* [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342)
@ 2016-04-27 17:03 Marek Polacek
2016-04-28 9:07 ` Jakub Jelinek
0 siblings, 1 reply; 5+ messages in thread
From: Marek Polacek @ 2016-04-27 17:03 UTC (permalink / raw)
To: GCC Patches, Jakub Jelinek
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 <polacek@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.
diff --git gcc/c-family/c-ubsan.c gcc/c-family/c-ubsan.c
index 4022bdf..b829c04 100644
--- gcc/c-family/c-ubsan.c
+++ gcc/c-family/c-ubsan.c
@@ -395,8 +395,11 @@ ubsan_maybe_instrument_reference_or_call (location_t loc, tree op, tree ptype,
int save_flag_delete_null_pointer_checks
= flag_delete_null_pointer_checks;
flag_delete_null_pointer_checks = 1;
- if (!tree_single_nonzero_warnv_p (op, &strict_overflow_p)
- || strict_overflow_p)
+ if ((!tree_single_nonzero_warnv_p (op, &strict_overflow_p)
+ || strict_overflow_p)
+ /* Instrumenting &TARGET_EXPR <...> is a waste and can result
+ in compile-time hog; see PR70342. */
+ && TREE_CODE (TREE_OPERAND (op, 0)) != TARGET_EXPR)
instrument = true;
flag_delete_null_pointer_checks
= save_flag_delete_null_pointer_checks;
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
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342)
2016-04-27 17:03 [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342) Marek Polacek
@ 2016-04-28 9:07 ` Jakub Jelinek
2016-04-28 14:10 ` Marek Polacek
0 siblings, 1 reply; 5+ messages in thread
From: Jakub Jelinek @ 2016-04-28 9:07 UTC (permalink / raw)
To: Marek Polacek; +Cc: GCC Patches
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 <polacek@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)?
Jakub
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342)
2016-04-28 9:07 ` Jakub Jelinek
@ 2016-04-28 14:10 ` Marek Polacek
2016-04-28 14:15 ` Jakub Jelinek
0 siblings, 1 reply; 5+ messages in thread
From: Marek Polacek @ 2016-04-28 14:10 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: GCC Patches
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 <polacek@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 <polacek@redhat.com>
Jakub Jelinek <jakub@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
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342)
2016-04-28 14:10 ` Marek Polacek
@ 2016-04-28 14:15 ` Jakub Jelinek
2016-04-29 12:35 ` Marek Polacek
0 siblings, 1 reply; 5+ messages in thread
From: Jakub Jelinek @ 2016-04-28 14:15 UTC (permalink / raw)
To: Marek Polacek; +Cc: GCC Patches
On Thu, Apr 28, 2016 at 04:10:01PM +0200, Marek Polacek wrote:
> That works too, though it of course affects all users, not just ubsan. Here's
Of course, but I think that is a good thing ;)
> the patch with your suggested change.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2016-04-28 Marek Polacek <polacek@redhat.com>
> Jakub Jelinek <jakub@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.
Ok for trunk.
For 6.2 dunno, either the same patch after a while, or perhaps your original
patch is safer (though, wonder if e.g. one can construct a testcase where it
will use instrument &(TARGET_EXPR <...>.field) nested many times and still
trigger the compile time hog with your patch).
Jakub
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342)
2016-04-28 14:15 ` Jakub Jelinek
@ 2016-04-29 12:35 ` Marek Polacek
0 siblings, 0 replies; 5+ messages in thread
From: Marek Polacek @ 2016-04-29 12:35 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: GCC Patches
On Thu, Apr 28, 2016 at 04:15:41PM +0200, Jakub Jelinek wrote:
> On Thu, Apr 28, 2016 at 04:10:01PM +0200, Marek Polacek wrote:
> > That works too, though it of course affects all users, not just ubsan. Here's
>
> Of course, but I think that is a good thing ;)
>
> > the patch with your suggested change.
> >
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> >
> > 2016-04-28 Marek Polacek <polacek@redhat.com>
> > Jakub Jelinek <jakub@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.
>
> Ok for trunk.
Thanks, committed.
> For 6.2 dunno, either the same patch after a while, or perhaps your original
> patch is safer (though, wonder if e.g. one can construct a testcase where it
> will use instrument &(TARGET_EXPR <...>.field) nested many times and still
> trigger the compile time hog with your patch).
Dunno either. I think I'll backport the same patch after a week or so.
Marek
^ permalink raw reply [flat|nested] 5+ messages in thread
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2016-04-27 17:03 [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342) Marek Polacek
2016-04-28 9:07 ` Jakub Jelinek
2016-04-28 14:10 ` Marek Polacek
2016-04-28 14:15 ` Jakub Jelinek
2016-04-29 12:35 ` Marek Polacek
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