[gcc r12-6377] analyzer: implement __analyzer_dump_escaped

[gcc r12-6377] analyzer: implement __analyzer_dump_escaped

[David Malcolm]

https://gcc.gnu.org/g:4409152a4acaec5b58a93996088d0df9aaa779b8

commit r12-6377-g4409152a4acaec5b58a93996088d0df9aaa779b8
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Fri Jan 7 13:36:00 2022 -0500

    analyzer: implement __analyzer_dump_escaped
    
    PR analyzer/103546 seems to involve an issue in how the analyzer
    tracks which decls have escaped, so this patch adds a way to directly
    test this from DejaGnu.
    
    gcc/analyzer/ChangeLog:
            * region-model-impl-calls.cc (cmp_decls): New.
            (cmp_decls_ptr_ptr): New.
            (region_model::impl_call_analyzer_dump_escaped): New.
            * region-model.cc (region_model::on_stmt_pre): Handle
            __analyzer_dump_escaped.
            * region-model.h (region_model::impl_call_analyzer_dump_escaped):
            New decl.
            * store.h (binding_cluster::get_base_region): New accessor.
    
    gcc/ChangeLog:
            * doc/analyzer.texi
            (Special Functions for Debugging the Analyzer): Document
            __analyzer_dump_escaped.
    
    gcc/testsuite/ChangeLog:
            * gcc.dg/analyzer/analyzer-decls.h (__analyzer_dump_escaped): New
            decl.
            * gcc.dg/analyzer/escaping-1.c: New test.

Diff:
---
 gcc/analyzer/region-model-impl-calls.cc        | 69 ++++++++++++++++++++++++++
 gcc/analyzer/region-model.cc                   |  2 +
 gcc/analyzer/region-model.h                    |  1 +
 gcc/analyzer/store.h                           |  2 +
 gcc/doc/analyzer.texi                          |  8 +++
 gcc/testsuite/gcc.dg/analyzer/analyzer-decls.h |  3 ++
 gcc/testsuite/gcc.dg/analyzer/escaping-1.c     | 27 ++++++++++
 7 files changed, 112 insertions(+)

diff --git a/gcc/analyzer/region-model-impl-calls.cc b/gcc/analyzer/region-model-impl-calls.cc
index 9063acd6be5..c20058ec778 100644
--- a/gcc/analyzer/region-model-impl-calls.cc
+++ b/gcc/analyzer/region-model-impl-calls.cc
@@ -264,6 +264,75 @@ region_model::impl_call_analyzer_dump_capacity (const gcall *call,
   warning_at (call->location, 0, "capacity: %qs", desc.m_buffer);
 }
 
+/* Compare D1 and D2 using their names, and then IDs to order them.  */
+
+static int
+cmp_decls (tree d1, tree d2)
+{
+  gcc_assert (DECL_P (d1));
+  gcc_assert (DECL_P (d2));
+  if (DECL_NAME (d1) && DECL_NAME (d2))
+    if (int cmp = strcmp (IDENTIFIER_POINTER (DECL_NAME (d1)),
+			  IDENTIFIER_POINTER (DECL_NAME (d2))))
+      return cmp;
+  return (int)DECL_UID (d1) - (int)DECL_UID (d2);
+}
+
+/* Comparator for use by vec<tree>::qsort,
+   using their names, and then IDs to order them.  */
+
+static int
+cmp_decls_ptr_ptr (const void *p1, const void *p2)
+{
+  tree const *d1 = (tree const *)p1;
+  tree const *d2 = (tree const *)p2;
+
+  return cmp_decls (*d1, *d2);
+}
+
+/* Handle a call to "__analyzer_dump_escaped".
+
+   Emit a warning giving the number of decls that have escaped, followed
+   by a comma-separated list of their names, in alphabetical order.
+
+   This is for use when debugging, and may be of use in DejaGnu tests.  */
+
+void
+region_model::impl_call_analyzer_dump_escaped (const gcall *call)
+{
+  auto_vec<tree> escaped_decls;
+  for (auto iter : m_store)
+    {
+      const binding_cluster *c = iter.second;
+      if (!c->escaped_p ())
+	continue;
+      if (tree decl = c->get_base_region ()->maybe_get_decl ())
+	escaped_decls.safe_push (decl);
+    }
+
+  /* Sort them into deterministic order; alphabetical is
+     probably most user-friendly.  */
+  escaped_decls.qsort (cmp_decls_ptr_ptr);
+
+  pretty_printer pp;
+  pp_format_decoder (&pp) = default_tree_printer;
+  pp_show_color (&pp) = pp_show_color (global_dc->printer);
+  bool first = true;
+  for (auto iter : escaped_decls)
+    {
+      if (first)
+	first = false;
+      else
+	pp_string (&pp, ", ");
+      pp_printf (&pp, "%qD", iter);
+    }
+  /* Print the number to make it easier to write DejaGnu tests for
+     the "nothing has escaped" case.  */
+  warning_at (call->location, 0, "escaped: %i: %s",
+	      escaped_decls.length (),
+	      pp_formatted_text (&pp));
+}
+
 /* Handle a call to "__analyzer_eval" by evaluating the input
    and dumping as a dummy warning, so that test cases can use
    dg-warning to validate the result (and so unexpected warnings will
diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index b7371948873..cb86d79c99d 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -999,6 +999,8 @@ region_model::on_stmt_pre (const gimple *stmt,
 	  impl_call_analyzer_describe (call, ctxt);
 	else if (is_special_named_call_p (call, "__analyzer_dump_capacity", 1))
 	  impl_call_analyzer_dump_capacity (call, ctxt);
+	else if (is_special_named_call_p (call, "__analyzer_dump_escaped", 0))
+	  impl_call_analyzer_dump_escaped (call);
 	else if (is_special_named_call_p (call, "__analyzer_dump_path", 0))
 	  {
 	    /* Handle the builtin "__analyzer_dump_path" by queuing a
diff --git a/gcc/analyzer/region-model.h b/gcc/analyzer/region-model.h
index 8e35be1f180..669f1c748ce 100644
--- a/gcc/analyzer/region-model.h
+++ b/gcc/analyzer/region-model.h
@@ -573,6 +573,7 @@ class region_model
 				    region_model_context *ctxt);
   void impl_call_analyzer_dump_capacity (const gcall *call,
 					 region_model_context *ctxt);
+  void impl_call_analyzer_dump_escaped (const gcall *call);
   void impl_call_analyzer_eval (const gcall *call,
 				region_model_context *ctxt);
   void impl_call_builtin_expect (const call_details &cd);
diff --git a/gcc/analyzer/store.h b/gcc/analyzer/store.h
index 4672886e281..f30b6bc8b2e 100644
--- a/gcc/analyzer/store.h
+++ b/gcc/analyzer/store.h
@@ -559,6 +559,8 @@ public:
 
   bool symbolic_p () const;
 
+  const region *get_base_region () const { return m_base_region; }
+
   void dump_to_pp (pretty_printer *pp, bool simple, bool multiline) const;
   void dump (bool simple) const;
 
diff --git a/gcc/doc/analyzer.texi b/gcc/doc/analyzer.texi
index 62faac44d7f..06eb98fe4d3 100644
--- a/gcc/doc/analyzer.texi
+++ b/gcc/doc/analyzer.texi
@@ -486,6 +486,14 @@ extern void __analyzer_dump_capacity (const void *ptr);
 will emit a warning describing the capacity of the base region of
 the region pointed to by the 1st argument.
 
+@smallexample
+extern void __analyzer_dump_escaped (void);
+@end smallexample
+
+will emit a warning giving the number of decls that have escaped on this
+analysis path, followed by a comma-separated list of their names,
+in alphabetical order.
+
 @smallexample
 __analyzer_dump_path ();
 @end smallexample
diff --git a/gcc/testsuite/gcc.dg/analyzer/analyzer-decls.h b/gcc/testsuite/gcc.dg/analyzer/analyzer-decls.h
index e8745c0933f..d05257949ff 100644
--- a/gcc/testsuite/gcc.dg/analyzer/analyzer-decls.h
+++ b/gcc/testsuite/gcc.dg/analyzer/analyzer-decls.h
@@ -18,6 +18,9 @@ extern void __analyzer_dump (void);
 /* Emit a warning describing the size of the base region of (*ptr).  */
 extern void __analyzer_dump_capacity (const void *ptr);
 
+/* Dump information about what decls have escaped at this point on the path.  */
+extern void __analyzer_dump_escaped (void);
+
 /* Dump information after analysis on all of the exploded nodes at this
    program point.
 
diff --git a/gcc/testsuite/gcc.dg/analyzer/escaping-1.c b/gcc/testsuite/gcc.dg/analyzer/escaping-1.c
new file mode 100644
index 00000000000..2dfd02b9ede
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/escaping-1.c
@@ -0,0 +1,27 @@
+#include "analyzer-decls.h"
+
+#define NULL ((void *)0)
+
+extern void unknown_fn (void *);
+
+static int only_used_by_test_1;
+
+static void test_1 (void)
+{
+  int local_1, local_2;
+  __analyzer_dump_escaped (); /* { dg-warning "escaped: 0: " } */
+
+  unknown_fn (NULL);
+  __analyzer_dump_escaped (); /* { dg-warning "escaped: 0: " } */
+
+  unknown_fn (&local_1);
+  __analyzer_dump_escaped (); /* { dg-warning "escaped: 1: 'local_1'" } */
+
+  /* Should be idempotent.  */
+  unknown_fn (&local_1);
+  __analyzer_dump_escaped (); /* { dg-warning "escaped: 1: 'local_1'" } */
+
+  /* Escape a static global.  */
+  unknown_fn (&only_used_by_test_1);
+  __analyzer_dump_escaped (); /* { dg-warning "escaped: 2: 'local_1', 'only_used_by_test_1'" } */
+}