Initial revision

gc/obj_map.c

@@ -0,0 +1,142 @@
+/* 
+ * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
+ * Copyright (c) 1991, 1992 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, October 9, 1995 1:09 pm PDT */
+  
+/* Routines for maintaining maps describing heap block
+ * layouts for various object sizes.  Allows fast pointer validity checks
+ * and fast location of object start locations on machines (such as SPARC)
+ * with slow division.
+ */
+ 
+# include "gc_priv.h"
+
+char * GC_invalid_map = 0;
+
+/* Invalidate the object map associated with a block.	Free blocks	*/
+/* are identified by invalid maps.					*/
+void GC_invalidate_map(hhdr)
+hdr *hhdr;
+{
+    register int displ;
+    
+    if (GC_invalid_map == 0) {
+        GC_invalid_map = GC_scratch_alloc(MAP_SIZE);
+        if (GC_invalid_map == 0) {
+            GC_err_printf0(
+            	"Cant initialize GC_invalid_map: insufficient memory\n");
+            EXIT();
+        }
+        for (displ = 0; displ < HBLKSIZE; displ++) {
+            MAP_ENTRY(GC_invalid_map, displ) = OBJ_INVALID;
+        }
+    }
+    hhdr -> hb_map = GC_invalid_map;
+}
+
+/* Consider pointers that are offset bytes displaced from the beginning */
+/* of an object to be valid.                                            */
+
+# if defined(__STDC__) || defined(__cplusplus)
+    void GC_register_displacement(GC_word offset)
+# else
+    void GC_register_displacement(offset) 
+    GC_word offset;
+# endif
+{
+# ifndef ALL_INTERIOR_POINTERS
+    DCL_LOCK_STATE;
+    
+    DISABLE_SIGNALS();
+    LOCK();
+    GC_register_displacement_inner(offset);
+    UNLOCK();
+    ENABLE_SIGNALS();
+# endif
+}
+
+void GC_register_displacement_inner(offset) 
+word offset;
+{
+# ifndef ALL_INTERIOR_POINTERS
+    register unsigned i;
+    
+    if (offset > MAX_OFFSET) {
+        ABORT("Bad argument to GC_register_displacement");
+    }
+    if (!GC_valid_offsets[offset]) {
+      GC_valid_offsets[offset] = TRUE;
+      GC_modws_valid_offsets[offset % sizeof(word)] = TRUE;
+      for (i = 0; i <= MAXOBJSZ; i++) {
+          if (GC_obj_map[i] != 0) {
+             if (i == 0) {
+               GC_obj_map[i][offset + HDR_BYTES] = (char)BYTES_TO_WORDS(offset);
+             } else {
+               register unsigned j;
+               register unsigned lb = WORDS_TO_BYTES(i);
+               
+               if (offset < lb) {
+                 for (j = offset + HDR_BYTES; j < HBLKSIZE; j += lb) {
+                   GC_obj_map[i][j] = (char)BYTES_TO_WORDS(offset);
+                 }
+               }
+             }
+          }
+      }
+    }
+# endif
+}
+
+
+/* Add a heap block map for objects of size sz to obj_map.	*/
+/* Return FALSE on failure.					*/
+GC_bool GC_add_map_entry(sz)
+word sz;
+{
+    register unsigned obj_start;
+    register unsigned displ;
+    register char * new_map;
+    
+    if (sz > MAXOBJSZ) sz = 0;
+    if (GC_obj_map[sz] != 0) {
+        return(TRUE);
+    }
+    new_map = GC_scratch_alloc(MAP_SIZE);
+    if (new_map == 0) return(FALSE);
+#   ifdef PRINTSTATS
+        GC_printf1("Adding block map for size %lu\n", (unsigned long)sz);
+#   endif
+    for (displ = 0; displ < HBLKSIZE; displ++) {
+        MAP_ENTRY(new_map,displ) = OBJ_INVALID;
+    }
+    if (sz == 0) {
+        for(displ = 0; displ <= MAX_OFFSET; displ++) {
+            if (OFFSET_VALID(displ)) {
+                MAP_ENTRY(new_map,displ+HDR_BYTES) = BYTES_TO_WORDS(displ);
+            }
+        }
+    } else {
+        for (obj_start = HDR_BYTES;
+             obj_start + WORDS_TO_BYTES(sz) <= HBLKSIZE;
+             obj_start += WORDS_TO_BYTES(sz)) {
+             for (displ = 0; displ < WORDS_TO_BYTES(sz); displ++) {
+                 if (OFFSET_VALID(displ)) {
+                     MAP_ENTRY(new_map, obj_start + displ) =
+                     				BYTES_TO_WORDS(displ);
+                 }
+             }
+        }
+    }
+    GC_obj_map[sz] = new_map;
+    return(TRUE);
+}