2013-10-29 Andrew Pinski <apinski@cavium.com>

        * tree-ssa-ifcombine.c: Include rtl.h and tm_p.h.
        (ifcombine_ifandif): Handle cases where
        maybe_fold_and_comparisons fails, combining the branches
        anyways.
        (tree_ssa_ifcombine): Inverse the order of
        the basic block walk, increases the number of combinings.
        * gimple.h (gsi_start_nondebug_after_labels_bb): New function.

2013-10-29  Andrew Pinski <apinski@cavium.com>
            Zhenqiang Chen  <zhenqiang.chen@linaro.org>

        * gcc.dg/tree-ssa/ssa-ifcombine-ccmp-1.c: New test case.
        * gcc.dg/tree-ssa/ssa-ifcombine-ccmp-2.c: New test case.
        * gcc.dg/tree-ssa/ssa-ifcombine-ccmp-3.c: New test case.
        * gcc.dg/tree-ssa/ssa-ifcombine-ccmp-4.c: New test case.
        * gcc.dg/tree-ssa/ssa-ifcombine-ccmp-5.c: New test case.
        * gcc.dg/tree-ssa/ssa-ifcombine-ccmp-6.c: New test case.
        * gcc.dg/tree-ssa/phi-opt-9.c: Use a function call to prevent
        conditional move to be used.
        * gcc.dg/tree-ssa/ssa-dom-thread-3.c: Remove.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@204194 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 48 insertions, 2 deletions

diff --git a/gcc/tree-ssa-ifcombine.c b/gcc/tree-ssa-ifcombine.c
index 0b9de258bf3..73ebfe8b24e 100644
--- a/gcc/tree-ssa-ifcombine.c
+++ b/gcc/tree-ssa-ifcombine.c
@@ -22,6 +22,10 @@ along with GCC; see the file COPYING3.  If not see
 #include "system.h"
 #include "coretypes.h"
 #include "tm.h"
+/* rtl is needed only because arm back-end requires it for
+   BRANCH_COST.  */
+#include "rtl.h"
+#include "tm_p.h"
 #include "tree.h"
 #include "basic-block.h"
 #include "tree-pretty-print.h"
@@ -32,6 +36,12 @@ along with GCC; see the file COPYING3.  If not see
 #include "ssa-iterators.h"
 #include "tree-pass.h"
 
+#ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
+#define LOGICAL_OP_NON_SHORT_CIRCUIT \
+  (BRANCH_COST (optimize_function_for_speed_p (cfun), \
+                false) >= 2)
+#endif
+
 /* This pass combines COND_EXPRs to simplify control flow.  It
    currently recognizes bit tests and comparisons in chains that
    represent logical and or logical or of two COND_EXPRs.
@@ -488,7 +498,35 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
 					    outer_cond_code,
 					    gimple_cond_lhs (outer_cond),
 					    gimple_cond_rhs (outer_cond))))
-	return false;
+	{
+	  tree t1, t2;
+	  gimple_stmt_iterator gsi;
+	  if (!LOGICAL_OP_NON_SHORT_CIRCUIT)
+	    return false;
+	  /* Only do this optimization if the inner bb contains only the conditional. */
+	  if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))
+	    return false;
+	  t1 = fold_build2_loc (gimple_location (inner_cond),
+				inner_cond_code,
+				boolean_type_node,
+				gimple_cond_lhs (inner_cond),
+				gimple_cond_rhs (inner_cond));
+	  t2 = fold_build2_loc (gimple_location (outer_cond),
+				outer_cond_code,
+				boolean_type_node,
+				gimple_cond_lhs (outer_cond),
+				gimple_cond_rhs (outer_cond));
+	  t = fold_build2_loc (gimple_location (inner_cond), 
+			       TRUTH_AND_EXPR, boolean_type_node, t1, t2);
+	  if (result_inv)
+	    {
+	      t = fold_build1 (TRUTH_NOT_EXPR, TREE_TYPE (t), t);
+	      result_inv = false;
+	    }
+	  gsi = gsi_for_stmt (inner_cond);
+	  t = force_gimple_operand_gsi_1 (&gsi, t, is_gimple_condexpr, NULL, true,
+					  GSI_SAME_STMT);
+        }
       if (result_inv)
 	t = fold_build1 (TRUTH_NOT_EXPR, TREE_TYPE (t), t);
       t = canonicalize_cond_expr_cond (t);
@@ -631,7 +669,15 @@ tree_ssa_ifcombine (void)
   bbs = single_pred_before_succ_order ();
   calculate_dominance_info (CDI_DOMINATORS);
 
-  for (i = 0; i < n_basic_blocks - NUM_FIXED_BLOCKS; ++i)
+  /* Search every basic block for COND_EXPR we may be able to optimize.
+
+     We walk the blocks in order that guarantees that a block with
+     a single predecessor is processed after the predecessor.
+     This ensures that we collapse outter ifs before visiting the
+     inner ones, and also that we do not try to visit a removed
+     block.  This is opposite of PHI-OPT, because we cascade the
+     combining rather than cascading PHIs. */
+  for (i = n_basic_blocks - NUM_FIXED_BLOCKS - 1; i >= 0; i--)
     {
       basic_block bb = bbs[i];
       gimple stmt = last_stmt (bb);