Reland "[lldb][RPC] Upstream lldb-rpc-gen tool" (llvm#146969)" Attempt 2

Second attempt at relanding the lldb-rpc-gen tool. This should fix an
assert that was hitting when building on Linux. The assert would hit in
the server source emitter, specifically when attemping to determine the
storage size for a return type is that is a pointer, but isn't a const
char *, const char ** or void pointer.

The assert would hit when attempting to generate
SBAttachInfo::GetProcessPluginName, which returns a const char *
(meaning it shouldn't have been in the code block for the assert at
all). The reason that it was hitting the assert when generating this
function is that lldb_rpc_gen::TypeIsConstCharPtr was returning false
for this function even though it did return a const char *. This was
happening because when checking the return type for a const char *,
TypeIsConstCharPtr would only check that the underlying type was a
signed char. This failed on Linux (but was fine on Darwin), as the
underlying type also needs to be checked for being an unsigned char.

Original PR Description:
This commit upstreams the lldb-rpc-gen tool, a ClangTool that generates
the LLDB RPC client and server interfaces. This tool, as well as LLDB
RPC itself is built by default. If it needs to be disabled, put
-DLLDB_BUILD_LLDBRPC=OFF in your CMake invocation.

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

Original PR Link:
github.com/llvm/pull/138031

Author: chelcassanova

lldb/cmake/modules/LLDBConfig.cmake

@@ -323,4 +323,23 @@ else()
     set(LLDB_CAN_USE_DEBUGSERVER OFF)
 endif()
 
+# In a cross-compile build, we need to skip building the generated
+# lldb-rpc sources in the first phase of host build so that they can
+# get built using the just-built Clang toolchain in the second phase.
+if (NOT DEFINED LLDB_CAN_USE_LLDB_RPC_SERVER)
+  if ((CMAKE_CROSSCOMPILING OR LLVM_HOST_TRIPLE MATCHES "${LLVM_DEFAULT_TARGET_TRIPLE}") AND
+      CMAKE_SYSTEM_NAME MATCHES "AIX|Android|Darwin|FreeBSD|Linux|NetBSD|OpenBSD|Windows")
+    set(LLDB_CAN_USE_LLDB_RPC_SERVER ON)
+  else()
+    set(LLDB_CAN_USE_LLDB_RPC_SERVER OFF)
+  endif()
+endif()
+
+if (CMAKE_CROSSCOMPILING)
+  set(LLDB_BUILD_LLDBRPC OFF CACHE BOOL "")
+  get_host_tool_path(lldb-rpc-gen LLDB_RPC_GEN_EXE lldb_rpc_gen_exe lldb_rpc_gen_target)
+else()
+  set(LLDB_BUILD_LLDBRPC ON CACHE BOOL "")
+endif()
+
 include(LLDBGenerateConfig)

lldb/test/CMakeLists.txt

@@ -132,6 +132,10 @@ if(TARGET lldb-framework)
   add_lldb_test_dependency(lldb-framework)
 endif()
 
+if (LLDB_CAN_USE_LLDB_RPC_SERVER)
+  add_lldb_test_dependency(lldb-rpc-generate-sources)
+endif()
+
 # Add dependencies that are not exported targets when building standalone.
 if(NOT LLDB_BUILT_STANDALONE)
   add_lldb_test_dependency(
@@ -249,7 +253,8 @@ llvm_canonicalize_cmake_booleans(
   LLDB_TEST_SHELL_DISABLE_REMOTE
   LLDB_TOOL_LLDB_SERVER_BUILD
   LLDB_USE_SYSTEM_DEBUGSERVER
-  LLDB_IS_64_BITS)
+  LLDB_IS_64_BITS
+  LLDB_BUILD_LLDBRPC)
 
 # Configure the individual test suites.
 add_subdirectory(API)

lldb/test/Shell/RPC/Generator/Inputs/SBDummy.h

@@ -0,0 +1,9 @@
+RUN: %lldb-rpc-gen --output-dir=%t %S/../Inputs/SBDummy.h
+
+RUN: ls %t | FileCheck %s
+
+# We're just making sure that the tool emits the class names,
+# methods and skipped methods file in the output directory.
+CHECK: SBAPI.def
+CHECK: SBClasses.def
+CHECK: SkippedMethods.txt

lldb/test/Shell/RPC/Generator/Tests/CheckRPCGenToolByproducts.test

@@ -0,0 +1,3 @@
+# All tests for the tool need lldb-rpc-gen to be built.
+if not config.lldb_has_lldbrpc:
+   config.unsupported = True

lldb/test/Shell/RPC/Generator/lit.local.cfg

@@ -156,6 +156,16 @@ def use_lldb_substitutions(config):
             extra_args=["platform"],
             unresolved="ignore",
         ),
+        ToolSubst(
+            "%lldb-rpc-gen",
+            command=FindTool("lldb-rpc-gen"),
+            # We need the LLDB build directory root to pass into the tool, not the test build root.
+            extra_args=[
+                "-p " + config.lldb_build_directory + "/..",
+                '--extra-arg="-resource-dir=' + config.clang_resource_dir + '"',
+            ],
+            unresolved="ignore",
+        ),
         "lldb-test",
         "lldb-dap",
         ToolSubst(

lldb/test/Shell/helper/toolchain.py

@@ -33,6 +33,7 @@ config.lldb_build_directory = "@LLDB_TEST_BUILD_DIRECTORY@"
 config.have_lldb_server = @LLDB_TOOL_LLDB_SERVER_BUILD@
 config.lldb_system_debugserver = @LLDB_USE_SYSTEM_DEBUGSERVER@
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
+config.lldb_has_lldbrpc = @LLDB_BUILD_LLDBRPC@
 # The shell tests use their own module caches.
 config.lldb_module_cache = os.path.join("@LLDB_TEST_MODULE_CACHE_LLDB@", "lldb-shell")
 config.clang_module_cache = os.path.join("@LLDB_TEST_MODULE_CACHE_CLANG@", "lldb-shell")

lldb/test/Shell/lit.site.cfg.py.in

@@ -10,6 +10,12 @@ add_subdirectory(lldb-fuzzer EXCLUDE_FROM_ALL)
 
 add_lldb_tool_subdirectory(lldb-instr)
 add_lldb_tool_subdirectory(lldb-dap)
+if (LLDB_BUILD_LLDBRPC)
+  add_lldb_tool_subdirectory(lldb-rpc-gen)
+endif()
+if (LLDB_CAN_USE_LLDB_RPC_SERVER)
+  add_subdirectory(lldb-rpc)
+endif()
 
 if (CMAKE_SYSTEM_NAME MATCHES "Darwin")
   add_lldb_tool_subdirectory(darwin-debug)

lldb/tools/CMakeLists.txt

@@ -0,0 +1,23 @@
+add_lldb_tool(lldb-rpc-gen
+    RPCCommon.cpp
+    server/RPCServerHeaderEmitter.cpp
+    server/RPCServerSourceEmitter.cpp
+    lldb-rpc-gen.cpp
+
+    CLANG_LIBS
+      clangAST
+      clangBasic
+      clangCodeGen
+      clangFrontend
+      clangLex
+      clangRewrite
+      clangSerialization
+      clangTooling
+
+    LINK_COMPONENTS
+      Support
+  )
+
+if (NOT DEFINED LLDB_RPC_GEN_EXE)
+  set(LLDB_RPC_GEN_EXE $<TARGET_FILE:lldb-rpc-gen> CACHE STRING "Executable that generates lldb-rpc-server")
+endif()