[PATCH] Remove repeating strlen instrumentation.

[Maxim Ostapenko]

Hi,

This patch removes repeating strlen instrumentation.

Regtested/bootstrapped on x86_64-unknown-linux-gnu.

Ok to commit?

-Maxim

gcc/ChangeLog:

2014-06-24  Max Ostapenko  <m.ostape...@partner.samsung.com>

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

gcc/testsuite/ChangeLog:

2014-06-24  Max Ostapenko  <m.ostape...@partner.samsung.com>

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


commit bd331eb20eb6d93d9959b46d3cf8f11ee509ce99
Author: Max Ostapenko <m.ostape...@partner.samsung.com>
Date:   Thu Jun 19 17:56:40 2014 +0400

    Do not instrument first byte in strlen if already instrumented.

diff --git a/gcc/asan.c b/gcc/asan.c
index 9eeafa8..20d78df 100644
--- a/gcc/asan.c
+++ b/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,
diff --git a/gcc/testsuite/c-c++-common/asan/no-redundant-instrumentation-9.c b/gcc/testsuite/c-c++-common/asan/no-redundant-instrumentation-9.c
new file mode 100644
index 0000000..c6575ad
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/no-redundant-instrumentation-9.c
@@ -0,0 +1,13 @@
+/* { 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" } } */