Add an build-time flag to transitively pin roots (#60)

Make.inc

@@ -747,22 +747,27 @@ JCFLAGS += -DGC_FIXED_HEAP
 endif
 
 ifeq ($(WITH_MMTK), 1)
+
 ifeq (${MMTK_JULIA_DIR},)
 $(error MMTK_JULIA_DIR must be set to use MMTk)
 endif
+
 JCXXFLAGS += -DMMTK_GC
 JCFLAGS += -DMMTK_GC
+
 ifeq (${MMTK_BUILD},)
 ifeq (debug,$(findstring debug,$(MAKECMDGOALS)))
 MMTK_BUILD = debug
 else
 MMTK_BUILD = release
 endif
 endif
+
 ifeq (${MMTK_PLAN},Immix)
 JCXXFLAGS += -DMMTK_PLAN_IMMIX
 JCFLAGS += -DMMTK_PLAN_IMMIX
 endif
+
 ifeq (${MMTK_PLAN},StickyImmix)
 JCXXFLAGS += -DMMTK_PLAN_STICKYIMMIX
 JCFLAGS += -DMMTK_PLAN_STICKYIMMIX
@@ -774,15 +779,23 @@ endif
 MMTK_DIR = ${MMTK_JULIA_DIR}/mmtk
 MMTK_API_INC = $(MMTK_DIR)/api
 MMTK_JULIA_INC = ${MMTK_JULIA_DIR}/julia
+
 ifeq ($(OS),Linux)
 MMTK_LIB_NAME := libmmtk_julia.so
 else
 $(error "Unsupported OS for MMTk")
 endif
+
 MMTK_LIB_SRC := $(MMTK_DIR)/target/$(MMTK_BUILD)/$(MMTK_LIB_NAME)
 MMTK_LIB_DST := $(BUILDROOT)/usr/lib/$(MMTK_LIB_NAME)
 MMTK_LIB := -lmmtk_julia
 LDFLAGS += -Wl,-rpath=$(BUILDROOT)/usr/lib/ -L$(BUILDROOT)/usr/lib/
+
+ifeq (${MMTK_TPIN_ROOTS}, 1)
+JCXXFLAGS += -DMMTK_TPIN_ROOTS
+JCFLAGS += -DMMTK_TPIN_ROOTS
+endif
+
 else
 MMTK_JULIA_INC :=
 MMTK_LIB :=

src/interpreter.c

@@ -52,7 +52,11 @@ extern void JL_GC_ENABLEFRAME(interpreter_state*) JL_NOTSAFEPOINT;
 #else
 
 #ifdef MMTK_GC
+#ifdef MMTK_TPIN_ROOTS
 #define JL_GC_ENCODE_PUSHFRAME(n)  ((((size_t)(n))<<3)|2)
+#else
+#define JL_GC_ENCODE_PUSHFRAME(n)  JL_GC_ENCODE_PUSHFRAME_NO_TPIN(n)
+#endif
 // For roots that are not transitively pinned
 #define JL_GC_ENCODE_PUSHFRAME_NO_TPIN(n)  ((((size_t)(n))<<3)|6)
 #else

src/julia.h

@@ -885,13 +885,20 @@ struct _jl_gcframe_t {
 // #define JL_GC_ENCODE_PUSH_NO_TPIN(n)       ((((size_t)(n))<<3)|5)
 // #define JL_GC_ENCODE_PUSHFRAME_NO_TPIN(n)  ((((size_t)(n))<<3)|6)
 
+#ifdef MMTK_TPIN_ROOTS
 // these are transitively pinning
 #define JL_GC_ENCODE_PUSHARGS(n)   (((size_t)(n))<<3)
 #define JL_GC_ENCODE_PUSH(n)       ((((size_t)(n))<<3)|1)
-
 // these only pin the root object itself
 #define JL_GC_ENCODE_PUSHARGS_NO_TPIN(n)   (((size_t)(n))<<3|4)
 #define JL_GC_ENCODE_PUSH_NO_TPIN(n)       ((((size_t)(n))<<3)|5)
+#else
+// No transitive pin
+#define JL_GC_ENCODE_PUSHARGS_NO_TPIN(n)   (((size_t)(n))<<3|4)
+#define JL_GC_ENCODE_PUSH_NO_TPIN(n)       ((((size_t)(n))<<3)|5)
+#define JL_GC_ENCODE_PUSHARGS(n)           JL_GC_ENCODE_PUSHARGS_NO_TPIN(n)
+#define JL_GC_ENCODE_PUSH(n)               JL_GC_ENCODE_PUSH_NO_TPIN(n)
+#endif
 #endif
 
 #ifdef __clang_gcanalyzer__