[gcc(refs/users/marxin/heads/loop-unswitching-switch-v5)] Restore old code that can handle floating point types.

[Martin Liska <marxin@gcc.gnu.org>]

https://gcc.gnu.org/g:31102db9992df9b12228e36cdc1b18cc7198a733

commit 31102db9992df9b12228e36cdc1b18cc7198a733
Author: Martin Liska <mliska@suse.cz>
Date:   Mon Nov 8 16:29:59 2021 +0100

    Restore old code that can handle floating point types.

Diff:
---
 gcc/tree-ssa-loop-unswitch.c | 52 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/gcc/tree-ssa-loop-unswitch.c b/gcc/tree-ssa-loop-unswitch.c
index 4b4bd471acd..1d169802252 100644
--- a/gcc/tree-ssa-loop-unswitch.c
+++ b/gcc/tree-ssa-loop-unswitch.c
@@ -300,6 +300,39 @@ tree_may_unswitch_on (basic_block bb, class loop *loop, edge *cond_edge)
   return NULL_TREE;
 }
 
+/* Simplifies COND using checks in front of the entry of the LOOP.  Just very
+   simplish (sufficient to prevent us from duplicating loop in unswitching
+   unnecessarily).  */
+
+static tree
+simplify_using_entry_checks (class loop *loop, tree cond)
+{
+  edge e = loop_preheader_edge (loop);
+  gimple *stmt;
+
+  while (1)
+    {
+      stmt = last_stmt (e->src);
+      if (stmt
+	  && gimple_code (stmt) == GIMPLE_COND
+	  && gimple_cond_code (stmt) == TREE_CODE (cond)
+	  && operand_equal_p (gimple_cond_lhs (stmt),
+			      TREE_OPERAND (cond, 0), 0)
+	  && operand_equal_p (gimple_cond_rhs (stmt),
+			      TREE_OPERAND (cond, 1), 0))
+	return (e->flags & EDGE_TRUE_VALUE
+		? boolean_true_node
+		: boolean_false_node);
+
+      if (!single_pred_p (e->src))
+	return cond;
+
+      e = single_pred_edge (e->src);
+      if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+	return cond;
+    }
+}
+
 /* Unswitch single LOOP.  NUM is number of unswitchings done; we do not allow
    it to grow too much, it is too easy to create example on that the code would
    grow exponentially.  */
@@ -393,6 +426,25 @@ tree_unswitch_single_loop (class loop *loop, int num)
 	      update_stmt (condition);
 	      changed = true;
 	    }
+	  else
+	    {
+	      /* FIXME: Remove legacy code for floating point type that
+		 is currently not supported by ranger.  */
+	      cond = simplify_using_entry_checks (loop, cond);
+	      if (integer_nonzerop (cond))
+		{
+		  gimple_cond_set_condition_from_tree (condition,
+						       boolean_true_node);
+		  changed = true;
+		}
+	      else if (integer_zerop (cond))
+		{
+		  /* Remove true path.  */
+		  gimple_cond_set_condition_from_tree (condition,
+						       boolean_false_node);
+		  changed = true;
+		}
+	    }
 	}
       else if (swtch != NULL)
 	{