[ubsan PATCH] Don't instrument static initializers (PR sanitizer/67279)

[ubsan PATCH] Don't instrument static initializers (PR sanitizer/67279)

[Marek Polacek]

I think it really doesn't make sense to instrument static initializers; we
wouldn't be able to error at run-time anyway.  Besides, it causes a compile-time
error.  Generally, I think *compiling* with -fsanitize=undefined shouldn't add
any new compile-time errors.  Yes, I know it does in some other cases; this is
just an incremental improvement.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2015-09-04  Marek Polacek  <polacek@redhat.com>

	PR sanitizer/67279
	* c-typeck.c (build_binary_op): Don't instrument static initializers.

	* gcc.dg/ubsan/pr67279.c: New test.

diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index c622a90..dc22396 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -11292,7 +11292,8 @@ build_binary_op (location_t location, enum tree_code code,
   if ((flag_sanitize & (SANITIZE_SHIFT | SANITIZE_DIVIDE
 			| SANITIZE_FLOAT_DIVIDE))
       && do_ubsan_in_current_function ()
-      && (doing_div_or_mod || doing_shift))
+      && (doing_div_or_mod || doing_shift)
+      && !require_constant_value)
     {
       /* OP0 and/or OP1 might have side-effects.  */
       op0 = c_save_expr (op0);
diff --git gcc/testsuite/gcc.dg/ubsan/pr67279.c gcc/testsuite/gcc.dg/ubsan/pr67279.c
index e69de29..5b5db42 100644
--- gcc/testsuite/gcc.dg/ubsan/pr67279.c
+++ gcc/testsuite/gcc.dg/ubsan/pr67279.c
@@ -0,0 +1,14 @@
+/* PR sanitizer/67279 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=undefined -w" } */
+
+#define INT_MIN (-__INT_MAX__ - 1)
+
+void
+foo (void)
+{
+  static int a1 = 1 << 31;
+  static int a2 = 10 << 30;
+  static int a3 = 100 << 28;
+  static int a4 = INT_MIN / -1;
+}

	Marek

Re: [ubsan PATCH] Don't instrument static initializers (PR sanitizer/67279)

[Jakub Jelinek]

On Fri, Sep 04, 2015 at 01:28:38PM +0200, Marek Polacek wrote:
> I think it really doesn't make sense to instrument static initializers; we
> wouldn't be able to error at run-time anyway.  Besides, it causes a compile-time
> error.  Generally, I think *compiling* with -fsanitize=undefined shouldn't add
> any new compile-time errors.  Yes, I know it does in some other cases; this is
> just an incremental improvement.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> 2015-09-04  Marek Polacek  <polacek@redhat.com>
> 
> 	PR sanitizer/67279
> 	* c-typeck.c (build_binary_op): Don't instrument static initializers.
> 
> 	* gcc.dg/ubsan/pr67279.c: New test.

Ok, but please make sure it is handled similarly in the C++ FE too (perhaps
incrementally).

	Jakub

Re: [ubsan PATCH] Don't instrument static initializers (PR sanitizer/67279)

[Marek Polacek]

On Fri, Sep 04, 2015 at 01:31:09PM +0200, Jakub Jelinek wrote:
> On Fri, Sep 04, 2015 at 01:28:38PM +0200, Marek Polacek wrote:
> > I think it really doesn't make sense to instrument static initializers; we
> > wouldn't be able to error at run-time anyway.  Besides, it causes a compile-time
> > error.  Generally, I think *compiling* with -fsanitize=undefined shouldn't add
> > any new compile-time errors.  Yes, I know it does in some other cases; this is
> > just an incremental improvement.
> > 
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> > 
> > 2015-09-04  Marek Polacek  <polacek@redhat.com>
> > 
> > 	PR sanitizer/67279
> > 	* c-typeck.c (build_binary_op): Don't instrument static initializers.
> > 
> > 	* gcc.dg/ubsan/pr67279.c: New test.
> 
> Ok, but please make sure it is handled similarly in the C++ FE too (perhaps
> incrementally).

cc1plus doesn't reject this particular testcase, so I didn't touch the C++ FE
this time.

Thanks.

	Marek