[circt-verilog-lsp] Add -C command line option

This PR extends the CIRCT Verilog LSP server with support for project command files (`-C` / `--command-file`) and improves robustness around source locations and diagnostics.

- **Command file support**
  - Added `commandFiles` option to `VerilogServerOptions`.
  - Extended the CLI with `-C`/`--command-file` flags to pass one or more command files.
  - Each buffer’s `Driver` now processes command files, filtering out the current main buffer to avoid duplication.
  - Implemented `removeFileToTemp` helper to strip the main file from command files and materialize a temporary version.

- **Source location handling**
  - Improved absolute/real path resolution when constructing LSP URIs.
  - Fallbacks added for when `slang::SourceManager` has no full path info.

- **Compilation setup**
  - Ensure all definitions in the buffer/project scope are treated as top modules.

- **Indexing improvements**
  - Skip top instances not defined in the current file.
  - Added guards against invalid or empty ranges (especially macro expansions).

Author: Scheremo

include/circt/Tools/circt-verilog-lsp-server/CirctVerilogLspServerMain.h

@@ -35,13 +35,17 @@ namespace circt {
 namespace lsp {
 struct VerilogServerOptions {
   VerilogServerOptions(const std::vector<std::string> &libDirs,
-                       const std::vector<std::string> &extraSourceLocationDirs)
-      : libDirs(libDirs), extraSourceLocationDirs(extraSourceLocationDirs) {}
+                       const std::vector<std::string> &extraSourceLocationDirs,
+                       const std::vector<std::string> &commandFiles)
+      : libDirs(libDirs), extraSourceLocationDirs(extraSourceLocationDirs),
+        commandFiles(commandFiles) {}
   /// Additional list of RTL directories to search.
   const std::vector<std::string> &libDirs;
-
   /// Additional list of external source directories to search.
   const std::vector<std::string> &extraSourceLocationDirs;
+  /// Additional list of command files that reference dependencies of the
+  /// project.
+  const std::vector<std::string> &commandFiles;
 };
 // namespace lsp
 

lib/Tools/circt-verilog-lsp-server/LSPServer.cpp

@@ -8,6 +8,7 @@
 
 #include "LSPServer.h"
 #include "VerilogServerImpl/VerilogServer.h"
+#include "llvm/Support/JSON.h"
 #include "llvm/Support/LSP/Protocol.h"
 #include "llvm/Support/LSP/Transport.h"
 #include <optional>

lib/Tools/circt-verilog-lsp-server/VerilogServerImpl/VerilogServer.cpp

@@ -23,6 +23,8 @@
 #include "mlir/IR/MLIRContext.h"
 #include "slang/ast/ASTVisitor.h"
 #include "slang/ast/Compilation.h"
+#include "slang/ast/Scope.h"
+#include "slang/ast/symbols/CompilationUnitSymbols.h"
 #include "slang/diagnostics/DiagnosticClient.h"
 #include "slang/diagnostics/Diagnostics.h"
 #include "slang/driver/Driver.h"
@@ -43,6 +45,8 @@
 #include "llvm/Support/SMLoc.h"
 #include "llvm/Support/SourceMgr.h"
 
+#include <filesystem>
+#include <fstream>
 #include <memory>
 #include <optional>
 #include <string>
@@ -248,15 +252,98 @@ void LSPDiagnosticClient::report(const slang::ReportedDiagnostic &slangDiag) {
 // VerilogDocument
 //===----------------------------------------------------------------------===//
 
+// Filter out the main buffer file from the command file list, if it is in
+// there.
+static inline bool
+mainBufferFileInCommandFileList(const std::string &cmdfileStr,
+                                const std::string &targetAbsStr) {
+  namespace fs = std::filesystem;
+
+  fs::path cmdfile(cmdfileStr);
+  fs::path targetAbs(targetAbsStr);
+  const fs::path base = cmdfile.parent_path();
+  std::error_code ec;
+
+  // Normalize target
+  fs::path target = fs::weakly_canonical(targetAbs, ec);
+  if (ec) {
+    ec.clear();
+    target = targetAbs.lexically_normal();
+  }
+
+  std::ifstream in(cmdfile);
+  if (!in) {
+    // return the original path so the caller still has a valid file to use
+    return false;
+  }
+
+  std::string line;
+
+  while (std::getline(in, line)) {
+    std::string s = line;
+    s.erase(0, s.find_first_not_of(" \t\r\n")); // left-trim
+
+    // Keep plusargs
+    if (!s.empty() &&
+        (s.rfind("+incdir+", 0) == 0 || s.rfind("+define+", 0) == 0 ||
+         s.rfind("-I", 0) == 0 || s.rfind("-D", 0) == 0)) {
+      continue;
+    }
+    // Preserve blank lines
+    if (s.empty()) {
+      continue;
+    }
+
+    // Treat everything else as a path (relative entries resolved vs. cmdfile
+    // dir)
+    fs::path candRel = s;
+    fs::path candAbs = candRel.is_absolute() ? candRel : (base / candRel);
+
+    fs::path cand = fs::weakly_canonical(candAbs, ec);
+    if (ec) {
+      ec.clear();
+      cand = candAbs.lexically_normal();
+    }
+
+    if (cand == target) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+static inline bool mainBufferFileInCommandFileList(llvm::StringRef cmdfile,
+                                                   llvm::StringRef target_abs) {
+  return mainBufferFileInCommandFileList(cmdfile.str(), target_abs.str());
+}
+
 VerilogDocument::VerilogDocument(
     VerilogServerContext &context, const llvm::lsp::URIForFile &uri,
     StringRef contents, std::vector<llvm::lsp::Diagnostic> &diagnostics)
     : globalContext(context), index(*this), uri(uri) {
-  unsigned int bufferId;
+  unsigned int mainBufferId;
+  bool skipMainBufferSlangImport = false;
+
+  llvm::SmallString<256> canonPath(uri.file());
+  if (std::error_code ec = llvm::sys::fs::real_path(uri.file(), canonPath))
+    canonPath = uri.file(); // fall back, but try to keep it absolute
+
+  // --- Apply project command files (the “-C”s) to this per-buffer driver ---
+  for (const std::string &cmdFile : context.options.commandFiles) {
+    if (!driver.processCommandFiles(cmdFile, false, true)) {
+      circt::lsp::Logger::error(Twine("Failed to open command file ") +
+                                cmdFile);
+    }
+    skipMainBufferSlangImport |=
+        mainBufferFileInCommandFileList(cmdFile, canonPath);
+  }
+
   if (auto memBufferOwn =
-          llvm::MemoryBuffer::getMemBufferCopy(contents, uri.file())) {
+          llvm::MemoryBuffer::getMemBufferCopy(contents, canonPath)) {
 
-    bufferId = sourceMgr.AddNewSourceBuffer(std::move(memBufferOwn), SMLoc());
+    mainBufferId =
+        sourceMgr.AddNewSourceBuffer(std::move(memBufferOwn), SMLoc());
   } else {
     circt::lsp::Logger::error(
         Twine("Failed to create memory buffer for file ") + uri.file());
@@ -273,17 +360,57 @@ VerilogDocument::VerilogDocument(
                  context.options.libDirs.end());
 
   // Populate source managers.
-  const llvm::MemoryBuffer *memBuffer = sourceMgr.getMemoryBuffer(bufferId);
+  const llvm::MemoryBuffer *memBuffer = sourceMgr.getMemoryBuffer(mainBufferId);
+
+  // This block compiles the top file to determine all definitions
+  // This is used in a second pass to declare all those definitions
+  // as top modules, so they are elaborated and subsequently indexed.
+  slang::driver::Driver topDriver;
+
+  auto topSlangBuffer =
+      topDriver.sourceManager.assignText(uri.file(), memBuffer->getBuffer());
+  topDriver.sourceLoader.addBuffer(topSlangBuffer);
+
+  topDriver.options.compilationFlags.emplace(
+      slang::ast::CompilationFlags::LintMode, false);
+  topDriver.options.compilationFlags.emplace(
+      slang::ast::CompilationFlags::DisableInstanceCaching, false);
+
+  if (!topDriver.processOptions()) {
+    return;
+  }
+
+  if (!topDriver.parseAllSources()) {
+    circt::lsp::Logger::error(Twine("Failed to parse Verilog file ") +
+                              uri.file());
+    return;
+  }
+
+  FailureOr<std::unique_ptr<slang::ast::Compilation>> topCompilation =
+      topDriver.createCompilation();
+  if (failed(topCompilation))
+    return;
+
+  std::vector<std::string> topModules;
+  for (const auto *defs : (*topCompilation)->getDefinitions())
+    topModules.emplace_back(defs->name);
+
+  // Make sure that all possible definitions in the main buffer are
+  // topModules!
+  driver.options.topModules = topModules;
 
   for (const auto &libDir : libDirs) {
     driver.sourceLoader.addSearchDirectories(libDir);
   }
 
-  // Assign text to slang.
-  auto slangBuffer =
-      driver.sourceManager.assignText(uri.file(), memBuffer->getBuffer());
-  driver.sourceLoader.addBuffer(slangBuffer);
-  bufferIDMap[slangBuffer.id.getId()] = bufferId;
+  // If the main buffer is **not** present in a command file, add it into
+  // slang's source manager and bind to llvm source manager.
+  if (!skipMainBufferSlangImport) {
+    auto slangBuffer =
+        driver.sourceManager.assignText(uri.file(), memBuffer->getBuffer());
+    driver.sourceLoader.addBuffer(slangBuffer);
+  }
+
   auto diagClient = std::make_shared<LSPDiagnosticClient>(*this, diagnostics);
   driver.diagEngine.addClient(diagClient);
 
@@ -308,6 +435,38 @@ VerilogDocument::VerilogDocument(
   if (failed(compilation))
     return;
 
+  // If the main buffer is present in a command file, compile it only once
+  // and import directly from the command file; then figure out which buffer id
+  // it was assigned and bind to llvm source manager.
+  llvm::SmallString<256> slangCanonPath("");
+  std::string slangRawPath;
+  std::unique_ptr<llvm::MemoryBuffer> newBuffer;
+  uint32_t newBufferId;
+
+  // Iterate through all buffers in the slang compilation and set up
+  // a binding to the LLVM Source Manager.
+  auto *sourceManager = (**compilation).getSourceManager();
+  for (auto slangBuffer : sourceManager->getAllBuffers()) {
+    slangRawPath = sourceManager->getRawFileName(slangBuffer);
+    if (std::error_code ec =
+            llvm::sys::fs::real_path(slangRawPath, slangCanonPath))
+      slangCanonPath = slangRawPath;
+
+    if (slangCanonPath == canonPath) {
+      bufferIDMap[slangBuffer.getId()] = mainBufferId;
+      continue;
+    }
+
+    if (!bufferIDMap.contains(slangBuffer.getId())) {
+      newBuffer = llvm::MemoryBuffer::getMemBufferCopy(
+          sourceManager->getSourceText(slangBuffer), slangCanonPath);
+      newBufferId = sourceMgr.AddNewSourceBuffer(std::move(newBuffer), SMLoc());
+      bufferIDMap[slangBuffer.getId()] = newBufferId;
+      continue;
+    }
+    circt::lsp::Logger::error(Twine("Failed to add buffer ID! "));
+  }
+
   for (auto &diag : (*compilation)->getAllDiagnostics())
     driver.diagEngine.issue(diag);
 
@@ -322,19 +481,27 @@ VerilogDocument::getLspLocation(slang::SourceLocation loc) const {
     auto line = slangSourceManager.getLineNumber(loc) - 1;
     auto column = slangSourceManager.getColumnNumber(loc) - 1;
     auto it = bufferIDMap.find(loc.buffer().getId());
-    // Check if the current buffer is the main file.
     if (it != bufferIDMap.end() && it->second == sourceMgr.getMainFileID())
       return llvm::lsp::Location(uri, llvm::lsp::Range(Position(line, column)));
 
-    // Otherwise, construct URI from slang source manager.
-    auto fileName = slangSourceManager.getFileName(loc);
-    auto loc = llvm::lsp::URIForFile::fromFile(fileName);
-    if (auto e = loc.takeError())
-      return llvm::lsp::Location();
-    return llvm::lsp::Location(loc.get(),
-                               llvm::lsp::Range(Position(line, column)));
-  }
+    llvm::StringRef fileName = slangSourceManager.getFileName(loc);
+    // Ensure absolute path for LSP:
+    llvm::SmallString<256> abs(fileName);
+    if (!llvm::sys::path::is_absolute(abs)) {
+      // Try realPath first
+      if (std::error_code ec = llvm::sys::fs::real_path(fileName, abs)) {
+        // Fallback: make it absolute relative to the process CWD
+        llvm::sys::fs::current_path(abs); // abs = CWD
+        llvm::sys::path::append(abs, fileName);
+      }
+    }
 
+    if (auto uriOrErr = llvm::lsp::URIForFile::fromFile(abs)) {
+      return llvm::lsp::Location(*uriOrErr,
+                                 llvm::lsp::Range(Position(line, column)));
+    }
+    return llvm::lsp::Location();
+  }
   return llvm::lsp::Location();
 }
 
@@ -524,6 +691,13 @@ struct VerilogIndexer : slang::ast::ASTVisitor<VerilogIndexer, true, true> {
       return;
     assert(range.start().valid() && range.end().valid() &&
            "range must be valid");
+
+    // TODO: This implementation does not handle expanded MACROs. Return
+    // instead.
+    if (range.start() >= range.end()) {
+      return;
+    }
+
     index.insertSymbol(symbol, range, isDefinition);
   }
 
@@ -581,7 +755,30 @@ struct VerilogIndexer : slang::ast::ASTVisitor<VerilogIndexer, true, true> {
         insertSymbol(def, item->package.location(), false);
       }
     }
+    visitDefault(expr);
+  }
+
+  void visit(const slang::ast::InstanceSymbol &expr) {
+    auto *def = &expr.getDefinition();
+    if (!def)
+      return;
 
+    // Add the module definition
+    insertSymbol(def, def->location, /*isDefinition=*/true);
+
+    // Walk up the syntax tree until we hit the type token;
+    // Link that token back to the instance declaration.
+    if (auto *hierInst =
+            expr.getSyntax()
+                ->as_if<slang::syntax::HierarchicalInstanceSyntax>())
+      if (auto *modInst =
+              hierInst->parent
+                  ->as_if<slang::syntax::HierarchyInstantiationSyntax>())
+        if (modInst->type)
+          insertSymbol(def, modInst->type.location(), false);
+
+    // Link the module instance name back to the module definition
+    insertSymbol(def, expr.location, /*isDefinition=*/false);
     visitDefault(expr);
   }
 
@@ -608,7 +805,13 @@ struct VerilogIndexer : slang::ast::ASTVisitor<VerilogIndexer, true, true> {
 void VerilogIndex::initialize(slang::ast::Compilation &compilation) {
   const auto &root = compilation.getRoot();
   VerilogIndexer visitor(*this);
+
   for (auto *inst : root.topInstances) {
+
+    // Skip all modules, interfaces, etc. that are not defined in this files
+    if (!(document.getLspLocation(inst->location).uri == document.getURI()))
+      continue;
+
     // Visit the body of the instance.
     inst->body.visit(visitor);
 
@@ -780,10 +983,17 @@ void circt::lsp::VerilogServer::findReferencesOf(
 void VerilogIndex::insertSymbol(const slang::ast::Symbol *symbol,
                                 slang::SourceRange from, bool isDefinition) {
   assert(from.start().valid() && from.end().valid());
+
+  // TODO: Currently doesn't handle expanded macros
+  if (!from.start().valid() || !from.end().valid() ||
+      from.start() >= from.end())
+    return;
+
   const char *startLoc = getDocument().getSMLoc(from.start()).getPointer();
   const char *endLoc = getDocument().getSMLoc(from.end()).getPointer() + 1;
-  if (!startLoc || !endLoc)
+  if (!startLoc || !endLoc || startLoc >= endLoc)
     return;
+
   assert(startLoc && endLoc);
 
   if (startLoc != endLoc && !intervalMap.overlaps(startLoc, endLoc)) {