Initial revision

gc/checksums.c

@@ -0,0 +1,201 @@
+/*
+ * Copyright (c) 1992-1994 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, March 29, 1995 12:51 pm PST */
+# ifdef CHECKSUMS
+
+# include "gc_priv.h"
+
+/* This is debugging code intended to verify the results of dirty bit	*/
+/* computations. Works only in a single threaded environment.		*/
+/* We assume that stubborn objects are changed only when they are 	*/
+/* enabled for writing.  (Certain kinds of writing are actually		*/
+/* safe under other conditions.)					*/
+# define NSUMS 2000
+
+# define OFFSET 0x10000
+
+typedef struct {
+	GC_bool new_valid;
+	word old_sum;
+	word new_sum;
+	struct hblk * block;	/* Block to which this refers + OFFSET  */
+				/* to hide it from colector.		*/
+} page_entry;
+
+page_entry GC_sums [NSUMS];
+
+word GC_checksum(h)
+struct hblk *h;
+{
+    register word *p = (word *)h;
+    register word *lim = (word *)(h+1);
+    register word result = 0;
+    
+    while (p < lim) {
+        result += *p++;
+    }
+    return(result | 0x80000000 /* doesn't look like pointer */);
+}
+
+# ifdef STUBBORN_ALLOC
+/* Check whether a stubborn object from the given block appears on	*/
+/* the appropriate free list.						*/
+GC_bool GC_on_free_list(h)
+struct hblk *h;
+{
+    register hdr * hhdr = HDR(h);
+    register int sz = hhdr -> hb_sz;
+    ptr_t p;
+    
+    if (sz > MAXOBJSZ) return(FALSE);
+    for (p = GC_sobjfreelist[sz]; p != 0; p = obj_link(p)) {
+        if (HBLKPTR(p) == h) return(TRUE);
+    }
+    return(FALSE);
+}
+# endif
+ 
+int GC_n_dirty_errors;
+int GC_n_changed_errors;
+int GC_n_clean;
+int GC_n_dirty;
+
+void GC_update_check_page(h, index)
+struct hblk *h;
+int index;
+{
+    page_entry *pe = GC_sums + index;
+    register hdr * hhdr = HDR(h);
+    
+    if (pe -> block != 0 && pe -> block != h + OFFSET) ABORT("goofed");
+    pe -> old_sum = pe -> new_sum;
+    pe -> new_sum = GC_checksum(h);
+#   ifndef MSWIN32
+        if (pe -> new_sum != 0 && !GC_page_was_ever_dirty(h)) {
+            GC_printf1("GC_page_was_ever_dirty(0x%lx) is wrong\n",
+        	       (unsigned long)h);
+        }
+#   endif
+    if (GC_page_was_dirty(h)) {
+    	GC_n_dirty++;
+    } else {
+    	GC_n_clean++;
+    }
+    if (pe -> new_valid && pe -> old_sum != pe -> new_sum) {
+    	if (!GC_page_was_dirty(h) || !GC_page_was_ever_dirty(h)) {
+    	    /* Set breakpoint here */GC_n_dirty_errors++;
+    	}
+#	ifdef STUBBORN_ALLOC
+    	  if (!IS_FORWARDING_ADDR_OR_NIL(hhdr)
+    	    && hhdr -> hb_map != GC_invalid_map
+    	    && hhdr -> hb_obj_kind == STUBBORN
+    	    && !GC_page_was_changed(h)
+    	    && !GC_on_free_list(h)) {
+    	    /* if GC_on_free_list(h) then reclaim may have touched it	*/
+    	    /* without any allocations taking place.			*/
+    	    /* Set breakpoint here */GC_n_changed_errors++;
+    	  }
+#	endif
+    }
+    pe -> new_valid = TRUE;
+    pe -> block = h + OFFSET;
+}
+
+word GC_bytes_in_used_blocks;
+
+void GC_add_block(h, dummy)
+struct hblk *h;
+word dummy;
+{
+   register hdr * hhdr = HDR(h);
+   register bytes = WORDS_TO_BYTES(hhdr -> hb_sz);
+   
+   bytes += HDR_BYTES + HBLKSIZE-1;
+   bytes &= ~(HBLKSIZE-1);
+   GC_bytes_in_used_blocks += bytes;
+}
+
+void GC_check_blocks()
+{
+    word bytes_in_free_blocks = 0;
+    struct hblk * h = GC_hblkfreelist;
+    hdr * hhdr = HDR(h);
+    word sz;
+    
+    GC_bytes_in_used_blocks = 0;
+    GC_apply_to_all_blocks(GC_add_block, (word)0);
+    while (h != 0) {
+        sz = hhdr -> hb_sz;
+        bytes_in_free_blocks += sz;
+        h = hhdr -> hb_next;
+        hhdr = HDR(h);
+    }
+    GC_printf2("GC_bytes_in_used_blocks = %ld, bytes_in_free_blocks = %ld ",
+    		GC_bytes_in_used_blocks, bytes_in_free_blocks);
+    GC_printf1("GC_heapsize = %ld\n", GC_heapsize);
+    if (GC_bytes_in_used_blocks + bytes_in_free_blocks != GC_heapsize) {
+    	GC_printf0("LOST SOME BLOCKS!!\n");
+    }
+}
+
+/* Should be called immediately after GC_read_dirty and GC_read_changed. */
+void GC_check_dirty()
+{
+    register int index;
+    register unsigned i;
+    register struct hblk *h;
+    register ptr_t start;
+    
+    GC_check_blocks();
+    
+    GC_n_dirty_errors = 0;
+    GC_n_changed_errors = 0;
+    GC_n_clean = 0;
+    GC_n_dirty = 0;
+    
+    index = 0;
+    for (i = 0; i < GC_n_heap_sects; i++) {
+    	start = GC_heap_sects[i].hs_start;
+        for (h = (struct hblk *)start;
+             h < (struct hblk *)(start + GC_heap_sects[i].hs_bytes);
+             h++) {
+             GC_update_check_page(h, index);
+             index++;
+             if (index >= NSUMS) goto out;
+        }
+    }
+out:
+    GC_printf2("Checked %lu clean and %lu dirty pages\n",
+    	      (unsigned long) GC_n_clean, (unsigned long) GC_n_dirty);
+    if (GC_n_dirty_errors > 0) {
+        GC_printf1("Found %lu dirty bit errors\n",
+        	   (unsigned long)GC_n_dirty_errors);
+    }
+    if (GC_n_changed_errors > 0) {
+    	GC_printf1("Found %lu changed bit errors\n",
+        	   (unsigned long)GC_n_changed_errors);
+	GC_printf0("These may be benign (provoked by nonpointer changes)\n");
+#	ifdef THREADS
+	    GC_printf0(
+	    "Also expect 1 per thread currently allocating a stubborn obj.\n");
+#	endif
+    }
+}
+
+# else
+
+extern int GC_quiet;
+	/* ANSI C doesn't allow translation units to be empty.	*/
+	/* So we guarantee this one is nonempty.		*/
+
+# endif /* CHECKSUMS */