vec.h (vec<T, [...]): Guard call to memset if len-oldlen != 0.

2016-12-01  Richard Biener  <rguenther@suse.de>
	    Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

	* vec.h (vec<T, A, vl_embed>::quick_grow_cleared): Guard call to
	memset if len-oldlen != 0.
	(vec<T, va_heap, vl_ptr>::safe_grow_cleared): Likewise.

Co-Authored-By: Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>

From-SVN: r243125

gcc/ChangeLog

+2016-12-01  Richard Biener  <rguenther@suse.de>
+	    Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
+
+	* vec.h (vec<T, A, vl_embed>::quick_grow_cleared): Guard call to
+	memset if len-oldlen != 0.
+	(vec<T, va_heap, vl_ptr>::safe_grow_cleared): Likewise.
+
 2016-12-01  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.md (*andndi3_doubleword): Depend on TARGET_SSE2.

gcc/vec.h

@@ -1092,8 +1092,10 @@ inline void
 vec<T, A, vl_embed>::quick_grow_cleared (unsigned len)
 {
   unsigned oldlen = length ();
+  size_t sz = sizeof (T) * (len - oldlen);
   quick_grow (len);
-  memset (&(address ()[oldlen]), 0, sizeof (T) * (len - oldlen));
+  if (sz != 0)
+    memset (&(address ()[oldlen]), 0, sz);
 }
 
 
@@ -1605,8 +1607,10 @@ inline void
 vec<T, va_heap, vl_ptr>::safe_grow_cleared (unsigned len MEM_STAT_DECL)
 {
   unsigned oldlen = length ();
+  size_t sz = sizeof (T) * (len - oldlen);
   safe_grow (len PASS_MEM_STAT);
-  memset (&(address ()[oldlen]), 0, sizeof (T) * (len - oldlen));
+  if (sz != 0)
+    memset (&(address ()[oldlen]), 0, sz);
 }