LowerAnnotations.cpp

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//===- LowerAnnotations.cpp - Lower Annotations -----------------*- C++ -*-===//
//
// 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 LowerAnnotations pass.  This pass processes FIRRTL
// annotations, rewriting them, scattering them, and dealing with non-local
// annotations.
//
//===----------------------------------------------------------------------===//
 
#include "circt/Dialect/FIRRTL/AnnotationDetails.h"
#include "circt/Dialect/FIRRTL/CHIRRTLDialect.h"
#include "circt/Dialect/FIRRTL/FIRRTLAnnotationHelper.h"
#include "circt/Dialect/FIRRTL/FIRRTLAnnotations.h"
#include "circt/Dialect/FIRRTL/FIRRTLAttributes.h"
#include "circt/Dialect/FIRRTL/FIRRTLInstanceGraph.h"
#include "circt/Dialect/FIRRTL/FIRRTLOps.h"
#include "circt/Dialect/FIRRTL/FIRRTLTypes.h"
#include "circt/Dialect/FIRRTL/FIRRTLUtils.h"
#include "circt/Dialect/FIRRTL/Passes.h"
#include "circt/Dialect/HW/HWAttributes.h"
#include "circt/Dialect/SV/SVAttributes.h"
#include "circt/Support/Debug.h"
#include "mlir/IR/Diagnostics.h"
#include "mlir/Pass/Pass.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Debug.h"
 
#define DEBUG_TYPE "firrtl-lower-annotations"
 
namespace circt {
namespace firrtl {
#define GEN_PASS_DEF_LOWERFIRRTLANNOTATIONS
#include "circt/Dialect/FIRRTL/Passes.h.inc"
} // namespace firrtl
} // namespace circt
 
using namespace circt;
using namespace firrtl;
using namespace chirrtl;
 
/// Get annotations or an empty set of annotations.
static ArrayAttr getAnnotationsFrom(Operation *op) {
  if (auto annots = op->getAttrOfType<ArrayAttr>(getAnnotationAttrName()))
    return annots;
  return ArrayAttr::get(op->getContext(), {});
}
 
/// Construct the annotation array with a new thing appended.
static ArrayAttr appendArrayAttr(ArrayAttr array, Attribute a) {
  if (!array)
    return ArrayAttr::get(a.getContext(), ArrayRef<Attribute>{a});
  SmallVector<Attribute> old(array.begin(), array.end());
  old.push_back(a);
  return ArrayAttr::get(a.getContext(), old);
}
 
/// Update an ArrayAttribute by replacing one entry.
static ArrayAttr replaceArrayAttrElement(ArrayAttr array, size_t elem,
                                         Attribute newVal) {
  SmallVector<Attribute> old(array.begin(), array.end());
  old[elem] = newVal;
  return ArrayAttr::get(array.getContext(), old);
}
 
/// Apply a new annotation to a resolved target.  This handles ports,
/// aggregates, modules, wires, etc.
static void addAnnotation(AnnoTarget ref, unsigned fieldIdx,
                          ArrayRef<NamedAttribute> anno) {
  auto *context = ref.getOp()->getContext();
  DictionaryAttr annotation;
  if (fieldIdx) {
    SmallVector<NamedAttribute> annoField(anno.begin(), anno.end());
    annoField.emplace_back(
        StringAttr::get(context, "circt.fieldID"),
        IntegerAttr::get(IntegerType::get(context, 32, IntegerType::Signless),
                         fieldIdx));
    annotation = DictionaryAttr::get(context, annoField);
  } else {
    annotation = DictionaryAttr::get(context, anno);
  }
 
  if (isa<OpAnnoTarget>(ref)) {
    auto newAnno = appendArrayAttr(getAnnotationsFrom(ref.getOp()), annotation);
    ref.getOp()->setAttr(getAnnotationAttrName(), newAnno);
    return;
  }
 
  auto portRef = cast<PortAnnoTarget>(ref);
  auto portAnnoRaw = ref.getOp()->getAttr(getPortAnnotationAttrName());
  ArrayAttr portAnno = dyn_cast_or_null<ArrayAttr>(portAnnoRaw);
  if (!portAnno || portAnno.size() != getNumPorts(ref.getOp())) {
    SmallVector<Attribute> emptyPortAttr(
        getNumPorts(ref.getOp()),
        ArrayAttr::get(ref.getOp()->getContext(), {}));
    portAnno = ArrayAttr::get(ref.getOp()->getContext(), emptyPortAttr);
  }
  portAnno = replaceArrayAttrElement(
      portAnno, portRef.getPortNo(),
      appendArrayAttr(dyn_cast<ArrayAttr>(portAnno[portRef.getPortNo()]),
                      annotation));
  ref.getOp()->setAttr("portAnnotations", portAnno);
}
 
/// Make an anchor for a non-local annotation.  Use the expanded path to build
/// the module and name list in the anchor.
static FlatSymbolRefAttr buildNLA(const AnnoPathValue &target,
                                  ApplyState &state) {
  OpBuilder b(state.circuit.getBodyRegion());
  SmallVector<Attribute> insts;
  for (auto inst : target.instances) {
    insts.push_back(OpAnnoTarget(inst).getNLAReference(
        state.getNamespace(inst->getParentOfType<FModuleLike>())));
  }
 
  insts.push_back(
      FlatSymbolRefAttr::get(target.ref.getModule().getModuleNameAttr()));
 
  auto instAttr = ArrayAttr::get(state.circuit.getContext(), insts);
  return state.hierPathCache.getRefFor(instAttr);
}
 
/// Scatter breadcrumb annotations corresponding to non-local annotations
/// along the instance path.  Returns symbol name used to anchor annotations to
/// path.
// FIXME: uniq annotation chain links
static FlatSymbolRefAttr scatterNonLocalPath(const AnnoPathValue &target,
                                             ApplyState &state) {
 
  FlatSymbolRefAttr sym = buildNLA(target, state);
  return sym;
}
 
//===----------------------------------------------------------------------===//
// Standard Utility Resolvers
//===----------------------------------------------------------------------===//
 
/// Always resolve to the circuit, ignoring the annotation.
static std::optional<AnnoPathValue> noResolve(DictionaryAttr anno,
                                              ApplyState &state) {
  return AnnoPathValue(state.circuit);
}
 
/// Implementation of standard resolution.  First parses the target path, then
/// resolves it.
static std::optional<AnnoPathValue> stdResolveImpl(StringRef rawPath,
                                                   ApplyState &state) {
  auto pathStr = canonicalizeTarget(rawPath);
  StringRef path{pathStr};
 
  auto tokens = tokenizePath(path);
  if (!tokens) {
    mlir::emitError(state.circuit.getLoc())
        << "Cannot tokenize annotation path " << rawPath;
    return {};
  }
 
  return resolveEntities(*tokens, state.circuit, state.symTbl,
                         state.targetCaches);
}
 
/// (SFC) FIRRTL SingleTargetAnnotation resolver.  Uses the 'target' field of
/// the annotation with standard parsing to resolve the path.  This requires
/// 'target' to exist and be normalized (per docs/FIRRTLAnnotations.md).
std::optional<AnnoPathValue> circt::firrtl::stdResolve(DictionaryAttr anno,
                                                       ApplyState &state) {
  auto target = anno.getNamed("target");
  if (!target) {
    mlir::emitError(state.circuit.getLoc())
        << "No target field in annotation " << anno;
    return {};
  }
  if (!isa<StringAttr>(target->getValue())) {
    mlir::emitError(state.circuit.getLoc())
        << "Target field in annotation doesn't contain string " << anno;
    return {};
  }
  return stdResolveImpl(cast<StringAttr>(target->getValue()).getValue(), state);
}
 
/// Resolves with target, if it exists.  If not, resolves to the circuit.
std::optional<AnnoPathValue> circt::firrtl::tryResolve(DictionaryAttr anno,
                                                       ApplyState &state) {
  auto target = anno.getNamed("target");
  if (target)
    return stdResolveImpl(cast<StringAttr>(target->getValue()).getValue(),
                          state);
  return AnnoPathValue(state.circuit);
}
 
//===----------------------------------------------------------------------===//
// Standard Utility Appliers
//===----------------------------------------------------------------------===//
 
/// An applier which puts the annotation on the target and drops the 'target'
/// field from the annotation.  Optionally handles non-local annotations.
LogicalResult circt::firrtl::applyWithoutTargetImpl(const AnnoPathValue &target,
 
                                                    DictionaryAttr anno,
                                                    ApplyState &state,
                                                    bool allowNonLocal) {
  if (!allowNonLocal && !target.isLocal()) {
    Annotation annotation(anno);
    auto diag = mlir::emitError(target.ref.getOp()->getLoc())
                << "is targeted by a non-local annotation \""
                << annotation.getClass() << "\" with target "
                << annotation.getMember("target")
                << ", but this annotation cannot be non-local";
    diag.attachNote() << "see current annotation: " << anno << "\n";
    return failure();
  }
  SmallVector<NamedAttribute> newAnnoAttrs;
  for (auto &na : anno) {
    if (na.getName().getValue() != "target") {
      newAnnoAttrs.push_back(na);
    } else if (!target.isLocal()) {
      auto sym = scatterNonLocalPath(target, state);
      newAnnoAttrs.push_back(
          {StringAttr::get(anno.getContext(), "circt.nonlocal"), sym});
    }
  }
  addAnnotation(target.ref, target.fieldIdx, newAnnoAttrs);
  return success();
}
 
/// Just drop the annotation.  This is intended for Annotations which are known,
/// but can be safely ignored.
LogicalResult drop(const AnnoPathValue &target, DictionaryAttr anno,
                   ApplyState &state) {
  return success();
}
//===----------------------------------------------------------------------===//
// Customized Appliers
//===----------------------------------------------------------------------===//
 
static LogicalResult applyDUTAnno(const AnnoPathValue &target,
                                  DictionaryAttr anno, ApplyState &state) {
  auto *op = target.ref.getOp();
  auto loc = op->getLoc();
 
  if (!target.isLocal())
    return mlir::emitError(loc) << "must be local";
 
  if (!isa<OpAnnoTarget>(target.ref) || !isa<FModuleLike>(op))
    return mlir::emitError(loc) << "can only target to a module";
 
  auto moduleOp = cast<FModuleLike>(op);
 
  // DUT has public visibility.
  mlir::SymbolTable::setSymbolVisibility(moduleOp.getOperation(),
                                         mlir::SymbolTable::Visibility::Public);
  SmallVector<NamedAttribute> newAnnoAttrs;
  for (auto &na : anno)
    if (na.getName().getValue() != "target")
      newAnnoAttrs.push_back(na);
  addAnnotation(target.ref, target.fieldIdx, newAnnoAttrs);
  return success();
}
 
// Like symbolizeConvention, but disallows the internal convention.
static std::optional<Convention> parseConvention(llvm::StringRef str) {
  return ::llvm::StringSwitch<::std::optional<Convention>>(str)
      .Case("scalarized", Convention::Scalarized)
      .Default(std::nullopt);
}
 
static LogicalResult applyConventionAnno(const AnnoPathValue &target,
                                         DictionaryAttr anno,
                                         ApplyState &state) {
  auto *op = target.ref.getOp();
  auto loc = op->getLoc();
  auto error = [&]() {
    auto diag = mlir::emitError(loc);
    diag << "circuit.ConventionAnnotation ";
    return diag;
  };
 
  auto opTarget = dyn_cast<OpAnnoTarget>(target.ref);
  if (!opTarget)
    return error() << "must target a module object";
 
  if (!target.isLocal())
    return error() << "must be local";
 
  auto conventionStrAttr =
      tryGetAs<StringAttr>(anno, anno, "convention", loc, conventionAnnoClass);
  if (!conventionStrAttr)
    return failure();
 
  auto conventionStr = conventionStrAttr.getValue();
  auto conventionOpt = parseConvention(conventionStr);
  if (!conventionOpt)
    return error() << "unknown convention " << conventionStr;
 
  auto convention = *conventionOpt;
 
  if (auto moduleOp = dyn_cast<FModuleOp>(op)) {
    moduleOp.setConvention(convention);
    return success();
  }
 
  if (auto extModuleOp = dyn_cast<FExtModuleOp>(op)) {
    extModuleOp.setConvention(convention);
    return success();
  }
 
  return error() << "can only target to a module or extmodule";
}
 
static LogicalResult applyBodyTypeLoweringAnno(const AnnoPathValue &target,
                                               DictionaryAttr anno,
                                               ApplyState &state) {
  auto *op = target.ref.getOp();
  auto loc = op->getLoc();
  auto error = [&]() {
    auto diag = mlir::emitError(loc);
    diag << bodyTypeLoweringAnnoClass;
    return diag;
  };
 
  auto opTarget = dyn_cast<OpAnnoTarget>(target.ref);
  if (!opTarget)
    return error() << "must target a module object";
 
  if (!target.isLocal())
    return error() << "must be local";
 
  auto moduleOp = dyn_cast<FModuleOp>(op);
 
  if (!moduleOp)
    return error() << "can only target to a module";
 
  auto conventionStrAttr =
      tryGetAs<StringAttr>(anno, anno, "convention", loc, conventionAnnoClass);
 
  if (!conventionStrAttr)
    return failure();
 
  auto conventionStr = conventionStrAttr.getValue();
  auto conventionOpt = parseConvention(conventionStr);
  if (!conventionOpt)
    return error() << "unknown convention " << conventionStr;
 
  auto convention = *conventionOpt;
 
  if (convention == Convention::Internal)
    // Convention is internal by default so there is nothing to change
    return success();
 
  auto conventionAttr = ConventionAttr::get(op->getContext(), convention);
 
  // `includeHierarchy` only valid in BodyTypeLowering.
  bool includeHierarchy = false;
  if (auto includeHierarchyAttr = tryGetAs<BoolAttr>(
          anno, anno, "includeHierarchy", loc, conventionAnnoClass))
    includeHierarchy = includeHierarchyAttr.getValue();
 
  if (includeHierarchy) {
    // If includeHierarchy is true, update the convention for all modules in
    // the hierarchy.
    for (auto *node :
         llvm::post_order(state.instancePathCache.instanceGraph[moduleOp])) {
      if (!node)
        continue;
      if (auto fmodule = dyn_cast<FModuleOp>(*node->getModule()))
        fmodule->setAttr("body_type_lowering", conventionAttr);
    }
  } else {
    // Update the convention.
    moduleOp->setAttr("body_type_lowering", conventionAttr);
  }
 
  return success();
}
 
static LogicalResult applyModulePrefixAnno(const AnnoPathValue &target,
                                           DictionaryAttr anno,
                                           ApplyState &state) {
  auto *op = target.ref.getOp();
  auto loc = op->getLoc();
  auto error = [&]() {
    auto diag = mlir::emitError(loc);
    diag << modulePrefixAnnoClass << " ";
    return diag;
  };
 
  auto opTarget = dyn_cast<OpAnnoTarget>(target.ref);
  if (!opTarget)
    return error() << "must target an operation";
 
  if (!isa<SeqMemOp, CombMemOp, MemOp>(opTarget.getOp()))
    return error() << "must target a memory operation";
 
  if (!target.isLocal())
    return error() << "must be local";
 
  auto prefixStrAttr =
      tryGetAs<StringAttr>(anno, anno, "prefix", loc, modulePrefixAnnoClass);
  if (!prefixStrAttr)
    return failure();
 
  if (auto mem = dyn_cast<SeqMemOp>(op))
    mem.setPrefixAttr(prefixStrAttr);
  else if (auto mem = dyn_cast<CombMemOp>(op))
    mem.setPrefixAttr(prefixStrAttr);
  else if (auto mem = dyn_cast<MemOp>(op))
    mem.setPrefixAttr(prefixStrAttr);
 
  return success();
}
 
static LogicalResult applyAttributeAnnotation(const AnnoPathValue &target,
                                              DictionaryAttr anno,
                                              ApplyState &state) {
  auto *op = target.ref.getOp();
 
  auto error = [&]() {
    auto diag = mlir::emitError(op->getLoc());
    diag << anno.getAs<StringAttr>("class").getValue() << " ";
    return diag;
  };
 
  if (!isa<OpAnnoTarget>(target.ref))
    return error()
           << "must target an operation. Currently ports are not supported";
 
  if (!target.isLocal())
    return error() << "must be local";
 
  if (!isa<FModuleOp, WireOp, NodeOp, RegOp, RegResetOp>(op))
    return error()
           << "unhandled operation. The target must be a module, wire, node or "
              "register";
 
  auto name = anno.getAs<StringAttr>("description");
  auto svAttr = sv::SVAttributeAttr::get(name.getContext(), name);
  sv::addSVAttributes(op, {svAttr});
  return success();
}
 
/// Update a memory op with attributes about memory file loading.
template <bool isInline>
static LogicalResult applyLoadMemoryAnno(const AnnoPathValue &target,
                                         DictionaryAttr anno,
                                         ApplyState &state) {
  if (!target.isLocal()) {
    mlir::emitError(state.circuit.getLoc())
        << "has a " << anno.get("class")
        << " annotation which is non-local, but this annotation is not allowed "
           "to be non-local";
    return failure();
  }
 
  auto *op = target.ref.getOp();
 
  if (!target.isOpOfType<MemOp, CombMemOp, SeqMemOp>()) {
    mlir::emitError(op->getLoc())
        << "can only apply a load memory annotation to a memory";
    return failure();
  }
 
  // The two annotations have different case usage in "filename".
  StringAttr filename = tryGetAs<StringAttr>(
      anno, anno, isInline ? "filename" : "fileName", op->getLoc(),
      anno.getAs<StringAttr>("class").getValue());
  if (!filename)
    return failure();
 
  auto hexOrBinary =
      tryGetAs<StringAttr>(anno, anno, "hexOrBinary", op->getLoc(),
                           anno.getAs<StringAttr>("class").getValue());
  if (!hexOrBinary)
    return failure();
 
  auto hexOrBinaryValue = hexOrBinary.getValue();
  if (hexOrBinaryValue != "h" && hexOrBinaryValue != "b") {
    auto diag = mlir::emitError(op->getLoc())
                << "has memory initialization annotation with invalid format, "
                   "'hexOrBinary' field must be either 'h' or 'b'";
    diag.attachNote() << "the full annotation is: " << anno;
    return failure();
  }
 
  op->setAttr("init", MemoryInitAttr::get(op->getContext(), filename,
                                          hexOrBinaryValue == "b", isInline));
 
  return success();
}
 
static LogicalResult applyOutputDirAnno(const AnnoPathValue &target,
                                        DictionaryAttr anno,
                                        ApplyState &state) {
  auto *op = target.ref.getOp();
  auto *context = op->getContext();
  auto loc = op->getLoc();
 
  auto error = [&]() {
    return mlir::emitError(loc) << outputDirAnnoClass << " ";
  };
 
  auto opTarget = dyn_cast<OpAnnoTarget>(target.ref);
  if (!opTarget)
    return error() << "must target a module";
  if (!target.isLocal())
    return error() << "must be local";
 
  auto moduleOp = dyn_cast<FModuleOp>(op);
  if (!moduleOp)
    return error() << "must target a module";
  if (!moduleOp.isPublic())
    return error() << "must target a public module";
  if (moduleOp->hasAttr("output_file"))
    return error() << "target already has an output file";
 
  auto dirname =
      tryGetAs<StringAttr>(anno, anno, "dirname", loc, outputDirAnnoClass);
  if (!dirname)
    return failure();
  if (dirname.empty())
    return error() << "dirname must not be empty";
 
  auto outputFile =
      hw::OutputFileAttr::getAsDirectory(context, dirname.getValue());
 
  moduleOp->setAttr("output_file", outputFile);
  return success();
}
 
/// Convert from FullAsyncResetAnnotation to FullResetAnnotation
static LogicalResult convertToFullResetAnnotation(const AnnoPathValue &target,
                                                  DictionaryAttr anno,
                                                  ApplyState &state) {
  auto *op = target.ref.getOp();
  auto *context = op->getContext();
 
  mlir::emitWarning(op->getLoc())
      << "'" << fullAsyncResetAnnoClass << "' is deprecated, use '"
      << fullResetAnnoClass << "' instead";
 
  NamedAttrList newAnno(anno.getValue());
  newAnno.set("class", StringAttr::get(context, fullResetAnnoClass));
  newAnno.append("resetType", StringAttr::get(context, "async"));
 
  DictionaryAttr newDictionary = DictionaryAttr::get(op->getContext(), newAnno);
 
  return applyWithoutTarget<false>(target, newDictionary, state);
}
 
/// Convert from IgnoreFullAsyncResetAnnotation to
/// ExcludeFromFullResetAnnotation
static LogicalResult convertToExcludeFromFullResetAnnotation(
    const AnnoPathValue &target, DictionaryAttr anno, ApplyState &state) {
  auto *op = target.ref.getOp();
  auto *context = op->getContext();
 
  mlir::emitWarning(op->getLoc())
      << "'" << ignoreFullAsyncResetAnnoClass << "' is deprecated, use '"
      << excludeFromFullResetAnnoClass << "' instead";
 
  NamedAttrList newAnno(anno.getValue());
  newAnno.set("class", StringAttr::get(context, excludeFromFullResetAnnoClass));
 
  DictionaryAttr newDictionary = DictionaryAttr::get(op->getContext(), newAnno);
 
  return applyWithoutTarget<true, FModuleOp>(target, newDictionary, state);
}
 
//===----------------------------------------------------------------------===//
// Driving table
//===----------------------------------------------------------------------===//
 
namespace circt::firrtl {
/// Resolution and application of a "firrtl.annotations.NoTargetAnnotation".
/// This should be used for any Annotation which does not apply to anything in
/// the FIRRTL Circuit, i.e., an Annotation which has no target.  Historically,
/// NoTargetAnnotations were used to control the Scala FIRRTL Compiler (SFC) or
/// its passes, e.g., to set the output directory or to turn on a pass.
/// Examples of these in the SFC are "firrtl.options.TargetDirAnnotation" to set
/// the output directory or "firrtl.stage.RunFIRRTLTransformAnnotation" to
/// cause the SFC to schedule a specified pass.  Instead of leaving these
/// floating or attaching them to the top-level MLIR module (which is a purer
/// interpretation of "no target"), we choose to attach them to the Circuit even
/// they do not "apply" to the Circuit.  This gives later passes a common place,
/// the Circuit, to search for these control Annotations.
static AnnoRecord NoTargetAnnotation = {noResolve,
                                        applyWithoutTarget<false, CircuitOp>};
 
static llvm::StringMap<AnnoRecord> annotationRecords{{
 
    // Testing Annotations (manually maintained for testing infrastructure)
    {"circt.test", {stdResolve, applyWithoutTarget<true>}},
    {"circt.testLocalOnly", {stdResolve, applyWithoutTarget<>}},
    {"circt.testNT", {noResolve, applyWithoutTarget<>}},
    {"circt.missing", {tryResolve, applyWithoutTarget<true>}},
 
// Auto-generated annotation records from FIRRTLAnnotations.td
#define GET_ANNOTATION_RECORD_LIST
#include "circt/Dialect/FIRRTL/FIRRTLAnnotationRecords.h.inc"
}};
 
LogicalResult
registerAnnotationRecord(StringRef annoClass, AnnoRecord annoRecord,
                         const std::function<void(llvm::Twine)> &errorHandler) {
 
  if (annotationRecords.insert({annoClass, annoRecord}).second)
    return LogicalResult::success();
  if (errorHandler)
    errorHandler("annotation record '" + annoClass + "' is registered twice\n");
  return LogicalResult::failure();
}
 
} // namespace circt::firrtl
 
/// Lookup a record for a given annotation class.  Optionally, returns the
/// record for "circuit.missing" if the record doesn't exist.
static const AnnoRecord *getAnnotationHandler(StringRef annoStr,
                                              bool ignoreAnnotationUnknown) {
  auto ii = annotationRecords.find(annoStr);
  if (ii != annotationRecords.end())
    return &ii->second;
  if (ignoreAnnotationUnknown)
    return &annotationRecords.find("circt.missing")->second;
  return nullptr;
}
 
//===----------------------------------------------------------------------===//
// Pass Infrastructure
//===----------------------------------------------------------------------===//
 
namespace {
struct LowerAnnotationsPass
    : public circt::firrtl::impl::LowerFIRRTLAnnotationsBase<
          LowerAnnotationsPass> {
  using Base::Base;
 
  void runOnOperation() override;
  LogicalResult applyAnnotation(DictionaryAttr anno, ApplyState &state);
  LogicalResult legacyToWiringProblems(ApplyState &state);
  LogicalResult solveWiringProblems(ApplyState &state);
 
  SmallVector<DictionaryAttr> worklistAttrs;
};
} // end anonymous namespace
 
LogicalResult LowerAnnotationsPass::applyAnnotation(DictionaryAttr anno,
                                                    ApplyState &state) {
  LLVM_DEBUG(llvm::dbgs() << "  - anno: " << anno << "\n";);
 
  // Lookup the class
  StringRef annoClassVal;
  if (auto annoClass = anno.getNamed("class"))
    annoClassVal = cast<StringAttr>(annoClass->getValue()).getValue();
  else if (ignoreAnnotationClassless)
    annoClassVal = "circt.missing";
  else
    return mlir::emitError(state.circuit.getLoc())
           << "Annotation without a class: " << anno;
 
  // See if we handle the class
  auto *record = getAnnotationHandler(annoClassVal, false);
  if (!record) {
    ++numUnhandled;
    if (!ignoreAnnotationUnknown)
      return mlir::emitError(state.circuit.getLoc())
             << "Unhandled annotation: " << anno;
 
    // Try again, requesting the fallback handler.
    record = getAnnotationHandler(annoClassVal, ignoreAnnotationUnknown);
    assert(record);
  }
 
  // Try to apply the annotation
  auto target = record->resolver(anno, state);
  if (!target)
    return mlir::emitError(state.circuit.getLoc())
           << "Unable to resolve target of annotation: " << anno;
  if (record->applier(*target, anno, state).failed())
    return mlir::emitError(state.circuit.getLoc())
           << "Unable to apply annotation: " << anno;
  return success();
}
 
/// Convert consumed SourceAnnotation and SinkAnnotation into WiringProblems,
/// using the pin attribute as newNameHint
LogicalResult LowerAnnotationsPass::legacyToWiringProblems(ApplyState &state) {
  for (const auto &[name, problem] : state.legacyWiringProblems) {
    if (!problem.source)
      return mlir::emitError(state.circuit.getLoc())
             << "Unable to resolve source for pin: " << name;
 
    if (problem.sinks.empty())
      return mlir::emitError(state.circuit.getLoc())
             << "Unable to resolve sink(s) for pin: " << name;
 
    for (const auto &sink : problem.sinks) {
      state.wiringProblems.push_back(
          {problem.source, sink, {}, WiringProblem::RefTypeUsage::Never});
    }
  }
  return success();
}
 
/// Modify the circuit to solve and apply all Wiring Problems in the circuit.  A
/// Wiring Problem is a mapping from a source to a sink that can be connected
/// via a base Type or RefType as requested.  This uses a two-step approach.
/// First, all Wiring Problems are analyzed to compute pending modifications to
/// modules. Second, modules are visited from leaves to roots to apply module
/// modifications.  Module modifications include addings ports and connecting
/// things up.
LogicalResult LowerAnnotationsPass::solveWiringProblems(ApplyState &state) {
  // Utility function to extract the defining module from a value which may be
  // either a BlockArgument or an Operation result.
  auto getModule = [](Value value) {
    if (BlockArgument blockArg = dyn_cast<BlockArgument>(value))
      return cast<FModuleLike>(blockArg.getParentBlock()->getParentOp());
    return value.getDefiningOp()->getParentOfType<FModuleLike>();
  };
 
  // Utility function to determine where to insert connection operations.
  auto findInsertionBlock = [&getModule](Value src, Value dest) -> Block * {
    // Check for easy case: both are in the same block.
    if (src.getParentBlock() == dest.getParentBlock())
      return src.getParentBlock();
 
    // If connecting across blocks, figure out where to connect.
    (void)getModule;
    assert(getModule(src) == getModule(dest));
    // Helper to determine if 'a' is available at 'b's block.
    auto safelyDoms = [&](Value a, Value b) {
      if (isa<BlockArgument>(a))
        return true;
      if (isa<BlockArgument>(b))
        return false;
      // Handle cases where 'b' is in child op after 'a'.
      auto *ancestor =
          a.getParentBlock()->findAncestorOpInBlock(*b.getDefiningOp());
      return ancestor && a.getDefiningOp()->isBeforeInBlock(ancestor);
    };
    if (safelyDoms(src, dest))
      return dest.getParentBlock();
    if (safelyDoms(dest, src))
      return src.getParentBlock();
    return {};
  };
 
  auto getNoopCast = [](Value v) -> mlir::UnrealizedConversionCastOp {
    auto op =
        dyn_cast_or_null<mlir::UnrealizedConversionCastOp>(v.getDefiningOp());
    if (op && op.getNumResults() == 1 && op.getNumOperands() == 1 &&
        op.getResultTypes()[0] == op.getOperandTypes()[0])
      return op;
    return {};
  };
 
  // Utility function to connect a destination to a source.  Always use a
  // ConnectOp as the widths may be uninferred.
  SmallVector<Operation *> opsToErase;
  auto connect = [&](Value src, Value dest,
                     ImplicitLocOpBuilder &builder) -> LogicalResult {
    // Strip away noop unrealized_conversion_cast's, used as placeholders.
    // In the future, these should be created/managed as part of creating WP's.
    if (auto op = getNoopCast(dest)) {
      dest = op.getOperand(0);
      opsToErase.push_back(op);
      std::swap(src, dest);
    } else if (auto op = getNoopCast(src)) {
      src = op.getOperand(0);
      opsToErase.push_back(op);
    }
 
    if (foldFlow(dest) == Flow::Source)
      std::swap(src, dest);
 
    // Figure out where to insert operations.
    auto *insertBlock = findInsertionBlock(src, dest);
    if (!insertBlock)
      return emitError(src.getLoc())
          .append("This value is involved with a Wiring Problem where the "
                  "destination is in the same module but neither dominates the "
                  "other, which is not supported.")
          .attachNote(dest.getLoc())
          .append("The destination is here.");
 
    // Insert at end, past invalidation in same block.
    builder.setInsertionPointToEnd(insertBlock);
 
    // Create RefSend/RefResolve if necessary.
    if (type_isa<RefType>(dest.getType()) != type_isa<RefType>(src.getType())) {
      if (type_isa<RefType>(dest.getType()))
        src = RefSendOp::create(builder, src);
      else
        src = RefResolveOp::create(builder, src);
    }
 
    // If the sink is a wire with no users, then convert this to a node.
    // This is done to convert the undriven wires created for GCView's
    // into the NodeOp's they're required to be in GrandCentral.cpp.
    if (auto destOp = dyn_cast_or_null<WireOp>(dest.getDefiningOp());
        destOp && dest.getUses().empty()) {
      // Only perform this if the type is suitable (passive).
      if (auto baseType = dyn_cast<FIRRTLBaseType>(src.getType());
          baseType && baseType.isPassive()) {
        // Note that the wire is replaced with the source type
        // regardless, continue this behavior.
        NodeOp::create(builder, src, destOp.getName())
            .setAnnotationsAttr(destOp.getAnnotations());
        opsToErase.push_back(destOp);
        return success();
      }
    }
 
    // Otherwise, just connect to the source.
    emitConnect(builder, dest, src);
 
    return success();
  };
 
  auto &instanceGraph = state.instancePathCache.instanceGraph;
  auto *context = state.circuit.getContext();
 
  // Examine all discovered Wiring Problems to determine modifications that need
  // to be made per-module.
  LLVM_DEBUG({ llvm::dbgs() << "Analyzing wiring problems:\n"; });
  DenseMap<FModuleLike, ModuleModifications> moduleModifications;
  DenseSet<Value> visitedSinks;
  for (auto e : llvm::enumerate(state.wiringProblems)) {
    auto index = e.index();
    auto problem = e.value();
    // This is a unique index that is assigned to this specific wiring problem
    // and is used as a key during wiring to know which Values (ports, sources,
    // or sinks) should be connected.
    auto source = problem.source;
    auto sink = problem.sink;
 
    // Check that no WiringProblems are trying to use the same sink.  This
    // should never happen.
    if (!visitedSinks.insert(sink).second) {
      auto diag = mlir::emitError(source.getLoc())
                  << "This sink is involved with a Wiring Problem which is "
                     "targeted by a source used by another Wiring Problem. "
                     "(This is both illegal and should be impossible.)";
      diag.attachNote(source.getLoc()) << "The source is here";
      return failure();
    }
    FModuleLike sourceModule = getModule(source);
    FModuleLike sinkModule = getModule(sink);
    if (isa<FExtModuleOp>(sourceModule) || isa<FExtModuleOp>(sinkModule)) {
      auto diag = mlir::emitError(source.getLoc())
                  << "This source is involved with a Wiring Problem which "
                     "includes an External Module port and External Module "
                     "ports anre not supported.";
      diag.attachNote(sink.getLoc()) << "The sink is here.";
      return failure();
    }
 
    LLVM_DEBUG({
      llvm::dbgs() << "  - index: " << index << "\n"
                   << "    source:\n"
                   << "      module: " << sourceModule.getModuleName() << "\n"
                   << "      value: " << source << "\n"
                   << "    sink:\n"
                   << "      module: " << sinkModule.getModuleName() << "\n"
                   << "      value: " << sink << "\n"
                   << "    newNameHint: " << problem.newNameHint << "\n";
    });
 
    // If the source and sink are in the same block, just wire them up.
    if (sink.getParentBlock() == source.getParentBlock()) {
      auto builder = ImplicitLocOpBuilder::atBlockEnd(UnknownLoc::get(context),
                                                      sink.getParentBlock());
      if (failed(connect(source, sink, builder)))
        return failure();
      continue;
    }
    // If both are in the same module but not same block, U-turn.
    // We may not be able to handle this, but that is checked below while
    // connecting.
    if (sourceModule == sinkModule) {
      LLVM_DEBUG(llvm::dbgs()
                 << "    LCA: " << sourceModule.getModuleName() << "\n");
      moduleModifications[sourceModule].connectionMap[index] = source;
      moduleModifications[sourceModule].uturns.push_back({index, sink});
      continue;
    }
 
    // Otherwise, get instance paths for source/sink, and compute LCA.
    auto sourcePaths = state.instancePathCache.getAbsolutePaths(sourceModule);
    auto sinkPaths = state.instancePathCache.getAbsolutePaths(sinkModule);
 
    if (sourcePaths.size() != 1 || sinkPaths.size() != 1) {
      auto diag =
          mlir::emitError(source.getLoc())
          << "This source is involved with a Wiring Problem where the source "
             "or the sink are multiply instantiated and this is not supported.";
      diag.attachNote(sink.getLoc()) << "The sink is here.";
      return failure();
    }
 
    FModuleOp lca =
        cast<FModuleOp>(instanceGraph.getTopLevelNode()->getModule());
    auto sources = sourcePaths[0];
    auto sinks = sinkPaths[0];
    while (!sources.empty() && !sinks.empty()) {
      if (sources.top() != sinks.top())
        break;
      auto newLCA = cast<InstanceOp>(*sources.top());
      lca = cast<FModuleOp>(newLCA.getReferencedModule(instanceGraph));
      sources = sources.dropFront();
      sinks = sinks.dropFront();
    }
 
    LLVM_DEBUG({
      llvm::dbgs() << "    LCA: " << lca.getModuleName() << "\n"
                   << "    sourcePath: " << sourcePaths[0] << "\n"
                   << "    sinkPaths:  " << sinkPaths[0] << "\n";
    });
 
    // Pre-populate the connectionMap of the module with the source and sink.
    moduleModifications[sourceModule].connectionMap[index] = source;
    moduleModifications[sinkModule].connectionMap[index] = sink;
 
    // Record port types that should be added to each module along the LCA path.
    Type sourceType, sinkType;
    auto useRefTypes =
        !noRefTypePorts &&
        problem.refTypeUsage == WiringProblem::RefTypeUsage::Prefer;
    if (useRefTypes) {
      // Use RefType ports if possible
      RefType refType = TypeSwitch<Type, RefType>(source.getType())
                            .Case<FIRRTLBaseType>([](FIRRTLBaseType base) {
                              return RefType::get(base.getPassiveType());
                            })
                            .Case<RefType>([](RefType ref) { return ref; });
      sourceType = refType;
      sinkType = refType.getType();
    } else {
      // Use specified port types.
      sourceType = source.getType();
      sinkType = sink.getType();
 
      // Types must be connectable, which means FIRRTLType's.
      auto sourceFType = type_dyn_cast<FIRRTLType>(sourceType);
      auto sinkFType = type_dyn_cast<FIRRTLType>(sinkType);
      if (!sourceFType)
        return emitError(source.getLoc())
               << "Wiring Problem source type \"" << sourceType
               << "\" must be a FIRRTL type";
      if (!sinkFType)
        return emitError(sink.getLoc())
               << "Wiring Problem sink type \"" << sinkType
               << "\" must be a FIRRTL type";
 
      // Otherwise they must be identical or FIRRTL type-equivalent
      // (connectable).
      if (sourceFType != sinkFType &&
          !areTypesEquivalent(sinkFType, sourceFType)) {
        // Support tapping mixed alignment -> passive , emulate probe behavior.
        if (auto sourceBaseType = dyn_cast<FIRRTLBaseType>(sourceFType);
            problem.refTypeUsage == WiringProblem::RefTypeUsage::Prefer &&
            sourceBaseType &&
            areTypesEquivalent(sinkFType, sourceBaseType.getPassiveType())) {
          // Change "sourceType" to the passive version that's type-equivalent,
          // this will be used for wiring on the "up" side.
          // This relies on `emitConnect` supporting connecting to the passive
          // version from the original source.
          sourceType = sourceBaseType.getPassiveType();
        } else {
          auto diag = mlir::emitError(source.getLoc())
                      << "Wiring Problem source type " << sourceType
                      << " does not match sink type " << sinkType;
          diag.attachNote(sink.getLoc()) << "The sink is here.";
          return failure();
        }
      }
    }
    // If wiring using references, check that the sink value we connect to is
    // passive.
    if (auto sinkFType = type_dyn_cast<FIRRTLType>(sink.getType());
        sinkFType && type_isa<RefType>(sourceType) &&
        !getBaseType(sinkFType).isPassive())
      return emitError(sink.getLoc())
             << "Wiring Problem sink type \"" << sink.getType()
             << "\" must be passive (no flips) when using references";
 
    // Record module modifications related to adding ports to modules.
    auto addPorts = [&](igraph::InstancePath insts, Value val, Type tpe,
                        Direction dir) -> LogicalResult {
      StringRef name, instName;
      for (auto instNode : llvm::reverse(insts)) {
        auto inst = cast<InstanceOp>(*instNode);
        auto mod = inst.getReferencedModule<FModuleOp>(instanceGraph);
        if (mod.isPublic()) {
          auto diag = emitError(mod.getLoc(),
                                "cannot wire port through this public module");
          diag.attachNote(source.getLoc()) << "source here";
          diag.attachNote(sink.getLoc()) << "sink here";
          return diag;
        }
        if (name.empty()) {
          if (problem.newNameHint.empty())
            name = state.getNamespace(mod).newName(
                getFieldName(
                    getFieldRefFromValue(val, /*lookThroughCasts=*/true),
                    /*nameSafe=*/true)
                    .first +
                "__bore");
          else
            name = state.getNamespace(mod).newName(problem.newNameHint);
        } else {
          assert(!instName.empty());
          name = state.getNamespace(mod).newName(instName + "_" + name);
        }
        moduleModifications[mod].portsToAdd.push_back(
            {index, {StringAttr::get(context, name), tpe, dir}});
        instName = inst.getInstanceName();
      }
      return success();
    };
 
    // Record the addition of ports.
    if (failed(addPorts(sources, source, sourceType, Direction::Out)) ||
        failed(addPorts(sinks, sink, sinkType, Direction::In)))
      return failure();
  }
 
  // Iterate over modules from leaves to roots, applying ModuleModifications to
  // each module.
  LLVM_DEBUG({ llvm::dbgs() << "Updating modules:\n"; });
  for (auto *op : llvm::post_order(instanceGraph.getTopLevelNode())) {
    auto fmodule = dyn_cast<FModuleOp>(*op->getModule());
    // Skip external modules and modules that have no modifications.
    if (!fmodule || !moduleModifications.count(fmodule))
      continue;
 
    auto modifications = moduleModifications[fmodule];
    LLVM_DEBUG({
      llvm::dbgs() << "  - module: " << fmodule.getModuleName() << "\n";
      llvm::dbgs() << "    ports:\n";
      for (auto [index, port] : modifications.portsToAdd) {
        llvm::dbgs() << "      - name: " << port.getName() << "\n"
                     << "        id: " << index << "\n"
                     << "        type: " << port.type << "\n"
                     << "        direction: "
                     << (port.direction == Direction::In ? "in" : "out")
                     << "\n";
      }
    });
 
    // Add ports to the module after all other existing ports.
    SmallVector<std::pair<unsigned, PortInfo>> newPorts;
    SmallVector<unsigned> problemIndices;
    for (auto [problemIdx, portInfo] : modifications.portsToAdd) {
      // Create the port.
      newPorts.push_back({fmodule.getNumPorts(), portInfo});
      problemIndices.push_back(problemIdx);
    }
    auto originalNumPorts = fmodule.getNumPorts();
    auto portIdx = fmodule.getNumPorts();
    fmodule.insertPorts(newPorts);
 
    auto builder = ImplicitLocOpBuilder::atBlockBegin(UnknownLoc::get(context),
                                                      fmodule.getBodyBlock());
 
    // Connect each port to the value stored in the connectionMap for this
    // wiring problem index.
    for (auto [problemIdx, portPair] : llvm::zip(problemIndices, newPorts)) {
      Value src = moduleModifications[fmodule].connectionMap[problemIdx];
      assert(src && "there did not exist a driver for the port");
      Value dest = fmodule.getArgument(portIdx++);
      if (failed(connect(src, dest, builder)))
        return failure();
    }
 
    // If a U-turn exists, this is an LCA and we need a U-turn connection. These
    // are the last connections made for this module.
    for (auto [problemIdx, dest] : moduleModifications[fmodule].uturns) {
      Value src = moduleModifications[fmodule].connectionMap[problemIdx];
      assert(src && "there did not exist a connection for the u-turn");
      if (failed(connect(src, dest, builder)))
        return failure();
    }
 
    // Update the connectionMap of all modules for which we created a port.
    for (auto *inst : instanceGraph.lookup(fmodule)->uses()) {
      InstanceOp useInst = cast<InstanceOp>(inst->getInstance());
      auto enclosingModule = useInst->getParentOfType<FModuleOp>();
      auto clonedInst = useInst.cloneWithInsertedPortsAndReplaceUses(newPorts);
      state.instancePathCache.replaceInstance(useInst, clonedInst);
      useInst->erase();
      // Record information in the moduleModifications strucutre for the module
      // _where this is instantiated_.  This is done so that when that module is
      // visited later, there will be information available for it to find ports
      // it needs to wire up.  If there is already an existing connection, then
      // this is a U-turn.
      for (auto [newPortIdx, problemIdx] : llvm::enumerate(problemIndices)) {
        auto &modifications = moduleModifications[enclosingModule];
        auto newPort = clonedInst->getResult(newPortIdx + originalNumPorts);
        if (modifications.connectionMap.count(problemIdx)) {
          modifications.uturns.push_back({problemIdx, newPort});
          continue;
        }
        modifications.connectionMap[problemIdx] = newPort;
      }
    }
  }
 
  // Delete unused WireOps created by producers of WiringProblems.
  for (auto *op : opsToErase)
    op->erase();
 
  return success();
}
 
// This is the main entrypoint for the lowering pass.
void LowerAnnotationsPass::runOnOperation() {
  CIRCT_DEBUG_SCOPED_PASS_LOGGER(this);
 
  CircuitOp circuit = getOperation();
  SymbolTable modules(circuit);
 
  // Grab the annotations from a non-standard attribute called "rawAnnotations".
  // This is a temporary location for all annotations that are earmarked for
  // processing by this pass as we migrate annotations from being handled by
  // FIRAnnotations/FIRParser into this pass.  While we do this, this pass is
  // not supposed to touch _other_ annotations to enable this pass to be run
  // after FIRAnnotations/FIRParser.
  auto annotations = circuit->getAttrOfType<ArrayAttr>(rawAnnotations);
  if (!annotations)
    return;
  circuit->removeAttr(rawAnnotations);
 
  // Populate the worklist in reverse order.  This has the effect of causing
  // annotations to be processed in the order in which they appear in the
  // original JSON.
  for (auto anno : llvm::reverse(annotations.getValue()))
    worklistAttrs.push_back(cast<DictionaryAttr>(anno));
 
  size_t numFailures = 0;
  size_t numAdded = 0;
  auto addToWorklist = [&](DictionaryAttr anno) {
    ++numAdded;
    worklistAttrs.push_back(anno);
  };
  InstancePathCache instancePathCache(getAnalysis<InstanceGraph>());
  ApplyState state{circuit, modules, addToWorklist, instancePathCache,
                   noRefTypePorts};
  LLVM_DEBUG(llvm::dbgs() << "Processing annotations:\n");
  while (!worklistAttrs.empty()) {
    auto attr = worklistAttrs.pop_back_val();
    if (applyAnnotation(attr, state).failed())
      ++numFailures;
  }
 
  if (failed(legacyToWiringProblems(state)))
    ++numFailures;
 
  if (failed(solveWiringProblems(state)))
    ++numFailures;
 
  // Update statistics
  numRawAnnotations += annotations.size();
  numAddedAnnos += numAdded;
  numAnnos += numAdded + annotations.size();
  numReusedHierPathOps += state.numReusedHierPaths;
 
  if (numFailures)
    signalPassFailure();
}