From: Marek Polacek <polacek@redhat.com>
To: GCC Patches <gcc-patches@gcc.gnu.org>, Jakub Jelinek <jakub@redhat.com>
Subject: [ubsan PATCH] Fix compile-time hog with &TARGET_EXPRs (PR sanitizer/70342)
Date: Wed, 27 Apr 2016 17:03:00 -0000 [thread overview]
Message-ID: <20160427170325.GK28445@redhat.com> (raw)
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
next reply other threads:[~2016-04-27 17:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-27 17:03 Marek Polacek [this message]
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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