tree-cfgcleanup.c (cleanup_control_expr_graph): Remove first_p paramter and handling.

2017-11-14  Richard Biener  <rguenther@suse.de>

	* tree-cfgcleanup.c (cleanup_control_expr_graph): Remove first_p
	paramter and handling.
	(cleanup_control_flow_bb): Likewise.
	(cleanup_control_flow_pre): New helper performing a DFS walk
	to call cleanup_control_flow_bb in PRE order.
	(cleanup_tree_cfg_1): Do the first phase of cleanup_control_flow_bb
	via cleanup_control_flow_pre.

From-SVN: r254730

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index af60aedf97a43f0e48b34ab969b37449f71f6030..e9bb5ae6542bb7dcbb9804558242fdaa17def14a 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2017-11-14  Richard Biener  <rguenther@suse.de>
+
+       * tree-cfgcleanup.c (cleanup_control_expr_graph): Remove first_p
+       paramter and handling.
+       (cleanup_control_flow_bb): Likewise.
+       (cleanup_control_flow_pre): New helper performing a DFS walk
+       to call cleanup_control_flow_bb in PRE order.
+       (cleanup_tree_cfg_1): Do the first phase of cleanup_control_flow_bb
+       via cleanup_control_flow_pre.
+
 2017-11-14  James Greenhalgh  <james.greenhalgh@arm.com>
 
        * config/aarch64/aarch64-simd.md

diff --git a/gcc/tree-cfgcleanup.c b/gcc/tree-cfgcleanup.c
index 9b7f08c586c39d6d37fc15280f395a6e847706e0..526793723dcede533ac63dbf32577d7e736bc04a 100644 (file)
--- a/gcc/tree-cfgcleanup.c
+++ b/gcc/tree-cfgcleanup.c
@@ -122,8 +122,7 @@ convert_single_case_switch (gswitch *swtch, gimple_stmt_iterator &gsi)
    at block BB.  */
 
 static bool
-cleanup_control_expr_graph (basic_block bb, gimple_stmt_iterator gsi,
-                           bool first_p)
+cleanup_control_expr_graph (basic_block bb, gimple_stmt_iterator gsi)
 {
   edge taken_edge;
   bool retval = false;
@@ -146,25 +145,14 @@ cleanup_control_expr_graph (basic_block bb, gimple_stmt_iterator gsi,
       switch (gimple_code (stmt))
        {
        case GIMPLE_COND:
-         /* During a first iteration on the CFG only remove trivially
-            dead edges but mark other conditions for re-evaluation.  */
-         if (first_p)
-           {
-             val = const_binop (gimple_cond_code (stmt), boolean_type_node,
-                                gimple_cond_lhs (stmt),
-                                gimple_cond_rhs (stmt));
-             if (! val)
-               bitmap_set_bit (cfgcleanup_altered_bbs, bb->index);
-           }
-         else
-           {
-             code_helper rcode;
-             tree ops[3] = {};
-             if (gimple_simplify (stmt, &rcode, ops, NULL, no_follow_ssa_edges,
-                                  no_follow_ssa_edges)
-                 && rcode == INTEGER_CST)
-               val = ops[0];
-           }
+         {
+           code_helper rcode;
+           tree ops[3] = {};
+           if (gimple_simplify (stmt, &rcode, ops, NULL, no_follow_ssa_edges,
+                                no_follow_ssa_edges)
+               && rcode == INTEGER_CST)
+             val = ops[0];
+         }
          break;
 
        case GIMPLE_SWITCH:
@@ -235,7 +223,7 @@ cleanup_call_ctrl_altering_flag (gimple *bb_end)
    true if anything changes.  */
 
 static bool
-cleanup_control_flow_bb (basic_block bb, bool first_p)
+cleanup_control_flow_bb (basic_block bb)
 {
   gimple_stmt_iterator gsi;
   bool retval = false;
@@ -258,7 +246,7 @@ cleanup_control_flow_bb (basic_block bb, bool first_p)
       || gimple_code (stmt) == GIMPLE_SWITCH)
     {
       gcc_checking_assert (gsi_stmt (gsi_last_bb (bb)) == stmt);
-      retval |= cleanup_control_expr_graph (bb, gsi, first_p);
+      retval |= cleanup_control_expr_graph (bb, gsi);
     }
   else if (gimple_code (stmt) == GIMPLE_GOTO
           && TREE_CODE (gimple_goto_dest (stmt)) == ADDR_EXPR
@@ -732,6 +720,45 @@ cleanup_tree_cfg_bb (basic_block bb)
   return false;
 }
 
+/* Do cleanup_control_flow_bb in PRE order.  */
+
+static bool
+cleanup_control_flow_pre ()
+{
+  bool retval = false;
+
+  auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1);
+  auto_sbitmap visited (last_basic_block_for_fn (cfun));
+  bitmap_clear (visited);
+
+  stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs));
+
+  while (! stack.is_empty ())
+    {
+      /* Look at the edge on the top of the stack.  */
+      edge_iterator ei = stack.last ();
+      basic_block dest = ei_edge (ei)->dest;
+
+      if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
+         && ! bitmap_bit_p (visited, dest->index))
+       {
+         bitmap_set_bit (visited, dest->index);
+         retval |= cleanup_control_flow_bb (dest);
+         if (EDGE_COUNT (dest->succs) > 0)
+           stack.quick_push (ei_start (dest->succs));
+       }
+      else
+       {
+         if (!ei_one_before_end_p (ei))
+           ei_next (&stack.last ());
+         else
+           stack.pop ();
+       }
+    }
+
+  return retval;
+}
+
 /* Iterate the cfg cleanups, while anything changes.  */
 
 static bool
@@ -752,17 +779,11 @@ cleanup_tree_cfg_1 (void)
   /* We cannot use FOR_EACH_BB_FN for the BB iterations below
      since the basic blocks may get removed.  */
 
-  /* Start by iterating over all basic blocks looking for edge removal
-     opportunities.  Do this first because incoming SSA form may be
-     invalid and we want to avoid performing SSA related tasks such
+  /* Start by iterating over all basic blocks in PRE order looking for
+     edge removal opportunities.  Do this first because incoming SSA form
+     may be invalid and we want to avoid performing SSA related tasks such
      as propgating out a PHI node during BB merging in that state.  */
-  n = last_basic_block_for_fn (cfun);
-  for (i = NUM_FIXED_BLOCKS; i < n; i++)
-    {
-      bb = BASIC_BLOCK_FOR_FN (cfun, i);
-      if (bb)
-       retval |= cleanup_control_flow_bb (bb, true);
-    }
+  retval |= cleanup_control_flow_pre ();
 
   /* After doing the above SSA form should be valid (or an update SSA
      should be required).  */
@@ -789,7 +810,7 @@ cleanup_tree_cfg_1 (void)
       if (!bb)
        continue;
 
-      retval |= cleanup_control_flow_bb (bb, false);
+      retval |= cleanup_control_flow_bb (bb);
       retval |= cleanup_tree_cfg_bb (bb);
     }