On Thu, Apr 28, 2016 at 11:07:30AM +0200, Jakub Jelinek wrote:
> On Wed, Apr 27, 2016 at 07:03:25PM +0200, Marek Polacek wrote:
> > This test took forever to compile with -fsanitize=null, because the
> > instrumentation was creating incredible amount of duplicated expressions,
> > in a
> > quadratic fashion. I think the problem is that we instrument &TARGET_EXPR
> > <>
> > expressions, which doesn't seem to be needed -- we only need to instrument
> > the
> > initializers in TARGET_EXPRs. With this patch, we avoid creating tons of
> > useless
> > expressions and the compile time is reduced from ~ infinity to <1s.
> >
> > Jakub, do you see any problem with this?
> >
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> >
> > 2016-04-27 Marek Polacek <pola...@redhat.com>
> >
> > PR sanitizer/70342
> > * c-ubsan.c (ubsan_maybe_instrument_reference_or_call): Don't
> > null-instrument &TARGET_EXPR <...>.
> >
> > * g++.dg/ubsan/null-7.C: New test.
>
> I wonder if this wouldn't be better handled in tree_single_nonzero_warnv_p,
> perhaps like:
>
> case ADDR_EXPR:
> {
> tree base = TREE_OPERAND (t, 0);
>
> if (!DECL_P (base))
> base = get_base_address (base);
> +
> + if (base && TREE_CODE (base) == TARGET_EXPR)
> + base = TARGET_EXPR_SLOT (base);
>
> if (!base)
> return false;
>
> (untested)?
That works too, though it of course affects all users, not just ubsan. Here's
the patch with your suggested change.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2016-04-28 Marek Polacek <pola...@redhat.com>
Jakub Jelinek <ja...@redhat.com>
PR sanitizer/70342
* fold-const.c (tree_single_nonzero_warnv_p): For TARGET_EXPR, use
TARGET_EXPR_SLOT as a base.
* g++.dg/ubsan/null-7.C: New test.
diff --git gcc/fold-const.c gcc/fold-const.c
index 96d8484..171ac83 100644
--- gcc/fold-const.c
+++ gcc/fold-const.c
@@ -13531,6 +13531,9 @@ tree_single_nonzero_warnv_p (tree t, bool
*strict_overflow_p)
if (!DECL_P (base))
base = get_base_address (base);
+ if (base && TREE_CODE (base) == TARGET_EXPR)
+ base = TARGET_EXPR_SLOT (base);
+
if (!base)
return false;
diff --git gcc/testsuite/g++.dg/ubsan/null-7.C
gcc/testsuite/g++.dg/ubsan/null-7.C
index e69de29..8284bc7 100644
--- gcc/testsuite/g++.dg/ubsan/null-7.C
+++ gcc/testsuite/g++.dg/ubsan/null-7.C
@@ -0,0 +1,24 @@
+// PR sanitizer/70342
+// { dg-do compile }
+// { dg-options "-fsanitize=null" }
+
+class A {};
+class B {
+public:
+ B(A);
+};
+class C {
+public:
+ C operator<<(B);
+};
+class D {
+ D(const int &);
+ C m_blackList;
+};
+D::D(const int &) {
+ m_blackList << A() << A() << A() << A() << A() << A() << A() << A() << A()
+ << A() << A() << A() << A() << A() << A() << A() << A() << A()
+ << A() << A() << A() << A() << A() << A() << A() << A() << A()
+ << A() << A() << A() << A() << A() << A() << A() << A() << A()
+ << A() << A() << A() << A() << A() << A() << A() << A() << A();
+}
Marek
