Changed in v4:
- Remove include of gcc-plugin.h, reworking includes accordingly.
- Wrap everything in #if ENABLE_ANALYZER
- Add call_string::validate, part of:
https://gcc.gnu.org/ml/gcc-patches/2019-11/msg02517.html
This patch adds call_string, a class for representing the
call stacks at a program_point, so that we can ensure that
paths through the code are interprocedurally valid.
gcc/ChangeLog:
* analyzer/call-string.cc: New file.
* analyzer/call-string.h: New file.
---
gcc/analyzer/call-string.cc | 224 ++++++++++++++++++++++++++++++++++++
gcc/analyzer/call-string.h | 76 ++++++++++++
2 files changed, 300 insertions(+)
create mode 100644 gcc/analyzer/call-string.cc
create mode 100644 gcc/analyzer/call-string.h
diff --git a/gcc/analyzer/call-string.cc b/gcc/analyzer/call-string.cc
new file mode 100644
index 000000000000..a9ff9cbfca44
--- /dev/null
+++ b/gcc/analyzer/call-string.cc
@@ -0,0 +1,224 @@
+/* Call stacks at program points.
+ Copyright (C) 2019 Free Software Foundation, Inc.
+ Contributed by David Malcolm <dmalc...@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "pretty-print.h"
+#include "tree.h"
+#include "options.h"
+#include "analyzer/call-string.h"
+#include "analyzer/supergraph.h"
+
+#if ENABLE_ANALYZER
+
+/* class call_string. */
+
+/* call_string's copy ctor. */
+
+call_string::call_string (const call_string &other)
+: m_return_edges (other.m_return_edges.length ())
+{
+ const return_superedge *e;
+ int i;
+ FOR_EACH_VEC_ELT (other.m_return_edges, i, e)
+ m_return_edges.quick_push (e);
+}
+
+/* call_string's assignment operator. */
+
+call_string&
+call_string::operator= (const call_string &other)
+{
+ // would be much simpler if we could rely on vec<> assignment op
+ m_return_edges.truncate (0);
+ m_return_edges.reserve (other.m_return_edges.length (), true);
+ const return_superedge *e;
+ int i;
+ FOR_EACH_VEC_ELT (other.m_return_edges, i, e)
+ m_return_edges.quick_push (e);
+ return *this;
+}
+
+/* call_string's equality operator. */
+
+bool
+call_string::operator== (const call_string &other) const
+{
+ if (m_return_edges.length () != other.m_return_edges.length ())
+ return false;
+ const return_superedge *e;
+ int i;
+ FOR_EACH_VEC_ELT (m_return_edges, i, e)
+ if (e != other.m_return_edges[i])
+ return false;
+ return true;
+}
+
+/* Print this to PP. */
+
+void
+call_string::print (pretty_printer *pp) const
+{
+ pp_string (pp, "[");
+
+ const return_superedge *e;
+ int i;
+ FOR_EACH_VEC_ELT (m_return_edges, i, e)
+ {
+ if (i > 0)
+ pp_string (pp, ", ");
+ pp_printf (pp, "(SN: %i -> SN: %i in %s)",
+ e->m_src->m_index, e->m_dest->m_index,
+ function_name (e->m_dest->m_fun));
+ }
+
+ pp_string (pp, "]");
+}
+
+/* Generate a hash value for this call_string. */
+
+hashval_t
+call_string::hash () const
+{
+ inchash::hash hstate;
+ int i;
+ const return_superedge *e;
+ FOR_EACH_VEC_ELT (m_return_edges, i, e)
+ hstate.add_ptr (e);
+ return hstate.end ();
+}
+
+/* Push the return superedge for CALL_SEDGE onto the end of this
+ call_string. */
+
+void
+call_string::push_call (const supergraph &sg,
+ const call_superedge *call_sedge)
+{
+ gcc_assert (call_sedge);
+ const return_superedge *return_sedge = call_sedge->get_edge_for_return (sg);
+ gcc_assert (return_sedge);
+ m_return_edges.safe_push (return_sedge);
+}
+
+/* Count the number of times the top-most call site appears in the
+ stack. */
+
+int
+call_string::calc_recursion_depth () const
+{
+ if (m_return_edges.is_empty ())
+ return 0;
+ const return_superedge *top_return_sedge
+ = m_return_edges[m_return_edges.length () - 1];
+
+ int result = 0;
+ const return_superedge *e;
+ int i;
+ FOR_EACH_VEC_ELT (m_return_edges, i, e)
+ if (e == top_return_sedge)
+ ++result;
+ return result;
+}
+
+/* Comparator for call strings.
+ Return negative if A is before B.
+ Return positive if B is after A.
+ Return 0 if they are equal. */
+
+int
+call_string::cmp (const call_string &a,
+ const call_string &b)
+{
+ int result = cmp_1 (a, b);
+
+ /* Check that the ordering is symmetric */
+#if CHECKING_P
+ int reversed = cmp_1 (b, a);
+ gcc_assert (reversed == -result);
+#endif
+
+ /* We should only have 0 for equal pairs. */
+ gcc_assert (result != 0
+ || a == b);
+
+ return result;
+}
+
+/* Implementation of call_string::cmp.
+ This implements a version of lexicographical order. */
+
+int
+call_string::cmp_1 (const call_string &a,
+ const call_string &b)
+{
+ unsigned len_a = a.length ();
+ unsigned len_b = b.length ();
+
+ unsigned i = 0;
+ while (1)
+ {
+ /* Consider index i; the strings have been equal up to it. */
+
+ /* Have both strings run out? */
+ if (i >= len_a && i >= len_b)
+ return 0;
+
+ /* Otherwise, has just one of the strings run out? */
+ if (i >= len_a)
+ return 1;
+ if (i >= len_b)
+ return -1;
+
+ /* Otherwise, compare the edges. */
+ const return_superedge *edge_a = a[i];
+ const return_superedge *edge_b = b[i];
+ int src_cmp = edge_a->m_src->m_index - edge_b->m_src->m_index;
+ if (src_cmp)
+ return src_cmp;
+ int dest_cmp = edge_a->m_dest->m_index - edge_b->m_dest->m_index;
+ if (dest_cmp)
+ return dest_cmp;
+ i++;
+ // TODO: test coverage for this
+ }
+}
+
+/* Assert that this object is sane. */
+
+void
+call_string::validate () const
+{
+ /* Skip this in a release build. */
+#if !CHECKING_P
+ return;
+#endif
+
+ /* Each entry's "caller" should be the "callee" of the previous entry. */
+ const return_superedge *e;
+ int i;
+ FOR_EACH_VEC_ELT (m_return_edges, i, e)
+ if (i > 0)
+ gcc_assert (e->get_caller_function ()
+ == m_return_edges[i - 1]->get_callee_function ());
+}
+
+#endif /* #if ENABLE_ANALYZER */
diff --git a/gcc/analyzer/call-string.h b/gcc/analyzer/call-string.h
new file mode 100644
index 000000000000..221867652e95
--- /dev/null
+++ b/gcc/analyzer/call-string.h
@@ -0,0 +1,76 @@
+/* Call stacks at program points.
+ Copyright (C) 2019 Free Software Foundation, Inc.
+ Contributed by David Malcolm <dmalc...@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
+#ifndef GCC_ANALYZER_CALL_STRING_H
+#define GCC_ANALYZER_CALL_STRING_H
+
+class supergraph;
+class call_superedge;
+class return_superedge;
+
+/* A string of return_superedge pointers, representing a call stack
+ at a program point.
+
+ This is used to ensure that we generate interprocedurally valid paths
+ i.e. that we return to the same callsite that called us.
+
+ The class actually stores the return edges, rather than the call edges,
+ since that's what we need to compare against. */
+
+class call_string
+{
+public:
+ call_string () : m_return_edges () {}
+ call_string (const call_string &other);
+ call_string& operator= (const call_string &other);
+
+ bool operator== (const call_string &other) const;
+
+ void print (pretty_printer *pp) const;
+
+ hashval_t hash () const;
+
+ bool empty_p () const { return m_return_edges.is_empty (); }
+
+ void push_call (const supergraph &sg,
+ const call_superedge *sedge);
+ const return_superedge *pop () { return m_return_edges.pop (); }
+
+ int calc_recursion_depth () const;
+
+ static int cmp (const call_string &a,
+ const call_string &b);
+
+ unsigned length () const { return m_return_edges.length (); }
+ const return_superedge *operator[] (unsigned idx) const
+ {
+ return m_return_edges[idx];
+ }
+
+ void validate () const;
+
+private:
+ static int cmp_1 (const call_string &a,
+ const call_string &b);
+
+ auto_vec<const return_superedge *> m_return_edges;
+};
+
+#endif /* GCC_ANALYZER_CALL_STRING_H */
--
2.21.0
