ExportVerilogInternals.h

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//===- ExportVerilogInternals.h - Shared Internal Impl Details --*- 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
//
//===----------------------------------------------------------------------===//
 
#ifndef CONVERSION_EXPORTVERILOG_EXPORTVERILOGINTERNAL_H
#define CONVERSION_EXPORTVERILOG_EXPORTVERILOGINTERNAL_H
 
#include "circt/Dialect/Comb/CombVisitors.h"
#include "circt/Dialect/HW/HWOps.h"
#include "circt/Dialect/HW/HWSymCache.h"
#include "circt/Dialect/HW/HWVisitors.h"
#include "circt/Dialect/SV/SVOps.h"
#include "circt/Dialect/SV/SVVisitors.h"
#include "mlir/IR/Location.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/FormattedStream.h"
#include <atomic>
 
namespace circt {
struct LoweringOptions;
 
namespace ExportVerilog {
class GlobalNameResolver;
 
/// Check if the value is from read of a wire or reg or is a port.
bool isSimpleReadOrPort(Value v);
 
/// Given an expression that is spilled into a temporary wire, try to
/// synthesize a better name than "_T_42" based on the structure of the
/// expression.
StringAttr inferStructuralNameForTemporary(Value expr);
 
/// This class keeps track of global names at the module/interface level.
/// It is built in a global pass over the entire design and then frozen to allow
/// concurrent accesses.
struct GlobalNameTable {
  GlobalNameTable(GlobalNameTable &&) = default;
 
  /// Return the string to use for the specified parameter name in the specified
  /// module.  Parameters may be renamed for a variety of reasons (e.g.
  /// conflicting with ports or Verilog keywords), and this returns the
  /// legalized name to use.
  StringRef getParameterVerilogName(Operation *module,
                                    StringAttr paramName) const {
    auto it = renamedParams.find(std::make_pair(module, paramName));
    return (it != renamedParams.end() ? it->second : paramName).getValue();
  }
 
  StringAttr getEnumPrefix(Type type) const {
    auto it = enumPrefixes.find(type);
    return it != enumPrefixes.end() ? it->second : StringAttr();
  }
 
private:
  friend class GlobalNameResolver;
  GlobalNameTable() {}
  GlobalNameTable(const GlobalNameTable &) = delete;
  void operator=(const GlobalNameTable &) = delete;
 
  void addRenamedParam(Operation *module, StringAttr oldName,
                       StringRef newName) {
    renamedParams[{module, oldName}] =
        StringAttr::get(oldName.getContext(), newName);
  }
 
  /// This contains entries for any parameters that got renamed.  The key is a
  /// moduleop/paramName tuple, the value is the name to use.
  DenseMap<std::pair<Operation *, Attribute>, StringAttr> renamedParams;
 
  // This contains prefixes for any typedecl'd enum types. Keys are type-aliases
  // of enum types.
  DenseMap<Type, StringAttr> enumPrefixes;
};
 
//===----------------------------------------------------------------------===//
// NameCollisionResolver
//===----------------------------------------------------------------------===//
 
struct NameCollisionResolver {
  NameCollisionResolver(const LoweringOptions &options) : options(options){};
 
  /// Given a name that may have collisions or invalid symbols, return a
  /// replacement name to use, or the original name if it was ok.
  StringRef getLegalName(StringRef originalName);
  StringRef getLegalName(StringAttr originalName) {
    return getLegalName(originalName.getValue());
  }
 
  /// Insert a string as an already-used name.
  void insertUsedName(StringRef name) {
    nextGeneratedNameIDs.insert({name, 0});
  }
 
  /// Handle to LoweringOptions.
  const LoweringOptions &options;
 
private:
  /// A map from used names to numeric suffix used as uniquification agent when
  /// resolving conflicts.
  llvm::StringMap<size_t> nextGeneratedNameIDs;
 
  NameCollisionResolver(const NameCollisionResolver &) = delete;
  void operator=(const NameCollisionResolver &) = delete;
};
 
//===----------------------------------------------------------------------===//
// FieldNameResolver
//===----------------------------------------------------------------------===//
 
struct FieldNameResolver {
  FieldNameResolver(const GlobalNameTable &globalNames,
                    const LoweringOptions &options)
      : globalNames(globalNames), options(options){};
 
  StringAttr getRenamedFieldName(StringAttr fieldName);
 
  /// Returns the field name for an enum field of a given enum field attr. In
  /// case a prefix can be inferred for the provided enum type (the enum type is
  /// a type alias), the prefix will be applied. If not, the raw field name
  /// is returned.
  std::string getEnumFieldName(hw::EnumFieldAttr attr);
 
private:
  void setRenamedFieldName(StringAttr fieldName, StringAttr newFieldName);
 
  /// Those contain entries for field names and types respectively. Struct types
  /// have names as field names, which must be renamed if they conflict with
  /// verilog keywords.
  DenseMap<StringAttr, StringAttr> renamedFieldNames;
 
  /// A map from used names to numeric suffix used as uniquification agent when
  /// resolving conflicts.
  llvm::StringMap<size_t> nextGeneratedNameIDs;
 
  // Handle to the global name table.
  const GlobalNameTable &globalNames;
 
  // Handle to lowering options.
  const LoweringOptions &options;
};
 
//===----------------------------------------------------------------------===//
// SharedEmitterState
//===----------------------------------------------------------------------===//
 
/// Information to control the emission of a single operation into a file.
struct OpFileInfo {
  /// The operation to be emitted.
  Operation *op;
 
  /// Where among the replicated per-file operations the `op` above should be
  /// emitted.
  size_t position = 0;
};
 
/// Information to control the emission of a list of operations into a file.
struct FileInfo {
  /// The operations to be emitted into a separate file, and where among the
  /// replicated per-file operations the operation should be emitted.
  SmallVector<OpFileInfo, 1> ops;
 
  /// Whether to emit the replicated per-file operations.
  bool emitReplicatedOps = true;
 
  /// Whether to include this file as part of the emitted file list.
  bool addToFilelist = true;
 
  /// If true, the file is a header.
  bool isHeader = false;
 
  /// If true, the file is known to be (system) verilog source code.
  /// This flag is used to distinguish verilog from other files such as json.
  bool isVerilog = true;
};
 
/// Track the output verilog line,column number information for every op.
class OpLocMap {
  /// Record the output location from where the op begins to print.
  void addBeginLoc(Operation *op) {
    map[op].emplace_back(LocationRange(LineColPair(*fStream)));
  }
  /// Record the output location where the op ends to print.
  void addEndLoc(Operation *op) {
    assert(!map[op].empty());
    assert(map[op].back().begin.isValid());
    assert(!map[op].back().end.isValid());
    map[op].back().end = LineColPair(*fStream);
  }
 
public:
  /// Data that is unique to each callback. The op and whether its a begin or
  /// end location.
  using DataType = std::pair<Operation *, bool>;
 
  OpLocMap(llvm::formatted_raw_ostream &fStream) : fStream(&fStream) {}
  OpLocMap() = default;
 
  /// Set the output stream.
  void setStream(llvm::formatted_raw_ostream &f) { fStream = &f; }
  /// Callback operator, invoked on the print events indicated by `data`.
  void operator()(DataType data) {
    assert(fStream);
    auto beginPrint = data.second;
    auto *op = data.first;
    if (beginPrint)
      addBeginLoc(op);
    else
      addEndLoc(op);
  }
 
  /// Called after the verilog has been exported and the corresponding locations
  /// are recorded in the map.
  void updateIRWithLoc(unsigned lineOffset, StringAttr fileName,
                       MLIRContext *context) {
    if (map.empty())
      return;
    if (!verilogLineAttr) {
      verilogLineAttr = StringAttr::get(context, "verilogLocations");
      metadataAttr = StringAttr::get(context, "Range");
    }
    for (auto &[op, locations] : map) {
      // An operation can have multiple verilog locations.
      SmallVector<Location> verilogLocs;
      for (auto &loc : locations) {
        // Create a location range attribute.
        SmallVector<Location, 2> beginEndPair;
        assert(loc.begin.isValid() && loc.end.isValid());
        beginEndPair.emplace_back(mlir::FileLineColLoc::get(
            fileName, loc.begin.line + lineOffset, loc.begin.col));
        beginEndPair.emplace_back(mlir::FileLineColLoc::get(
            fileName, loc.end.line + lineOffset, loc.end.col));
        // Add it to the verilog locations of the op.
        verilogLocs.emplace_back(
            mlir::FusedLoc::get(context, beginEndPair, metadataAttr));
      }
      // Update the location attribute with a fused loc of the original location
      // and verilog locations.
      op->setLoc(mlir::FusedLoc::get(
          context, {op->getLoc(), mlir::FusedLoc::get(context, verilogLocs,
                                                      verilogLineAttr)}));
    }
  }
  void clear() { map.clear(); }
 
private:
  struct LineColPair {
    unsigned line = ~0U;
    unsigned col = ~0U;
    LineColPair() = default;
    /// Given an output stream, store the current offset.
    LineColPair(llvm::formatted_raw_ostream &s)
        : line(s.getLine()), col(s.getColumn()) {}
    bool isValid() { return (line != -1U && col != -1U); }
  };
  struct LocationRange {
    LineColPair begin;
    LineColPair end;
    LocationRange(LineColPair begin) : begin(begin) {}
  };
  using Locations = SmallVector<LocationRange, 2>;
  /// Map to store the verilog locations for each op.
  DenseMap<Operation *, Locations> map;
  /// The corresponding output stream, which provides the current print location
  /// on the stream.
  llvm::formatted_raw_ostream *fStream;
  /// Cache to store string attributes.
  StringAttr verilogLineAttr, metadataAttr;
};
 
/// This class wraps an operation or a fixed string that should be emitted.
class StringOrOpToEmit {
public:
  explicit StringOrOpToEmit(Operation *op) : pointerData(op), length(~0ULL) {}
 
  explicit StringOrOpToEmit(StringRef string) {
    pointerData = (Operation *)nullptr;
    setString(string);
  }
 
  ~StringOrOpToEmit() {
    if (const void *ptr = pointerData.dyn_cast<const void *>())
      free(const_cast<void *>(ptr));
  }
 
  /// If the value is an Operation*, return it.  Otherwise return null.
  Operation *getOperation() const {
    return pointerData.dyn_cast<Operation *>();
  }
 
  /// If the value wraps a string, return it.  Otherwise return null.
  StringRef getStringData() const {
    if (const void *ptr = pointerData.dyn_cast<const void *>())
      return StringRef((const char *)ptr, length);
    return StringRef();
  }
 
  /// This method transforms the entry from an operation to a string value.
  void setString(StringRef value) {
    assert(pointerData.is<Operation *>() && "shouldn't already be a string");
    length = value.size();
    void *data = malloc(length);
    memcpy(data, value.data(), length);
    pointerData = (const void *)data;
  }
 
  // These move just fine.
  StringOrOpToEmit(StringOrOpToEmit &&rhs)
      : pointerData(rhs.pointerData), length(rhs.length) {
    rhs.pointerData = (Operation *)nullptr;
  }
 
  /// Verilog output location information for entry. This is
  /// required since each entry can be emitted in parallel.
  OpLocMap verilogLocs;
 
private:
  StringOrOpToEmit(const StringOrOpToEmit &) = delete;
  void operator=(const StringOrOpToEmit &) = delete;
  PointerUnion<Operation *, const void *> pointerData;
  size_t length;
};
 
/// This class tracks the top-level state for the emitters, which is built and
/// then shared across all per-file emissions that happen in parallel.
struct SharedEmitterState {
  /// The MLIR module to emit.
  ModuleOp designOp;
 
  /// The main file that collects all operations that are neither replicated
  /// per-file ops nor specifically assigned to a file.
  FileInfo rootFile;
 
  /// The additional files to emit, with the output file name as the key into
  /// the map.
  llvm::MapVector<StringAttr, FileInfo> files;
 
  /// The various file lists and their contents to emit
  llvm::StringMap<SmallVector<StringAttr>> fileLists;
 
  /// A list of operations replicated in each output file (e.g., `sv.verbatim`
  /// or `sv.ifdef` without dedicated output file).
  SmallVector<Operation *, 0> replicatedOps;
 
  /// Whether any error has been encountered during emission.
  std::atomic<bool> encounteredError = {};
 
  /// A cache of symbol -> defining ops built once and used by each of the
  /// verilog module emitters.  This is built at "gatherFiles" time.
  hw::HWSymbolCache symbolCache;
 
  // Emitter options extracted from the top-level module.
  const LoweringOptions &options;
 
  /// This is a set is populated at "gather" time, containing the hw.module
  /// operations that have a sv.bind in them.
  SmallPtrSet<Operation *, 8> modulesContainingBinds;
 
  /// Information about renamed global symbols, parameters, etc.
  const GlobalNameTable globalNames;
 
  explicit SharedEmitterState(ModuleOp designOp, const LoweringOptions &options,
                              GlobalNameTable globalNames)
      : designOp(designOp), options(options),
        globalNames(std::move(globalNames)) {}
  void gatherFiles(bool separateModules);
 
  using EmissionList = std::vector<StringOrOpToEmit>;
 
  void collectOpsForFile(const FileInfo &fileInfo, EmissionList &thingsToEmit,
                         bool emitHeader = false);
  void emitOps(EmissionList &thingsToEmit, llvm::formatted_raw_ostream &os,
               StringAttr fileName, bool parallelize);
};
 
//===----------------------------------------------------------------------===//
// Other utilities
//===----------------------------------------------------------------------===//
 
/// Return true for operations that must always be inlined into a containing
/// expression for correctness.
static inline bool isExpressionAlwaysInline(Operation *op) {
  // We need to emit array indexes inline per verilog "lvalue" semantics.
  if (isa<sv::ArrayIndexInOutOp>(op) || isa<sv::StructFieldInOutOp>(op) ||
      isa<sv::IndexedPartSelectInOutOp>(op) || isa<sv::ReadInOutOp>(op))
    return true;
 
  // An SV interface modport is a symbolic name that is always inlined.
  if (isa<sv::GetModportOp>(op) || isa<sv::ReadInterfaceSignalOp>(op))
    return true;
 
  // XMRs can't be spilled if they are on the lhs.  Conservatively never spill
  // them.
  if (isa<sv::XMROp, sv::XMRRefOp>(op))
    return true;
 
  if (isa<sv::SampledOp>(op))
    return true;
 
  return false;
}
 
StringRef getSymOpName(Operation *symOp);
 
/// Return whether an operation is a constant.
static inline bool isConstantExpression(Operation *op) {
  return isa<hw::ConstantOp, sv::ConstantXOp, sv::ConstantZOp,
             sv::ConstantStrOp>(op);
}
 
/// This predicate returns true if the specified operation is considered a
/// potentially inlinable Verilog expression.  These nodes always have a single
/// result, but may have side effects (e.g. `sv.verbatim.expr.se`).
/// MemoryEffects should be checked if a client cares.
bool isVerilogExpression(Operation *op);
 
/// Return true if this is a zero bit type, e.g. a zero bit integer or array
/// thereof.
bool isZeroBitType(Type type);
 
/// Return true if this expression should be emitted inline into any statement
/// that uses it.
bool isExpressionEmittedInline(Operation *op, const LoweringOptions &options);
 
/// For each module we emit, do a prepass over the structure, pre-lowering and
/// otherwise rewriting operations we don't want to emit.
LogicalResult prepareHWModule(Block &block, const LoweringOptions &options);
LogicalResult prepareHWModule(hw::HWModuleOp module,
                              const LoweringOptions &options);
 
void pruneZeroValuedLogic(hw::HWModuleOp module);
 
/// Rewrite module names and interfaces to not conflict with each other or with
/// Verilog keywords.
GlobalNameTable legalizeGlobalNames(ModuleOp topLevel,
                                    const LoweringOptions &options);
 
} // namespace ExportVerilog
} // namespace circt
 
#endif // CONVERSION_EXPORTVERILOG_EXPORTVERILOGINTERNAL_H