[1/2] Split return functionality of get_non_stale_global_range.

From 310719594aa20e8d012f478ab3208f889b558bac Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Fri, 19 Nov 2021 12:59:12 -0500
Subject: [PATCH 2/3] Split return functionality of get_non_stale_global_range.

Get_non_stale_global_range returns true only when there is a cache entry that
is not out of date.  Change it so that it returns true if there was a cache
value, but return the temporal comparison result in an auxiallary flag.

	* gimple-range-cache.cc (ranger_cache::get_global_range): Always
	return a range, return if it came from the cache or not.
	(get_non_stale_global_range): Rename to get_global_range, and return
	the temporal state in a flag.
	* gimple-range-cache.h (get_non_stale_global_range): Rename and adjust.
	* gimple-range.cc (gimple_ranger::range_of_expr): No need to query
	get_global_range.
	(gimple_ranger::range_of_stmt): Adjust for global cache temporal state
	returned in a flag.
---
 gcc/gimple-range-cache.cc | 55 ++++++++++++++++++++-------------------
 gcc/gimple-range-cache.h  |  2 +-
 gcc/gimple-range.cc       | 21 ++++++++-------
 3 files changed, 41 insertions(+), 37 deletions(-)

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index b347edeb474..fe31e9462aa 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -923,44 +923,45 @@  ranger_cache::dump_bb (FILE *f, basic_block bb)
 }
 
 // Get the global range for NAME, and return in R.  Return false if the
-// global range is not set.
+// global range is not set, and return the legacy global value in R.
 
 bool
 ranger_cache::get_global_range (irange &r, tree name) const
 {
-  return m_globals.get_global_range (r, name);
+  if (m_globals.get_global_range (r, name))
+    return true;
+  r = gimple_range_global (name);
+  return false;
 }
 
-// Get the global range for NAME, and return in R if the value is not stale.
-// If the range is set, but is stale, mark it current and return false.
-// If it is not set pick up the legacy global value, mark it current, and
-// return false.
-// Note there is always a value returned in R. The return value indicates
-// whether that value is an up-to-date calculated value or not..
+// Get the global range for NAME, and return in R.  Return false if the
+// global range is not set, and R will contain the legacy global value.
+// CURRENT_P is set to true if the value was in cache and not stale.
+// Otherwise, set CURRENT_P to false and mark as it always current.
+// If the global cache did not have a value, initialize it as well.
+// After this call, the global cache will have a value.
 
 bool
-ranger_cache::get_non_stale_global_range (irange &r, tree name)
+ranger_cache::get_global_range (irange &r, tree name, bool &current_p)
 {
-  if (m_globals.get_global_range (r, name))
-    {
-      // Use this value if the range is constant or current.
-      if (r.singleton_p ()
-	  || m_temporal->current_p (name, m_gori.depend1 (name),
-				    m_gori.depend2 (name)))
-	return true;
-    }
+  bool had_global = get_global_range (r, name);
+
+  // If there was a global value, set current flag, otherwise set a value.
+  current_p = false;
+  if (had_global)
+    current_p = r.singleton_p ()
+		|| m_temporal->current_p (name, m_gori.depend1 (name),
+					  m_gori.depend2 (name));
   else
-    {
-      // Global has never been accessed, so pickup the legacy global value.
-      r = gimple_range_global (name);
-      m_globals.set_global_range (name, r);
-    }
-  // After a stale check failure, mark the value as always current until a
-  // new one is set.
-  m_temporal->set_always_current (name);
-  return false;
+    m_globals.set_global_range (name, r);
+
+  // If the existing value was not current, mark it as always current.
+  if (!current_p)
+    m_temporal->set_always_current (name);
+  return current_p;
 }
-//  Set the global range of NAME to R.
+
+//  Set the global range of NAME to R and give it a timestamp.
 
 void
 ranger_cache::set_global_range (tree name, const irange &r)
diff --git a/gcc/gimple-range-cache.h b/gcc/gimple-range-cache.h
index 49c13d1e85f..eb7a875c46b 100644
--- a/gcc/gimple-range-cache.h
+++ b/gcc/gimple-range-cache.h
@@ -100,7 +100,7 @@  public:
   bool block_range (irange &r, basic_block bb, tree name, bool calc = true);
 
   bool get_global_range (irange &r, tree name) const;
-  bool get_non_stale_global_range (irange &r, tree name);
+  bool get_global_range (irange &r, tree name, bool &current_p);
   void set_global_range (tree name, const irange &r);
 
   void propagate_updated_value (tree name, basic_block bb);
diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 9ca568ce55d..e3ab3a8bb48 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -85,8 +85,7 @@  gimple_ranger::range_of_expr (irange &r, tree expr, gimple *stmt)
   if (!stmt)
     {
       int_range_max tmp;
-      if (!m_cache.get_global_range (r, expr))
-        r = gimple_range_global (expr);
+      m_cache.get_global_range (r, expr);
       // Pick up implied context information from the on-entry cache
       // if current_bb is set.  Do not attempt any new calculations.
       if (current_bb && m_cache.block_range (tmp, current_bb, expr, false))
@@ -282,15 +281,19 @@  gimple_ranger::range_of_stmt (irange &r, gimple *s, tree name)
     }
   else if (!gimple_range_ssa_p (name))
     res = get_tree_range (r, name, NULL);
-  // Check if the stmt has already been processed, and is not stale.
-  else if (m_cache.get_non_stale_global_range (r, name))
-    {
-      if (idx)
-	tracer.trailer (idx, " cached", true, name, r);
-      return true;
-    }
   else
     {
+      bool current;
+      // Check if the stmt has already been processed, and is not stale.
+      if (m_cache.get_global_range (r, name, current))
+	{
+	  if (current)
+	    {
+	      if (idx)
+		tracer.trailer (idx, " cached", true, name, r);
+	      return true;
+	    }
+	}
       // Otherwise calculate a new value.
       int_range_max tmp;
       fold_range_internal (tmp, s, name);
-- 
2.17.2