From 87dd4c8c83768aafad92588853fd84a6070553d6 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Fri, 29 Jul 2022 12:05:38 -0400
Subject: [PATCH] Check equivalencies when calculating range on entry.

When propagating on-entry values in the cache, checking if any equivalence
has a known value can improve results.  No new calculations are made.
Only queries via dominators which do not populate the cache are checked.

	PR tree-optimization/106474
	gcc/
	* gimple-range-cache.cc (ranger_cache::fill_block_cache): Query
	range of equivalences that may contribute to the range.

	gcc/testsuite/
	* g++.dg/pr106474.C: New.
---
 gcc/gimple-range-cache.cc       | 45 ++++++++++++++++++++++++++++++++-
 gcc/testsuite/g++.dg/pr106474.C | 16 ++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/pr106474.C

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index d9e160c9a2a..4782d47265e 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -1211,13 +1211,56 @@ ranger_cache::fill_block_cache (tree name, basic_block bb, basic_block def_bb)
   // Check if a dominators can supply the range.
   if (range_from_dom (block_result, name, bb, RFD_FILL))
     {
-      m_on_entry.set_bb_range (name, bb, block_result);
       if (DEBUG_RANGE_CACHE)
 	{
 	  fprintf (dump_file, "Filled from dominator! :  ");
 	  block_result.dump (dump_file);
 	  fprintf (dump_file, "\n");
 	}
+      // See if any equivalences can refine it.
+      if (m_oracle)
+	{
+	  unsigned i;
+	  bitmap_iterator bi;
+	  // Query equivalences in read-only mode.
+	  const_bitmap equiv = m_oracle->equiv_set (name, bb);
+	  EXECUTE_IF_SET_IN_BITMAP (equiv, 0, i, bi)
+	    {
+	      if (i == SSA_NAME_VERSION (name))
+		continue;
+	      tree equiv_name = ssa_name (i);
+	      basic_block equiv_bb = gimple_bb (SSA_NAME_DEF_STMT (equiv_name));
+
+	      // Check if the equiv has any ranges calculated.
+	      if (!m_gori.has_edge_range_p (equiv_name))
+		continue;
+
+	      // Check if the equiv definition dominates this block
+	      if (equiv_bb == bb ||
+		  (equiv_bb && !dominated_by_p (CDI_DOMINATORS, bb, equiv_bb)))
+		continue;
+
+	      Value_Range equiv_range (TREE_TYPE (equiv_name));
+	      if (range_from_dom (equiv_range, equiv_name, bb, RFD_READ_ONLY))
+		{
+		  if (block_result.intersect (equiv_range))
+		    {
+		      if (DEBUG_RANGE_CACHE)
+			{
+			  fprintf (dump_file, "Equivalence update! :  ");
+			  print_generic_expr (dump_file, equiv_name, TDF_SLIM);
+			  fprintf (dump_file, "had range  :  ");
+			  equiv_range.dump (dump_file);
+			  fprintf (dump_file, " refining range to :");
+			  block_result.dump (dump_file);
+			  fprintf (dump_file, "\n");
+			}
+		    }
+		}
+	    }
+	}
+
+      m_on_entry.set_bb_range (name, bb, block_result);
       gcc_checking_assert (m_workback.length () == 0);
       return;
     }
diff --git a/gcc/testsuite/g++.dg/pr106474.C b/gcc/testsuite/g++.dg/pr106474.C
new file mode 100644
index 00000000000..6cd37a20643
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr106474.C
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp " } */
+
+void foo();
+static void __attribute__ ((noinline)) DCEMarker0_() {foo ();}
+
+void f(bool s, bool c) {
+    if ((!c == !s) && !c) {
+        if (s) {
+            DCEMarker0_();
+        }
+    }
+}
+
+// With equivalences, vrp should be able to remove all IFs.
+/* { dg-final { scan-tree-dump-not "goto" "evrp" } } */