Initial revision

1 files changed, 280 insertions, 0 deletions

diff --git a/gc/gc_mark.h b/gc/gc_mark.h
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+/*
+ * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose,  provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+ */
+/* Boehm, November 7, 1994 4:56 pm PST */
+
+/*
+ * Declarations of mark stack.  Needed by marker and client supplied mark
+ * routines.  To be included after gc_priv.h.
+ */
+#ifndef GC_MARK_H
+# define GC_MARK_H
+
+/* A client supplied mark procedure.  Returns new mark stack pointer.	*/
+/* Primary effect should be to push new entries on the mark stack.	*/
+/* Mark stack pointer values are passed and returned explicitly.	*/
+/* Global variables decribing mark stack are not necessarily valid.	*/
+/* (This usually saves a few cycles by keeping things in registers.)	*/
+/* Assumed to scan about PROC_BYTES on average.  If it needs to do	*/
+/* much more work than that, it should do it in smaller pieces by	*/
+/* pushing itself back on the mark stack.				*/
+/* Note that it should always do some work (defined as marking some	*/
+/* objects) before pushing more than one entry on the mark stack.	*/
+/* This is required to ensure termination in the event of mark stack	*/
+/* overflows.								*/
+/* This procedure is always called with at least one empty entry on the */
+/* mark stack.								*/
+/* Currently we require that mark procedures look for pointers in a	*/
+/* subset of the places the conservative marker would.  It must be safe	*/
+/* to invoke the normal mark procedure instead.				*/
+# define PROC_BYTES 100
+/* The real declarations of the following are in gc_priv.h, so that	*/
+/* we can avoid scanning the following table.				*/
+/*
+typedef struct ms_entry * (*mark_proc)(   word * addr, mark_stack_ptr,
+					  mark_stack_limit, env   );
+					  
+# define LOG_MAX_MARK_PROCS 6
+# define MAX_MARK_PROCS (1 << LOG_MAX_MARK_PROCS)
+extern mark_proc GC_mark_procs[MAX_MARK_PROCS];
+*/
+
+extern word GC_n_mark_procs;
+
+/* Object descriptors on mark stack or in objects.  Low order two	*/
+/* bits are tags distinguishing among the following 4 possibilities	*/
+/* for the high order 30 bits.						*/
+#define DS_TAG_BITS 2
+#define DS_TAGS   ((1 << DS_TAG_BITS) - 1)
+#define DS_LENGTH 0	/* The entire word is a length in bytes that	*/
+			/* must be a multiple of 4.			*/
+#define DS_BITMAP 1	/* 30 bits are a bitmap describing pointer	*/
+			/* fields.  The msb is 1 iff the first word	*/
+			/* is a pointer.				*/
+			/* (This unconventional ordering sometimes	*/
+			/* makes the marker slightly faster.)		*/
+			/* Zeroes indicate definite nonpointers.  Ones	*/
+			/* indicate possible pointers.			*/
+			/* Only usable if pointers are word aligned.	*/
+#   define BITMAP_BITS (WORDSZ - DS_TAG_BITS)
+#define DS_PROC   2
+			/* The objects referenced by this object can be */
+			/* pushed on the mark stack by invoking		*/
+			/* PROC(descr).  ENV(descr) is passed as the	*/
+			/* last argument.				*/
+#   define PROC(descr) \
+		(GC_mark_procs[((descr) >> DS_TAG_BITS) & (MAX_MARK_PROCS-1)])
+#   define ENV(descr) \
+		((descr) >> (DS_TAG_BITS + LOG_MAX_MARK_PROCS))
+#   define MAX_ENV \
+  	      (((word)1 << (WORDSZ - DS_TAG_BITS - LOG_MAX_MARK_PROCS)) - 1)
+#   define MAKE_PROC(proc_index, env) \
+	    (((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \
+	    | DS_PROC)
+#define DS_PER_OBJECT 3	/* The real descriptor is at the		*/
+			/* byte displacement from the beginning of the	*/
+			/* object given by descr & ~DS_TAGS		*/
+			
+typedef struct ms_entry {
+    word * mse_start;   /* First word of object */
+    word mse_descr;	/* Descriptor; low order two bits are tags,	*/
+    			/* identifying the upper 30 bits as one of the	*/
+    			/* following:					*/
+} mse;
+
+extern word GC_mark_stack_size;
+
+extern mse * GC_mark_stack_top;
+
+extern mse * GC_mark_stack;
+
+word GC_find_start();
+
+mse * GC_signal_mark_stack_overflow();
+
+# ifdef GATHERSTATS
+#   define ADD_TO_ATOMIC(sz) GC_atomic_in_use += (sz)
+#   define ADD_TO_COMPOSITE(sz) GC_composite_in_use += (sz)
+# else
+#   define ADD_TO_ATOMIC(sz)
+#   define ADD_TO_COMPOSITE(sz)
+# endif
+
+/* Push the object obj with corresponding heap block header hhdr onto 	*/
+/* the mark stack.							*/
+# define PUSH_OBJ(obj, hhdr, mark_stack_top, mark_stack_limit) \
+{ \
+    register word _descr = (hhdr) -> hb_descr; \
+        \
+    if (_descr == 0) { \
+    	ADD_TO_ATOMIC((hhdr) -> hb_sz); \
+    } else { \
+        ADD_TO_COMPOSITE((hhdr) -> hb_sz); \
+        mark_stack_top++; \
+        if (mark_stack_top >= mark_stack_limit) { \
+          mark_stack_top = GC_signal_mark_stack_overflow(mark_stack_top); \
+        } \
+        mark_stack_top -> mse_start = (obj); \
+        mark_stack_top -> mse_descr = _descr; \
+    } \
+}
+
+#ifdef PRINT_BLACK_LIST
+#   define GC_FIND_START(current, hhdr, source) \
+	GC_find_start(current, hhdr, source)
+#else
+#   define GC_FIND_START(current, hhdr, source) \
+	GC_find_start(current, hhdr)
+#endif
+
+/* Push the contents of current onto the mark stack if it is a valid	*/
+/* ptr to a currently unmarked object.  Mark it.			*/
+/* If we assumed a standard-conforming compiler, we could probably	*/
+/* generate the exit_label transparently.				*/
+# define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \
+		       source, exit_label) \
+{ \
+    register int displ;  /* Displacement in block; first bytes, then words */ \
+    register hdr * hhdr; \
+    register map_entry_type map_entry; \
+    \
+    GET_HDR(current,hhdr); \
+    if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { \
+         current = GC_FIND_START(current, hhdr, (word)source); \
+         if (current == 0) goto exit_label; \
+         hhdr = HDR(current); \
+    } \
+    displ = HBLKDISPL(current); \
+    map_entry = MAP_ENTRY((hhdr -> hb_map), displ); \
+    if (map_entry == OBJ_INVALID) { \
+        GC_ADD_TO_BLACK_LIST_NORMAL(current, source); goto exit_label; \
+    } \
+    displ = BYTES_TO_WORDS(displ); \
+    displ -= map_entry; \
+	\
+    { \
+        register word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(displ); \
+        register word mark_word = *mark_word_addr; \
+        register word mark_bit = (word)1 << modWORDSZ(displ); \
+          \
+        if (mark_word & mark_bit) { \
+	      /* Mark bit is already set */ \
+	      goto exit_label; \
+        } \
+        GC_STORE_BACK_PTR((ptr_t)source, (ptr_t)HBLKPTR(current) \
+				      + WORDS_TO_BYTES(displ)); \
+        *mark_word_addr = mark_word | mark_bit; \
+    } \
+    PUSH_OBJ(((word *)(HBLKPTR(current)) + displ), hhdr, \
+    	     mark_stack_top, mark_stack_limit) \
+  exit_label: ; \
+}
+
+#ifdef PRINT_BLACK_LIST
+#   define PUSH_ONE_CHECKED(p, ip, source) \
+	GC_push_one_checked(p, ip, (ptr_t)(source))
+#else
+#   define PUSH_ONE_CHECKED(p, ip, source) \
+	GC_push_one_checked(p, ip)
+#endif
+
+/*
+ * Push a single value onto mark stack. Mark from the object pointed to by p.
+ * P is considered valid even if it is an interior pointer.
+ * Previously marked objects are not pushed.  Hence we make progress even
+ * if the mark stack overflows.
+ */
+# define GC_PUSH_ONE_STACK(p, source) \
+    if ((ptr_t)(p) >= GC_least_plausible_heap_addr 	\
+	 && (ptr_t)(p) < GC_greatest_plausible_heap_addr) {	\
+	 PUSH_ONE_CHECKED(p, TRUE, source);	\
+    }
+
+/*
+ * As above, but interior pointer recognition as for
+ * normal for heap pointers.
+ */
+# ifdef ALL_INTERIOR_POINTERS
+#   define AIP TRUE
+# else
+#   define AIP FALSE
+# endif
+# define GC_PUSH_ONE_HEAP(p,source) \
+    if ((ptr_t)(p) >= GC_least_plausible_heap_addr 	\
+	 && (ptr_t)(p) < GC_greatest_plausible_heap_addr) {	\
+	 PUSH_ONE_CHECKED(p,AIP,source);	\
+    }
+
+/*
+ * Mark from one finalizable object using the specified
+ * mark proc. May not mark the object pointed to by 
+ * real_ptr. That is the job of the caller, if appropriate
+ */
+# define GC_MARK_FO(real_ptr, mark_proc) \
+{ \
+    (*(mark_proc))(real_ptr); \
+    while (!GC_mark_stack_empty()) GC_mark_from_mark_stack(); \
+    if (GC_mark_state != MS_NONE) { \
+        GC_set_mark_bit(real_ptr); \
+        while (!GC_mark_some((ptr_t)0)); \
+    } \
+}
+
+extern GC_bool GC_mark_stack_too_small;
+				/* We need a larger mark stack.  May be	*/
+				/* set by client supplied mark routines.*/
+
+typedef int mark_state_t;	/* Current state of marking, as follows:*/
+				/* Used to remember where we are during */
+				/* concurrent marking.			*/
+
+				/* We say something is dirty if it was	*/
+				/* written since the last time we	*/
+				/* retrieved dirty bits.  We say it's 	*/
+				/* grungy if it was marked dirty in the	*/
+				/* last set of bits we retrieved.	*/
+				
+				/* Invariant I: all roots and marked	*/
+				/* objects p are either dirty, or point */
+				/* to objects q that are either marked 	*/
+				/* or a pointer to q appears in a range	*/
+				/* on the mark stack.			*/
+
+# define MS_NONE 0		/* No marking in progress. I holds.	*/
+				/* Mark stack is empty.			*/
+
+# define MS_PUSH_RESCUERS 1	/* Rescuing objects are currently 	*/
+				/* being pushed.  I holds, except	*/
+				/* that grungy roots may point to 	*/
+				/* unmarked objects, as may marked	*/
+				/* grungy objects above scan_ptr.	*/
+
+# define MS_PUSH_UNCOLLECTABLE 2
+				/* I holds, except that marked 		*/
+				/* uncollectable objects above scan_ptr */
+				/* may point to unmarked objects.	*/
+				/* Roots may point to unmarked objects	*/
+
+# define MS_ROOTS_PUSHED 3	/* I holds, mark stack may be nonempty  */
+
+# define MS_PARTIALLY_INVALID 4	/* I may not hold, e.g. because of M.S. */
+				/* overflow.  However marked heap	*/
+				/* objects below scan_ptr point to	*/
+				/* marked or stacked objects.		*/
+
+# define MS_INVALID 5		/* I may not hold.			*/
+
+extern mark_state_t GC_mark_state;
+
+#endif  /* GC_MARK_H */
+