Do not instrument first byte in strlen if already instrumented.

gcc/
	* asan.c (instrument_strlen_call): Do not instrument first byte in strlen
	if already instrumented.

gcc/testsuite/
	* c-c++-common/asan/no-redundant-instrumentation-9.c: New test.

From-SVN: r212332

gcc/ChangeLog

+2014-06-24  Max Ostapenko  <m.ostapenko@partner.samsung.com>
+
+	* asan.c (instrument_strlen_call): Do not instrument first byte in strlen
+	if already instrumented.
+
 2014-07-07  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* config/arm/arm.opt (mwords-little-endian): Delete.

gcc/asan.c

@@ -2026,6 +2026,7 @@ instrument_strlen_call (gimple_stmt_iterator *iter)
 
   location_t loc = gimple_location (call);
   tree str_arg = gimple_call_arg (call, 0);
+  bool start_instrumented = has_mem_ref_been_instrumented (str_arg, 1);
 
   tree cptr_type = build_pointer_type (char_type_node);
   gimple str_arg_ssa =
@@ -2037,7 +2038,8 @@ instrument_strlen_call (gimple_stmt_iterator *iter)
 
   build_check_stmt (loc, gimple_assign_lhs (str_arg_ssa), NULL_TREE, 1, iter,
 		    /*non_zero_len_p*/true, /*before_p=*/true,
-		    /*is_store=*/false, /*is_scalar_access*/true, /*align*/0);
+		    /*is_store=*/false, /*is_scalar_access*/true, /*align*/0,
+		    start_instrumented, start_instrumented);
 
   gimple g =
     gimple_build_assign_with_ops (POINTER_PLUS_EXPR,

gcc/testsuite/ChangeLog

+2014-06-24  Max Ostapenko  <m.ostapenko@partner.samsung.com>
+
+	* c-c++-common/asan/no-redundant-instrumentation-9.c: New test.
+
 2014-07-07  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/58898

gcc/testsuite/c-c++-common/asan/no-redundant-instrumentation-9.c

+/* { dg-options "-fdump-tree-asan0" } */
+/* { dg-do compile } */
+/* { dg-skip-if "" { *-*-* } { "*" } { "-O0" } } */
+
+__SIZE_TYPE__
+f (char *a)
+{
+  a[0] = '1';
+  return  __builtin_strlen (a);
+}
+
+/* { dg-final { scan-tree-dump-times "__asan_report_load1" 1 "asan0" } } */
+/* { dg-final { cleanup-tree-dump "asan0" } } */