operands[3];
  }
  auto functionType = cast<FunctionType>(fnType);
 
  if ((isVoidType(resultType) && functionType.getNumResults() != 0) ||
      (functionType.getNumResults() == 1 &&
       functionType.getResult(0) != resultType)) {
    return emitError(unknownLoc, "mismatch in function type ")
           << functionType << " and return type " << resultType << " specified";
  }
 
  std::string fnName = getFunctionSymbol(fnID);
  auto funcOp = spirv::FuncOp::create(opBuilder, unknownLoc, fnName,
                                      functionType, fnControl.value());
  // Processing other function attributes.
  if (decorations.count(fnID)) {
    for (auto attr : decorations[fnID].getAttrs()) {
      funcOp->setAttr(attr.getName(), attr.getValue());
    }
  }
  curFunction = funcMap[fnID] = funcOp;
  auto *entryBlock = funcOp.addEntryBlock();
  LLVM_DEBUG({
    logger.startLine()
        << "//===-------------------------------------------===//\n";
    logger.startLine() << "[fn] name: " << fnName << "\n";
    logger.startLine() << "[fn] type: " << fnType << "\n";
    logger.startLine() << "[fn] ID: " << fnID << "\n";
    logger.startLine() << "[fn] entry block: " << entryBlock << "\n";
    logger.indent();
  });
 
  SmallVector<Attribute> argAttrs;
  argAttrs.resize(functionType.getNumInputs());
 
  // Parse the op argument instructions
  if (functionType.getNumInputs()) {
    for (size_t i = 0, e = functionType.getNumInputs(); i != e; ++i) {
      auto argType = functionType.getInput(i);
      spirv::Opcode opcode = spirv::Opcode::OpNop;
      ArrayRef<uint32_t> operands;
      if (failed(sliceInstruction(opcode, operands,
                                  spirv::Opcode::OpFunctionParameter))) {
        return failure();
      }
      if (opcode != spirv::Opcode::OpFunctionParameter) {
        return emitError(
                   unknownLoc,
                   "missing OpFunctionParameter instruction for argument ")
               << i;
      }
      if (operands.size() != 2) {
        return emitError(
            unknownLoc,
            "expected result type and result <id> for OpFunctionParameter");
      }
      auto argDefinedType = getType(operands[0]);
      if (!argDefinedType || argDefinedType != argType) {
        return emitError(unknownLoc,
                         "mismatch in argument type between function type "
                         "definition ")
               << functionType << " and argument type definition "
               << argDefinedType << " at argument " << i;
      }
      if (getValue(operands[1])) {
        return emitError(unknownLoc, "duplicate definition of result <id> ")
               << operands[1];
      }
      if (failed(setFunctionArgAttrs(operands[1], argAttrs, i))) {
        return failure();
      }
 
      auto argValue = funcOp.getArgument(i);
      valueMap[operands[1]] = argValue;
    }
  }
 
  if (llvm::any_of(argAttrs, [](Attribute attr) {
        auto argAttr = cast<DictionaryAttr>(attr);
        return !argAttr.empty();
      }))
    funcOp.setArgAttrsAttr(ArrayAttr::get(context, argAttrs));
 
  // entryBlock is needed to access the arguments, Once that is done, we can
  // erase the block for functions with 'Import' LinkageAttributes, since these
  // are essentially function declarations, so they have no body.
  auto linkageAttr = funcOp.getLinkageAttributes();
  auto hasImportLinkage =
      linkageAttr && (linkageAttr.value().getLinkageType().getValue() ==
                      spirv::LinkageType::Import);
  if (hasImportLinkage)
    funcOp.eraseBody();
 
  // RAII guard to reset the insertion point to the module's region after
  // deserializing the body of this function.
  OpBuilder::InsertionGuard moduleInsertionGuard(opBuilder);
 
  spirv::Opcode opcode = spirv::Opcode::OpNop;
  ArrayRef<uint32_t> instOperands;
 
  // Special handling for the entry block. We need to make sure it starts with
  // an OpLabel instruction. The entry block takes the same parameters as the
  // function. All other blocks do not take any parameter. We have already
  // created the entry block, here we need to register it to the correct label
  // <id>.
  if (failed(sliceInstruction(opcode, instOperands,
                              spirv::Opcode::OpFunctionEnd))) {
    return failure();
  }
  if (opcode == spirv::Opcode::OpFunctionEnd) {
    return processFunctionEnd(instOperands);
  }
  if (opcode != spirv::Opcode::OpLabel) {
    return emitError(unknownLoc, "a basic block must start with OpLabel");
  }
  if (instOperands.size() != 1) {
    return emitError(unknownLoc, "OpLabel should only have result <id>");
  }
  blockMap[instOperands[0]] = entryBlock;
  if (failed(processLabel(instOperands))) {
    return failure();
  }
 
  // Then process all the other instructions in the function until we hit
  // OpFunctionEnd.
  while (succeeded(sliceInstruction(opcode, instOperands,
                                    spirv::Opcode::OpFunctionEnd)) &&
         opcode != spirv::Opcode::OpFunctionEnd) {
    if (failed(processInstruction(opcode, instOperands))) {
      return failure();
    }
  }
  if (opcode != spirv::Opcode::OpFunctionEnd) {
    return failure();
  }
 
  return processFunctionEnd(instOperands);
}
 
LogicalResult
spirv::Deserializer::processFunctionEnd(ArrayRef<uint32_t> operands) {
  // Process OpFunctionEnd.
  if (!operands.empty()) {
    return emitError(unknownLoc, "unexpected operands for OpFunctionEnd");
  }
 
  // Wire up block arguments from OpPhi instructions.
  // Put all structured control flow in spirv.mlir.selection/spirv.mlir.loop
  // ops.
  if (failed(wireUpBlockArgument()) || failed(structurizeControlFlow())) {
    return failure();
  }
 
  curBlock = nullptr;
  curFunction = std::nullopt;
 
  LLVM_DEBUG({
    logger.unindent();
    logger.startLine()
        << "//===-------------------------------------------===//\n";
  });
  return success();
}
 
std::optional<std::pair<Attribute, Type>>
spirv::Deserializer::getConstant(uint32_t id) {
  auto constIt = constantMap.find(id);
  if (constIt == constantMap.end())
    return std::nullopt;
  return constIt->getSecond();
}
 
std::optional<std::pair<Attribute, Type>>
spirv::Deserializer::getConstantCompositeReplicate(uint32_t id) {
  if (auto it = constantCompositeReplicateMap.find(id);
      it != constantCompositeReplicateMap.end())
    return it->second;
  return std::nullopt;
}
 
std::optional<spirv::SpecConstOperationMaterializationInfo>
spirv::Deserializer::getSpecConstantOperation(uint32_t id) {
  auto constIt = specConstOperationMap.find(id);
  if (constIt == specConstOperationMap.end())
    return std::nullopt;
  return constIt->getSecond();
}
 
std::string spirv::Deserializer::getFunctionSymbol(uint32_t id) {
  auto funcName = nameMap.lookup(id).str();
  if (funcName.empty()) {
    funcName = "spirv_fn_" + std::to_string(id);
  }
  return funcName;
}
 
std::string spirv::Deserializer::getSpecConstantSymbol(uint32_t id) {
  auto constName = nameMap.lookup(id).str();
  if (constName.empty()) {
    constName = "spirv_spec_const_" + std::to_string(id);
  }
  return constName;
}
 
spirv::SpecConstantOp
spirv::Deserializer::createSpecConstant(Location loc, uint32_t resultID,
                                        TypedAttr defaultValue) {
  auto symName = opBuilder.getStringAttr(getSpecConstantSymbol(resultID));
  auto op = spirv::SpecConstantOp::create(opBuilder, unknownLoc, symName,
                                          defaultValue);
  if (decorations.count(resultID)) {
    for (auto attr : decorations[resultID].getAttrs())
      op->setAttr(attr.getName(), attr.getValue());
  }
  specConstMap[resultID] = op;
  return op;
}
 
LogicalResult
spirv::Deserializer::processGlobalVariable(ArrayRef<uint32_t> operands) {
  unsigned wordIndex = 0;
  if (operands.size() < 3) {
    return emitError(
        unknownLoc,
        "OpVariable needs at least 3 operands, type, <id> and storage class");
  }
 
  // Result Type.
  auto type = getType(operands[wordIndex]);
  if (!type) {
    return emitError(unknownLoc, "unknown result type <id> : ")
           << operands[wordIndex];
  }
  auto ptrType = dyn_cast<spirv::PointerType>(type);
  if (!ptrType) {
    return emitError(unknownLoc,
                     "expected a result type <id> to be a spirv.ptr, found : ")
           << type;
  }
  wordIndex++;
 
  // Result <id>.
  auto variableID = operands[wordIndex];
  auto variableName = nameMap.lookup(variableID).str();
  if (variableName.empty()) {
    variableName = "spirv_var_" + std::to_string(variableID);
  }
  wordIndex++;
 
  // Storage class.
  auto storageClass = static_cast<spirv::StorageClass>(operands[wordIndex]);
  if (ptrType.getStorageClass() != storageClass) {
    return emitError(unknownLoc, "mismatch in storage class of pointer type ")
           << type << " and that specified in OpVariable instruction  : "
           << stringifyStorageClass(storageClass);
  }
  wordIndex++;
 
  // Initializer.
  FlatSymbolRefAttr initializer = nullptr;
 
  if (wordIndex < operands.size()) {
    Operation *op = nullptr;
 
    if (auto initOp = getGlobalVariable(operands[wordIndex]))
      op = initOp;
    else if (auto initOp = getSpecConstant(operands[wordIndex]))
      op = initOp;
    else if (auto initOp = getSpecConstantComposite(operands[wordIndex]))
      op = initOp;
    else
      return emitError(unknownLoc, "unknown <id> ")
             << operands[wordIndex] << "used as initializer";
 
    initializer = SymbolRefAttr::get(op);
    wordIndex++;
  }
  if (wordIndex != operands.size()) {
    return emitError(unknownLoc,
                     "found more operands than expected when deserializing "
                     "OpVariable instruction, only ")
           << wordIndex << " of " << operands.size() << " processed";
  }
  auto loc = createFileLineColLoc(opBuilder);
  auto varOp = spirv::GlobalVariableOp::create(
      opBuilder, loc, TypeAttr::get(type),
      opBuilder.getStringAttr(variableName), initializer);
 
  // Decorations.
  if (decorations.count(variableID)) {
    for (auto attr : decorations[variableID].getAttrs())
      varOp->setAttr(attr.getName(), attr.getValue());
  }
  globalVariableMap[variableID] = varOp;
  return success();
}
 
IntegerAttr spirv::Deserializer::getConstantInt(uint32_t id) {
  auto constInfo = getConstant(id);
  if (!constInfo) {
    return nullptr;
  }
  return dyn_cast<IntegerAttr>(constInfo->first);
}
 
LogicalResult spirv::Deserializer::processName(ArrayRef<uint32_t> operands) {
  if (operands.size() < 2) {
    return emitError(unknownLoc, "OpName needs at least 2 operands");
  }
  if (!nameMap.lookup(operands[0]).empty()) {
    return emitError(unknownLoc, "duplicate name found for result <id> ")
           << operands[0];
  }
  unsigned wordIndex = 1;
  StringRef name = decodeStringLiteral(operands, wordIndex);
  if (wordIndex != operands.size()) {
    return emitError(unknownLoc,
                     "unexpected trailing words in OpName instruction");
  }
  nameMap[operands[0]] = name;
  return success();
}
 
//===----------------------------------------------------------------------===//
// Type
//===----------------------------------------------------------------------===//
 
LogicalResult spirv::Deserializer::processType(spirv::Opcode opcode,
                                               ArrayRef<uint32_t> operands) {
  if (operands.empty()) {
    return emitError(unknownLoc, "type instruction with opcode ")
           << spirv::stringifyOpcode(opcode) << " needs at least one <id>";
  }
 
  /// TODO: Types might be forward declared in some instructions and need to be
  /// handled appropriately.
  if (typeMap.count(operands[0])) {
    return emitError(unknownLoc, "duplicate definition for result <id> ")
           << operands[0];
  }
 
  switch (opcode) {
  case spirv::Opcode::OpTypeVoid:
    if (operands.size() != 1)
      return emitError(unknownLoc, "OpTypeVoid must have no parameters");
    typeMap[operands[0]] = opBuilder.getNoneType();
    break;
  case spirv::Opcode::OpTypeBool:
    if (operands.size() != 1)
      return emitError(unknownLoc, "OpTypeBool must have no parameters");
    typeMap[operands[0]] = opBuilder.getI1Type();
    break;
  case spirv::Opcode::OpTypeInt: {
    if (operands.size() != 3)
      return emitError(
          unknownLoc, "OpTypeInt must have bitwidth and signedness parameters");
 
    // SPIR-V OpTypeInt "Signedness specifies whether there are signed semantics
    // to preserve or validate.
    // 0 indicates unsigned, or no signedness semantics
    // 1 indicates signed semantics."
    //
    // So we cannot differentiate signless and unsigned integers; always use
    // signless semantics for such cases.
    auto sign = operands[2] == 1 ? IntegerType::SignednessSemantics::Signed
                                 : IntegerType::SignednessSemantics::Signless;
    typeMap[operands[0]] = IntegerType::get(context, operands[1], sign);
  } break;
  case spirv::Opcode::OpTypeFloat: {
    if (operands.size() != 2 && operands.size() != 3)
      return emitError(unknownLoc,
                       "OpTypeFloat expects either 2 operands (type, bitwidth) "
                       "or 3 operands (type, bitwidth, encoding), but got ")
             << operands.size();
    uint32_t bitWidth = operands[1];
 
    Type floatTy;
    switch (bitWidth) {
    case 16:
      floatTy = opBuilder.getF16Type();
      break;
    case 32:
      floatTy = opBuilder.getF32Type();
      break;
    case 64:
      floatTy = opBuilder.getF64Type();
      break;
    default:
      return emitError(unknownLoc, "unsupported OpTypeFloat bitwidth: ")
             << bitWidth;
    }
 
    if (operands.size() == 3) {
      if (spirv::FPEncoding(operands[2]) != spirv::FPEncoding::BFloat16KHR)
        return emitError(unknownLoc, "unsupported OpTypeFloat FP encoding: ")
               << operands[2];
      if (bitWidth != 16)
        return emitError(unknownLoc,
                         "invalid OpTypeFloat bitwidth for bfloat16 encoding: ")
               << bitWidth << " (expected 16)";
      floatTy = opBuilder.getBF16Type();
    }
 
    typeMap[operands[0]] = floatTy;
  } break;
  case spirv::Opcode::OpTypeVector: {
    if (operands.size() != 3) {
      return emitError(
          unknownLoc,
          "OpTypeVector must have element type and count parameters");
    }
    Type elementTy = getType(operands[1]);
    if (!elementTy) {
      return emitError(unknownLoc, "OpTypeVector references undefined <id> ")
             << operands[1];
    }
    typeMap[operands[0]] = VectorType::get({operands[2]}, elementTy);
  } break;
  case spirv::Opcode::OpTypePointer: {
    return processOpTypePointer(operands);
  } break;
  case spirv::Opcode::OpTypeArray:
    return processArrayType(operands);
  case spirv::Opcode::OpTypeCooperativeMatrixKHR:
    return processCooperativeMatrixTypeKHR(operands);
  case spirv::Opcode::OpTypeFunction:
    return processFunctionType(operands);
  case spirv::Opcode::OpTypeImage:
    return processImageType(operands);
  case spirv::Opcode::OpTypeSampledImage:
    return processSampledImageType(operands);
  case spirv::Opcode::OpTypeRuntimeArray:
    return processRuntimeArrayType(operands);
  case spirv::Opcode::OpTypeStruct:
    return processStructType(operands);
  case spirv::Opcode::OpTypeMatrix:
    return processMatrixType(operands);
  case spirv::Opcode::OpTypeTensorARM:
    return processTensorARMType(operands);
  default:
    return emitError(unknownLoc, "unhandled type instruction");
  }
  return success();
}
 
LogicalResult
spirv::Deserializer::processOpTypePointer(ArrayRef<uint32_t> operands) {
  if (operands.size() != 3)
    return emitError(unknownLoc, "OpTypePointer must have two parameters");
 
  auto pointeeType = getType(operands[2]);
  if (!pointeeType)
    return emitError(unknownLoc, "unknown OpTypePointer pointee type <id> ")
           << operands[2];
 
  uint32_t typePointerID = operands[0];
  auto storageClass = static_cast<spirv::StorageClass>(operands[1]);
  typeMap[typePointerID] = spirv::PointerType::get(pointeeType, storageClass);
 
  for (auto *deferredStructIt = std::begin(deferredStructTypesInfos);
       deferredStructIt != std::end(deferredStructTypesInfos);) {
    for (auto *unresolvedMemberIt =
             std::begin(deferredStructIt->unresolvedMemberTypes);
         unresolvedMemberIt !=
         std::end(deferredStructIt->unresolvedMemberTypes);) {
      if (unresolvedMemberIt->first == typePointerID) {
        // The newly constructed pointer type can resolve one of the
        // deferred struct type members; update the memberTypes list and
        // clean the unresolvedMemberTypes list accordingly.
        deferredStructIt->memberTypes[unresolvedMemberIt->second] =
            typeMap[typePointerID];
        unresolvedMemberIt =
            deferredStructIt->unresolvedMemberTypes.erase(unresolvedMemberIt);
      } else {
        ++unresolvedMemberIt;
      }
    }
 
    if (deferredStructIt->unresolvedMemberTypes.empty()) {
      // All deferred struct type members are now resolved, set the struct body.
      auto structType = deferredStructIt->deferredStructType;
 
      assert(structType && "expected a spirv::StructType");
      assert(structType.isIdentified() && "expected an indentified struct");
 
      if (failed(structType.trySetBody(
              deferredStructIt->memberTypes, deferredStructIt->offsetInfo,
              deferredStructIt->memberDecorationsInfo,
              deferredStructIt->structDecorationsInfo)))
        return failure();
 
      deferredStructIt = deferredStructTypesInfos.erase(deferredStructIt);
    } else {
      ++deferredStructIt;
    }
  }
 
  return success();
}
 
LogicalResult
spirv::Deserializer::processArrayType(ArrayRef<uint32_t> operands) {
  if (operands.size() != 3) {
    return emitError(unknownLoc,
                     "OpTypeArray must have element type and count parameters");
  }
 
  Type elementTy = getType(operands[1]);
  if (!elementTy) {
    return emitError(unknownLoc, "OpTypeArray references undefined <id> ")
           << operands[1];
  }
 
  unsigned count = 0;
  // TODO: The count can also come frome a specialization constant.
  auto countInfo = getConstant(operands[2]);
  if (!countInfo) {
    return emitError(unknownLoc, "OpTypeArray count <id> ")
           << operands[2] << "can only come from normal constant right now";
  }
 
  if (auto intVal = dyn_cast<IntegerAttr>(countInfo->first)) {
    count = intVal.getValue().getZExtValue();
  } else {
    return emitError(unknownLoc, "OpTypeArray count must come from a "
                                 "scalar integer constant instruction");
  }
 
  typeMap[operands[0]] = spirv::ArrayType::get(
      elementTy, count, typeDecorations.lookup(operands[0]));
  return success();
}
 
LogicalResult
spirv::Deserializer::processFunctionType(ArrayRef<uint32_t> operands) {
  assert(!operands.empty() && "No operands for processing function type");
  if (operands.size() == 1) {
    return emitError(unknownLoc, "missing return type for OpTypeFunction");
  }
  auto returnType = getType(operands[1]);
  if (!returnType) {
    return emitError(unknownLoc, "unknown return type in OpTypeFunction");
  }
  SmallVector<Type, 1> argTypes;
  for (size_t i = 2, e = operands.size(); i < e; ++i) {
    auto ty = getType(operands[i]);
    if (!ty) {
      return emitError(unknownLoc, "unknown argument type in OpTypeFunction");
    }
    argTypes.push_back(ty);
  }
  ArrayRef<Type> returnTypes;
  if (!isVoidType(returnType)) {
    returnTypes = llvm::ArrayRef(returnType);
  }
  typeMap[operands[0]] = FunctionType::get(context, argTypes, returnTypes);
  return success();
}
 
LogicalResult spirv::Deserializer::processCooperativeMatrixTypeKHR(
    ArrayRef<uint32_t> operands) {
  if (operands.size() != 6) {
    return emitError(unknownLoc,
                     "OpTypeCooperativeMatrixKHR must have element type, "
                     "scope, row and column parameters, and use");
  }
 
  Type elementTy = getType(operands[1]);
  if (!elementTy) {
    return emitError(unknownLoc,
                     "OpTypeCooperativeMatrixKHR references undefined <id> ")
           << operands[1];
  }
 
  std::optional<spirv::Scope> scope =
      spirv::symbolizeScope(getConstantInt(operands[2]).getInt());
  if (!scope) {
    return emitError(
               unknownLoc,
               "OpTypeCooperativeMatrixKHR references undefined scope <id> ")
           << operands[2];
  }
 
  IntegerAttr rowsAttr = getConstantInt(operands[3]);
  IntegerAttr columnsAttr = getConstantInt(operands[4]);
  IntegerAttr useAttr = getConstantInt(operands[5]);
 
  if (!rowsAttr)
    return emitError(unknownLoc, "OpTypeCooperativeMatrixKHR `Rows` references "
                                 "undefined constant <id> ")
           << operands[3];
 
  if (!columnsAttr)
    return emitError(unknownLoc, "OpTypeCooperativeMatrixKHR `Columns` "
                                 "references undefined constant <id> ")
           << operands[4];
 
  if (!useAttr)
    return emitError(unknownLoc, "OpTypeCooperativeMatrixKHR `Use` references "
                                 "undefined constant <id> ")
           << operands[5];
 
  unsigned rows = rowsAttr.getInt();
  unsigned columns = columnsAttr.getInt();
 
  std::optional<spirv::CooperativeMatrixUseKHR> use =
      spirv::symbolizeCooperativeMatrixUseKHR(useAttr.getInt());
  if (!use) {
    return emitError(
               unknownLoc,
               "OpTypeCooperativeMatrixKHR references undefined use <id> ")
           << operands[5];
  }
 
  typeMap[operands[0]] =
      spirv::CooperativeMatrixType::get(elementTy, rows, columns, *scope, *use);
  return success();
}
 
LogicalResult
spirv::Deserializer::processRuntimeArrayType(ArrayRef<uint32_t> operands) {
  if (operands.size() != 2) {
    return emitError(unknownLoc, "OpTypeRuntimeArray must have two operands");
  }
  Type memberType = getType(operands[1]);
  if (!memberType) {
    return emitError(unknownLoc,
                     "OpTypeRuntimeArray references undefined <id> ")
           << operands[1];
  }
  typeMap[operands[0]] = spirv::RuntimeArrayType::get(
      memberType, typeDecorations.lookup(operands[0]));
  return success();
}
 
LogicalResult
spirv::Deserializer::processStructType(ArrayRef<uint32_t> operands) {
  // TODO: Find a way to handle identified structs when debug info is stripped.
 
  if (operands.empty()) {
    return emitError(unknownLoc, "OpTypeStruct must have at least result <id>");
  }
 
  if (operands.size() == 1) {
    // Handle empty struct.
    typeMap[operands[0]] =
        spirv::StructType::getEmpty(context, nameMap.lookup(operands[0]).str());
    return success();
  }
 
  // First element is operand ID, second element is member index in the struct.
  SmallVector<std::pair<uint32_t, unsigned>, 0> unresolvedMemberTypes;
  SmallVector<Type, 4> memberTypes;
 
  for (auto op : llvm::drop_begin(operands, 1)) {
    Type memberType = getType(op);
    bool typeForwardPtr = (typeForwardPointerIDs.count(op) != 0);
 
    if (!memberType && !typeForwardPtr)
      return emitError(unknownLoc, "OpTypeStruct references undefined <id> ")
             << op;
 
    if (!memberType)
      unresolvedMemberTypes.emplace_back(op, memberTypes.size());
 
    memberTypes.push_back(memberType);
  }
 
  SmallVector<spirv::StructType::OffsetInfo, 0> offsetInfo;
  SmallVector<spirv::StructType::MemberDecorationInfo, 0> memberDecorationsInfo;
  if (memberDecorationMap.count(operands[0])) {
    auto &allMemberDecorations = memberDecorationMap[operands[0]];
    for (auto memberIndex : llvm::seq<uint32_t>(0, memberTypes.size())) {
      if (allMemberDecorations.count(memberIndex)) {
        for (auto &memberDecoration : allMemberDecorations[memberIndex]) {
          // Check for offset.
          if (memberDecoration.first == spirv::Decoration::Offset) {
            // If offset info is empty, resize to the number of members;
            if (offsetInfo.empty()) {
              offsetInfo.resize(memberTypes.size());
            }
            offsetInfo[memberIndex] = memberDecoration.second[0];
          } else {
            auto intType = mlir::IntegerType::get(context, 32);
            if (!memberDecoration.second.empty()) {
              memberDecorationsInfo.emplace_back(
                  memberIndex, memberDecoration.first,
                  IntegerAttr::get(intType, memberDecoration.second[0]));
            } else {
              memberDecorationsInfo.emplace_back(
                  memberIndex, memberDecoration.first, UnitAttr::get(context));
            }
          }
        }
      }
    }
  }
 
  SmallVector<spirv::StructType::StructDecorationInfo, 0> structDecorationsInfo;
  if (decorations.count(operands[0])) {
    NamedAttrList &allDecorations = decorations[operands[0]];
    for (NamedAttribute &decorationAttr : allDecorations) {
      std::optional<spirv::Decoration> decoration = spirv::symbolizeDecoration(
          llvm::convertToCamelFromSnakeCase(decorationAttr.getName(), true));
      assert(decoration.has_value());
      structDecorationsInfo.emplace_back(decoration.value(),
                                         decorationAttr.getValue());
    }
  }
 
  uint32_t structID = operands[0];
  std::string structIdentifier = nameMap.lookup(structID).str();
 
  if (structIdentifier.empty()) {
    assert(unresolvedMemberTypes.empty() &&
           "didn't expect unresolved member types");
    typeMap[structID] = spirv::StructType::get(
        memberTypes, offsetInfo, memberDecorationsInfo, structDecorationsInfo);
  } else {
    auto structTy = spirv::StructType::getIdentified(context, structIdentifier);
    typeMap[structID] = structTy;
 
    if (!unresolvedMemberTypes.empty())
      deferredStructTypesInfos.push_back(
          {structTy, unresolvedMemberTypes, memberTypes, offsetInfo,
           memberDecorationsInfo, structDecorationsInfo});
    else if (failed(structTy.trySetBody(memberTypes, offsetInfo,
                                        memberDecorationsInfo,
                                        structDecorationsInfo)))
      return failure();
  }
 
  // TODO: Update StructType to have member name as attribute as
  // well.
  return success();
}
 
LogicalResult
spirv::Deserializer::processMatrixType(ArrayRef<uint32_t> operands) {
  if (operands.size() != 3) {
    // Three operands are needed: result_id, column_type, and column_count
    return emitError(unknownLoc, "OpTypeMatrix must have 3 operands"
                                 " (result_id, column_type, and column_count)");
  }
  // Matrix columns must be of vector type
  Type elementTy = getType(operands[1]);
  if (!elementTy) {
    return emitError(unknownLoc,
                     "OpTypeMatrix references undefined column type.")
           << operands[1];
  }
 
  uint32_t colsCount = operands[2];
  typeMap[operands[0]] = spirv::MatrixType::get(elementTy, colsCount);
  return success();
}
 
LogicalResult
spirv::Deserializer::processTensorARMType(ArrayRef<uint32_t> operands) {
  unsigned size = operands.size();
  if (size < 2 || size > 4)
    return emitError(unknownLoc, "OpTypeTensorARM must have 2-4 operands "
                                 "(result_id, element_type, (rank), (shape)) ")
           << size;
 
  Type elementTy = getType(operands[1]);
  if (!elementTy)
    return emitError(unknownLoc,
                     "OpTypeTensorARM references undefined element type ")
           << operands[1];
 
  if (size == 2) {
    typeMap[operands[0]] = TensorArmType::get({}, elementTy);
    return success();
  }
 
  IntegerAttr rankAttr = getConstantInt(operands[2]);
  if (!rankAttr)
    return emitError(unknownLoc, "OpTypeTensorARM rank must come from a "
                                 "scalar integer constant instruction");
  unsigned rank = rankAttr.getValue().getZExtValue();
  if (size == 3) {
    SmallVector<int64_t, 4> shape(rank, ShapedType::kDynamic);
    typeMap[operands[0]] = TensorArmType::get(shape, elementTy);
    return success();
  }
 
  std::optional<std::pair<Attribute, Type>> shapeInfo =
      getConstant(operands[3]);
  if (!shapeInfo)
    return emitError(unknownLoc, "OpTypeTensorARM shape must come from a "
                                 "constant instruction of type OpTypeArray");
 
  ArrayAttr shapeArrayAttr = llvm::dyn_cast<ArrayAttr>(shapeInfo->first);
  SmallVector<int64_t, 1> shape;
  for (auto dimAttr : shapeArrayAttr.getValue()) {
    auto dimIntAttr = llvm::dyn_cast<IntegerAttr>(dimAttr);
    if (!dimIntAttr)
      return emitError(unknownLoc, "OpTypeTensorARM shape has an invalid "
                                   "dimension size");
    shape.push_back(dimIntAttr.getValue().getSExtValue());
  }
  typeMap[operands[0]] = TensorArmType::get(shape, elementTy);
  return success();
}
 
LogicalResult
spirv::Deserializer::processTypeForwardPointer(ArrayRef<uint32_t> operands) {
  if (operands.size() != 2)
    return emitError(unknownLoc,
                     "OpTypeForwardPointer instruction must have two operands");
 
  typeForwardPointerIDs.insert(operands[0]);
  // TODO: Use the 2nd operand (Storage Class) to validate the OpTypePointer
  // instruction that defines the actual type.
 
  return success();
}
 
LogicalResult
spirv::Deserializer::processImageType(ArrayRef<uint32_t> operands) {
  // TODO: Add support for Access Qualifier.
  if (operands.size() != 8)
    return emitError(
        unknownLoc,
        "OpTypeImage with non-eight operands are not supported yet");
 
  Type elementTy = getType(operands[1]);
  if (!elementTy)
    return emitError(unknownLoc, "OpTypeImage references undefined <id>: ")
           << operands[1];
 
  auto dim = spirv::symbolizeDim(operands[2]);
  if (!dim)
    return emitError(unknownLoc, "unknown Dim for OpTypeImage: ")
           << operands[2];
 
  auto depthInfo = spirv::symbolizeImageDepthInfo(operands[3]);
  if (!depthInfo)
    return emitError(unknownLoc, "unknown Depth for OpTypeImage: ")
           << operands[3];
 
  auto arrayedInfo = spirv::symbolizeImageArrayedInfo(operands[4]);
  if (!arrayedInfo)
    return emitError(unknownLoc, "unknown Arrayed for OpTypeImage: ")
           << operands[4];
 
  auto samplingInfo = spirv::symbolizeImageSamplingInfo(operands[5]);
  if (!samplingInfo)
    return emitError(unknownLoc, "unknown MS for OpTypeImage: ") << operands[5];
 
  auto samplerUseInfo = spirv::symbolizeImageSamplerUseInfo(operands[6]);
  if (!samplerUseInfo)
    return emitError(unknownLoc, "unknown Sampled for OpTypeImage: ")
           << operands[6];
 
  auto format = spirv::symbolizeImageFormat(operands[7]);
  if (!format)
    return emitError(unknownLoc, "unknown Format for OpTypeImage: ")
           << operands[7];
 
  typeMap[operands[0]] = spirv::ImageType::get(
      elementTy, dim.value(), depthInfo.value(), arrayedInfo.value(),
      samplingInfo.value(), samplerUseInfo.value(), format.value());
  return success();
}
 
LogicalResult
spirv::Deserializer::processSampledImageType(ArrayRef<uint32_t> operands) {
  if (operands.size() != 2)
    return emitError(unknownLoc, "OpTypeSampledImage must have two operands");
 
  Type elementTy = getType(operands[1]);
  if (!elementTy)
    return emitError(unknownLoc,
                     "OpTypeSampledImage references undefined <id>: ")
           << operands[1];
 
  typeMap[operands[0]] = spirv::SampledImageType::get(elementTy);
  return success();
}
 
//===----------------------------------------------------------------------===//
// Constant
//===----------------------------------------------------------------------===//
 
LogicalResult spirv::Deserializer::processConstant(ArrayRef<uint32_t> operands,
                                                   bool isSpec) {
  StringRef opname = isSpec ? "OpSpecConstant" : "OpConstant";
 
  if (operands.size() < 2) {
    return emitError(unknownLoc)
           << opname << " must have type <id> and result <id>";
  }
  if (operands.size() < 3) {
    return emitError(unknownLoc)
           << opname << " must have at least 1 more parameter";
  }
 
  Type resultType = getType(operands[0]);
  if (!resultType) {
    return emitError(unknownLoc, "undefined result type from <id> ")
           << operands[0];
  }
 
  auto checkOperandSizeForBitwidth = [&](unsigned bitwidth) -> LogicalResult {
    if (bitwidth == 64) {
      if (operands.size() == 4) {
        return success();
      }
      return emitError(unknownLoc)
             << opname << " should have 2 parameters for 64-bit values";
    }
    if (bitwidth <= 32) {
      if (operands.size() == 3) {
        return success();
      }
 
      return emitError(unknownLoc)
             << opname
             << " should have 1 parameter for values with no more than 32 bits";
    }
    return emitError(unknownLoc, "unsupported OpConstant bitwidth: ")
           << bitwidth;
  };
 
  auto resultID = operands[1];
 
  if (auto intType = dyn_cast<IntegerType>(resultType)) {
    auto bitwidth = intType.getWidth();
    if (failed(checkOperandSizeForBitwidth(bitwidth))) {
      return failure();
    }
 
    APInt value;
    if (bitwidth == 64) {
      // 64-bit integers are represented with two SPIR-V words. According to
      // SPIR-V spec: "When the type’s bit width is larger than one word, the
      // literal’s low-order words appear first."
      struct DoubleWord {
        uint32_t word1;
        uint32_t word2;
      } words = {operands[2], operands[3]};
      value = APInt(64, llvm::bit_cast<uint64_t>(words), /*isSigned=*/true);
    } else if (bitwidth <= 32) {
      value = APInt(bitwidth, operands[2], /*isSigned=*/true,
                    /*implicitTrunc=*/true);
    }
 
    auto attr = opBuilder.getIntegerAttr(intType, value);
 
    if (isSpec) {
      createSpecConstant(unknownLoc, resultID, attr);
    } else {
      // For normal constants, we just record the attribute (and its type) for
      // later materialization at use sites.
      constantMap.try_emplace(resultID, attr, intType);
    }
 
    return success();
  }
 
  if (auto floatType = dyn_cast<FloatType>(resultType)) {
    auto bitwidth = floatType.getWidth();
    if (failed(checkOperandSizeForBitwidth(bitwidth))) {
      return failure();
    }
 
    APFloat value(0.f);
    if (floatType.isF64()) {
      // Double values are represented with two SPIR-V words. According to
      // SPIR-V spec: "When the type’s bit width is larger than one word, the
      // literal’s low-order words appear first."
      struct DoubleWord {
        uint32_t word1;
        uint32_t word2;
      } words = {operands[2], operands[3]};
      value = APFloat(llvm::bit_cast<double>(words));
    } else if (floatType.isF32()) {
      value = APFloat(llvm::bit_cast<float>(operands[2]));
    } else if (floatType.isF16()) {
      APInt data(16, operands[2]);
      value = APFloat(APFloat::IEEEhalf(), data);
    } else if (floatType.isBF16()) {
      APInt data(16, operands[2]);
      value = APFloat(APFloat::BFloat(), data);
    }
 
    auto attr = opBuilder.getFloatAttr(floatType, value);
    if (isSpec) {
      createSpecConstant(unknownLoc, resultID, attr);
    } else {
      // For normal constants, we just record the attribute (and its type) for
      // later materialization at use sites.
      constantMap.try_emplace(resultID, attr, floatType);
    }
 
    return success();
  }
 
  return emitError(unknownLoc, "OpConstant can only generate values of "
                               "scalar integer or floating-point type");
}
 
LogicalResult spirv::Deserializer::processConstantBool(
    bool isTrue, ArrayRef<uint32_t> operands, bool isSpec) {
  if (operands.size() != 2) {
    return emitError(unknownLoc, "Op")
           << (isSpec ? "Spec" : "") << "Constant"
           << (isTrue ? "True" : "False")
           << " must have type <id> and result <id>";
  }
 
  auto attr = opBuilder.getBoolAttr(isTrue);
  auto resultID = operands[1];
  if (isSpec) {
    createSpecConstant(unknownLoc, resultID, attr);
  } else {
    // For normal constants, we just record the attribute (and its type) for
    // later materialization at use sites.
    constantMap.try_emplace(resultID, attr, opBuilder.getI1Type());
  }
 
  return success();
}
 
LogicalResult
spirv::Deserializer::processConstantComposite(ArrayRef<uint32_t> operands) {
  if (operands.size() < 2) {
    return emitError(unknownLoc,
                     "OpConstantComposite must have type <id> and result <id>");
  }
  if (operands.size() < 3) {
    return emitError(unknownLoc,
                     "OpConstantComposite must have at least 1 parameter");
  }
 
  Type resultType = getType(operands[0]);
  if (!resultType) {
    return emitError(unknownLoc, "undefined result type from <id> ")
           << operands[0];
  }
 
  SmallVector<Attribute, 4> elements;
  elements.reserve(operands.size() - 2);
  for (unsigned i = 2, e = operands.size(); i < e; ++i) {
    auto elementInfo = getConstant(operands[i]);
    if (!elementInfo) {
      return emitError(unknownLoc, "OpConstantComposite component <id> ")
             << operands[i] << " must come from a normal constant";
    }
    elements.push_back(elementInfo->first);
  }
 
  auto resultID = operands[1];
  if (auto tensorType = dyn_cast<TensorArmType>(resultType)) {
    SmallVector<Attribute> flattenedElems;
    for (Attribute element : elements) {
      if (auto denseElemAttr = dyn_cast<DenseElementsAttr>(element)) {
        for (auto value : denseElemAttr.getValues<Attribute>())
          flattenedElems.push_back(value);
      } else {
        flattenedElems.push_back(element);
      }
    }
    auto attr = DenseElementsAttr::get(tensorType, flattenedElems);
    constantMap.try_emplace(resultID, attr, tensorType);
  } else if (auto shapedType = dyn_cast<ShapedType>(resultType)) {
    auto attr = DenseElementsAttr::get(shapedType, elements);
    // For normal constants, we just record the attribute (and its type) for
    // later materialization at use sites.
    constantMap.try_emplace(resultID, attr, shapedType);
  } else if (auto arrayType = dyn_cast<spirv::ArrayType>(resultType)) {
    auto attr = opBuilder.getArrayAttr(elements);
    constantMap.try_emplace(resultID, attr, resultType);
  } else {
    return emitError(unknownLoc, "unsupported OpConstantComposite type: ")
           << resultType;
  }
 
  return success();
}
 
LogicalResult spirv::Deserializer::processConstantCompositeReplicateEXT(
    ArrayRef<uint32_t> operands) {
  if (operands.size() != 3) {
    return emitError(
               unknownLoc,
               "OpConstantCompositeReplicateEXT expects 3 operands but found ")
           << operands.size();
  }
 
  Type resultType = getType(operands[0]);
  if (!resultType) {
    return emitError(unknownLoc, "undefined result type from <id> ")
           << operands[0];
  }
 
  auto compositeType = dyn_cast<CompositeType>(resultType);
  if (!compositeType) {
    return emitError(unknownLoc,
                     "result type from <id> is not a composite type")
           << operands[0];
  }
 
  uint32_t resultID = operands[1];
  uint32_t constantID = operands[2];
 
  std::optional<std::pair<Attribute, Type>> constantInfo =
      getConstant(constantID);
  if (constantInfo.has_value()) {
    constantCompositeReplicateMap.try_emplace(
        resultID, constantInfo.value().first, resultType);
    return success();
  }
 
  std::optional<std::pair<Attribute, Type>> replicatedConstantCompositeInfo =
      getConstantCompositeReplicate(constantID);
  if (replicatedConstantCompositeInfo.has_value()) {
    constantCompositeReplicateMap.try_emplace(
        resultID, replicatedConstantCompositeInfo.value().first, resultType);
    return success();
  }
 
  return emitError(unknownLoc, "OpConstantCompositeReplicateEXT operand <id> ")
         << constantID
         << " must come from a normal constant or a "
            "OpConstantCompositeReplicateEXT";
}
 
LogicalResult
spirv::Deserializer::processSpecConstantComposite(ArrayRef<uint32_t> operands) {
  if (operands.size() < 2) {
    return emitError(
        unknownLoc,
        "OpSpecConstantComposite must have type <id> and result <id>");
  }
  if (operands.size() < 3) {
    return emitError(unknownLoc,
                     "OpSpecConstantComposite must have at least 1 parameter");
  }
 
  Type resultType = getType(operands[0]);
  if (!resultType) {
    return emitError(unknownLoc, "undefined result type from <id> ")
           << operands[0];
  }
 
  auto resultID = operands[1];
  auto symName = opBuilder.getStringAttr(getSpecConstantSymbol(resultID));
 
  SmallVector<Attribute, 4> elements;
  elements.reserve(operands.size() - 2);
  for (unsigned i = 2, e = operands.size(); i < e; ++i) {
    auto elementInfo = getSpecConstant(operands[i]);
    elements.push_back(SymbolRefAttr::get(elementInfo));
  }
 
  auto op = spirv::SpecConstantCompositeOp::create(
      opBuilder, unknownLoc, TypeAttr::get(resultType), symName,
      opBuilder.getArrayAttr(elements));
  specConstCompositeMap[resultID] = op;
 
  return success();
}
 
LogicalResult spirv::Deserializer::processSpecConstantCompositeReplicateEXT(
    ArrayRef<uint32_t> operands) {
  if (operands.size() != 3) {
    return emitError(unknownLoc, "OpSpecConstantCompositeReplicateEXT expects "
                                 "3 operands but found ")
           << operands.size();
  }
 
  Type resultType = getType(operands[0]);
  if (!resultType) {
    return emitError(unknownLoc, "undefined result type from <id> ")
           << operands[0];
  }
 
  auto compositeType = dyn_cast<CompositeType>(resultType);
  if (!compositeType) {
    return emitError(unknownLoc,
                     "result type from <id> is not a composite type")
           << operands[0];
  }
 
  uint32_t resultID = operands[1];
 
  auto symName = opBuilder.getStringAttr(getSpecConstantSymbol(resultID));
  spirv::SpecConstantOp constituentSpecConstantOp =
      getSpecConstant(operands[2]);
  auto op = spirv::EXTSpecConstantCompositeReplicateOp::create(
      opBuilder, unknownLoc, TypeAttr::get(resultType), symName,
      SymbolRefAttr::get(constituentSpecConstantOp));
 
  specConstCompositeReplicateMap[resultID] = op;
 
  return success();
}
 
LogicalResult
spirv::Deserializer::processSpecConstantOperation(ArrayRef<uint32_t> operands) {
  if (operands.size() < 3)
    return emitError(unknownLoc, "OpConstantOperation must have type <id>, "
                                 "result <id>, and operand opcode");
 
  uint32_t resultTypeID = operands[0];
 
  if (!getType(resultTypeID))
    return emitError(unknownLoc, "undefined result type from <id> ")
           << resultTypeID;
 
  uint32_t resultID = operands[1];
  spirv::Opcode enclosedOpcode = static_cast<spirv::Opcode>(operands[2]);
  auto emplaceResult = specConstOperationMap.try_emplace(
      resultID,
      SpecConstOperationMaterializationInfo{
          enclosedOpcode, resultTypeID,
          SmallVector<uint32_t>{operands.begin() + 3, operands.end()}});
 
  if (!emplaceResult.second)
    return emitError(unknownLoc, "value with <id>: ")
           << resultID << " is probably defined before.";
 
  return success();
}
 
Value spirv::Deserializer::materializeSpecConstantOperation(
    uint32_t resultID, spirv::Opcode enclosedOpcode, uint32_t resultTypeID,
    ArrayRef<uint32_t> enclosedOpOperands) {
 
  Type resultType = getType(resultTypeID);
 
  // Instructions wrapped by OpSpecConstantOp need an ID for their
  // Deserializer::processOp<op_name>(...) to emit the corresponding SPIR-V
  // dialect wrapped op. For that purpose, a new value map is created and "fake"
  // ID in that map is assigned to the result of the enclosed instruction. Note
  // that there is no need to update this fake ID since we only need to
  // reference the created Value for the enclosed op from the spv::YieldOp
  // created later in this method (both of which are the only values in their
  // region: the SpecConstantOperation's region). If we encounter another
  // SpecConstantOperation in the module, we simply re-use the fake ID since the
  // previous Value assigned to it isn't visible in the current scope anyway.
  DenseMap<uint32_t, Value> newValueMap;
  llvm::SaveAndRestore valueMapGuard(valueMap, newValueMap);
  constexpr uint32_t fakeID = static_cast<uint32_t>(-3);
 
  SmallVector<uint32_t, 4> enclosedOpResultTypeAndOperands;
  enclosedOpResultTypeAndOperands.push_back(resultTypeID);
  enclosedOpResultTypeAndOperands.push_back(fakeID);
  enclosedOpResultTypeAndOperands.append(enclosedOpOperands.begin(),
                                         enclosedOpOperands.end());
 
  // Process enclosed instruction before creating the enclosing
  // specConstantOperation (and its region). This way, references to constants,
  // global variables, and spec constants will be materialized outside the new
  // op's region. For more info, see Deserializer::getValue's implementation.
  if (failed(
          processInstruction(enclosedOpcode, enclosedOpResultTypeAndOperands)))
    return Value();
 
  // Since the enclosed op is emitted in the current block, split it in a
  // separate new block.
  Block *enclosedBlock = curBlock->splitBlock(&curBlock->back());
 
  auto loc = createFileLineColLoc(opBuilder);
  auto specConstOperationOp =
      spirv::SpecConstantOperationOp::create(opBuilder, loc, resultType);
 
  Region &body = specConstOperationOp.getBody();
  // Move the new block into SpecConstantOperation's body.
  body.getBlocks().splice(body.end(), curBlock->getParent()->getBlocks(),
                          Region::iterator(enclosedBlock));
  Block &block = body.back();
 
  // RAII guard to reset the insertion point to the module's region after
  // deserializing the body of the specConstantOperation.
  OpBuilder::InsertionGuard moduleInsertionGuard(opBuilder);
  opBuilder.setInsertionPointToEnd(&block);
 
  spirv::YieldOp::create(opBuilder, loc, block.front().getResult(0));
  return specConstOperationOp.getResult();
}
 
LogicalResult
spirv::Deserializer::processConstantNull(ArrayRef<uint32_t> operands) {
  if (operands.size() != 2) {
    return emitError(unknownLoc,
                     "OpConstantNull must only have type <id> and result <id>");
  }
 
  Type resultType = getType(operands[0]);
  if (!resultType) {
    return emitError(unknownLoc, "undefined result type from <id> ")
           << operands[0];
  }
 
  auto resultID = operands[1];
  Attribute attr;
  if (resultType.isIntOrFloat() || isa<VectorType>(resultType)) {
    attr = opBuilder.getZeroAttr(resultType);
  } else if (auto tensorType = dyn_cast<TensorArmType>(resultType)) {
    if (auto element = opBuilder.getZeroAttr(tensorType.getElementType()))
      attr = DenseElementsAttr::get(tensorType, element);
  }
 
  if (attr) {
    // For normal constants, we just record the attribute (and its type) for
    // later materialization at use sites.
    constantMap.try_emplace(resultID, attr, resultType);
    return success();
  }
 
  return emitError(unknownLoc, "unsupported OpConstantNull type: ")
         << resultType;
}
 
//===----------------------------------------------------------------------===//
// Control flow
//===----------------------------------------------------------------------===//
 
Block *spirv::Deserializer::getOrCreateBlock(uint32_t id) {
  if (auto *block = getBlock(id)) {
    LLVM_DEBUG(logger.startLine() << "[block] got exiting block for id = " << id
                                  << " @ " << block << "\n");
    return block;
  }
 
  // We don't know where this block will be placed finally (in a
  // spirv.mlir.selection or spirv.mlir.loop or function). Create it into the
  // function for now and sort out the proper place later.
  auto *block = curFunction->addBlock();
  LLVM_DEBUG(logger.startLine() << "[block] created block for id = " << id
                                << " @ " << block << "\n");
  return blockMap[id] = block;
}
 
LogicalResult spirv::Deserializer::processBranch(ArrayRef<uint32_t> operands) {
  if (!curBlock) {
    return emitError(unknownLoc, "OpBranch must appear inside a block");
  }
 
  if (operands.size() != 1) {
    return emitError(unknownLoc, "OpBranch must take exactly one target label");
  }
 
  auto *target = getOrCreateBlock(operands[0]);
  auto loc = createFileLineColLoc(opBuilder);
  // The preceding instruction for the OpBranch instruction could be an
  // OpLoopMerge or an OpSelectionMerge instruction, in this case they will have
  // the same OpLine information.
  spirv::BranchOp::create(opBuilder, loc, target);
 
  clearDebugLine();
  return success();
}
 
LogicalResult
spirv::Deserializer::processBranchConditional(ArrayRef<uint32_t> operands) {
  if (!curBlock) {
    return emitError(unknownLoc,
                     "OpBranchConditional must appear inside a block");
  }
 
  if (operands.size() != 3 && operands.size() != 5) {
    return emitError(unknownLoc,
                     "OpBranchConditional must have condition, true label, "
                     "false label, and optionally two branch weights");
  }
 
  auto condition = getValue(operands[0]);
  auto *trueBlock = getOrCreateBlock(operands[1]);
  auto *falseBlock = getOrCreateBlock(operands[2]);
 
  std::optional<std::pair<uint32_t, uint32_t>> weights;
  if (operands.size() == 5) {
    weights = std::make_pair(operands[3], operands[4]);
  }
  // The preceding instruction for the OpBranchConditional instruction could be
  // an OpSelectionMerge instruction, in this case they will have the same
  // OpLine information.
  auto loc = createFileLineColLoc(opBuilder);
  spirv::BranchConditionalOp::create(
      opBuilder, loc, condition, trueBlock,
      /*trueArguments=*/ArrayRef<Value>(), falseBlock,
      /*falseArguments=*/ArrayRef<Value>(), weights);
 
  clearDebugLine();
  return success();
}
 
LogicalResult spirv::Deserializer::processLabel(ArrayRef<uint32_t> operands) {
  if (!curFunction) {
    return emitError(unknownLoc, "OpLabel must appear inside a function");
  }
 
  if (operands.size() != 1) {
    return emitError(unknownLoc, "OpLabel should only have result <id>");
  }
 
  auto labelID = operands[0];
  // We may have forward declared this block.
  auto *block = getOrCreateBlock(labelID);
  LLVM_DEBUG(logger.startLine()
             << "[block] populating block " << block << "\n");
  // If we have seen this block, make sure it was just a forward declaration.
  assert(block->empty() && "re-deserialize the same block!");
 
  opBuilder.setInsertionPointToStart(block);
  blockMap[labelID] = curBlock = block;
 
  return success();
}
 
LogicalResult
spirv::Deserializer::processSelectionMerge(ArrayRef<uint32_t> operands) {
  if (!curBlock) {
    return emitError(unknownLoc, "OpSelectionMerge must appear in a block");
  }
 
  if (operands.size() < 2) {
    return emitError(
        unknownLoc,
        "OpSelectionMerge must specify merge target and selection control");
  }
 
  auto *mergeBlock = getOrCreateBlock(operands[0]);
  auto loc = createFileLineColLoc(opBuilder);
  auto selectionControl = operands[1];
 
  if (!blockMergeInfo.try_emplace(curBlock, loc, selectionControl, mergeBlock)
           .second) {
    return emitError(
        unknownLoc,
        "a block cannot have more than one OpSelectionMerge instruction");
  }
 
  return success();
}
 
LogicalResult
spirv::Deserializer::processLoopMerge(ArrayRef<uint32_t> operands) {
  if (!curBlock) {
    return emitError(unknownLoc, "OpLoopMerge must appear in a block");
  }
 
  if (operands.size() < 3) {
    return emitError(unknownLoc, "OpLoopMerge must specify merge target, "
                                 "continue target and loop control");
  }
 
  auto *mergeBlock = getOrCreateBlock(operands[0]);
  auto *continueBlock = getOrCreateBlock(operands[1]);
  auto loc = createFileLineColLoc(opBuilder);
  uint32_t loopControl = operands[2];
 
  if (!blockMergeInfo
           .try_emplace(curBlock, loc, loopControl, mergeBlock, continueBlock)
           .second) {
    return emitError(
        unknownLoc,
        "a block cannot have more than one OpLoopMerge instruction");
  }
 
  return success();
}
 
LogicalResult spirv::Deserializer::processPhi(ArrayRef<uint32_t> operands) {
  if (!curBlock) {
    return emitError(unknownLoc, "OpPhi must appear in a block");
  }
 
  if (operands.size() < 4) {
    return emitError(unknownLoc, "OpPhi must specify result type, result <id>, "
                                 "and variable-parent pairs");
  }
 
  // Create a block argument for this OpPhi instruction.
  Type blockArgType = getType(operands[0]);
  BlockArgument blockArg = curBlock->addArgument(blockArgType, unknownLoc);
  valueMap[operands[1]] = blockArg;
  LLVM_DEBUG(logger.startLine()
             << "[phi] created block argument " << blockArg
             << " id = " << operands[1] << " of type " << blockArgType << "\n");
 
  // For each (value, predecessor) pair, insert the value to the predecessor's
  // blockPhiInfo entry so later we can fix the block argument there.
  for (unsigned i = 2, e = operands.size(); i < e; i += 2) {
    uint32_t value = operands[i];
    Block *predecessor = getOrCreateBlock(operands[i + 1]);
    std::pair<Block *, Block *> predecessorTargetPair{predecessor, curBlock};
    blockPhiInfo[predecessorTargetPair].push_back(value);
    LLVM_DEBUG(logger.startLine() << "[phi] predecessor @ " << predecessor
                                  << " with arg id = " << value << "\n");
  }
 
  return success();
}
 
namespace {
/// A class for putting all blocks in a structured selection/loop in a
/// spirv.mlir.selection/spirv.mlir.loop op.
class ControlFlowStructurizer {
public:
#ifndef NDEBUG
  ControlFlowStructurizer(Location loc, uint32_t control,
                          spirv::BlockMergeInfoMap &mergeInfo, Block *header,
                          Block *merge, Block *cont,
                          llvm::ScopedPrinter &logger)
      : location(loc), control(control), blockMergeInfo(mergeInfo),
        headerBlock(header), mergeBlock(merge), continueBlock(cont),
        logger(logger) {}
#else
  ControlFlowStructurizer(Location loc, uint32_t control,
                          spirv::BlockMergeInfoMap &mergeInfo, Block *header,
                          Block *merge, Block *cont)
      : location(loc), control(control), blockMergeInfo(mergeInfo),
        headerBlock(header), mergeBlock(merge), continueBlock(cont) {}
#endif
 
  /// Structurizes the loop at the given `headerBlock`.
  ///
  /// This method will create an spirv.mlir.loop op in the `mergeBlock` and move
  /// all blocks in the structured loop into the spirv.mlir.loop's region. All
  /// branches to the `headerBlock` will be redirected to the `mergeBlock`. This
  /// method will also update `mergeInfo` by remapping all blocks inside to the
  /// newly cloned ones inside structured control flow op's regions.
  LogicalResult structurize();
 
private:
  /// Creates a new spirv.mlir.selection op at the beginning of the
  /// `mergeBlock`.
  spirv::SelectionOp createSelectionOp(uint32_t selectionControl);
 
  /// Creates a new spirv.mlir.loop op at the beginning of the `mergeBlock`.
  spirv::LoopOp createLoopOp(uint32_t loopControl);
 
  /// Collects all blocks reachable from `headerBlock` except `mergeBlock`.
  void collectBlocksInConstruct();
 
  Location location;
  uint32_t control;
 
  spirv::BlockMergeInfoMap &blockMergeInfo;
 
  Block *headerBlock;
  Block *mergeBlock;
  Block *continueBlock; // nullptr for spirv.mlir.selection
 
  SetVector<Block *> constructBlocks;
 
#ifndef NDEBUG
  /// A logger used to emit information during the deserialzation process.
  llvm::ScopedPrinter &logger;
#endif
};
} // namespace
 
spirv::SelectionOp
ControlFlowStructurizer::createSelectionOp(uint32_t selectionControl) {
  // Create a builder and set the insertion point to the beginning of the
  // merge block so that the newly created SelectionOp will be inserted there.
  OpBuilder builder(&mergeBlock->front());
 
  auto control = static_cast<spirv::SelectionControl>(selectionControl);
  auto selectionOp = spirv::SelectionOp::create(builder, location, control);
  selectionOp.addMergeBlock(builder);
 
  return selectionOp;
}
 
spirv::LoopOp ControlFlowStructurizer::createLoopOp(uint32_t loopControl) {
  // Create a builder and set the insertion point to the beginning of the
  // merge block so that the newly created LoopOp will be inserted there.
  OpBuilder builder(&mergeBlock->front());
 
  auto control = static_cast<spirv::LoopControl>(loopControl);
  auto loopOp = spirv::LoopOp::create(builder, location, control);
  loopOp.addEntryAndMergeBlock(builder);
 
  return loopOp;
}
 
void ControlFlowStructurizer::collectBlocksInConstruct() {
  assert(constructBlocks.empty() && "expected empty constructBlocks");
 
  // Put the header block in the work list first.
  constructBlocks.insert(headerBlock);
 
  // For each item in the work list, add its successors excluding the merge
  // block.
  for (unsigned i = 0; i < constructBlocks.size(); ++i) {
    for (auto *successor : constructBlocks[i]->getSuccessors())
      if (successor != mergeBlock)
        constructBlocks.insert(successor);
  }
}
 
LogicalResult ControlFlowStructurizer::structurize() {
  Operation *op = nullptr;
  bool isLoop = continueBlock != nullptr;
  if (isLoop) {
    if (auto loopOp = createLoopOp(control))
      op = loopOp.getOperation();
  } else {
    if (auto selectionOp = createSelectionOp(control))
      op = selectionOp.getOperation();
  }
  if (!op)
    return failure();
  Region &body = op->getRegion(0);
 
  IRMapping mapper;
  // All references to the old merge block should be directed to the
  // selection/loop merge block in the SelectionOp/LoopOp's region.
  mapper.map(mergeBlock, &body.back());
 
  collectBlocksInConstruct();
 
  // We've identified all blocks belonging to the selection/loop's region. Now
  // need to "move" them into the selection/loop. Instead of really moving the
  // blocks, in the following we copy them and remap all values and branches.
  // This is because:
  // * Inserting a block into a region requires the block not in any region
  //   before. But selections/loops can nest so we can create selection/loop ops
  //   in a nested manner, which means some blocks may already be in a
  //   selection/loop region when to be moved again.
  // * It's much trickier to fix up the branches into and out of the loop's
  //   region: we need to treat not-moved blocks and moved blocks differently:
  //   Not-moved blocks jumping to the loop header block need to jump to the
  //   merge point containing the new loop op but not the loop continue block's
  //   back edge. Moved blocks jumping out of the loop need to jump to the
  //   merge block inside the loop region but not other not-moved blocks.
  //   We cannot use replaceAllUsesWith clearly and it's harder to follow the
  //   logic.
 
  // Create a corresponding block in the SelectionOp/LoopOp's region for each
  // block in this loop construct.
  OpBuilder builder(body);
  for (auto *block : constructBlocks) {
    // Create a block and insert it before the selection/loop merge block in the
    // SelectionOp/LoopOp's region.
    auto *newBlock = builder.createBlock(&body.back());
    mapper.map(block, newBlock);
    LLVM_DEBUG(logger.startLine() << "[cf] cloned block " << newBlock
                                  << " from block " << block << "\n");
    if (!isFnEntryBlock(block)) {
      for (BlockArgument blockArg : block->getArguments()) {
        auto newArg =
            newBlock->addArgument(blockArg.getType(), blockArg.getLoc());
        mapper.map(blockArg, newArg);
        LLVM_DEBUG(logger.startLine() << "[cf] remapped block argument "
                                      << blockArg << " to " << newArg << "\n");
      }
    } else {
      LLVM_DEBUG(logger.startLine()
                 << "[cf] block " << block << " is a function entry block\n");
    }
 
    for (auto &op : *block)
      newBlock->push_back(op.clone(mapper));
  }
 
  // Go through all ops and remap the operands.
  auto remapOperands = [&](Operation *op) {
    for (auto &operand : op->getOpOperands())
      if (Value mappedOp = mapper.lookupOrNull(operand.get()))
        operand.set(mappedOp);
    for (auto &succOp : op->getBlockOperands())
      if (Block *mappedOp = mapper.lookupOrNull(succOp.get()))
        succOp.set(mappedOp);
  };
  for (auto &block : body)
    block.walk(remapOperands);
 
  // We have created the SelectionOp/LoopOp and "moved" all blocks belonging to
  // the selection/loop construct into its region. Next we need to fix the
  // connections between this new SelectionOp/LoopOp with existing blocks.
 
  // All existing incoming branches should go to the merge block, where the
  // SelectionOp/LoopOp resides right now.
  headerBlock->replaceAllUsesWith(mergeBlock);
 
  LLVM_DEBUG({
    logger.startLine() << "[cf] after cloning and fixing references:\n";
    headerBlock->getParentOp()->print(logger.getOStream());
    logger.startLine() << "\n";
  });
 
  if (isLoop) {
    if (!mergeBlock->args_empty()) {
      return mergeBlock->getParentOp()->emitError(
          "OpPhi in loop merge block unsupported");
    }
 
    // The loop header block may have block arguments. Since now we place the
    // loop op inside the old merge block, we need to make sure the old merge
    // block has the same block argument list.
    for (BlockArgument blockArg : headerBlock->getArguments())
      mergeBlock->addArgument(blockArg.getType(), blockArg.getLoc());
 
    // If the loop header block has block arguments, make sure the spirv.Branch
    // op matches.
    SmallVector<Value, 4> blockArgs;
    if (!headerBlock->args_empty())
      blockArgs = {mergeBlock->args_begin(), mergeBlock->args_end()};
 
    // The loop entry block should have a unconditional branch jumping to the
    // loop header block.
    builder.setInsertionPointToEnd(&body.front());
    spirv::BranchOp::create(builder, location, mapper.lookupOrNull(headerBlock),
                            ArrayRef<Value>(blockArgs));
  }
 
  // Values defined inside the selection region that need to be yielded outside
  // the region.
  SmallVector<Value> valuesToYield;
  // Outside uses of values that were sunk into the selection region. Those uses
  // will be replaced with values returned by the SelectionOp.
  SmallVector<Value> outsideUses;
 
  // Move block arguments of the original block (`mergeBlock`) into the merge
  // block inside the selection (`body.back()`). Values produced by block
  // arguments will be yielded by the selection region. We do not update uses or
  // erase original block arguments yet. It will be done later in the code.
  //
  // Code below is not executed for loops as it would interfere with the logic
  // above. Currently block arguments in the merge block are not supported, but
  // instead, the code above copies those arguments from the header block into
  // the merge block. As such, running the code would yield those copied
  // arguments that is most likely not a desired behaviour. This may need to be
  // revisited in the future.
  if (!isLoop)
    for (BlockArgument blockArg : mergeBlock->getArguments()) {
      // Create new block arguments in the last block ("merge block") of the
      // selection region. We create one argument for each argument in
      // `mergeBlock`. This new value will need to be yielded, and the original
      // value replaced, so add them to appropriate vectors.
      body.back().addArgument(blockArg.getType(), blockArg.getLoc());
      valuesToYield.push_back(body.back().getArguments().back());
      outsideUses.push_back(blockArg);
    }
 
  // All the blocks cloned into the SelectionOp/LoopOp's region can now be
  // cleaned up.
  LLVM_DEBUG(logger.startLine() << "[cf] cleaning up blocks after clone\n");
  // First we need to drop all operands' references inside all blocks. This is
  // needed because we can have blocks referencing SSA values from one another.
  for (auto *block : constructBlocks)
    block->dropAllReferences();
 
  // All internal uses should be removed from original blocks by now, so
  // whatever is left is an outside use and will need to be yielded from
  // the newly created selection / loop region.
  for (Block *block : constructBlocks) {
    for (Operation &op : *block) {
      if (!op.use_empty())
        for (Value result : op.getResults()) {
          valuesToYield.push_back(mapper.lookupOrNull(result));
          outsideUses.push_back(result);
        }
    }
    for (BlockArgument &arg : block->getArguments()) {
      if (!arg.use_empty()) {
        valuesToYield.push_back(mapper.lookupOrNull(arg));
        outsideUses.push_back(arg);
      }
    }
  }
 
  assert(valuesToYield.size() == outsideUses.size());
 
  // If we need to yield any values from the selection / loop region we will
  // take care of it here.
  if (!valuesToYield.empty()) {
    LLVM_DEBUG(logger.startLine()
               << "[cf] yielding values from the selection / loop region\n");
 
    // Update `mlir.merge` with values to be yield.
    auto mergeOps = body.back().getOps<spirv::MergeOp>();
    Operation *merge = llvm::getSingleElement(mergeOps);
    assert(merge);
    merge->setOperands(valuesToYield);
 
    // MLIR does not allow changing the number of results of an operation, so
    // we create a new SelectionOp / LoopOp with required list of results and
    // move the region from the initial SelectionOp / LoopOp. The initial
    // operation is then removed. Since we move the region to the new op all
    // links between blocks and remapping we have previously done should be
    // preserved.
    builder.setInsertionPoint(&mergeBlock->front());
 
    Operation *newOp = nullptr;
 
    if (isLoop)
      newOp = spirv::LoopOp::create(builder, location,
                                    TypeRange(ValueRange(outsideUses)),
                                    static_cast<spirv::LoopControl>(control));
    else
      newOp = spirv::SelectionOp::create(
          builder, location, TypeRange(ValueRange(outsideUses)),
          static_cast<spirv::SelectionControl>(control));
 
    newOp->getRegion(0).takeBody(body);
 
    // Remove initial op and swap the pointer to the newly created one.
    op->erase();
    op = newOp;
 
    // Update all outside uses to use results of the SelectionOp / LoopOp and
    // remove block arguments from the original merge block.
    for (unsigned i = 0, e = outsideUses.size(); i != e; ++i)
      outsideUses[i].replaceAllUsesWith(op->getResult(i));
 
    // We do not support block arguments in loop merge block. Also running this
    // function with loop would break some of the loop specific code above
    // dealing with block arguments.
    if (!isLoop)
      mergeBlock->eraseArguments(0, mergeBlock->getNumArguments());
  }
 
  // Check that whether some op in the to-be-erased blocks still has uses. Those
  // uses come from blocks that won't be sinked into the SelectionOp/LoopOp's
  // region. We cannot handle such cases given that once a value is sinked into
  // the SelectionOp/LoopOp's region, there is no escape for it.
  for (auto *block : constructBlocks) {
    for (Operation &op : *block)
      if (!op.use_empty())
        return op.emitOpError("failed control flow structurization: value has "
                              "uses outside of the "
                              "enclosing selection/loop construct");
    for (BlockArgument &arg : block->getArguments())
      if (!arg.use_empty())
        return emitError(arg.getLoc(), "failed control flow structurization: "
                                       "block argument has uses outside of the "
                                       "enclosing selection/loop construct");
  }
 
  // Then erase all old blocks.
  for (auto *block : constructBlocks) {
    // We've cloned all blocks belonging to this construct into the structured
    // control flow op's region. Among these blocks, some may compose another
    // selection/loop. If so, they will be recorded within blockMergeInfo.
    // We need to update the pointers there to the newly remapped ones so we can
    // continue structurizing them later.
    //
    // We need to walk each block as constructBlocks do not include blocks
    // internal to ops already structured within those blocks. It is not
    // fully clear to me why the mergeInfo of blocks (yet to be structured)
    // inside already structured selections/loops get invalidated and needs
    // updating, however the following example code can cause a crash (depending
    // on the structuring order), when the most inner selection is being
    // structured after the outer selection and loop have been already
    // structured:
    //
    //  spirv.mlir.for {
    //    // ...
    //    spirv.mlir.selection {
    //      // ..
    //      // A selection region that hasn't been yet structured!
    //      // ..
    //    }
    //    // ...
    //  }
    //
    // If the loop gets structured after the outer selection, but before the
    // inner selection. Moving the already structured selection inside the loop
    // will invalidate the mergeInfo of the region that is not yet structured.
    // Just going over constructBlocks will not check and updated header blocks
    // inside the already structured selection region. Walking block fixes that.
    //
    // TODO: If structuring was done in a fixed order starting with inner
    // most constructs this most likely not be an issue and the whole code
    // section could be removed. However, with the current non-deterministic
    // order this is not possible.
    //
    // TODO: The asserts in the following assumes input SPIR-V blob forms
    // correctly nested selection/loop constructs. We should relax this and
    // support error cases better.
    auto updateMergeInfo = [&](Block *block) -> WalkResult {
      auto it = blockMergeInfo.find(block);
      if (it != blockMergeInfo.end()) {
        // Use the original location for nested selection/loop ops.
        Location loc = it->second.loc;
 
        Block *newHeader = mapper.lookupOrNull(block);
        if (!newHeader)
          return emitError(loc, "failed control flow structurization: nested "
                                "loop header block should be remapped!");
 
        Block *newContinue = it->second.continueBlock;
        if (newContinue) {
          newContinue = mapper.lookupOrNull(newContinue);
          if (!newContinue)
            return emitError(loc, "failed control flow structurization: nested "
                                  "loop continue block should be remapped!");
        }
 
        Block *newMerge = it->second.mergeBlock;
        if (Block *mappedTo = mapper.lookupOrNull(newMerge))
          newMerge = mappedTo;
 
        // The iterator should be erased before adding a new entry into
        // blockMergeInfo to avoid iterator invalidation.
        blockMergeInfo.erase(it);
        blockMergeInfo.try_emplace(newHeader, loc, it->second.control, newMerge,
                                   newContinue);
      }
 
      return WalkResult::advance();
    };
 
    if (block->walk(updateMergeInfo).wasInterrupted())
      return failure();
 
    // The structured selection/loop's entry block does not have arguments.
    // If the function's header block is also part of the structured control
    // flow, we cannot just simply erase it because it may contain arguments
    // matching the function signature and used by the cloned blocks.
    if (isFnEntryBlock(block)) {
      LLVM_DEBUG(logger.startLine() << "[cf] changing entry block " << block
                                    << " to only contain a spirv.Branch op\n");
      // Still keep the function entry block for the potential block arguments,
      // but replace all ops inside with a branch to the merge block.
      block->clear();
      builder.setInsertionPointToEnd(block);
      spirv::BranchOp::create(builder, location, mergeBlock);
    } else {
      LLVM_DEBUG(logger.startLine() << "[cf] erasing block " << block << "\n");
      block->erase();
    }
  }
 
  LLVM_DEBUG(logger.startLine()
             << "[cf] after structurizing construct with header block "
             << headerBlock << ":\n"
             << *op << "\n");
 
  return success();
}
 
LogicalResult spirv::Deserializer::wireUpBlockArgument() {
  LLVM_DEBUG({
    logger.startLine()
        << "//----- [phi] start wiring up block arguments -----//\n";
    logger.indent();
  });
 
  OpBuilder::InsertionGuard guard(opBuilder);
 
  for (const auto &info : blockPhiInfo) {
    Block *block = info.first.first;
    Block *target = info.first.second;
    const BlockPhiInfo &phiInfo = info.second;
    LLVM_DEBUG({
      logger.startLine() << "[phi] block " << block << "\n";
      logger.startLine() << "[phi] before creating block argument:\n";
      block->getParentOp()->print(logger.getOStream());
      logger.startLine() << "\n";
    });
 
    // Set insertion point to before this block's terminator early because we
    // may materialize ops via getValue() call.
    auto *op = block->getTerminator();
    opBuilder.setInsertionPoint(op);
 
    SmallVector<Value, 4> blockArgs;
    blockArgs.reserve(phiInfo.size());
    for (uint32_t valueId : phiInfo) {
      if (Value value = getValue(valueId)) {
        blockArgs.push_back(value);
        LLVM_DEBUG(logger.startLine() << "[phi] block argument " << value
                                      << " id = " << valueId << "\n");
      } else {
        return emitError(unknownLoc, "OpPhi references undefined value!");
      }
    }
 
    if (auto branchOp = dyn_cast<spirv::BranchOp>(op)) {
      // Replace the previous branch op with a new one with block arguments.
      spirv::BranchOp::create(opBuilder, branchOp.getLoc(),
                              branchOp.getTarget(), blockArgs);
      branchOp.erase();
    } else if (auto branchCondOp = dyn_cast<spirv::BranchConditionalOp>(op)) {
      assert((branchCondOp.getTrueBlock() == target ||
              branchCondOp.getFalseBlock() == target) &&
             "expected target to be either the true or false target");
      if (target == branchCondOp.getTrueTarget())
        spirv::BranchConditionalOp::create(
            opBuilder, branchCondOp.getLoc(), branchCondOp.getCondition(),
            blockArgs, branchCondOp.getFalseBlockArguments(),
            branchCondOp.getBranchWeightsAttr(), branchCondOp.getTrueTarget(),
            branchCondOp.getFalseTarget());
      else
        spirv::BranchConditionalOp::create(
            opBuilder, branchCondOp.getLoc(), branchCondOp.getCondition(),
            branchCondOp.getTrueBlockArguments(), blockArgs,
            branchCondOp.getBranchWeightsAttr(), branchCondOp.getTrueBlock(),
            branchCondOp.getFalseBlock());
 
      branchCondOp.erase();
    } else {
      return emitError(unknownLoc, "unimplemented terminator for Phi creation");
    }
 
    LLVM_DEBUG({
      logger.startLine() << "[phi] after creating block argument:\n";
      block->getParentOp()->print(logger.getOStream());
      logger.startLine() << "\n";
    });
  }
  blockPhiInfo.clear();
 
  LLVM_DEBUG({
    logger.unindent();
    logger.startLine()
        << "//--- [phi] completed wiring up block arguments ---//\n";
  });
  return success();
}
 
LogicalResult spirv::Deserializer::splitConditionalBlocks() {
  // Create a copy, so we can modify keys in the original.
  BlockMergeInfoMap blockMergeInfoCopy = blockMergeInfo;
  for (auto it = blockMergeInfoCopy.begin(), e = blockMergeInfoCopy.end();
       it != e; ++it) {
    auto &[block, mergeInfo] = *it;
 
    // Skip processing loop regions. For loop regions continueBlock is non-null.
    if (mergeInfo.continueBlock)
      continue;
 
    if (!block->mightHaveTerminator())
      continue;
 
    Operation *terminator = block->getTerminator();
    assert(terminator);
 
    if (!isa<spirv::BranchConditionalOp>(terminator))
      continue;
 
    // Check if the current header block is a merge block of another construct.
    bool splitHeaderMergeBlock = false;
    for (const auto &[_, mergeInfo] : blockMergeInfo) {
      if (mergeInfo.mergeBlock == block)
        splitHeaderMergeBlock = true;
    }
 
    // Do not split a block that only contains a conditional branch, unless it
    // is also a merge block of another construct - in that case we want to
    // split the block. We do not want two constructs to share header / merge
    // block.
    if (!llvm::hasSingleElement(*block) || splitHeaderMergeBlock) {
      Block *newBlock = block->splitBlock(terminator);
      OpBuilder builder(block, block->end());
      spirv::BranchOp::create(builder, block->getParent()->getLoc(), newBlock);
 
      // After splitting we need to update the map to use the new block as a
      // header.
      blockMergeInfo.erase(block);
      blockMergeInfo.try_emplace(newBlock, mergeInfo);
    }
  }
 
  return success();
}
 
LogicalResult spirv::Deserializer::structurizeControlFlow() {
  if (!options.enableControlFlowStructurization) {
    LLVM_DEBUG(
        {
          logger.startLine()
              << "//----- [cf] skip structurizing control flow -----//\n";
          logger.indent();
        });
    return success();
  }
 
  LLVM_DEBUG({
    logger.startLine()
        << "//----- [cf] start structurizing control flow -----//\n";
    logger.indent();
  });
 
  LLVM_DEBUG({
    logger.startLine() << "[cf] split conditional blocks\n";
    logger.startLine() << "\n";
  });
 
  if (failed(splitConditionalBlocks())) {
    return failure();
  }
 
  // TODO: This loop is non-deterministic. Iteration order may vary between runs
  // for the same shader as the key to the map is a pointer. See:
  // https://github.com/llvm/llvm-project/issues/128547
  while (!blockMergeInfo.empty()) {
    Block *headerBlock = blockMergeInfo.begin()->first;
    BlockMergeInfo mergeInfo = blockMergeInfo.begin()->second;
 
    LLVM_DEBUG({
      logger.startLine() << "[cf] header block " << headerBlock << ":\n";
      headerBlock->print(logger.getOStream());
      logger.startLine() << "\n";
    });
 
    auto *mergeBlock = mergeInfo.mergeBlock;
    assert(mergeBlock && "merge block cannot be nullptr");
    if (mergeInfo.continueBlock && !mergeBlock->args_empty())
      return emitError(unknownLoc, "OpPhi in loop merge block unimplemented");
    LLVM_DEBUG({
      logger.startLine() << "[cf] merge block " << mergeBlock << ":\n";
      mergeBlock->print(logger.getOStream());
      logger.startLine() << "\n";
    });
 
    auto *continueBlock = mergeInfo.continueBlock;
    LLVM_DEBUG(if (continueBlock) {
      logger.startLine() << "[cf] continue block " << continueBlock << ":\n";
      continueBlock->print(logger.getOStream());
      logger.startLine() << "\n";
    });
    // Erase this case before calling into structurizer, who will update
    // blockMergeInfo.
    blockMergeInfo.erase(blockMergeInfo.begin());
    ControlFlowStructurizer structurizer(mergeInfo.loc, mergeInfo.control,
                                         blockMergeInfo, headerBlock,
                                         mergeBlock, continueBlock
#ifndef NDEBUG
                                         ,
                                         logger
#endif
    );
    if (failed(structurizer.structurize()))
      return failure();
  }
 
  LLVM_DEBUG({
    logger.unindent();
    logger.startLine()
        << "//--- [cf] completed structurizing control flow ---//\n";
  });
  return success();
}
 
//===----------------------------------------------------------------------===//
// Debug
//===----------------------------------------------------------------------===//
 
Location spirv::Deserializer::createFileLineColLoc(OpBuilder opBuilder) {
  if (!debugLine)
    return unknownLoc;
 
  auto fileName = debugInfoMap.lookup(debugLine->fileID).str();
  if (fileName.empty())
    fileName = "<unknown>";
  return FileLineColLoc::get(opBuilder.getStringAttr(fileName), debugLine->line,
                             debugLine->column);
}
 
LogicalResult
spirv::Deserializer::processDebugLine(ArrayRef<uint32_t> operands) {
  // According to SPIR-V spec:
  // "This location information applies to the instructions physically
  // following this instruction, up to the first occurrence of any of the
  // following: the next end of block, the next OpLine instruction, or the next
  // OpNoLine instruction."
  if (operands.size() != 3)
    return emitError(unknownLoc, "OpLine must have 3 operands");
  debugLine = DebugLine{operands[0], operands[1], operands[2]};
  return success();
}
 
void spirv::Deserializer::clearDebugLine() { debugLine = std::nullopt; }
 
LogicalResult
spirv::Deserializer::processDebugString(ArrayRef<uint32_t> operands) {
  if (operands.size() < 2)
    return emitError(unknownLoc, "OpString needs at least 2 operands");
 
  if (!debugInfoMap.lookup(operands[0]).empty())
    return emitError(unknownLoc,
                     "duplicate debug string found for result <id> ")
           << operands[0];
 
  unsigned wordIndex = 1;
  StringRef debugString = decodeStringLiteral(operands, wordIndex);
  if (wordIndex != operands.size())
    return emitError(unknownLoc,
                     "unexpected trailing words in OpString instruction");
 
  debugInfoMap[operands[0]] = debugString;
  return success();
}