PR analyzer/93356 reports an ICE handling __builtin_isnan due to a
failing assertion:
674 gcc_assert (lhs_ec_id != rhs_ec_id);
with op=UNORDERED_EXPR.
when attempting to add an UNORDERED_EXPR constraint.
This is an overzealous assertion, but underlying it are various forms of
sloppiness regarding NaN within the analyzer:
(a) the assumption in the constraint_manager that equivalence classes
are reflexive (X == X), which isn't the case for NaN.
(b) Hardcoding the "honor_nans" param to false when calling
invert_tree_comparison throughout the analyzer.
(c) Ignoring ORDERED_EXPR, UNORDERED_EXPR, and the UN-prefixed
comparison codes.
I wrote a patch for this which tracks the NaN-ness of floating-point
values and uses this to address all of the above.
However, to minimize changes in gcc 10 stage 4, here's a simpler patch
which rejects attempts to query or add constraints on floating-point
values, instead treating any floating-point comparison as "unknown", and
silently dropping the constraints at edges.
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Committed to master as r10-6361-ge978955dd720d5cc0e5141a1e9bbbbb943a3cc41.
gcc/analyzer/ChangeLog:
PR analyzer/93356
* region-model.cc (region_model::eval_condition): In both
overloads, bail out immediately on floating-point types.
(region_model::eval_condition_without_cm): Likewise.
(region_model::add_constraint): Likewise.
gcc/testsuite/ChangeLog:
PR analyzer/93356
* gcc.dg/analyzer/conditionals-notrans.c (test_float_selfcmp):
Add.
* gcc.dg/analyzer/conditionals-trans.c: Mark floating point
comparison test as failing.
(test_float_selfcmp): Add.
* gcc.dg/analyzer/data-model-1.c: Mark floating point comparison
tests as failing.
* gcc.dg/analyzer/torture/pr93356.c: New test.
gcc/ChangeLog:
PR analyzer/93356
* doc/analyzer.texi (Limitations): Note that constraints on
floating-point values are currently ignored.
---
gcc/analyzer/region-model.cc | 25 +++++++++++++++++++
gcc/doc/analyzer.texi | 2 ++
.../gcc.dg/analyzer/conditionals-notrans.c | 6 +++++
.../gcc.dg/analyzer/conditionals-trans.c | 9 ++++++-
gcc/testsuite/gcc.dg/analyzer/data-model-1.c | 9 ++++---
.../gcc.dg/analyzer/torture/pr93356.c | 6 +++++
6 files changed, 53 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/analyzer/torture/pr93356.c
diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index c838454a1eb..a15088a2e3c 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -5144,6 +5144,15 @@ region_model::eval_condition (svalue_id lhs_sid,
enum tree_code op,
svalue_id rhs_sid) const
{
+ svalue *lhs = get_svalue (lhs_sid);
+ svalue *rhs = get_svalue (rhs_sid);
+
+ /* For now, make no attempt to capture constraints on floating-point
+ values. */
+ if ((lhs->get_type () && FLOAT_TYPE_P (lhs->get_type ()))
+ || (rhs->get_type () && FLOAT_TYPE_P (rhs->get_type ())))
+ return tristate::unknown ();
+
tristate ts = eval_condition_without_cm (lhs_sid, op, rhs_sid);
if (ts.is_known ())
@@ -5173,6 +5182,12 @@ region_model::eval_condition_without_cm (svalue_id
lhs_sid,
/* See what we know based on the values. */
if (lhs && rhs)
{
+ /* For now, make no attempt to capture constraints on floating-point
+ values. */
+ if ((lhs->get_type () && FLOAT_TYPE_P (lhs->get_type ()))
+ || (rhs->get_type () && FLOAT_TYPE_P (rhs->get_type ())))
+ return tristate::unknown ();
+
if (lhs == rhs)
{
/* If we have the same svalue, then we have equality
@@ -5252,6 +5267,11 @@ bool
region_model::add_constraint (tree lhs, enum tree_code op, tree rhs,
region_model_context *ctxt)
{
+ /* For now, make no attempt to capture constraints on floating-point
+ values. */
+ if (FLOAT_TYPE_P (TREE_TYPE (lhs)) || FLOAT_TYPE_P (TREE_TYPE (rhs)))
+ return true;
+
svalue_id lhs_sid = get_rvalue (lhs, ctxt);
svalue_id rhs_sid = get_rvalue (rhs, ctxt);
@@ -5385,6 +5405,11 @@ region_model::eval_condition (tree lhs,
tree rhs,
region_model_context *ctxt)
{
+ /* For now, make no attempt to model constraints on floating-point
+ values. */
+ if (FLOAT_TYPE_P (TREE_TYPE (lhs)) || FLOAT_TYPE_P (TREE_TYPE (rhs)))
+ return tristate::unknown ();
+
return eval_condition (get_rvalue (lhs, ctxt), op, get_rvalue (rhs, ctxt));
}
diff --git a/gcc/doc/analyzer.texi b/gcc/doc/analyzer.texi
index 81acdd8998b..1fe4bcefd1b 100644
--- a/gcc/doc/analyzer.texi
+++ b/gcc/doc/analyzer.texi
@@ -390,6 +390,8 @@ Lack of function pointer analysis
@item
The constraint-handling code assumes reflexivity in some places
(that values are equal to themselves), which is not the case for NaN.
+As a simple workaround, constraints on floating-point values are
+currently ignored.
@item
The region model code creates lots of little mutable objects at each
@code{region_model} (and thus per @code{exploded_node}) rather than
diff --git a/gcc/testsuite/gcc.dg/analyzer/conditionals-notrans.c
b/gcc/testsuite/gcc.dg/analyzer/conditionals-notrans.c
index 3b6e28cf539..a00127b1a7f 100644
--- a/gcc/testsuite/gcc.dg/analyzer/conditionals-notrans.c
+++ b/gcc/testsuite/gcc.dg/analyzer/conditionals-notrans.c
@@ -157,3 +157,9 @@ void test_range_float_ge_le (float f)
__analyzer_eval (f == 4); /* { dg-warning "TRUE" "desired" { xfail *-*-*
} } */
/* { dg-bogus "UNKNOWN" "status quo" { xfail *-*-* } .-1 } */
}
+
+void test_float_selfcmp (float f)
+{
+ __analyzer_eval (f == f); /* { dg-warning "UNKNOWN" } */
+ __analyzer_eval (f != f); /* { dg-warning "UNKNOWN" } */
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/conditionals-trans.c
b/gcc/testsuite/gcc.dg/analyzer/conditionals-trans.c
index ab34618c411..f032789e6c4 100644
--- a/gcc/testsuite/gcc.dg/analyzer/conditionals-trans.c
+++ b/gcc/testsuite/gcc.dg/analyzer/conditionals-trans.c
@@ -140,5 +140,12 @@ void test_range_float_ge_le (float f)
{
if (f >= 4)
if (f <= 4)
- __analyzer_eval (f == 4); /* { dg-warning "TRUE" } */
+ __analyzer_eval (f == 4); /* { dg-warning "TRUE" "PR 93356" { xfail
*-*-* } } */
+ /* { dg-warning "UNKNOWN" "disabled float comparisons" { target *-*-* } .-1
} */
+}
+
+void test_float_selfcmp (float f)
+{
+ __analyzer_eval (f == f); /* { dg-warning "UNKNOWN" } */
+ __analyzer_eval (f != f); /* { dg-warning "UNKNOWN" } */
}
diff --git a/gcc/testsuite/gcc.dg/analyzer/data-model-1.c
b/gcc/testsuite/gcc.dg/analyzer/data-model-1.c
index 91685f578a4..3f925941f87 100644
--- a/gcc/testsuite/gcc.dg/analyzer/data-model-1.c
+++ b/gcc/testsuite/gcc.dg/analyzer/data-model-1.c
@@ -209,14 +209,16 @@ void test_13 (struct outer *o)
{
__analyzer_eval (o->mid.in.f == 0.f); /* { dg-warning "UNKNOWN" } */
o->mid.in.f = 0.f;
- __analyzer_eval (o->mid.in.f == 0.f); /* { dg-warning "TRUE" } */
+ __analyzer_eval (o->mid.in.f == 0.f); /* { dg-warning "TRUE" "PR 93356" {
xfail *-*-* } } */
+ /* { dg-warning "UNKNOWN" "disabled float comparisons" { target *-*-* } .-1
} */
}
void test_14 (struct outer o)
{
__analyzer_eval (o.mid.in.f == 0.f); /* { dg-warning "UNKNOWN" } */
o.mid.in.f = 0.f;
- __analyzer_eval (o.mid.in.f == 0.f); /* { dg-warning "TRUE" } */
+ __analyzer_eval (o.mid.in.f == 0.f); /* { dg-warning "TRUE" "PR 93356" {
xfail *-*-* } } */
+ /* { dg-warning "UNKNOWN" "disabled float comparisons" { target *-*-* } .-1
} */
}
void test_15 (const char *str)
@@ -947,7 +949,8 @@ void test_42 (void)
float f;
i = 42;
f = i;
- __analyzer_eval (f == 42.0); /* { dg-warning "TRUE" } */
+ __analyzer_eval (f == 42.0); /* { dg-warning "TRUE" "PR 93356" { xfail *-*-*
} } */
+ /* { dg-warning "UNKNOWN" "disabled float comparisons" { target *-*-* } .-1
} */
}
void test_43 (void)
diff --git a/gcc/testsuite/gcc.dg/analyzer/torture/pr93356.c
b/gcc/testsuite/gcc.dg/analyzer/torture/pr93356.c
new file mode 100644
index 00000000000..5db20d8e523
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/torture/pr93356.c
@@ -0,0 +1,6 @@
+void
+test (double d)
+{
+ if (__builtin_isnan (d))
+ return;
+}
--
2.21.0
