analyzer: add region::is_named_decl_p

This patch adds a debug function that I've found handy when debugging
a problem with handling the decl "yy_buffer_stack" in PR analyzer/103546.

gcc/analyzer/ChangeLog:
	* region.cc (region::is_named_decl_p): New.
	* region.h (region::is_named_decl_p): New decl.

gcc/ChangeLog:
	* doc/analyzer.texi (Other Debugging Techniques): Document
	region::is_named_decl_p.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

gcc/analyzer/region.cc

@@ -638,6 +638,20 @@ region::symbolic_for_unknown_ptr_p () const
   return false;
 }
 
+/* Return true if this is a region for a decl with name DECL_NAME.
+   Intended for use when debugging (for assertions and conditional
+   breakpoints).  */
+
+DEBUG_FUNCTION bool
+region::is_named_decl_p (const char *decl_name) const
+{
+  if (tree decl = maybe_get_decl ())
+    if (DECL_NAME (decl)
+	&& !strcmp (IDENTIFIER_POINTER (DECL_NAME (decl)), decl_name))
+      return true;
+  return false;
+}
+
 /* region's ctor.  */
 
 region::region (complexity c, unsigned id, const region *parent, tree type)

gcc/analyzer/region.h

@@ -189,6 +189,8 @@ public:
 
   const complexity &get_complexity () const { return m_complexity; }
 
+  bool is_named_decl_p (const char *decl_name) const;
+
  protected:
   region (complexity c, unsigned id, const region *parent, tree type);
 

gcc/doc/analyzer.texi

@@ -545,3 +545,13 @@ and the exploded graph in compressed JSON form.
 One approach when tracking down where a particular bogus state is
 introduced into the @code{exploded_graph} is to add custom code to
 @code{program_state::validate}.
+
+The debug function @code{region::is_named_decl_p} can be used when debugging,
+such as for assertions and conditional breakpoints.  For example, when
+tracking down a bug in handling a decl called @code{yy_buffer_stack}, I
+temporarily added a:
+@smallexample
+  gcc_assert (!m_base_region->is_named_decl_p ("yy_buffer_stack"));
+@end smallexample
+to @code{binding_cluster::mark_as_escaped} to trap a point where
+@code{yy_buffer_stack} was mistakenly being treated as having escaped.