[lldb[RPC] Upstream RPC server interface emitters

This commit upstreams the LLDB RPC server interface emitters. These
emitters generate the server-side API interfaces for RPC, which
communicate directly with liblldb itself out of process using the SB
API.

https://discourse.llvm.org/t/rfc-upstreaming-lldb-rpc/85804

Author: chelcassanova

lldb/test/Shell/RPC/Generator/Inputs/Server/CheckBasicIncludesEmit.h

@@ -0,0 +1,6 @@
+// This ia a basic header file used to check that the server-side emitter
+// for rpc-gen emits an expected set of includes in a generated source file.
+#ifndef LLDB_API_SBRPC_CHECKBASICINCLUDE_H
+#define LLDB_API_SBRPC_CHECKBASICINCLUDE_H
+
+#endif // LLDB_API_SBRPC_CHECKBASICINCLUDE_H

lldb/test/Shell/RPC/Generator/Inputs/Server/CheckConstCharPointer.h

@@ -0,0 +1,14 @@
+#ifndef LLDB_API_SBRPC_CHECKCONSTCHARPOINTER_H
+#define LLDB_API_SBRPC_CHECKCONSTCHARPOINTER_H
+
+namespace lldb {
+class LLDB_API SBRPC_CHECKCONSTCHARPOINTER {
+public:
+  // const char * parameters must decoded as rpc_common::ConstCharPointer in server side
+  // source files.
+  int CheckConstCharPointer(char *string);
+
+}; // class SBRPC_CHECKCONSTCHARPOINTER
+} // namespace lldb
+
+#endif // LLDB_API_SBRPC_CHECKCONSTCHARPOINTER_H

lldb/test/Shell/RPC/Generator/Tests/Server/CheckBasicIncludesEmit.test

@@ -0,0 +1,15 @@
+# Disabling until the lldb-rpc-gen tool lands.
+UNSUPPORTED: system-windows, system-linux, system-darwin
+RUN: mkdir -p %t/server
+RUN: mkdir -p %t/lib
+RUN: %lldb-rpc-gen --output-dir=%t %S/../../Inputs/CheckBasicIncludesEmit.h
+
+RUN: cat %t/lib/CheckBasicIncludesEmit.cpp | FileCheck %s
+
+# All server-side source files must have these includes at the top of their files.
+CHECK: #include "RPCUserServer.h"
+CHECK: #include "SBAPI.h"
+CHECK: #include <lldb-rpc/common/RPCArgument.h>
+CHECK: #include <lldb-rpc/common/RPCCommon.h>
+CHECK: #include <lldb-rpc/common/RPCFunction.h>
+CHECK: #include <lldb/API/LLDB.h>

lldb/test/Shell/RPC/Generator/Tests/Server/CheckConstCharPointer.test

@@ -0,0 +1,11 @@
+# Disabling until the lldb-rpc-gen tool lands.
+UNSUPPORTED: system-windows, system-linux, system-darwin
+RUN: mkdir -p %t/server
+RUN: mkdir -p %t/lib
+RUN: %lldb-rpc-gen --output-dir=%t %S/../../Inputs/CheckConstCharPointer.h
+
+RUN: cat %t/lib/CheckConstCharPointer.cpp | FileCheck %s
+
+# const char * pointers must be decoded as rpc_common::ConstCharPointer objects
+# in server side source files.
+CHECK: rpc_common::ConstCharPointer string

lldb/tools/lldb-rpc/lldb-rpc-gen/server/RPCServerHeaderEmitter.cpp

@@ -0,0 +1,75 @@
+//===-- RPCServerHeaderEmitter.cpp ----------------------------------------===//
+//
+// 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 "RPCServerHeaderEmitter.h"
+#include "RPCCommon.h"
+
+#include "clang/AST/AST.h"
+#include "clang/AST/Mangle.h"
+#include "clang/Frontend/CompilerInstance.h"
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/ToolOutputFile.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+using namespace lldb_rpc_gen;
+
+void RPCServerHeaderEmitter::EmitMethod(const Method &method) {
+  // We'll be using the mangled name in order to disambiguate
+  // overloaded methods.
+  const std::string &MangledName = method.MangledName;
+
+  EmitLine("class " + MangledName +
+           " : public rpc_common::RPCFunctionInstance {");
+  EmitLine("public:");
+  IndentLevel++;
+  EmitConstructor(MangledName);
+  EmitDestructor(MangledName);
+  EmitHandleRPCCall();
+  IndentLevel--;
+  EmitLine("};");
+}
+
+void RPCServerHeaderEmitter::EmitHandleRPCCall() {
+  EmitLine("bool HandleRPCCall(rpc_common::Connection &connection, "
+           "rpc_common::RPCStream &send, rpc_common::RPCStream &response) "
+           "override;");
+}
+
+void RPCServerHeaderEmitter::EmitConstructor(const std::string &MangledName) {
+  EmitLine(MangledName + "() : RPCFunctionInstance(\"" + MangledName +
+           "\") {}");
+}
+
+void RPCServerHeaderEmitter::EmitDestructor(const std::string &MangledName) {
+  EmitLine("~" + MangledName + "() override {}");
+}
+
+std::string RPCServerHeaderEmitter::GetHeaderGuard() {
+  const std::string UpperFilenameNoExt =
+      llvm::sys::path::stem(
+          llvm::sys::path::filename(OutputFile->getFilename()))
+          .upper();
+  return "GENERATED_LLDB_RPC_SERVER_" + UpperFilenameNoExt + "_H";
+}
+
+void RPCServerHeaderEmitter::Begin() {
+  const std::string HeaderGuard = GetHeaderGuard();
+  EmitLine("#ifndef " + HeaderGuard);
+  EmitLine("#define " + HeaderGuard);
+  EmitLine("");
+  EmitLine("#include <lldb-rpc/common/RPCFunction.h>");
+  EmitLine("");
+  EmitLine("namespace rpc_server {");
+}
+
+void RPCServerHeaderEmitter::End() {
+  EmitLine("} // namespace rpc_server");
+  EmitLine("#endif // " + GetHeaderGuard());
+}

lldb/tools/lldb-rpc/lldb-rpc-gen/server/RPCServerHeaderEmitter.h

@@ -0,0 +1,47 @@
+//===-- RPCServerHeaderEmitter.h ----------------------------------------===//
+//
+// 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 LLDB_RPC_GEN_RPCSERVERHEADEREMITTER_H
+#define LLDB_RPC_GEN_RPCSERVERHEADEREMITTER_H
+
+#include "RPCCommon.h"
+
+#include "clang/AST/AST.h"
+#include "llvm/Support/ToolOutputFile.h"
+
+using namespace clang;
+
+namespace lldb_rpc_gen {
+/// Emit the source code for server-side *.h files.
+class RPCServerHeaderEmitter : public FileEmitter {
+public:
+  RPCServerHeaderEmitter(std::unique_ptr<llvm::ToolOutputFile> &&OutputFile)
+      : FileEmitter(std::move(OutputFile)) {
+    Begin();
+  }
+
+  ~RPCServerHeaderEmitter() { End(); }
+
+  void EmitMethod(const Method &method);
+
+private:
+  void EmitHandleRPCCall();
+
+  void EmitConstructor(const std::string &MangledName);
+
+  void EmitDestructor(const std::string &MangledName);
+
+  std::string GetHeaderGuard();
+
+  void Begin();
+
+  void End();
+};
+} // namespace lldb_rpc_gen
+
+#endif // LLDB_RPC_GEN_RPCSERVERHEADEREMITTER_H