The following adds a missing range-op for __builtin_expect which
helps -Wuse-after-free to detect the case a realloc original
pointer is used when the result was NULL.
Bootstrap and regtest running on x86_64-unknown-linux-gnu, OK?
PR tree-optimization/109170
* gimple-range-op.cc (cfn_expect): New.
(gimple_range_op_handler::maybe_builtin_call): Handle
__builtin_expect.
* gcc.dg/Wuse-after-free-pr109170.c: New testcase.
---
gcc/gimple-range-op.cc | 25 +++++++++++++++++++
.../gcc.dg/Wuse-after-free-pr109170.c | 15 +++++++++++
2 files changed, 40 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/Wuse-after-free-pr109170.c
diff --git a/gcc/gimple-range-op.cc b/gcc/gimple-range-op.cc
index a5d625387e7..f3d6e29e58d 100644
--- a/gcc/gimple-range-op.cc
+++ b/gcc/gimple-range-op.cc
@@ -309,6 +309,25 @@ public:
}
} op_cfn_constant_p;
+// Implement range operator for integral CFN_BUILT_IN_EXPECT.
+class cfn_expect : public range_operator
+{
+public:
+ using range_operator::fold_range;
+ virtual bool fold_range (irange &r, tree, const irange &lh,
+ const irange &, relation_trio) const
+ {
+ r = lh;
+ return true;
+ }
+ virtual bool op1_range (irange &r, tree, const irange &lhs,
+ const irange &, relation_trio) const
+ {
+ r = lhs;
+ return true;
+ }
+} op_cfn_expect;
+
// Implement range operator for CFN_BUILT_IN_SIGNBIT.
class cfn_signbit : public range_operator_float
{
@@ -966,6 +985,12 @@ gimple_range_op_handler::maybe_builtin_call ()
m_int = &op_cfn_parity;
break;
+ case CFN_BUILT_IN_EXPECT:
+ m_valid = true;
+ m_op1 = gimple_call_arg (call, 0);
+ m_int = &op_cfn_expect;
+ break;
+
default:
break;
}
diff --git a/gcc/testsuite/gcc.dg/Wuse-after-free-pr109170.c
b/gcc/testsuite/gcc.dg/Wuse-after-free-pr109170.c
new file mode 100644
index 00000000000..fa7dc66d66c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wuse-after-free-pr109170.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wuse-after-free" } */
+
+unsigned long bufmax = 0;
+unsigned long __open_catalog_bufmax;
+void *realloc(void *, __SIZE_TYPE__);
+void free(void *);
+
+void __open_catalog(char *buf)
+{
+ char *old_buf = buf;
+ buf = realloc (buf, bufmax);
+ if (__builtin_expect ((buf == ((void *)0)), 0))
+ free (old_buf); /* { dg-bogus "used after" } */
+}
--
2.35.3
