[committed] analyzer: fix sense in range::add_bound [PR94362]
Commit Message
On Sun, 2022-01-23 at 17:34 +0100, Mikael Morin wrote:
> Hello,
>
> Le 21/01/2022 à 00:59, David Malcolm via Gcc-patches a écrit :
> > diff --git a/gcc/analyzer/constraint-manager.cc
> > b/gcc/analyzer/constraint-manager.cc
> > index 568e7150ea7..7c4a85bbb24 100644
> > --- a/gcc/analyzer/constraint-manager.cc
> > +++ b/gcc/analyzer/constraint-manager.cc
> > @@ -301,6 +301,80 @@ range::above_upper_bound (tree rhs_const)
> > const
> > m_upper_bound.m_constant).is_true ();
> > }
> >
> > +/* Attempt to add B to the bound of the given kind of this range.
> > + Return true if feasible; false if infeasible. */
> > +
> > +bool
> > +range::add_bound (bound b, enum bound_kind bound_kind)
> > +{
> > + b.ensure_closed (bound_kind);
> > +
> > + switch (bound_kind)
> > + {
> > + default:
> > + gcc_unreachable ();
> > + case BK_LOWER:
> > + /* Discard redundant bounds. */
> > + if (m_lower_bound.m_constant)
> > + {
> > + m_lower_bound.ensure_closed (BK_LOWER);
> > + if (!tree_int_cst_lt (b.m_constant,
> > + m_lower_bound.m_constant))
> > + return true;
>
> isn’t this condition reversed?
>
> > + }
> > + m_lower_bound = b;
> > + break;
> > + case BK_UPPER:
> > + /* Discard redundant bounds. */
> > + if (m_upper_bound.m_constant)
> > + {
> > + m_upper_bound.ensure_closed (BK_UPPER);
> > + if (tree_int_cst_le (b.m_constant,
> > + m_upper_bound.m_constant))
> > + return true;
>
> same here.
>
> All the tests added have just one lower and one upper bound, so they
> don’t use the short-circuit code, but amending one of them as follows
> makes the problem appear as the test starts to fails. It should
> continue to work, shouldn’t it?
>
>
> diff --git a/gcc/analyzer/constraint-manager.cc
> b/gcc/analyzer/constraint-manager.cc
> index 7c4a85bbb24..3f38b857722 100644
> --- a/gcc/analyzer/constraint-manager.cc
> +++ b/gcc/analyzer/constraint-manager.cc
> @@ -3697,6 +3697,7 @@ test_constant_comparisons ()
> region_model_manager mgr;
> {
> region_model model (&mgr);
> + ADD_SAT_CONSTRAINT (model, int_1, LT_EXPR, a);
> ADD_SAT_CONSTRAINT (model, int_3, LT_EXPR, a);
> ADD_UNSAT_CONSTRAINT (model, a, LT_EXPR, int_4);
> }
Good catch, thanks.
Fixed as follows, which also moves the rejection of contradictory
constraints in range::add_bound to earlier, so that this code can
be self-tested.
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Pushed to trunk as r12-6875-ge966a508e03fe28bfca65a1e60e579fa90355ea6.
gcc/analyzer/ChangeLog:
PR analyzer/94362
* constraint-manager.cc (range::add_bound): Fix tests for
discarding redundant constraints. Perform test for rejecting
unsatisfiable constraints earlier so that they don't update
the object on failure.
(selftest::test_range): New.
(selftest::test_constant_comparisons): Add test coverage for
existing constraints becoming narrower until they are
unsatisfiable.
(selftest::run_constraint_manager_tests): Call test_range.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
---
gcc/analyzer/constraint-manager.cc | 93 +++++++++++++++++++++++++-----
1 file changed, 79 insertions(+), 14 deletions(-)
@@ -318,35 +318,42 @@ range::add_bound (bound b, enum bound_kind bound_kind)
if (m_lower_bound.m_constant)
{
m_lower_bound.ensure_closed (BK_LOWER);
- if (!tree_int_cst_lt (b.m_constant,
- m_lower_bound.m_constant))
+ if (tree_int_cst_le (b.m_constant,
+ m_lower_bound.m_constant))
return true;
}
+ if (m_upper_bound.m_constant)
+ {
+ m_upper_bound.ensure_closed (BK_UPPER);
+ /* Reject B <= V <= UPPER when B > UPPER. */
+ if (!tree_int_cst_le (b.m_constant,
+ m_upper_bound.m_constant))
+ return false;
+ }
m_lower_bound = b;
break;
+
case BK_UPPER:
/* Discard redundant bounds. */
if (m_upper_bound.m_constant)
{
m_upper_bound.ensure_closed (BK_UPPER);
- if (tree_int_cst_le (b.m_constant,
- m_upper_bound.m_constant))
+ if (!tree_int_cst_lt (b.m_constant,
+ m_upper_bound.m_constant))
return true;
}
+ if (m_lower_bound.m_constant)
+ {
+ m_lower_bound.ensure_closed (BK_LOWER);
+ /* Reject LOWER <= V <= B when LOWER > B. */
+ if (!tree_int_cst_le (m_lower_bound.m_constant,
+ b.m_constant))
+ return false;
+ }
m_upper_bound = b;
break;
}
- if (m_lower_bound.m_constant
- && m_upper_bound.m_constant)
- {
- m_lower_bound.ensure_closed (BK_LOWER);
- m_upper_bound.ensure_closed (BK_UPPER);
- /* Reject LOWER <= V <= UPPER when LOWER > UPPER. */
- if (!tree_int_cst_le (m_lower_bound.m_constant,
- m_upper_bound.m_constant))
- return false;
- }
return true;
}
@@ -3093,6 +3100,49 @@ namespace selftest {
These have to be written in terms of a region_model, since
the latter is responsible for managing svalue instances. */
+/* Verify that range::add_bound works as expected. */
+
+static void
+test_range ()
+{
+ tree int_0 = build_int_cst (integer_type_node, 0);
+ tree int_1 = build_int_cst (integer_type_node, 1);
+ tree int_2 = build_int_cst (integer_type_node, 2);
+ tree int_5 = build_int_cst (integer_type_node, 5);
+
+ {
+ range r;
+ ASSERT_FALSE (r.constrained_to_single_element ());
+
+ /* (r >= 1). */
+ ASSERT_TRUE (r.add_bound (GE_EXPR, int_1));
+
+ /* Redundant. */
+ ASSERT_TRUE (r.add_bound (GE_EXPR, int_0));
+ ASSERT_TRUE (r.add_bound (GT_EXPR, int_0));
+
+ ASSERT_FALSE (r.constrained_to_single_element ());
+
+ /* Contradiction. */
+ ASSERT_FALSE (r.add_bound (LT_EXPR, int_1));
+
+ /* (r < 5). */
+ ASSERT_TRUE (r.add_bound (LT_EXPR, int_5));
+ ASSERT_FALSE (r.constrained_to_single_element ());
+
+ /* Contradiction. */
+ ASSERT_FALSE (r.add_bound (GE_EXPR, int_5));
+
+ /* (r < 2). */
+ ASSERT_TRUE (r.add_bound (LT_EXPR, int_2));
+ ASSERT_TRUE (r.constrained_to_single_element ());
+
+ /* Redundant. */
+ ASSERT_TRUE (r.add_bound (LE_EXPR, int_1));
+ ASSERT_TRUE (r.constrained_to_single_element ());
+ }
+}
+
/* Verify that setting and getting simple conditions within a region_model
work (thus exercising the underlying constraint_manager). */
@@ -3700,6 +3750,20 @@ test_constant_comparisons ()
ADD_SAT_CONSTRAINT (model, int_3, LT_EXPR, a);
ADD_UNSAT_CONSTRAINT (model, a, LT_EXPR, int_4);
}
+ {
+ region_model model (&mgr);
+ ADD_SAT_CONSTRAINT (model, int_1, LT_EXPR, a);
+ ADD_SAT_CONSTRAINT (model, int_3, LT_EXPR, a);
+ ADD_SAT_CONSTRAINT (model, a, LT_EXPR, int_5);
+ ADD_UNSAT_CONSTRAINT (model, a, LT_EXPR, int_4);
+ }
+ {
+ region_model model (&mgr);
+ ADD_SAT_CONSTRAINT (model, int_1, LT_EXPR, a);
+ ADD_SAT_CONSTRAINT (model, a, LT_EXPR, int_5);
+ ADD_SAT_CONSTRAINT (model, int_3, LT_EXPR, a);
+ ADD_UNSAT_CONSTRAINT (model, a, LT_EXPR, int_4);
+ }
{
region_model model (&mgr);
ADD_SAT_CONSTRAINT (model, a, LT_EXPR, int_4);
@@ -4323,6 +4387,7 @@ run_constraint_manager_tests (bool transitivity)
int saved_flag_analyzer_transitivity = flag_analyzer_transitivity;
flag_analyzer_transitivity = transitivity;
+ test_range ();
test_constraint_conditions ();
if (flag_analyzer_transitivity)
{