[FIRRTL] Cache a symbol table instead of doing linear lookups every i…

…nstance. (#6871)

roughly triples modules parsing performance on large designs. This is about a 2x speedup for overall parsing stage.  Mostly solves #6772 for now.

lib/Dialect/FIRRTL/Import/FIRParser.cpp

@@ -1541,12 +1541,14 @@ struct FIRStmtParser : public FIRParser {
  explicit FIRStmtParser(Block &blockToInsertInto,
  FIRModuleContext &moduleContext,
  hw::InnerSymbolNamespace &modNameSpace,
- FIRVersion version, SymbolRefAttr layerSym = {})
+ const SymbolTable &circuitSymTbl, FIRVersion version,
+ SymbolRefAttr layerSym = {})
  : FIRParser(moduleContext.getConstants(), moduleContext.getLexer(),
  version),
  builder(UnknownLoc::get(getContext()), getContext()),
  locationProcessor(this->builder), moduleContext(moduleContext),
- modNameSpace(modNameSpace), layerSym(layerSym) {
+ modNameSpace(modNameSpace), layerSym(layerSym),
+ circuitSymTbl(circuitSymTbl) {
  builder.setInsertionPointToEnd(&blockToInsertInto);
  }
 
@@ -1662,6 +1664,8 @@ struct FIRStmtParser : public FIRParser {
  // An optional symbol that contains the current layer block that we are in.
  // This is used to construct a nested symbol for a layer block operation.
  SymbolRefAttr layerSym;
+
+ const SymbolTable &circuitSymTbl;
 };
 
 } // end anonymous namespace
@@ -2632,7 +2636,8 @@ ParseResult FIRStmtParser::parseSubBlock(Block &blockToInsertInto,
  // We parse the substatements into their own parser, so they get inserted
  // into the specified 'when' region.
  auto subParser = std::make_unique<FIRStmtParser>(
- blockToInsertInto, moduleContext, modNameSpace, version, layerSym);
+ blockToInsertInto, moduleContext, modNameSpace, circuitSymTbl, version,
+ layerSym);
 
  // Figure out whether the body is a single statement or a nested one.
  auto stmtIndent = getIndentation();
@@ -2932,9 +2937,9 @@ ParseResult FIRStmtParser::parseWhen(unsigned whenIndent) {
  // the outer 'when'.
  if (getToken().is(FIRToken::kw_when)) {
  // We create a sub parser for the else block.
- auto subParser =
- std::make_unique<FIRStmtParser>(whenStmt.getElseBlock(), moduleContext,
-  modNameSpace, version, layerSym);
+ auto subParser = std::make_unique<FIRStmtParser>(
+ whenStmt.getElseBlock(), moduleContext, modNameSpace, circuitSymTbl,
+ version, layerSym);
 
  return subParser->parseSimpleStmt(whenIndent);
  }
@@ -3072,8 +3077,9 @@ ParseResult FIRStmtParser::parseMatch(unsigned matchIndent) {
  return failure();
 
  // Parse a block of statements that are indented more than the case.
- auto subParser = std::make_unique<FIRStmtParser>(
- *caseBlock, moduleContext, modNameSpace, version, layerSym);
+ auto subParser =
+ std::make_unique<FIRStmtParser>(*caseBlock, moduleContext, modNameSpace,
+ circuitSymTbl, version, layerSym);
  if (subParser->parseSimpleStmtBlock(*caseIndent))
  return failure();
  }
@@ -3942,10 +3948,7 @@ ParseResult FIRStmtParser::parseInstanceChoice() {
 
 FModuleLike FIRStmtParser::getReferencedModule(SMLoc loc,
  StringRef moduleName) {
- auto circuit =
- builder.getBlock()->getParentOp()->getParentOfType<CircuitOp>();
- auto referencedModule =
- dyn_cast_or_null<FModuleLike>(circuit.lookupSymbol(moduleName));
+ auto referencedModule = circuitSymTbl.lookup<FModuleLike>(moduleName);
  if (!referencedModule) {
  emitError(loc,
  "use of undefined module name '" + moduleName + "' in instance");
@@ -4486,7 +4489,8 @@ struct FIRCircuitParser : public FIRParser {
  unsigned indent;
  };
 
- ParseResult parseModuleBody(DeferredModuleToParse &deferredModule);
+ ParseResult parseModuleBody(const SymbolTable &circuitSymTbl,
+ DeferredModuleToParse &deferredModule);
 
  SmallVector<DeferredModuleToParse, 0> deferredModules;
  ModuleOp mlirModule;
@@ -5261,7 +5265,8 @@ ParseResult FIRCircuitParser::parseLayer(CircuitOp circuit) {
 
 // Parse the body of this module.
 ParseResult
-FIRCircuitParser::parseModuleBody(DeferredModuleToParse &deferredModule) {
+FIRCircuitParser::parseModuleBody(const SymbolTable &circuitSymTbl,
+ DeferredModuleToParse &deferredModule) {
  FModuleLike moduleOp = deferredModule.moduleOp;
  auto &body = moduleOp->getRegion(0).front();
  auto &portLocs = deferredModule.portLocs;
@@ -5289,7 +5294,8 @@ FIRCircuitParser::parseModuleBody(DeferredModuleToParse &deferredModule) {
  }
 
  hw::InnerSymbolNamespace modNameSpace(moduleOp);
- FIRStmtParser stmtParser(body, moduleContext, modNameSpace, version);
+ FIRStmtParser stmtParser(body, moduleContext, modNameSpace, circuitSymTbl,
+ version);
 
  // Parse the moduleBlock.
  auto result = stmtParser.parseSimpleStmtBlock(deferredModule.indent);
@@ -5453,10 +5459,36 @@ ParseResult FIRCircuitParser::parseCircuit(
  // proactively touch it to make sure that it is always already created.
  (void)getLexer().translateLocation(info.getFIRLoc());
 
+ // Pre-verify symbol table, so we can construct it next. Ideally, we would do
+ // this verification through the trait.
+ { // Memory is tight in parsing.
+ // Check that all symbols are uniquely named within child regions.
+ DenseMap<Attribute, Location> nameToOrigLoc;
+ for (auto &op : *circuit.getBodyBlock()) {
+ // Check for a symbol name attribute.
+ auto nameAttr =
+ op.getAttrOfType<StringAttr>(mlir::SymbolTable::getSymbolAttrName());
+ if (!nameAttr)
+ continue;
+
+ // Try to insert this symbol into the table.
+ auto it = nameToOrigLoc.try_emplace(nameAttr, op.getLoc());
+ if (!it.second) {
+ op.emitError()
+ .append("redefinition of symbol named '", nameAttr.getValue(), "'")
+ .attachNote(it.first->second)
+ .append("see existing symbol definition here");
+ return failure();
+ }
+ }
+ }
+
+ SymbolTable circuitSymTbl(circuit);
+
  // Next, parse all the module bodies.
  auto anyFailed = mlir::failableParallelForEachN(
  getContext(), 0, deferredModules.size(), [&](size_t index) {
- if (parseModuleBody(deferredModules[index]))
+ if (parseModuleBody(circuitSymTbl, deferredModules[index]))
  return failure();
  return success();
  });
@@ -5491,7 +5523,8 @@ circt::firrtl::importFIRFile(SourceMgr &sourceMgr, MLIRContext *context,
 
  // This is the result module we are parsing into.
  mlir::OwningOpRef<mlir::ModuleOp> module(ModuleOp::create(
- FileLineColLoc::get(context, sourceBuf->getBufferIdentifier(), /*line=*/0,
+ FileLineColLoc::get(context, sourceBuf->getBufferIdentifier(),
+ /*line=*/0,
  /*column=*/0)));
  SharedParserConstants state(context, options);
  FIRLexer lexer(sourceMgr, context);