Add some optimizations for jumpthreading using vrp information

This uses the vrp information to expand the handling for constants to
handling ranges as well.

[r27098]

diff --git a/ir/opt/jumpthreading.c b/ir/opt/jumpthreading.c
index 02ca3bf..3e53ddb 100644 (file)
--- a/ir/opt/jumpthreading.c
+++ b/ir/opt/jumpthreading.c
@@ -45,6 +45,7 @@
 #include "opt_confirms.h"
 #include "iropt_dbg.h"
 #include "irpass.h"
+#include "vrp.h"
 
 #undef AVOID_PHIB
 
@@ -371,6 +372,27 @@ static int eval_cmp_tv(pn_Cmp pnc, tarval *tv_left, tarval *tv_right)
        return 1;
 }
 
+/**
+ * returns whether the cmp evaluates to true or false according to vrp
+ * information , or can't be evaluated!
+ * 1: true, 0: false, -1: can't evaluate
+ *
+ * @param pnc       the compare mode of the Compare
+ * @param left   the left node
+ * @param right  the right node
+ */
+static int eval_cmp_vrp(pn_Cmp pnc, ir_node *left, ir_node *right)
+{
+       pn_Cmp cmp_result = vrp_cmp(left, right);
+
+       /* does the compare evaluate to true? */
+       if (cmp_result == pn_Cmp_False)
+               return -1;
+       if ((cmp_result & pnc) != cmp_result)
+               return 0;
+
+       return 1;
+}
 /**
  * returns whether the cmp evaluates to true or false, or can't be evaluated!
  * 1: true, 0: false, -1: can't evaluate
@@ -641,8 +663,15 @@ static void thread_jumps(ir_node* block, void* data)
                                tarval *tv_right = get_Const_tarval(right);
 
                                selector_evaluated = eval_cmp_tv(pnc, tv_left, tv_right);
-                               if (selector_evaluated < 0)
-                                       return;
+                       }
+                       if (selector_evaluated < 0) {
+                               /* This is only the case if the predecessor nodes are not
+                                * constant or the comparison could not be evaluated.
+                                * Try with VRP information now.
+                                */
+                               int pnc = get_Proj_proj(selector);
+
+                               selector_evaluated = eval_cmp_vrp(pnc, left, right);
                        }
                }
        } else if (is_Const_or_Confirm(selector)) {