FIRRTLAnnotationHelper.cpp

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//===- FIRRTLAnnotationHelper.cpp - FIRRTL Annotation Lookup ----*- 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 implements helpers mapping annotations to operations.
//
//===----------------------------------------------------------------------===//
 
#include "circt/Dialect/FIRRTL/FIRRTLAnnotationHelper.h"
#include "circt/Dialect/FIRRTL/AnnotationDetails.h"
#include "circt/Dialect/FIRRTL/FIRRTLUtils.h"
#include "mlir/IR/ImplicitLocOpBuilder.h"
#include "llvm/Support/Debug.h"
 
#define DEBUG_TYPE "lower-annos"
 
using namespace circt;
using namespace firrtl;
using namespace chirrtl;
 
using llvm::StringRef;
 
// Some types have been expanded so the first layer of aggregate path is
// a return value.
static LogicalResult updateExpandedPort(StringRef field, AnnoTarget &ref) {
  if (auto mem = dyn_cast<MemOp>(ref.getOp()))
    for (size_t p = 0, pe = mem.getPortNames().size(); p < pe; ++p)
      if (mem.getPortName(p) == field) {
        ref = PortAnnoTarget(mem, p);
        return success();
      }
  ref.getOp()->emitError("Cannot find port with name ") << field;
  return failure();
}
 
/// Try to resolve an non-array aggregate name from a target given the type and
/// operation of the resolved target.  This needs to deal with places where we
/// represent bundle returns as split into constituent parts.
static FailureOr<unsigned> findBundleElement(Operation *op, Type type,
                                             StringRef field) {
  auto bundle = type_dyn_cast<BundleType>(type);
  if (!bundle) {
    op->emitError("field access '")
        << field << "' into non-bundle type '" << type << "'";
    return failure();
  }
  auto idx = bundle.getElementIndex(field);
  if (!idx) {
    op->emitError("cannot resolve field '")
        << field << "' in subtype '" << bundle << "'";
    return failure();
  }
  return *idx;
}
 
/// Try to resolve an array index from a target given the type of the resolved
/// target.
static FailureOr<unsigned> findVectorElement(Operation *op, Type type,
                                             StringRef indexStr) {
  size_t index;
  if (indexStr.getAsInteger(10, index)) {
    op->emitError("Cannot convert '") << indexStr << "' to an integer";
    return failure();
  }
  auto vec = type_dyn_cast<FVectorType>(type);
  if (!vec) {
    op->emitError("index access '")
        << index << "' into non-vector type '" << type << "'";
    return failure();
  }
  return index;
}
 
static FailureOr<unsigned> findFieldID(AnnoTarget &ref,
                                       ArrayRef<TargetToken> tokens) {
  if (tokens.empty())
    return 0;
 
  auto *op = ref.getOp();
  auto fieldIdx = 0;
  // The first field for some ops refers to expanded return values.
  if (isa<MemOp>(op)) {
    if (failed(updateExpandedPort(tokens.front().name, ref)))
      return {};
    tokens = tokens.drop_front();
  }
 
  auto type = ref.getType();
  if (!type)
    return op->emitError(tokens.front().isIndex ? "index" : "field")
           << " access in annotation not supported for this operation";
 
  for (auto token : tokens) {
    if (token.isIndex) {
      auto result = findVectorElement(op, type, token.name);
      if (failed(result))
        return failure();
      auto vector = type_cast<FVectorType>(type);
      type = vector.getElementType();
      fieldIdx += vector.getFieldID(*result);
    } else {
      auto result = findBundleElement(op, type, token.name);
      if (failed(result))
        return failure();
      auto bundle = type_cast<BundleType>(type);
      type = bundle.getElementType(*result);
      fieldIdx += bundle.getFieldID(*result);
    }
  }
  return fieldIdx;
}
 
void TokenAnnoTarget::toVector(SmallVectorImpl<char> &out) const {
  out.push_back('~');
  out.append(circuit.begin(), circuit.end());
  out.push_back('|');
  for (auto modInstPair : instances) {
    out.append(modInstPair.first.begin(), modInstPair.first.end());
    out.push_back('/');
    out.append(modInstPair.second.begin(), modInstPair.second.end());
    out.push_back(':');
  }
  out.append(module.begin(), module.end());
  if (name.empty())
    return;
  out.push_back('>');
  out.append(name.begin(), name.end());
  for (auto comp : component) {
    out.push_back(comp.isIndex ? '[' : '.');
    out.append(comp.name.begin(), comp.name.end());
    if (comp.isIndex)
      out.push_back(']');
  }
}
 
std::string firrtl::canonicalizeTarget(StringRef target) {
 
  if (target.empty())
    return target.str();
 
  // If this is a normal Target (not a Named), erase that field in the JSON
  // object and return that Target.
  if (target[0] == '~')
    return target.str();
 
  // This is a legacy target using the firrtl.annotations.Named type.  This
  // can be trivially canonicalized to a non-legacy target, so we do it with
  // the following three mappings:
  //   1. CircuitName => CircuitTarget, e.g., A -> ~A
  //   2. ModuleName => ModuleTarget, e.g., A.B -> ~A|B
  //   3. ComponentName => ReferenceTarget, e.g., A.B.C -> ~A|B>C
  std::string newTarget = ("~" + target).str();
  auto n = newTarget.find('.');
  if (n != std::string::npos)
    newTarget[n] = '|';
  n = newTarget.find('.');
  if (n != std::string::npos)
    newTarget[n] = '>';
  return newTarget;
}
 
std::optional<AnnoPathValue>
firrtl::resolveEntities(TokenAnnoTarget path, CircuitOp circuit,
                        SymbolTable &symTbl, CircuitTargetCache &cache) {
  // Validate circuit name.
  if (!path.circuit.empty() && circuit.getName() != path.circuit) {
    mlir::emitError(circuit.getLoc())
        << "circuit name doesn't match annotation '" << path.circuit << '\'';
    return {};
  }
  // Circuit only target.
  if (path.module.empty()) {
    assert(path.name.empty() && path.instances.empty() &&
           path.component.empty());
    return AnnoPathValue(circuit);
  }
 
  // Resolve all instances for non-local paths.
  SmallVector<InstanceOp> instances;
  for (auto p : path.instances) {
    auto mod = symTbl.lookup<FModuleOp>(p.first);
    if (!mod) {
      mlir::emitError(circuit.getLoc())
          << "module doesn't exist '" << p.first << '\'';
      return {};
    }
    auto resolved = cache.lookup(mod, p.second);
    if (!resolved || !isa<InstanceOp>(resolved.getOp())) {
      mlir::emitError(circuit.getLoc()) << "cannot find instance '" << p.second
                                        << "' in '" << mod.getName() << "'";
      return {};
    }
    instances.push_back(cast<InstanceOp>(resolved.getOp()));
  }
  // The final module is where the named target is (or is the named target).
  auto mod = symTbl.lookup<FModuleLike>(path.module);
  if (!mod) {
    mlir::emitError(circuit.getLoc())
        << "module doesn't exist '" << path.module << '\'';
    return {};
  }
 
  // ClassOps may not participate in annotation targeting. Neither the class
  // itself, nor any "named thing" defined under it, may be targeted by an anno.
  if (isa<ClassOp>(mod)) {
    mlir::emitError(mod.getLoc()) << "annotations cannot target classes";
    return {};
  }
 
  AnnoTarget ref;
  if (path.name.empty()) {
    assert(path.component.empty());
    ref = OpAnnoTarget(mod);
  } else {
    ref = cache.lookup(mod, path.name);
    if (!ref) {
      mlir::emitError(circuit.getLoc()) << "cannot find name '" << path.name
                                        << "' in " << mod.getModuleName();
      return {};
    }
    // AnnoTarget::getType() is not safe (CHIRRTL ops crash, null if instance),
    // avoid. For now, only references in ports can be targets, check that.
    // TODO: containsReference().
    if (isa<PortAnnoTarget>(ref) && isa<RefType>(ref.getType())) {
      mlir::emitError(circuit.getLoc())
          << "cannot target reference-type '" << path.name << "' in "
          << mod.getModuleName();
      return {};
    }
  }
 
  // If the reference is pointing to an instance op, we have to move the target
  // to the module.  This is done both because it is logical to have one
  // representation (this effectively canonicalizes a reference target on an
  // instance into an instance target) and because the SFC has a pass that does
  // this conversion.  E.g., this is converting (where "bar" is an instance):
  //   ~Foo|Foo>bar
  // Into:
  //   ~Foo|Foo/bar:Bar
  ArrayRef<TargetToken> component(path.component);
  if (auto instance = dyn_cast<InstanceOp>(ref.getOp())) {
    instances.push_back(instance);
    auto target = cast<FModuleLike>(instance.getReferencedOperation(symTbl));
    if (component.empty()) {
      ref = OpAnnoTarget(target);
    } else if (component.front().isIndex) {
      mlir::emitError(circuit.getLoc())
          << "illegal target '" << path.str() << "' indexes into an instance";
      return {};
    } else {
      auto field = component.front().name;
      ref = AnnoTarget();
      for (size_t p = 0, pe = getNumPorts(target); p < pe; ++p)
        if (target.getPortName(p) == field) {
          ref = PortAnnoTarget(target, p);
          break;
        }
      if (!ref) {
        mlir::emitError(circuit.getLoc())
            << "cannot find port '" << field << "' in module "
            << target.getModuleName();
        return {};
      }
      // TODO: containsReference().
      if (isa<RefType>(ref.getType())) {
        mlir::emitError(circuit.getLoc())
            << "annotation cannot target reference-type port '" << field
            << "' in module " << target.getModuleName();
        return {};
      }
      component = component.drop_front();
    }
  }
 
  // If we have aggregate specifiers, resolve those now. This call can update
  // the ref to target a port of a memory.
  auto result = findFieldID(ref, component);
  if (failed(result))
    return {};
  auto fieldIdx = *result;
 
  return AnnoPathValue(instances, ref, fieldIdx);
}
 
/// split a target string into it constituent parts.  This is the primary parser
/// for targets.
std::optional<TokenAnnoTarget> firrtl::tokenizePath(StringRef origTarget) {
  // An empty string is not a legal target.
  if (origTarget.empty())
    return {};
  StringRef target = origTarget;
  TokenAnnoTarget retval;
  std::tie(retval.circuit, target) = target.split('|');
  if (!retval.circuit.empty() && retval.circuit[0] == '~')
    retval.circuit = retval.circuit.drop_front();
  while (target.count(':')) {
    StringRef nla;
    std::tie(nla, target) = target.split(':');
    StringRef inst, mod;
    std::tie(mod, inst) = nla.split('/');
    retval.instances.emplace_back(mod, inst);
  }
  // remove aggregate
  auto targetBase =
      target.take_until([](char c) { return c == '.' || c == '['; });
  auto aggBase = target.drop_front(targetBase.size());
  std::tie(retval.module, retval.name) = targetBase.split('>');
  while (!aggBase.empty()) {
    if (aggBase[0] == '.') {
      aggBase = aggBase.drop_front();
      StringRef field = aggBase.take_front(aggBase.find_first_of("[."));
      aggBase = aggBase.drop_front(field.size());
      retval.component.push_back({field, false});
    } else if (aggBase[0] == '[') {
      aggBase = aggBase.drop_front();
      StringRef index = aggBase.take_front(aggBase.find_first_of(']'));
      aggBase = aggBase.drop_front(index.size() + 1);
      retval.component.push_back({index, true});
    } else {
      return {};
    }
  }
 
  return retval;
}
 
std::optional<AnnoPathValue> firrtl::resolvePath(StringRef rawPath,
                                                 CircuitOp circuit,
                                                 SymbolTable &symTbl,
                                                 CircuitTargetCache &cache) {
  auto pathStr = canonicalizeTarget(rawPath);
  StringRef path{pathStr};
 
  auto tokens = tokenizePath(path);
  if (!tokens) {
    mlir::emitError(circuit.getLoc())
        << "Cannot tokenize annotation path " << rawPath;
    return {};
  }
 
  return resolveEntities(*tokens, circuit, symTbl, cache);
}
 
//===----------------------------------------------------------------------===//
// AnnoTargetCache
//===----------------------------------------------------------------------===//
 
void AnnoTargetCache::gatherTargets(FModuleLike mod) {
  // Add ports
  for (const auto &p : llvm::enumerate(mod.getPorts()))
    insertPort(mod, p.index());
 
  // And named things
  mod.walk([&](Operation *op) { insertOp(op); });
}
 
//===----------------------------------------------------------------------===//
// HierPathOpCache
//===----------------------------------------------------------------------===//
 
HierPathCache::HierPathCache(Operation *op, SymbolTable &symbolTable)
    : builder(OpBuilder::atBlockBegin(&op->getRegion(0).front())),
      symbolTable(symbolTable) {
 
  // Populate the cache with any symbols preexisting.
  for (auto &region : op->getRegions())
    for (auto &block : region.getBlocks())
      for (auto path : block.getOps<hw::HierPathOp>())
        cache[path.getNamepathAttr()] = path;
}
 
hw::HierPathOp HierPathCache::getOpFor(ArrayAttr attr) {
  auto &op = cache[attr];
  if (!op) {
    op = hw::HierPathOp::create(builder, UnknownLoc::get(builder.getContext()),
                                "nla", /*sym_visibility=*/{}, attr);
    symbolTable.insert(op);
    op.setVisibility(SymbolTable::Visibility::Private);
  }
  return op;
}
 
//===----------------------------------------------------------------------===//
// Code related to handling Grand Central Mem Taps annotations
//===----------------------------------------------------------------------===//
 
LogicalResult circt::firrtl::applyGCTMemTaps(const AnnoPathValue &target,
                                             DictionaryAttr anno,
                                             ApplyState &state) {
  auto loc = state.circuit.getLoc();
 
  auto sourceAttr =
      tryGetAs<StringAttr>(anno, anno, "source", loc, memTapAnnoClass);
  if (!sourceAttr)
    return failure();
 
  auto sourceTargetStr = canonicalizeTarget(sourceAttr.getValue());
  std::optional<AnnoPathValue> srcTarget = resolvePath(
      sourceTargetStr, state.circuit, state.symTbl, state.targetCaches);
  if (!srcTarget)
    return mlir::emitError(loc, "cannot resolve source target path '")
           << sourceTargetStr << "'";
 
  auto tapsAttr = tryGetAs<ArrayAttr>(anno, anno, "sink", loc, memTapAnnoClass);
  if (!tapsAttr || tapsAttr.empty())
    return mlir::emitError(loc, "sink must have at least one entry");
 
  auto tap = dyn_cast_or_null<StringAttr>(tapsAttr[0]);
  if (!tap) {
    return mlir::emitError(
               loc, "Annotation '" + Twine(memTapAnnoClass) +
                        "' with path '.taps[0" +
                        "]' contained an unexpected type (expected a string).")
               .attachNote()
           << "The full Annotation is reprodcued here: " << anno << "\n";
  }
 
  auto wireTargetStr = canonicalizeTarget(tap.getValue());
  if (!tokenizePath(wireTargetStr))
    return failure();
  std::optional<AnnoPathValue> wireTarget = resolvePath(
      wireTargetStr, state.circuit, state.symTbl, state.targetCaches);
  if (!wireTarget)
    return mlir::emitError(loc, "Annotation '" + Twine(memTapAnnoClass) +
                                    "' with path '.taps[0]' contains target '" +
                                    wireTargetStr +
                                    "' that cannot be resolved.")
               .attachNote()
           << "The full Annotation is reproduced here: " << anno << "\n";
 
  auto combMem = dyn_cast<chirrtl::CombMemOp>(srcTarget->ref.getOp());
  if (!combMem)
    return srcTarget->ref.getOp()->emitOpError(
        "unsupported operation, only CombMem can be used as the source of "
        "MemTap");
  if (!combMem.getType().getElementType().isGround())
    return combMem.emitOpError(
        "cannot generate MemTap to a memory with aggregate data type");
  if (tapsAttr.size() != combMem.getType().getNumElements())
    return mlir::emitError(
        loc, "sink cannot specify more taps than the depth of the memory");
  if (srcTarget->instances.empty()) {
    auto path = state.instancePathCache.getAbsolutePaths(
        combMem->getParentOfType<FModuleOp>());
    if (path.size() > 1)
      return combMem.emitOpError(
          "cannot be resolved as source for MemTap, multiple paths from top "
          "exist and unique instance cannot be resolved");
    srcTarget->instances.append(path.back().begin(), path.back().end());
  }
 
  ImplicitLocOpBuilder builder(combMem->getLoc(), combMem);
 
  // Lower memory taps to real ports on the memory.  This is done if the taps
  // are supposed to be synthesized.
  if (state.noRefTypePorts) {
    // Create new ports _after_ all other ports to avoid permuting existing
    // ports.
    builder.setInsertionPointToEnd(
        combMem->getParentOfType<FModuleOp>().getBodyBlock());
 
    // Determine the clock to use for the debug ports.  Error if the same clock
    // is not used for all ports or if no clock port is found.
    Value clock;
    for (auto *portOp : combMem.getResult().getUsers()) {
      for (auto result : portOp->getResults()) {
        for (auto *user : result.getUsers()) {
          auto accessOp = dyn_cast<chirrtl::MemoryPortAccessOp>(user);
          if (!accessOp)
            continue;
          auto newClock = accessOp.getClock();
          if (clock && clock != newClock)
            return combMem.emitOpError(
                "has different clocks on different ports (this is ambiguous "
                "when compiling without reference types)");
          clock = newClock;
        }
      }
    }
    if (!clock)
      return combMem.emitOpError(
          "does not have an access port to determine a clock connection (this "
          "is necessary when compiling without reference types)");
 
    // Add one port per memory address.
    SmallVector<Value> data;
    Type uintType = builder.getType<UIntType>();
    for (uint64_t i = 0, e = combMem.getType().getNumElements(); i != e; ++i) {
      auto port = chirrtl::MemoryPortOp::create(
          builder, combMem.getType().getElementType(),
          CMemoryPortType::get(builder.getContext()), combMem.getResult(),
          MemDirAttr::Read, builder.getStringAttr("memTap_" + Twine(i)),
          builder.getArrayAttr({}));
      chirrtl::MemoryPortAccessOp::create(
          builder, port.getPort(),
          ConstantOp::create(builder, uintType, APSInt::getUnsigned(i)), clock);
      data.push_back(port.getData());
    }
 
    // Package up all the reads into a vector.
    auto sendVal = VectorCreateOp::create(
        builder,
        FVectorType::get(combMem.getType().getElementType(),
                         combMem.getType().getNumElements()),
        data);
    auto sink = wireTarget->ref.getOp()->getResult(0);
 
    // Add a wiring problem to hook up the vector to the destination wire.
    state.wiringProblems.push_back(
        {sendVal, sink, "memTap", WiringProblem::RefTypeUsage::Never});
    return success();
  }
 
  // Normal memory handling.  Create a debug port.
  builder.setInsertionPointAfter(combMem);
  // Construct the type for the debug port.
  auto debugType = RefType::get(FVectorType::get(
      combMem.getType().getElementType(), combMem.getType().getNumElements()));
  Value memDbgPort =
      chirrtl::MemoryDebugPortOp::create(
          builder, debugType, combMem,
          state.getNamespace(srcTarget->ref.getModule()).newName("memTap"))
          .getResult();
 
  auto sendVal = memDbgPort;
  if (wireTarget->ref.getOp()->getResult(0).getType() !=
      type_cast<RefType>(sendVal.getType()).getType())
    return wireTarget->ref.getOp()->emitError(
        "cannot generate the MemTap, wiretap Type does not match the memory "
        "type");
  auto sink = wireTarget->ref.getOp()->getResult(0);
  state.wiringProblems.push_back(
      {sendVal, sink, "memTap", WiringProblem::RefTypeUsage::Prefer});
  return success();
}