Hi!
I have a patch which disables -faggressive-loop-optimizations and
-fstrict-overflow when -fsanitize=undefined is switched on. Compiler
with aggressive optimizations may decrease quality of sanitization by
optimistically proposing something it actually should check.
Details are in https://gcc.gnu.org/ml/gcc/2014-11/msg00148.html
--Marat
gcc/ChangeLog:
2014-11-12 Marat Zakirov <m.zaki...@samsung.com>
* opts.c (finish_options): Disable aggressive opts for sanitizer.
(common_handle_option): Move code to finish_options.
gcc/testsuite/ChangeLog:
2014-11-12 Marat Zakirov <m.zaki...@samsung.com>
* c-c++-common/asan/aggressive-opts.c: New test.
diff --git a/gcc/opts.c b/gcc/opts.c
index 752cc84..db7768f 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -903,6 +903,19 @@ finish_options (struct gcc_options *opts, struct gcc_options *opts_set,
if (opts->x_flag_sanitize_recover & SANITIZE_LEAK)
error_at (loc, "-fsanitize-recover=leak is not supported");
+
+ /* When instrumenting the pointers, we don't want to remove
+ the null pointer checks. */
+ if (opts->x_flag_sanitize & (SANITIZE_NULL | SANITIZE_NONNULL_ATTRIBUTE
+ | SANITIZE_RETURNS_NONNULL_ATTRIBUTE))
+ opts->x_flag_delete_null_pointer_checks = 0;
+
+ /* Aggressive compiler optimizations may cause false negatives. */
+ if (opts->x_flag_sanitize)
+ {
+ opts->x_flag_aggressive_loop_optimizations = 0;
+ opts->x_flag_strict_overflow = 0;
+ }
}
#define LEFT_COLUMN 27
@@ -1621,12 +1634,6 @@ common_handle_option (struct gcc_options *opts,
if (code != OPT_fsanitize_)
break;
- /* When instrumenting the pointers, we don't want to remove
- the null pointer checks. */
- if (opts->x_flag_sanitize & (SANITIZE_NULL | SANITIZE_NONNULL_ATTRIBUTE
- | SANITIZE_RETURNS_NONNULL_ATTRIBUTE))
- opts->x_flag_delete_null_pointer_checks = 0;
-
/* Kernel ASan implies normal ASan but does not yet support
all features. */
if (opts->x_flag_sanitize & SANITIZE_KERNEL_ADDRESS)
diff --git a/gcc/testsuite/c-c++-common/asan/aggressive-opts.c b/gcc/testsuite/c-c++-common/asan/aggressive-opts.c
new file mode 100644
index 0000000..dfb2f0e
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/aggressive-opts.c
@@ -0,0 +1,28 @@
+/* { dg-options "-fdump-tree-asan" } */
+/* { dg-do compile } */
+/* { dg-skip-if "" { *-*-* } { "*" } { "-O3" } } */
+
+int ext;
+
+int
+Perl_do_sv_dump()
+{
+ int freq[10];
+ int i;
+ int max = 0;
+
+ if (max < ext)
+ max = ext;
+
+ for (i = 0; i <= max; i++)
+ if (freq[i])
+ ext = 0;
+
+ if (i > 20)
+ return freq[i];
+ else
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "ASAN_CHECK" 2 "asan1" } } */
+/* { dg-final { cleanup-tree-dump "asan" } } */
