Link against the Boehm-Demers-Weiser Garbage Collector using FetchCon…

…tent. (#3930)

* Make the Boehm GC a Git submodule.

* Review comments.

CMakeLists.txt

@@ -44,8 +44,7 @@ OPTION (ENABLE_P4TEST "Build the P4Test backend (required for the full test suit
 OPTION (ENABLE_TEST_TOOLS "Build the P4Tools development platform" OFF)
 OPTION (ENABLE_P4C_GRAPHS "Build the p4c-graphs backend" ON)
 OPTION (ENABLE_PROTOBUF_STATIC "Link against Protobuf statically" ON)
-OPTION (ENABLE_GC "Use libgc" ON)
-OPTION (ENABLE_MULTITHREAD "Use multithreading" OFF)
+OPTION (ENABLE_GC "Compile with the Boehm-Demers-Weiser garbage collector." ON)
 OPTION (ENABLE_WERROR "Treat warnings as errors" OFF)
 OPTION (ENABLE_SANITIZERS "Enable sanitizers" OFF)
 OPTION (STATIC_BUILD_WITH_DYNAMIC_GLIBC "Build a (mostly) statically linked release binary. \
@@ -103,11 +102,18 @@ else()
     WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
   set (P4C_VERSION "${P4C_SEM_VERSION_STRING} (SHA: ${P4C_GIT_SHA} BUILD: ${CMAKE_BUILD_TYPE})")
 endif()
+
 # P4 General Utilities
 include(P4CUtils)
 # CMake Utilities to fetch dependencies.
 include(FetchContent)
 set(CMAKE_POLICY_DEFAULT_CMP0077 NEW)
+# More utilities.
+include(CheckIncludeFile)
+include(CheckIncludeFileCXX)
+include(CheckFunctionExists)
+include(FindPythonModule)
+include(CPack)
 # TODO: Remove this deprecated include eventually.
 include(UnifiedBuild)
 
@@ -198,6 +204,10 @@ p4c_obtain_abseil()
 include(Protobuf)
 p4c_obtain_protobuf()
 
+# We require -pthread to make std::call_once work, even if we're not using threads...
+set(THREADS_PREFER_PTHREAD_FLAG ON)
+find_package(Threads REQUIRED)
+
 # The boost graph headers are optional and only required by the graphs back end.
 find_package (Boost QUIET COMPONENTS graph)
 if (Boost_FOUND)
@@ -207,20 +217,18 @@ else ()
 endif ()
 find_package (Boost REQUIRED COMPONENTS iostreams)
 
+# Compile with the Boehm garbage collector (https://github.com/ivmai/bdwgc), if requested.
+# One can disable the GC, e.g., to run under Valgrind, by editing config.h.
 if (ENABLE_GC)
-  find_package (LibGc 7.4.2 REQUIRED)
-  set (HAVE_LIBGC 1)
+  include(BDWGC)
+  p4c_obtain_bdwgc()
 endif ()
 if (ENABLE_MULTITHREAD)
   add_definitions(-DMULTITHREAD)
 endif()
-# we require -pthread to make std::call_once work, even if we're not using threads...
-set(THREADS_PREFER_PTHREAD_FLAG ON)
-find_package(Threads REQUIRED)
 list (APPEND P4C_LIB_DEPS ${CMAKE_THREAD_LIBS_INIT})
 include_directories(SYSTEM ${Boost_INCLUDE_DIRS})
 include_directories(SYSTEM ${PROTOBUF_INCLUDE_DIRS})
-include_directories(SYSTEM ${LIBGC_INCLUDE_DIR})
 set (HAVE_LIBBOOST_IOSTREAMS 1)
 list (APPEND P4C_LIB_DEPS ${Boost_LIBRARIES})
 if (ENABLE_GC)
@@ -229,19 +237,18 @@ endif ()
 set (P4C_ABSL_LIBRARIES absl::flat_hash_map absl::flat_hash_set)
 list (APPEND P4C_LIB_DEPS ${P4C_ABSL_LIBRARIES})
 
-# other required libraries
+# Other required libraries.
 p4c_add_library (rt clock_gettime HAVE_CLOCK_GETTIME)
 
-# check includes
-include (CheckIncludeFile)
-include (CheckIncludeFileCXX)
+# Check includes.
 check_include_file(execinfo.h HAVE_EXECINFO_H)
 check_include_file(ucontext.h HAVE_UCONTEXT_H)
 check_include_file(backtrace-supported.h HAVE_LIBBACKTRACE)
 check_include_file_cxx(mm_malloc.h HAVE_MM_MALLOC_H)
 check_include_file_cxx(cxxabi.h HAVE_CXXABI_H)
 if (HAVE_LIBBACKTRACE)
-set (P4C_LIB_DEPS "${P4C_LIB_DEPS};-lbacktrace")
+  message(STATUS "Linking libbacktrace.")
+  set (P4C_LIB_DEPS "${P4C_LIB_DEPS};-lbacktrace")
 endif ()
 
 # check functions
@@ -252,16 +259,13 @@ if (ENABLE_GC)
   set (CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} ${LIBGC_LIBRARIES})
 endif ()
 
-include (CheckFunctionExists)
 check_function_exists (memchr HAVE_MEMCHR)
 check_function_exists (pipe2 HAVE_PIPE2)
-check_function_exists (GC_print_stats HAVE_GC_PRINT_STATS)
 
 # restore CMAKE_REQUIRED_LIBRARIES
 set (CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES_PRECHECK})
 
 # python modules
-include (FindPythonModule)
 find_python_module (difflib REQUIRED)
 find_python_module (shutil REQUIRED)
 find_python_module (tempfile REQUIRED)
@@ -421,7 +425,7 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(p4runtime)
 set(FETCHCONTENT_QUIET ${FETCHCONTENT_QUIET_PREV})
-message("Done with setting up P4Runtime for P4C.")
+message(STATUS "Done with setting up P4Runtime for P4C.")
 # The standard P4Runtime protocol buffers message definitions live in the PI
 # repo, which is included in this repo as a git module.
 set(P4RUNTIME_STD_DIR ${p4runtime_SOURCE_DIR}/proto CACHE INTERNAL
@@ -626,6 +630,5 @@ SET(CPACK_SOURCE_PACKAGE_FILE_NAME
    "p4c-${P4C_SEM_VERSION_STRING}")
 SET(CPACK_SOURCE_IGNORE_FILES
    "${PROJECT_SOURCE_DIR}/${CMAKE_PROJECT_NAME}-*;${PROJECT_SOURCE_DIR}/${CMAKE_PROJECT_NAME}_*;/build/;/.git/;/config.log;/CMakeFiles/;CMakeCache.txt$;.tar.gz$;/_CPack_Packages;/Makefile$;~$;/build-deb;/clean-deb;/filter-empty-entries;/make-symbols;/make-ppa;/make-deb;/debian.conf;/make-rpm;/rpm.conf;${CPACK_SOURCE_IGNORE_FILES}")
-INCLUDE(CPack)
 
 ADD_CUSTOM_TARGET(dist COMMAND ${CMAKE_MAKE_PROGRAM} clean package_source)

backends/p4tools/cmake/common.cmake

@@ -7,9 +7,6 @@ if(CCACHE_PROGRAM)
   set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
 endif()
 
-# Use libgc.
-find_package(LibGc 7.2.0 REQUIRED)
-
 # Helper for defining a p4tools executable target.
 function(add_p4tools_executable target source)
   add_executable(${target} ${source} ${ARGN})

backends/p4tools/common/control_plane/CMakeLists.txt

@@ -5,4 +5,4 @@ set(
 )
 
 add_library(p4tools-control-plane STATIC ${P4C_TOOLS_CONTROL_PLANE_SOURCES})
-target_link_libraries(p4tools-control-plane PRIVATE controlplane)
+target_link_libraries(p4tools-control-plane PRIVATE controlplane PRIVATE p4ctoolkit)

cmake/BDWGC.cmake

@@ -0,0 +1,74 @@
+macro(p4c_obtain_bdwgc)
+  option(
+    P4C_USE_PREINSTALLED_BDWGC
+    "Look for a preinstalled version of BDWGC in the system instead of installing a prebuilt binary using FetchContent."
+    OFF
+  )
+  set(LIBGC_LIBRARIES gc gccpp cord)
+  set(HAVE_LIBGC 1)
+
+  if(P4C_USE_PREINSTALLED_BDWGC)
+    option(ENABLE_MULTITHREAD "Use multithreading" OFF)
+    find_package(LibGc 7.2.0 REQUIRED)
+    check_function_exists (GC_print_stats HAVE_GC_PRINT_STATS)
+  else()
+    # Print out download state while setting up BDWGC.
+    set(FETCHCONTENT_QUIET_PREV ${FETCHCONTENT_QUIET})
+    set(BUILD_SHARED_LIBS_PREV ${BUILD_SHARED_LIBS})
+    set(FETCHCONTENT_QUIET OFF)
+
+    # BDWGC options.
+    set(BUILD_SHARED_LIBS OFF CACHE BOOL "")
+    # Turn on C++ support.
+    set(enable_cplusplus ON CACHE BOOL "C++ support")
+    set(install_headers OFF CACHE BOOL "Install header and pkg-config metadata files.")
+    set(enable_docs ${ENABLE_DOCS} CACHE BOOL "Build and install documentation.")
+    # We may have to compile very large programs which allocate a lot on the heap.
+    set(enable_large_config ON CACHE BOOL "Optimize for large heap or root set.")
+    # Redirect all malloc calls in the program.
+    set(enable_redirect_malloc OFF CACHE BOOL "Redirect malloc and friends to GC routines.")
+    # Try to enable thread-local-storage for better performance.
+    set(enable_thread_local_alloc ON CACHE BOOL "Turn on thread-local allocation optimization")
+    # Other BDWGC options to avoid crashes.
+    set(without_libatomic_ops OFF CACHE BOOL "Use atomic_ops.h in libatomic_ops/src")
+    set(enable_disclaim ON CACHE BOOL "Support alternative finalization interface")
+    set(enable_handle_fork ON CACHE BOOL "Attempt to ensure a usable collector after fork()")
+
+    fetchcontent_declare(
+      bdwgc
+      GIT_REPOSITORY https://github.com/ivmai/bdwgc.git
+      GIT_TAG e340b2e869e02718de9c9d7fa440ef4b35785388 # 8.2.6
+      GIT_PROGRESS TRUE
+      PATCH_COMMAND
+        git apply ${P4C_SOURCE_DIR}/cmake/bdwgc.patch || git apply
+        ${P4C_SOURCE_DIR}/cmake/bdwgc.patch -R --check && echo
+        "Patch does not apply because the patch was already applied."
+    )
+    fetchcontent_makeavailable_but_exclude_install(bdwgc)
+
+    # Bdwgc source code may trigger warnings which we need to ignore.
+    target_compile_options(gc PRIVATE "-Wno-error" "-w")
+    target_compile_options(gccpp PRIVATE "-Wno-error" "-w")
+    target_compile_options(cord PRIVATE "-Wno-error" "-w")
+
+    # Add some extra compile definitions which allow us to use our customizations.
+    # SKIP_CPP_DEFINITIONS to enable static linking without producing duplicate symbol errors.
+    # GC_USE_DLOPEN_WRAP needs to be enabled to handle threads correctly. This option is usually active with "enable_redirect_malloc" but we currently supply our own malloc overrides.
+    target_compile_definitions(gc PUBLIC GC_USE_DLOPEN_WRAP SKIP_CPP_DEFINITIONS)
+    target_compile_definitions(gccpp PUBLIC GC_USE_DLOPEN_WRAP SKIP_CPP_DEFINITIONS)
+
+    # Set up temporary variable modifications for check_symbol_exists.
+    set(CMAKE_REQUIRED_INCLUDES_PREV ${CMAKE_REQUIRED_INCLUDES})
+    set(CMAKE_REQUIRED_LIBRARIES_PREV ${CMAKE_REQUIRED_LIBRARIES})
+    set(CMAKE_REQUIRED_INCLUDES ${gc_SOURCE_DIR}/include)
+    set(CMAKE_REQUIRED_LIBRARIES ${LIBGC_LIBRARIES})
+    check_symbol_exists(GC_print_stats private/gc_priv.h HAVE_GC_PRINT_STATS)
+    # Reset all temporary variable modifications.
+    set(FETCHCONTENT_QUIET ${FETCHCONTENT_QUIET_PREV})
+    set(CMAKE_REQUIRED_INCLUDES ${CMAKE_REQUIRED_INCLUDES_PREV})
+    set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES_PREV})
+    set(BUILD_SHARED_LIBS ${BUILD_SHARED_LIBS_PREV} CACHE BOOL "")
+
+    message(STATUS "Done with setting up BDWGC for P4C.")
+  endif()
+endmacro(p4c_obtain_bdwgc)

cmake/bdwgc.patch

@@ -0,0 +1,13 @@
+diff --git a/gc_cpp.cc b/gc_cpp.cc
+index 341805a6..fb6b0a01 100644
+--- a/gc_cpp.cc
++++ b/gc_cpp.cc
+@@ -38,7 +38,7 @@ built-in "new" and "delete".
+ #endif
+ #include "gc_cpp.h"
+
+-#if !(defined(_MSC_VER) || defined(__DMC__)) || defined(GC_NO_INLINE_STD_NEW)
++#if !defined(SKIP_CPP_DEFINITIONS) && (!(defined(_MSC_VER) || defined(__DMC__)) || defined(GC_NO_INLINE_STD_NEW))
+
+ #if defined(GC_NEW_ABORTS_ON_OOM) || defined(_LIBCPP_NO_EXCEPTIONS)
+ # define GC_ALLOCATOR_THROW_OR_ABORT() GC_abort_on_oom()

frontends/CMakeLists.txt

@@ -239,6 +239,10 @@ add_parser(v1)
 add_parser(p4)
 
 add_library (frontend-parser-gen OBJECT ${p4PARSER_GEN_SRCS} ${v1PARSER_GEN_SRCS})
+target_link_libraries (frontend-parser-gen
+  # These libraries are exposed by a header.
+  PUBLIC p4ctoolkit
+)
 add_dependencies (frontend-parser-gen mkp4dirs mkv1dirs ir-generated)
 
 set (FRONTEND_SOURCES
@@ -259,7 +263,9 @@ if (FLEX_INCLUDE_DIRS)
 endif ()
 add_library (frontend STATIC ${FRONTEND_SOURCES})
 target_link_libraries (frontend
-  PRIVATE frontend-parser-gen
   PRIVATE absl::strings
+  # These libraries are exposed by a header.
+  PUBLIC frontend-parser-gen
   PUBLIC absl::flat_hash_set
-  PUBLIC absl::flat_hash_map)
+  PUBLIC absl::flat_hash_map
+)

ir/CMakeLists.txt

@@ -67,8 +67,7 @@ set (BASE_IR_DEF_FILES
 set (IR_DEF_FILES ${IR_DEF_FILES} ${BASE_IR_DEF_FILES} PARENT_SCOPE)
 
 add_library (ir STATIC ${IR_SRCS})
-target_link_libraries(ir
-  PRIVATE absl::flat_hash_map)
+target_link_libraries(ir PRIVATE absl::flat_hash_map ${LIBGC_LIBRARIES})
 add_dependencies(ir genIR)
 
 

ir/visitor.cpp

@@ -24,7 +24,7 @@ limitations under the License.
 #include "lib/hash.h"
 
 #if HAVE_LIBGC
-#include <gc/gc.h>
+#include <gc.h>
 #endif
 
 #include "dbprint.h"

lib/CMakeLists.txt

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-set (LIBP4CTOOLKIT_SRCS
+set(LIBP4CTOOLKIT_SRCS
     alloc_trace.cpp
     backtrace_exception.cpp
     bitrange.cpp
@@ -41,7 +41,7 @@ set (LIBP4CTOOLKIT_SRCS
     timer.cpp
 )
 
-set (LIBP4CTOOLKIT_HDRS
+set(LIBP4CTOOLKIT_HDRS
     algorithm.h
     alloc_trace.h
     backtrace_exception.h
@@ -95,4 +95,8 @@ add_library(p4ctoolkit STATIC ${LIBP4CTOOLKIT_SRCS})
 
 # Disable libcall (realloc, malloc) optimizations which may cause infinite loops.
 set_target_properties(p4ctoolkit PROPERTIES COMPILE_FLAGS -fno-builtin)
-target_link_libraries(p4ctoolkit absl::bits)
+target_link_libraries(p4ctoolkit
+  # These libraries are exposed by a header.
+  PUBLIC absl::bits
+  PUBLIC ${LIBGC_LIBRARIES}
+)

lib/bitvec.h

@@ -30,7 +30,7 @@ limitations under the License.
 #include "config.h"
 
 #if HAVE_LIBGC
-#include <gc/gc_cpp.h>
+#include <gc_cpp.h>
 #define IF_HAVE_LIBGC(X) X
 #else
 #define IF_HAVE_LIBGC(X)

lib/gc.cpp

@@ -13,6 +13,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
+#include "lib/gc.h"
 
 // Some systems (e.g. those with GNU libc) declare posix_memalign with an
 // exception specifier. Compilers (clang including) might have special handling
@@ -28,8 +29,9 @@ limitations under the License.
 #endif
 
 #if HAVE_LIBGC
-#include <gc/gc_cpp.h>
-#include <gc/gc_mark.h>
+#include <gc.h>
+#include <gc_cpp.h>
+#include <gc_mark.h>
 #endif /* HAVE_LIBGC */
 #include <sys/mman.h>
 #if HAVE_EXECINFO_H
@@ -42,14 +44,14 @@ limitations under the License.
 
 #include "backtrace_exception.h"
 #include "cstring.h"
-#include "gc.h"
 #include "log.h"
 #include "n4.h"
 
 // One can disable the GC, e.g., to run under Valgrind, by editing config.h or toggling
 // -DENABLE_GC=OFF in CMake.
 #if HAVE_LIBGC
 static bool done_init, started_init;
+
 // emergency pool to allow a few extra allocations after a bad_alloc is thrown so we
 // can generate reasonable errors, a stack trace, etc
 static char emergency_pool[16 * 1024];
@@ -152,15 +154,14 @@ alloc_trace_cb_t set_alloc_trace(void (*fn)(void *, void **, size_t), void *arg)
     return old;
 }
 
-// clang-format off
-void operator delete(void* p) noexcept {
+void operator delete(void *p) noexcept {
     if (p >= emergency_pool && p < emergency_pool + sizeof(emergency_pool)) {
         return;
     }
     gc::operator delete(p);
 }
 
-void operator delete(void* p, std::size_t /*size*/) noexcept {
+void operator delete(void *p, std::size_t /*size*/) noexcept {
     if (p >= emergency_pool && p < emergency_pool + sizeof(emergency_pool)) {
         return;
     }
@@ -169,14 +170,11 @@ void operator delete(void* p, std::size_t /*size*/) noexcept {
 
 // FIXME: We can get rid of GC_base here with suitable new libgc
 // See https://github.com/ivmai/bdwgc/issues/589 for more info
-void operator delete(void *p, std::align_val_t) noexcept {
-    gc::operator delete(GC_base(p));
-}
+void operator delete(void *p, std::align_val_t) noexcept { gc::operator delete(GC_base(p)); }
 
 void operator delete(void *p, std::size_t, std::align_val_t) noexcept {
     gc::operator delete(GC_base(p));
 }
-// clang-format on
 
 void *operator new[](std::size_t size) { return ::operator new(size); }
 void *operator new[](std::size_t size, std::align_val_t alignment) {

lib/indent.cpp

@@ -16,7 +16,7 @@ limitations under the License.
 
 #include "config.h"
 #if HAVE_LIBGC
-#include <gc/gc_cpp.h>
+#include <gc_cpp.h>
 #define NOGC_ARGS (NoGC, 0, 0)
 #else
 #define NOGC_ARGS

lib/log.cpp

@@ -16,7 +16,7 @@ limitations under the License.
 
 #include "config.h"
 #if HAVE_LIBGC
-#include <gc/gc_cpp.h>
+#include <gc_cpp.h>
 #define NOGC_ARGS (NoGC, 0, 0)
 #else
 #define NOGC_ARGS