[llvm] [llvm-lsp] LSP server for LLVM IR (PR #161969)

[Michal Vlasák via llvm-commits]

================
@@ -0,0 +1,213 @@
+//===-- llvm-lsp-server.cpp -------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/JSON.h"
+#include "llvm/Support/Program.h"
+
+#include "IRDocument.h"
+#include "llvm-lsp-server.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/raw_ostream.h"
+#include <string>
+
+using namespace llvm;
+
+static cl::OptionCategory LlvmLspServerCategory("llvm-lsp-server options");
+static cl::opt<std::string> LogFilePath("log-file",
+                                        cl::desc("Path to log file"),
+                                        cl::init("/tmp/llvm-lsp-server.log"),
+                                        cl::cat(LlvmLspServerCategory));
+
+static lsp::Position llvmFileLocToLspPosition(const FileLoc &Pos) {
+  return lsp::Position(Pos.Line, Pos.Col);
+}
+
+static lsp::Range llvmFileLocRangeToLspRange(const FileLocRange &Range) {
+  return lsp::Range(llvmFileLocToLspPosition(Range.Start),
+                    llvmFileLocToLspPosition(Range.End));
+}
+
+llvm::Error LspServer::run() {
+  registerMessageHandlers();
+  return Transport.run(MessageHandler);
+}
+
+void LspServer::sendInfo(const std::string &Message) {
+  ShowMessageSender(lsp::ShowMessageParams(lsp::MessageType::Info, Message));
+}
+
+void LspServer::sendError(const std::string &Message) {
+  ShowMessageSender(lsp::ShowMessageParams(lsp::MessageType::Error, Message));
+}
+
+void LspServer::handleRequestInitialize(
+    const lsp::InitializeParams &Params,
+    lsp::Callback<llvm::json::Value> Reply) {
+  lsp::Logger::info("Received Initialize Message!");
+  sendInfo("Hello! Welcome to LLVM IR Language Server!");
+
+  // clang-format off
+  json::Object ResponseParams{
+    {"capabilities",
+      json::Object{
+          {"textDocumentSync",
+          json::Object{
+              {"openClose", true},
+              {"change", 0}, // We dont want to sync the documents.
+          }
+        },
+        {"referencesProvider", true},
+        {"documentSymbolProvider", true},
+      }
+    }
+  };
+  // clang-format on
+  Reply(json::Value(std::move(ResponseParams)));
+}
+
+void LspServer::handleNotificationTextDocumentDidOpen(
+    const lsp::DidOpenTextDocumentParams &Params) {
+  lsp::Logger::info("Received didOpen Message!");
+  StringRef Filepath = Params.textDocument.uri.file();
+  sendInfo("LLVM Language Server Recognized that you opened " + Filepath.str());
+
+  // Prepare IRDocument for Queries
+  lsp::Logger::info("Creating IRDocument for {}", Filepath.str());
+  OpenDocuments[Filepath.str()] = std::make_unique<IRDocument>(Filepath.str());
+}
+
+void LspServer::handleRequestGetReferences(
+    const lsp::ReferenceParams &Params,
+    lsp::Callback<std::vector<lsp::Location>> Reply) {
+  auto Filepath = Params.textDocument.uri.file();
+  auto Line = Params.position.line;
+  auto Character = Params.position.character;
+  assert(Line >= 0);
+  assert(Character >= 0);
+  std::stringstream SS;
+  std::vector<lsp::Location> Result;
+  const auto &Doc = OpenDocuments[Filepath.str()];
+  if (Instruction *MaybeI = Doc->getInstructionAtLocation(Line, Character)) {
+    auto TryAddReference = [&Result, &Params, &Doc](Instruction *I) {
+      auto MaybeInstLocation = Doc->ParserContext.getInstructionLocation(I);
+      if (!MaybeInstLocation)
+        return;
+      Result.emplace_back(
+          lsp::Location(Params.textDocument.uri,
+                        llvmFileLocRangeToLspRange(MaybeInstLocation.value())));
+    };
+    TryAddReference(MaybeI);
+    for (User *U : MaybeI->users()) {
+      if (auto *UserInst = dyn_cast<Instruction>(U)) {
+        TryAddReference(UserInst);
+      }
+    }
+  }
+
+  Reply(std::move(Result));
+}
+
+void LspServer::handleRequestTextDocumentDocumentSymbol(
+    const lsp::DocumentSymbolParams &Params,
+    lsp::Callback<std::vector<lsp::DocumentSymbol>> Reply) {
+  if (OpenDocuments.find(Params.textDocument.uri.file().str()) ==
+      OpenDocuments.end()) {
+    lsp::Logger::error(
+        "Document in textDocument/documentSymbol request not open: {}",
+        Params.textDocument.uri.file());
+    return Reply(
+        make_error<lsp::LSPError>(formatv("Did not open file previously {}",
+                                          Params.textDocument.uri.file()),
+                                  lsp::ErrorCode::InvalidParams));
+  }
+  auto &Doc = OpenDocuments[Params.textDocument.uri.file().str()];
+  std::vector<lsp::DocumentSymbol> Result;
+  for (const auto &Fn : Doc->getFunctions()) {
+    lsp::DocumentSymbol Func;
+    Func.name = Fn.getNameOrAsOperand();
+    Func.kind = lsp::SymbolKind::Function;
+    auto MaybeLoc = Doc->ParserContext.getFunctionLocation(&Fn);
+    if (!MaybeLoc)
+      continue;
+    Func.range = llvmFileLocRangeToLspRange(*MaybeLoc);
+    Func.selectionRange = Func.range;
----------------
vlasakm wrote:

What's the difference betwee nrange and selectionRange? Should we do something different here?

https://github.com/llvm/llvm-project/pull/161969