ggc-common.c [!ENABLE_VALGRIND_CHECKING] (VALGRIND_DISCARD): Define as empty.

* ggc-common.c [!ENABLE_VALGRIND_CHECKING] (VALGRIND_DISCARD):
	Define as empty.
	(ggc_realloc): Update valgrind annotations.
	* ggc-page.c [!ENABLE_VALGRIND_CHECKING] (VALGRIND_DISCARD):
	Define as empty.
 	(alloc_anon, free_page, ggc_alloc, poison_pages): Add machinery to
	valgrind-annotate memory.

From-SVN: r59310

gcc/ChangeLog

@@ -18,6 +18,14 @@
 	* gcc.c (execute) [ENABLE_VALGRIND_CHECKING]: Arrange to prepend
 	VALGRIND_PATH -q to each command.
 
+	* ggc-common.c [!ENABLE_VALGRIND_CHECKING] (VALGRIND_DISCARD):
+	Define as empty.
+	(ggc_realloc): Update valgrind annotations.
+	* ggc-page.c [!ENABLE_VALGRIND_CHECKING] (VALGRIND_DISCARD):
+	Define as empty.
+ 	(alloc_anon, free_page, ggc_alloc, poison_pages): Add machinery to
+	valgrind-annotate memory.
+
 2002-11-20  Ulrich Weigand  <uweigand@de.ibm.com>
 
 	* recog.c (constrain_operands): Prefer exact match over reloadable

gcc/ggc-common.c

@@ -30,6 +30,12 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "varray.h"
 #include "ggc.h"
 #include "langhooks.h"
+#ifdef ENABLE_VALGRIND_CHECKING
+#include <valgrind.h>
+#else
+/* Avoid #ifdef:s when we can help it.  */
+#define VALGRIND_DISCARD(x)
+#endif
 
 /* Statistics about the allocation.  */
 static ggc_statistics *ggc_stats;
@@ -155,10 +161,36 @@ ggc_realloc (x, size)
 
   old_size = ggc_get_size (x);
   if (size <= old_size)
-    return x;
+    {
+      /* Mark the unwanted memory as unaccessible.  We also need to make
+	 the "new" size accessible, since ggc_get_size returns the size of
+	 the pool, not the size of the individually allocated object, the
+	 size which was previously made accessible.  Unfortunately, we
+	 don't know that previously allocated size.  Without that
+	 knowledge we have to lose some initialization-tracking for the
+	 old parts of the object.  An alternative is to mark the whole
+	 old_size as reachable, but that would lose tracking of writes 
+	 after the end of the object (by small offsets).  Discard the
+	 handle to avoid handle leak.  */
+      VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) x + size,
+						old_size - size));
+      VALGRIND_DISCARD (VALGRIND_MAKE_READABLE (x, size));
+      return x;
+    }
 
   r = ggc_alloc (size);
+
+  /* Since ggc_get_size returns the size of the pool, not the size of the
+     individually allocated object, we'd access parts of the old object
+     that were marked invalid with the memcpy below.  We lose a bit of the
+     initialization-tracking since some of it may be uninitialized.  */
+  VALGRIND_DISCARD (VALGRIND_MAKE_READABLE (x, old_size));
+
   memcpy (r, x, old_size);
+
+  /* The old object is not supposed to be used anymore.  */
+  VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (x, old_size));
+
   return r;
 }
 

gcc/ggc-page.c

@@ -29,6 +29,12 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "ggc.h"
 #include "timevar.h"
 #include "params.h"
+#ifdef ENABLE_VALGRIND_CHECKING
+#include <valgrind.h>
+#else
+/* Avoid #ifdef:s when we can help it.  */
+#define VALGRIND_DISCARD(x)
+#endif
 
 /* Prefer MAP_ANON(YMOUS) to /dev/zero, since we don't need to keep a
    file open.  Prefer either to valloc.  */
@@ -524,6 +530,11 @@ alloc_anon (pref, size)
   /* Remember that we allocated this memory.  */
   G.bytes_mapped += size;
 
+  /* Pretend we don't have access to the allocated pages.  We'll enable
+     access to smaller pieces of the area in ggc_alloc.  Discard the
+     handle to avoid handle leak.  */
+  VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (page, size));
+
   return page;
 }
 #endif
@@ -750,6 +761,10 @@ free_page (entry)
 	     "Deallocating page at %p, data %p-%p\n", (PTR) entry,
 	     entry->page, entry->page + entry->bytes - 1);
 
+  /* Mark the page as inaccessible.  Discard the handle to avoid handle
+     leak.  */
+  VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (entry->page, entry->bytes));
+
   set_page_table_entry (entry->page, NULL);
 
 #ifdef USING_MALLOC_PAGE_GROUPS
@@ -943,11 +958,27 @@ ggc_alloc (size)
   result = entry->page + object_offset;
 
 #ifdef ENABLE_GC_CHECKING
+  /* Keep poisoning-by-writing-0xaf the object, in an attempt to keep the
+     exact same semantics in presence of memory bugs, regardless of
+     ENABLE_VALGRIND_CHECKING.  We override this request below.  Drop the
+     handle to avoid handle leak.  */
+  VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result, OBJECT_SIZE (order)));
+
   /* `Poison' the entire allocated object, including any padding at
      the end.  */
   memset (result, 0xaf, OBJECT_SIZE (order));
+
+  /* Make the bytes after the end of the object unaccessible.  Discard the
+     handle to avoid handle leak.  */
+  VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) result + size,
+					    OBJECT_SIZE (order) - size));
 #endif
 
+  /* Tell Valgrind that the memory is there, but its content isn't
+     defined.  The bytes at the end of the object are still marked
+     unaccessible.  */
+  VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (result, size));
+
   /* Keep track of how many bytes are being allocated.  This
      information is used in deciding when to collect.  */
   G.allocated += OBJECT_SIZE (order);
@@ -1433,7 +1464,19 @@ poison_pages ()
 	      word = i / HOST_BITS_PER_LONG;
 	      bit = i % HOST_BITS_PER_LONG;
 	      if (((p->in_use_p[word] >> bit) & 1) == 0)
-		memset (p->page + i * size, 0xa5, size);
+		{
+		  char *object = p->page + i * size;
+
+		  /* Keep poison-by-write when we expect to use Valgrind,
+		     so the exact same memory semantics is kept, in case
+		     there are memory errors.  We override this request
+		     below.  */
+		  VALGRIND_DISCARD (VALGRIND_MAKE_WRITABLE (object, size));
+		  memset (object, 0xa5, size);
+
+		  /* Drop the handle to avoid handle leak.  */
+		  VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (object, size));
+		}
 	    }
 	}
     }