From 9eef1943b8c3b67effea5a054ee9fa45542c6239 Mon Sep 17 00:00:00 2001
From: David Malcolm <dmalcolm@redhat.com>
Date: Fri, 29 May 2020 10:04:53 -0400
Subject: [PATCH 193/315] FIXME: fix flickering test in data-model-14.c

---
 gcc/analyzer/analyzer.h       |  1 +
 gcc/analyzer/engine.cc        | 19 ++++++++++++++-----
 gcc/analyzer/region-model2.cc | 17 ++++++++++++++---
 gcc/analyzer/region-model2.h  |  7 +++++++
 4 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/gcc/analyzer/analyzer.h b/gcc/analyzer/analyzer.h
index 00d27d77071..7b49af636b9 100644
--- a/gcc/analyzer/analyzer.h
+++ b/gcc/analyzer/analyzer.h
@@ -64,6 +64,7 @@ class svalue2;
   class unaryop_svalue2;
   class binop_svalue2;
 class region2;
+  class frame_region2;
   class function_region2;
   class label_region2;
   class decl_region2;
diff --git a/gcc/analyzer/engine.cc b/gcc/analyzer/engine.cc
index 238b0fa40fb..4df661c9e39 100644
--- a/gcc/analyzer/engine.cc
+++ b/gcc/analyzer/engine.cc
@@ -735,12 +735,14 @@ readability (const_tree expr)
     case MEM_REF:
       /* Impose a slight readability penalty relative to that of
 	 operand 0.  */
-      return readability (TREE_OPERAND (expr, 0)) - 1;
+      return readability (TREE_OPERAND (expr, 0)) - 16;
 
     case SSA_NAME:
       {
 	if (tree var = SSA_NAME_VAR (expr))
-	  return readability (var);
+	  /* Slightly favor the underlying var over the SSA name to
+	     avoid having them compare equal.  */
+	  return readability (var) - 1;
 	/* Avoid printing '<unknown>' for SSA names for temporaries.  */
 	return -1;
       }
@@ -749,7 +751,7 @@ readability (const_tree expr)
     case PARM_DECL:
     case VAR_DECL:
       /* Arbitrarily-chosen "high readability" value.  */
-      return 256;
+      return 65536;
 
     default:
       return 0;
@@ -767,11 +769,18 @@ readability_comparator (const void *p1, const void *p2)
   path_var pv1 = *(path_var const *)p1;
   path_var pv2 = *(path_var const *)p2;
 
-  /* TODO: should we consider stack depths?  */
   int r1 = readability (pv1.m_tree);
   int r2 = readability (pv2.m_tree);
+  if (int cmp = r2 - r1)
+    return cmp;
 
-  return r2 - r1;
+  /* Favor items that are deeper on the stack and hence more recent;
+     this also favors locals over globals.  */
+  if (int cmp = pv2.m_stack_depth - pv1.m_stack_depth)
+    return cmp;
+
+  /* TODO: We ought to find ways of sorting such cases.  */
+  return 0;
 }
 
 /* Create an sm_context and use it to call SM's on_leak vfunc, so that
diff --git a/gcc/analyzer/region-model2.cc b/gcc/analyzer/region-model2.cc
index f786f7bd386..204d5a03302 100644
--- a/gcc/analyzer/region-model2.cc
+++ b/gcc/analyzer/region-model2.cc
@@ -2462,12 +2462,23 @@ decl_region2::dump_to_pp (pretty_printer *pp, bool simple) const
 bool
 decl_region2::get_representative_path_var (path_var *out) const
 {
-  // FIXME: use correct stack depth
-  // FIXME: should we store a path_var, rather that a tree?
-  *out = path_var (m_decl, 0);
+  *out = path_var (m_decl, get_stack_depth ());
   return true;
 }
 
+/* FIXME.  */
+
+int
+decl_region2::get_stack_depth () const
+{
+  if (get_parent_region () == NULL)
+    return 0;
+  if (const frame_region2 *frame_reg
+	= get_parent_region ()->dyn_cast_frame_region2 ())
+    return frame_reg->get_stack_depth ();
+  return 0;
+}
+
 /* class field_region2 : public region2.  */
 
 void
diff --git a/gcc/analyzer/region-model2.h b/gcc/analyzer/region-model2.h
index 2e3953174f7..c380a1bf43b 100644
--- a/gcc/analyzer/region-model2.h
+++ b/gcc/analyzer/region-model2.h
@@ -850,6 +850,8 @@ public:
   static int cmp_ids (const region2 *reg1, const region2 *reg2);
 
   virtual enum kind get_kind () const = 0;
+  virtual const frame_region2 *
+  dyn_cast_frame_region2 () const { return NULL; }
   virtual const function_region2 *
   dyn_cast_function_region2 () const { return NULL; }
   virtual const symbolic_region2 *
@@ -999,6 +1001,10 @@ public:
 
   /* region2 vfuncs.  */
   enum kind get_kind () const FINAL OVERRIDE { return RK_FRAME; }
+  const frame_region2 * dyn_cast_frame_region2 () const FINAL OVERRIDE
+  {
+    return this;
+  }
   void dump_to_pp (pretty_printer *pp, bool simple) const FINAL OVERRIDE;
 #if 0
   void add_to_hash (inchash::hash &hstate) const FINAL OVERRIDE;
@@ -1369,6 +1375,7 @@ public:
   bool get_representative_path_var (path_var *out) const FINAL OVERRIDE;
 
   tree get_decl () const { return m_decl; }
+  int get_stack_depth () const;
 
 protected:
   void add_to_hash (inchash::hash &hstate) const OVERRIDE;
-- 
2.26.2