Decoupling MMTk from the code and adding it as a third-party heap option

Make.inc

@@ -80,9 +80,6 @@ HAVE_SSP := 0
 WITH_GC_VERIFY := 0
 WITH_GC_DEBUG_ENV := 0
 
-# Use stock if MMTK_PLAN hasn't been defined
-MMTK_PLAN ?= None
-
 # Enable DTrace support
 WITH_DTRACE := 0
 
@@ -836,34 +833,42 @@ JCXXFLAGS += -DGC_DEBUG_ENV
 JCFLAGS += -DGC_DEBUG_ENV
 endif
 
-ifneq (${MMTK_PLAN},None)
-JCXXFLAGS += -DMMTK_GC
-JCFLAGS += -DMMTK_GC
-# Do a release build on the binding by default
-MMTK_BUILD ?= release
+# By default we use the stock GC
+WITH_THIRD_PARTY_GC ?= 0
+
+# Convert to lowercase
+USE_THIRD_PARTY_GC := $(shell echo $(WITH_THIRD_PARTY_GC) | tr A-Z a-z)
+
+# NB: When adding a new GC, make sure to add -DWITH_THIRD_PARTY_HEAP=<#NEW_GC>
+# to the variables JCFLAGS and JCXXFLAGS according to the mapping (MMTK=1, #NEW_GC=2)
+
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
+JCXXFLAGS += -DWITH_THIRD_PARTY_HEAP=1
+JCFLAGS += -DWITH_THIRD_PARTY_HEAP=1
+
+# Must specify a supported MMTk Plan: Immix or StickyImmix
 ifeq (${MMTK_PLAN},Immix)
 JCXXFLAGS += -DMMTK_PLAN_IMMIX
 JCFLAGS += -DMMTK_PLAN_IMMIX
 else ifeq (${MMTK_PLAN},StickyImmix)
 JCXXFLAGS += -DMMTK_PLAN_STICKYIMMIX
 JCFLAGS += -DMMTK_PLAN_STICKYIMMIX
 else
-$(error "Unsupported MMTk plan: $(MMTK_PLAN)")
+$(error "Unsupported MMTk plan: $(MMTK_PLAN). Supported plans: Immix or StickyImmix.")
 endif
 
+# Do a release build on the binding by default
+MMTK_BUILD ?= release
+
 # Location of mmtk-julia binding
 # (needed for api/*.h and .so file)
 MMTK_JULIA_DIR ?= $(BUILDROOT)/usr/lib/mmtk_julia
-
 MMTK_DIR = ${MMTK_JULIA_DIR}/mmtk
 MMTK_API_INC = ${MMTK_DIR}/api
-
 MMTK_LIB := -lmmtk_julia
-else
-MMTK_JULIA_INC :=
-MMTK_LIB :=
 endif
 
+
 ifeq ($(WITH_DTRACE), 1)
 JCXXFLAGS += -DUSE_DTRACE
 JCFLAGS += -DUSE_DTRACE
@@ -964,19 +969,17 @@ ARCH := $(BUILD_OS)
 endif
 endif
 
-# MMTk is only available on x86_64 Linux for now
-ifneq (${MMTK_PLAN},None)
 
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
+# MMTk is only available on x86_64 Linux for now
 ifeq ($(OS),Linux)
 MMTK_LIB_NAME := libmmtk_julia.so
 else
 $(error "Unsupported OS for MMTk")
 endif
-
 ifneq ($(ARCH),x86_64)
 $(error "Unsupported build architecture for MMTk")
 endif
-
 endif
 
 # Detect common pre-SSE2 JULIA_CPU_TARGET values known not to work (#7185)
@@ -1405,7 +1408,12 @@ CSL_NEXT_GLIBCXX_VERSION=GLIBCXX_3\.4\.34|GLIBCXX_3\.5\.|GLIBCXX_4\.
 # Note: we explicitly _do not_ define `CSL` here, since it requires some more
 # advanced techniques to decide whether it should be installed from a BB source
 # or not.  See `deps/csl.mk` for more detail.
-BB_PROJECTS := BLASTRAMPOLINE OPENBLAS LLVM LIBSUITESPARSE OPENLIBM GMP OPENSSL LIBSSH2 NGHTTP2 MPFR CURL LIBGIT2 PCRE LIBUV LIBUNWIND DSFMT OBJCONV ZLIB P7ZIP LLD LIBTRACYCLIENT BOLT MMTK_JULIA
+BB_PROJECTS := BLASTRAMPOLINE OPENBLAS LLVM LIBSUITESPARSE OPENLIBM GMP OPENSSL LIBSSH2 NGHTTP2 MPFR CURL LIBGIT2 PCRE LIBUV LIBUNWIND DSFMT OBJCONV ZLIB P7ZIP LLD LIBTRACYCLIENT BOLT
+
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
+BB_PROJECTS += MMTK_JULIA
+endif
+
 define SET_BB_DEFAULT
 # First, check to see if BB is disabled on a global setting
 ifeq ($$(USE_BINARYBUILDER),0)

Makefile

@@ -281,7 +281,7 @@ endif
 endif
 endif
 
-ifneq (${MMTK_PLAN},None)
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
 # Make sure we use the right version of $MMTK_PLAN, $MMTK_MOVING and $MMTK_BUILD
 # if we use the BinaryBuilder version of mmtk-julia
 ifeq ($(USE_BINARYBUILDER_MMTK_JULIA),1)
@@ -291,10 +291,10 @@ else ifeq (${MMTK_PLAN},StickyImmix)
 LIB_PATH_PLAN = sticky
 endif
 
-ifeq ($(MMTK_MOVING), 0)
-LIB_PATH_MOVING := non_moving
-else
+ifeq ($(MMTK_MOVING), 1)
 LIB_PATH_MOVING := moving
+else
+LIB_PATH_MOVING := non_moving
 endif
 
 JL_PRIVATE_LIBS-0 += $(LIB_PATH_PLAN)/$(LIB_PATH_MOVING)/$(MMTK_BUILD)/libmmtk_julia

deps/Makefile

@@ -195,7 +195,7 @@ DEP_LIBS += libwhich
 endif
 endif
 
-ifneq (${MMTK_PLAN},None)
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
 DEP_LIBS += mmtk_julia
 endif
 

doc/src/devdocs/gc-mmtk.md

@@ -1,26 +1,23 @@
 # Julia + MMTk
 
-There has been quite a lot of effort to refactor the GC code inside Julia to support external GCs. The first step to enable using different GC algorithms for Julia was the design and implementation of a [GC interface](https://docs.google.com/document/d/1v0jtSrIpdEDNOxj5S9g1jPqSpuAkNWhr_T8ToFC9RLI/edit?usp=sharing). To drive that interface, we added support for building Julia with [MMTk](https://www.mmtk.io). MMTk is a memory management toolkit providing language implementers with a framework to implement flexible and performant GCs. The flexibility comes from the fact that it is possible to switch implementations fairly easily. MMTk supports state-of-the-art high-performance implementations that are continuously added and maintained in the core part of the framework. MMTk is under active development and has been used by other programming languages such as [Java](https://github.com/mmtk/mmtk-openjdk) and [Ruby](https://github.com/ruby/mmtk). To support a language, it is necessary to implement an *MMTk binding*, which contains the code that connects the language to [mmtk-core](https://github.com/mmtk/mmtk-core). The mmtk-julia binding can be found in [this repository](https://github.com/mmtk/mmtk-julia).
+There has been quite a lot of effort to refactor the GC code inside Julia to support external GCs. The first step to enable using different GC algorithms for Julia was the design and implementation of a [GC interface](https://docs.google.com/document/d/1v0jtSrIpdEDNOxj5S9g1jPqSpuAkNWhr_T8ToFC9RLI/edit?usp=sharing). To drive that interface, we added support for building Julia with [MMTk](https://www.mmtk.io) (Memory Management Toolkit). Using Julia + MMTk enables testing different GC implementations, allowing developers to choose a specific implementation when building Julia from source. The connection between Julia and MMTk is done via a *binding*, which links the language runtime with MMTk core. The mmtk-julia binding is written in Rust and can be found in [this repository](https://github.com/mmtk/mmtk-julia).
 
 > [!NOTE]
 > Using a different GC requires building Julia from source. It is not possible to switch implementations at runtime. To see what version of the GC is currently being used, run `versioninfo()` from the Julia REPL and it should show the version under `GC: ...`.
 
 ## Building Julia with MMTk
 
-There are 3 different ways of building Julia with MMTk: building from source using a fixed release of the binding, checking out a custom version in the mmtk-julia [repository](https://github.com/mmtk/mmtk-julia) or using a precompiled binary from Julia's BinaryBuilder. The easiest way is to use the BinaryBuilder binary. Simply set the variable `MMTK_PLAN` to one of the supported plans below and build Julia as usual.
+There are 3 different ways of building Julia with MMTk: building from source using a fixed release of the binding, checking out a custom version in the mmtk-julia [repository](https://github.com/mmtk/mmtk-julia) or using a precompiled binary from Julia's BinaryBuilder. The easiest way is to use the BinaryBuilder binary. First, to enable MMTk as a third-party GC, set the variable `WITH_THIRD_PARTY_GC` to `mmtk`. Then, for example, to use the Immix as the GC, simply set the variable `MMTK_PLAN=Immix` and build Julia as usual.
 
-There are different configurations supported by the following variables, which can be set in a `Make.user` file or as an environment variable.
+There are different configurations supported by the following variables, which can be set in a `Make.user` file or as an environment variable. Note that at this time, setting `MMTK_PLAN=StickyImmix` (to use a generational version of Immix) or `MMTK_MOVING=1` (to enable object movement) will likely cause segmentation faults or other build failures, since we have not added support for these configurations yet.
 
 | Variable      |       |        |
 |---------------|--------------|---------------|
 | `MMTK_PLAN`     | Immix        | StickyImmix   |
 | `MMTK_MOVING`   | 0            | 1             |
 | `MMTK_BUILD`    | release      | debug         |
 
-If only `MMTK_PLAN` is set, then the default is to do a non-moving, release build.
-
-> [!IMPORTANT]
-> While the binding supports building all versions above, we have only integrated non-moving Immix into Julia. Support for the other versions should be added in the near future.
+Note that when setting only `MMTK_PLAN`, then the default is to do a non-moving, release build.
 
 ### Building mmtk-julia from source
 

src/Makefile

@@ -29,7 +29,7 @@ ifeq ($(USECLANG),1)
 FLAGS += -Wno-return-type-c-linkage -Wno-atomic-alignment
 endif
 
-ifneq (${MMTK_PLAN},None)
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
 FLAGS += -I$(MMTK_API_INC)
 endif
 
@@ -46,7 +46,7 @@ endif
 
 # GC source code. It depends on which GC implementation to use.
 GC_SRCS := gc-common gc-stacks gc-alloc-profiler gc-heap-snapshot
-ifneq (${MMTK_PLAN},None)
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
 GC_SRCS += gc-mmtk
 else
 GC_SRCS += gc-stock gc-debug gc-pages gc-page-profiler
@@ -67,7 +67,7 @@ CG_LLVMLINK :=
 ifeq ($(JULIACODEGEN),LLVM)
 # Currently these files are used by both GCs. But we should make the list specific to stock, and MMTk should have its own implementation.
 GC_CODEGEN_SRCS := llvm-final-gc-lowering llvm-late-gc-lowering llvm-gc-invariant-verifier
-ifneq (${MMTK_PLAN},None)
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
 FLAGS += -I$(MMTK_API_INC)
 GC_CODEGEN_SRCS += llvm-late-gc-lowering-mmtk
 else
@@ -122,7 +122,7 @@ UV_HEADERS += uv.h
 UV_HEADERS += uv/*.h
 endif
 PUBLIC_HEADERS := $(BUILDDIR)/julia_version.h $(wildcard $(SRCDIR)/support/*.h) $(addprefix $(SRCDIR)/,work-stealing-queue.h gc-interface.h gc-tls-common.h julia.h julia_assert.h julia_threads.h julia_fasttls.h julia_locks.h julia_atomics.h jloptions.h)
-ifneq (${MMTK_PLAN},None)
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
 	PUBLIC_HEADERS += $(addprefix $(SRCDIR)/,gc-tls-mmtk.h)
 else
 	PUBLIC_HEADERS += $(addprefix $(SRCDIR)/,gc-tls-stock.h)
@@ -191,8 +191,14 @@ LIBJULIA_PATH_REL := libjulia
 endif
 
 COMMON_LIBPATHS := -L$(build_libdir) -L$(build_shlibdir)
-RT_LIBS := $(WHOLE_ARCHIVE) $(LIBUV) $(WHOLE_ARCHIVE) $(LIBUTF8PROC) $(NO_WHOLE_ARCHIVE) $(LIBUNWIND) $(RT_LLVMLINK) $(OSLIBS) $(LIBTRACYCLIENT) $(LIBITTAPI) $(MMTK_LIB)
-CG_LIBS := $(LIBUNWIND) $(CG_LLVMLINK) $(OSLIBS) $(LIBTRACYCLIENT) $(LIBITTAPI) $(MMTK_LIB)
+RT_LIBS := $(WHOLE_ARCHIVE) $(LIBUV) $(WHOLE_ARCHIVE) $(LIBUTF8PROC) $(NO_WHOLE_ARCHIVE) $(LIBUNWIND) $(RT_LLVMLINK) $(OSLIBS) $(LIBTRACYCLIENT) $(LIBITTAPI)
+CG_LIBS := $(LIBUNWIND) $(CG_LLVMLINK) $(OSLIBS) $(LIBTRACYCLIENT) $(LIBITTAPI)
+
+ifeq (${USE_THIRD_PARTY_GC},mmtk)
+RT_LIBS += $(MMTK_LIB)
+CG_LIBS += $(MMTK_LIB)
+endif
+
 RT_DEBUG_LIBS := $(COMMON_LIBPATHS) $(WHOLE_ARCHIVE) $(BUILDDIR)/flisp/libflisp-debug.a $(WHOLE_ARCHIVE) $(BUILDDIR)/support/libsupport-debug.a -ljulia-debug $(RT_LIBS)
 CG_DEBUG_LIBS := $(COMMON_LIBPATHS) $(CG_LIBS) -ljulia-debug -ljulia-internal-debug
 RT_RELEASE_LIBS := $(COMMON_LIBPATHS) $(WHOLE_ARCHIVE) $(BUILDDIR)/flisp/libflisp.a $(WHOLE_ARCHIVE) $(BUILDDIR)/support/libsupport.a -ljulia $(RT_LIBS)

src/julia_threads.h

@@ -4,11 +4,16 @@
 #ifndef JL_THREADS_H
 #define JL_THREADS_H
 
-#ifndef MMTK_GC
+#ifndef WITH_THIRD_PARTY_HEAP
 #include "gc-tls-stock.h"
 #else
+// Pick the appropriate third-party implementation
+#ifdef WITH_THIRD_PARTY_HEAP
+#if WITH_THIRD_PARTY_HEAP == 1
 #include "gc-tls-mmtk.h"
 #endif
+#endif
+#endif
 #include "gc-tls-common.h"
 #include "julia_atomics.h"
 #ifndef _OS_WINDOWS_