This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[patch] Fix comments and indentation in tree-if-conv.c


Hi,

while working on improving the if-conversion pass to solve
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43423
I fixed the comments, indentation, and the order of the static functions
in tree-if-conv.c.  The attached patches passed bootstrap and test
on amd64-linux.  Ok for trunk?

Thanks,
Sebastian Pop
--
AMD / Open Source Compiler Engineering / GNU Tools
From d5e0e6b66bfd1a989b127e194911f657e40a6b19 Mon Sep 17 00:00:00 2001
From: Sebastian Pop <sebpop@gmail.com>
Date: Mon, 1 Mar 2010 05:41:00 -0600
Subject: [PATCH 1/3] Fix comments in ifconvert.

	* tree-if-conv.c: Fix indentation and comments.
---
 gcc/tree-if-conv.c |  125 +++++++++++++++++++++++++---------------------------
 1 files changed, 60 insertions(+), 65 deletions(-)

diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index a008384..5ff8644 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -134,12 +134,12 @@ static bool bb_with_exit_edge_p (struct loop *, basic_block);
 /* List of basic blocks in if-conversion-suitable order.  */
 static basic_block *ifc_bbs;
 
-/* Main entry point.
-   Apply if-conversion to the LOOP. Return true if successful otherwise return
-   false. If false is returned then loop remains unchanged.
-   FOR_VECTORIZER is a boolean flag. It indicates whether if-conversion is used
-   for vectorizer or not. If it is used for vectorizer, additional checks are
-   used. (Vectorization checks are not yet implemented).  */
+/* Main entry point.  Apply if-conversion to the LOOP.  Return true if
+   successful otherwise return false.  If false is returned then loop
+   remains unchanged.  FOR_VECTORIZER is a boolean flag.  It indicates
+   whether if-conversion is used for vectorizer or not.  If it is used
+   for vectorizer, additional checks are used. (Vectorization checks
+   are not yet implemented).  */
 
 static bool
 tree_if_conversion (struct loop *loop, bool for_vectorizer)
@@ -150,8 +150,8 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
 
   ifc_bbs = NULL;
 
-  /* if-conversion is not appropriate for all loops. First, check if loop  is
-     if-convertible or not.  */
+  /* If-conversion is not appropriate for all loops.  First, check if
+     loop is if-convertible or not.  */
   if (!if_convertible_loop_p (loop, for_vectorizer))
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
@@ -192,7 +192,7 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
 	{
 	  basic_block bb_n = single_succ (bb);
 
-	  /* Successor bb inherits predicate of its predecessor. If there
+	  /* Successor bb inherits predicate of its predecessor.  If there
 	     is no predicate in predecessor bb, then consider successor bb
 	     as always executed.  */
 	  if (cond == NULL_TREE)
@@ -203,7 +203,7 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
     }
 
   /* Now, all statements are if-converted and basic blocks are
-     annotated appropriately. Combine all basic block into one huge
+     annotated appropriately.  Combine all basic block into one huge
      basic block.  */
   combine_blocks (loop);
 
@@ -215,12 +215,12 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
   return true;
 }
 
-/* if-convert stmt T which is part of LOOP.
+/* If-convert stmt T which is part of LOOP.
    If T is a GIMPLE_ASSIGN then it is converted into conditional modify
    expression using COND.  For conditional expressions, add condition in the
    destination basic block's predicate list and remove conditional
-   expression itself. BSI is the iterator used to traverse statements of
-   loop. It is used here when it is required to delete current statement.  */
+   expression itself.  BSI is the iterator used to traverse statements of
+   loop.  It is used here when it is required to delete current statement.  */
 
 static tree
 tree_if_convert_stmt (struct loop *  loop, gimple t, tree cond,
@@ -249,11 +249,11 @@ tree_if_convert_stmt (struct loop *  loop, gimple t, tree cond,
       break;
 
     case GIMPLE_ASSIGN:
-      /* This GIMPLE_ASSIGN is killing previous value of LHS. Appropriate
-	 value will be selected by PHI node based on condition. It is possible
+      /* This GIMPLE_ASSIGN is killing previous value of LHS.  Appropriate
+	 value will be selected by PHI node based on condition.  It is possible
 	 that before this transformation, PHI nodes was selecting default
-	 value and now it will use this new value. This is OK because it does
-	 not change validity the program.  */
+	 value and now it will use this new value.  This is OK because it does
+	 not change the validity of the program.  */
       break;
 
     case GIMPLE_COND:
@@ -269,10 +269,10 @@ tree_if_convert_stmt (struct loop *  loop, gimple t, tree cond,
   return cond;
 }
 
-/* STMT is a GIMPLE_COND. Update two destination's predicate list.
-   Remove COND_EXPR, if it is not the loop exit condition. Otherwise
+/* STMT is a GIMPLE_COND.  Update two destination's predicate list.
+   Remove COND_EXPR, if it is not the loop exit condition.  Otherwise
    update loop exit condition appropriately.  GSI is the iterator
-   used to traverse statement list. STMT is part of loop LOOP.  */
+   used to traverse statement list.  STMT is part of loop LOOP.  */
 
 static void
 tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
@@ -292,15 +292,15 @@ tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
 
   /* Add new condition into destination's predicate list.  */
 
-  /* If C is true then TRUE_EDGE is taken.  */
+  /* If C is true, then TRUE_EDGE is taken.  */
   add_to_dst_predicate_list (loop, true_edge, cond, c, gsi);
 
-  /* If 'c' is false then FALSE_EDGE is taken.  */
+  /* If C is false, then FALSE_EDGE is taken.  */
   c2 = invert_truthvalue_loc (loc, unshare_expr (c));
   add_to_dst_predicate_list (loop, false_edge, cond, c2, gsi);
 
-  /* Now this conditional statement is redundant. Remove it.
-     But, do not remove exit condition! Update exit condition
+  /* Now this conditional statement is redundant.  Remove it.
+     But, do not remove exit condition!  Update exit condition
      using new condition.  */
   if (!bb_with_exit_edge_p (loop, gimple_bb (stmt)))
     {
@@ -310,12 +310,12 @@ tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
   return;
 }
 
-/* Return true, iff PHI is if-convertible. PHI is part of loop LOOP
+/* Return true, iff PHI is if-convertible.  PHI is part of loop LOOP
    and it belongs to basic block BB.
    PHI is not if-convertible
-   - if it has more than 2 arguments.
-   - Virtual PHI is immediately used in another PHI node.
-   - Virtual PHI on BB other than header.  */
+   - if it has more than 2 arguments,
+   - virtual PHI is immediately used in another PHI node,
+   - virtual PHI on BB other than header.  */
 
 static bool
 if_convertible_phi_p (struct loop *loop, basic_block bb, gimple phi)
@@ -360,10 +360,10 @@ if_convertible_phi_p (struct loop *loop, basic_block bb, gimple phi)
 
 /* Return true, if STMT is if-convertible.
    GIMPLE_ASSIGN statement is not if-convertible if,
-   - It is not movable.
-   - It could trap.
+   - it is not movable,
+   - it could trap,
    - LHS is not var decl.
-  GIMPLE_ASSIGN is part of block BB, which is inside loop LOOP.  */
+   GIMPLE_ASSIGN is part of block BB, which is inside loop LOOP.  */
 
 static bool
 if_convertible_gimple_assign_stmt_p (struct loop *loop, basic_block bb,
@@ -420,8 +420,8 @@ if_convertible_gimple_assign_stmt_p (struct loop *loop, basic_block bb,
 
 /* Return true, iff STMT is if-convertible.
    Statement is if-convertible if,
-   - It is if-convertible GIMPLE_ASSGIN
-   - It is GIMPLE_LABEL or GIMPLE_COND.
+   - it is if-convertible GIMPLE_ASSGIN,
+   - it is GIMPLE_LABEL or GIMPLE_COND.
    STMT is inside block BB, which is inside loop LOOP.  */
 
 static bool
@@ -459,10 +459,10 @@ if_convertible_stmt_p (struct loop *loop, basic_block bb, gimple stmt)
 
 /* Return true, iff BB is if-convertible.
    Note: This routine does _not_ check basic block statements and phis.
-   Basic block is not if-convertible if,
-   - Basic block is non-empty and it is after exit block (in BFS order).
-   - Basic block is after exit block but before latch.
-   - Basic block edge(s) is not normal.
+   Basic block is not if-convertible if:
+   - basic block is non-empty and it is after exit block (in BFS order),
+   - basic block is after exit block but before latch,
+   - basic block edge(s) is not normal.
    EXIT_BB_SEEN is true if basic block with exit edge is already seen.
    BB is inside loop LOOP.  */
 
@@ -513,15 +513,16 @@ if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
 }
 
 /* Return true, iff LOOP is if-convertible.
-   LOOP is if-convertible if,
-   - It is innermost.
-   - It has two or more basic blocks.
-   - It has only one exit.
-   - Loop header is not the exit edge.
-   - If its basic blocks and phi nodes are if convertible. See above for
+   LOOP is if-convertible if:
+   - it is innermost,
+   - it has two or more basic blocks,
+   - it has only one exit,
+   - loop header is not the exit edge,
+   - if its basic blocks and phi nodes are if convertible.  See above for
      more info.
-   FOR_VECTORIZER enables vectorizer specific checks. For example, support
-   for vector conditions, data dependency checks etc.. (Not implemented yet).  */
+   FOR_VECTORIZER enables vectorizer specific checks, for example, support
+   for vector conditions, data dependency checks, etc.
+   (Not implemented yet).  */
 
 static bool
 if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
@@ -587,21 +588,16 @@ if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
       if (!if_convertible_bb_p (loop, bb, exit_bb))
 	return false;
 
-      /* Check statements.  */
       for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
 	if (!if_convertible_stmt_p (loop, bb, gsi_stmt (itr)))
 	  return false;
-      /* ??? Check data dependency for vectorizer.  */
 
-      /* What about phi nodes ? */
       itr = gsi_start_phis (bb);
 
-      /* Clear aux field of incoming edges to a bb with a phi node.  */
       if (!gsi_end_p (itr))
 	FOR_EACH_EDGE (e, ei, bb->preds)
 	  e->aux = NULL;
 
-      /* Check statements.  */
       for (; !gsi_end_p (itr); gsi_next (&itr))
 	if (!if_convertible_phi_p (loop, bb, gsi_stmt (itr)))
 	  return false;
@@ -610,8 +606,6 @@ if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
 	exit_bb = bb;
     }
 
-  /* OK. Did not find any potential issues so go ahead in if-convert
-     this loop. Now there is no looking back.  */
   if (dump_file)
     fprintf (dump_file,"Applying if-conversion\n");
 
@@ -679,7 +673,7 @@ add_to_dst_predicate_list (struct loop * loop, edge e,
 }
 
 /* During if-conversion aux field from basic block structure is used to hold
-   predicate list. Clean each basic block's predicate list for the given LOOP.
+   predicate list.  Clean each basic block's predicate list for the given LOOP.
    Also clean aux field of successor edges, used to hold true and false
    condition from conditional expression.  */
 
@@ -702,7 +696,7 @@ clean_predicate_lists (struct loop *loop)
 }
 
 /* Basic block BB has two predecessors. Using predecessor's aux field, set
-   appropriate condition COND for the PHI node replacement. Return true block
+   appropriate condition COND for the PHI node replacement.  Return true block
    whose phi arguments are selected when cond is true.  */
 
 static basic_block
@@ -1013,7 +1007,7 @@ combine_blocks (struct loop *loop)
     }
 
   /* Now if possible, merge loop header and block with exit edge.
-     This reduces number of basic blocks to 2. Auto vectorizer addresses
+     This reduces number of basic blocks to 2.  Auto vectorizer addresses
      loops with two nodes only.  FIXME: Use cleanup_tree_cfg().  */
   if (exit_bb
       && exit_bb != loop->header
@@ -1021,7 +1015,7 @@ combine_blocks (struct loop *loop)
     merge_blocks (loop->header, exit_bb);
 }
 
-/* Make a new temp variable of type TYPE. Add GIMPLE_ASSIGN to assign EXP
+/* Make a new temp variable of type TYPE.  Add GIMPLE_ASSIGN to assign EXP
    to the new variable.  */
 
 static gimple
@@ -1064,11 +1058,11 @@ pred_blocks_visited_p (basic_block bb, bitmap *visited)
   return true;
 }
 
-/* Get body of a LOOP in suitable order for if-conversion.
-   It is caller's responsibility to deallocate basic block
-   list.  If-conversion suitable order is, BFS order with one
-   additional constraint. Select block in BFS block, if all
-   pred are already selected.  */
+/* Get body of a LOOP in suitable order for if-conversion.  It is
+   caller's responsibility to deallocate basic block list.
+   If-conversion suitable order is, breadth first sort (BFS) order
+   with an additional constraint: select a block only if all its
+   predecessors are already selected.  */
 
 static basic_block *
 get_loop_body_in_if_conv_order (const struct loop *loop)
@@ -1099,6 +1093,7 @@ get_loop_body_in_if_conv_order (const struct loop *loop)
 	  free (blocks);
 	  return NULL;
 	}
+
       if (!bitmap_bit_p (visited, bb->index))
 	{
 	  if (pred_blocks_visited_p (bb, &visited)
@@ -1109,13 +1104,13 @@ get_loop_body_in_if_conv_order (const struct loop *loop)
 	      blocks[visited_count++] = bb;
 	    }
 	}
+
       index++;
+
       if (index == loop->num_nodes
 	  && visited_count != loop->num_nodes)
-	{
-	  /* Not done yet.  */
-	  index = 0;
-	}
+	/* Not done yet.  */
+	index = 0;
     }
   free (blocks_in_bfs_order);
   BITMAP_FREE (visited);
-- 
1.6.3.3

From 60870cf44ec19593e2942ea6e56e2691bf1fe854 Mon Sep 17 00:00:00 2001
From: Sebastian Pop <sebpop@gmail.com>
Date: Thu, 11 Mar 2010 11:58:23 -0600
Subject: [PATCH 2/3] Sort static functions in topological order.

	* tree-if-conv.c: Sort static functions in topological order.
---
 gcc/tree-if-conv.c |  553 ++++++++++++++++++++++++----------------------------
 1 files changed, 259 insertions(+), 294 deletions(-)

diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 5ff8644..3b2386a 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -100,119 +100,150 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-pass.h"
 #include "target.h"
 
-
-/* local function prototypes */
-static unsigned int main_tree_if_conversion (void);
-static tree tree_if_convert_stmt (struct loop *loop, gimple, tree,
-				  gimple_stmt_iterator *);
-static void tree_if_convert_cond_stmt (struct loop *, gimple, tree,
-				       gimple_stmt_iterator *);
-static bool if_convertible_phi_p (struct loop *, basic_block, gimple);
-static bool if_convertible_gimple_assign_stmt_p (struct loop *, basic_block,
-    						 gimple);
-static bool if_convertible_stmt_p (struct loop *, basic_block, gimple);
-static bool if_convertible_bb_p (struct loop *, basic_block, basic_block);
-static bool if_convertible_loop_p (struct loop *, bool);
-static void add_to_predicate_list (basic_block, tree);
-static tree add_to_dst_predicate_list (struct loop * loop, edge,
-				       tree, tree,
-				       gimple_stmt_iterator *);
-static void clean_predicate_lists (struct loop *loop);
-static basic_block find_phi_replacement_condition (struct loop *loop,
-						   basic_block, tree *,
-						   gimple_stmt_iterator *);
-static void replace_phi_with_cond_gimple_assign_stmt (gimple, tree,
-						      basic_block,
-						      gimple_stmt_iterator *);
-static void process_phi_nodes (struct loop *);
-static void combine_blocks (struct loop *);
-static gimple ifc_temp_var (tree, tree);
-static bool pred_blocks_visited_p (basic_block, bitmap *);
-static basic_block * get_loop_body_in_if_conv_order (const struct loop *loop);
-static bool bb_with_exit_edge_p (struct loop *, basic_block);
-
 /* List of basic blocks in if-conversion-suitable order.  */
 static basic_block *ifc_bbs;
 
-/* Main entry point.  Apply if-conversion to the LOOP.  Return true if
-   successful otherwise return false.  If false is returned then loop
-   remains unchanged.  FOR_VECTORIZER is a boolean flag.  It indicates
-   whether if-conversion is used for vectorizer or not.  If it is used
-   for vectorizer, additional checks are used. (Vectorization checks
-   are not yet implemented).  */
+/* Make a new temp variable of type TYPE.  Add GIMPLE_ASSIGN to assign EXP
+   to the new variable.  */
 
-static bool
-tree_if_conversion (struct loop *loop, bool for_vectorizer)
+static gimple
+ifc_temp_var (tree type, tree exp)
 {
-  basic_block bb;
-  gimple_stmt_iterator itr;
-  unsigned int i;
+  const char *name = "_ifc_";
+  tree var, new_name;
+  gimple stmt;
 
-  ifc_bbs = NULL;
+  /* Create new temporary variable.  */
+  var = create_tmp_var (type, name);
+  add_referenced_var (var);
 
-  /* If-conversion is not appropriate for all loops.  First, check if
-     loop is if-convertible or not.  */
-  if (!if_convertible_loop_p (loop, for_vectorizer))
+  /* Build new statement to assign EXP to new variable.  */
+  stmt = gimple_build_assign (var, exp);
+
+  /* Get SSA name for the new variable and set make new statement
+     its definition statement.  */
+  new_name = make_ssa_name (var, stmt);
+  gimple_assign_set_lhs (stmt, new_name);
+  SSA_NAME_DEF_STMT (new_name) = stmt;
+  update_stmt (stmt);
+
+  return stmt;
+}
+
+/* Add condition COND into predicate list of basic block BB.  */
+
+static void
+add_to_predicate_list (basic_block bb, tree new_cond)
+{
+  tree cond = (tree) bb->aux;
+
+  if (cond)
+    cond = fold_build2_loc (EXPR_LOCATION (cond),
+			TRUTH_OR_EXPR, boolean_type_node,
+			unshare_expr (cond), new_cond);
+  else
+    cond = new_cond;
+
+  bb->aux = cond;
+}
+
+/* Add condition COND into BB's predicate list.  PREV_COND is
+   existing condition.  */
+
+static tree
+add_to_dst_predicate_list (struct loop *loop, edge e,
+			   tree prev_cond, tree cond,
+			   gimple_stmt_iterator *gsi)
+{
+  tree new_cond = NULL_TREE;
+
+  if (!flow_bb_inside_loop_p (loop, e->dest))
+    return NULL_TREE;
+
+  if (prev_cond == boolean_true_node || !prev_cond)
+    new_cond = unshare_expr (cond);
+  else
     {
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	fprintf (dump_file,"-------------------------\n");
-      if (ifc_bbs)
-	{
-	  free (ifc_bbs);
-	  ifc_bbs = NULL;
-	}
-      free_dominance_info (CDI_POST_DOMINATORS);
-      return false;
+      tree tmp;
+      gimple tmp_stmt = NULL;
+
+      prev_cond = force_gimple_operand_gsi (gsi, unshare_expr (prev_cond),
+					    true, NULL, true, GSI_SAME_STMT);
+
+      cond = force_gimple_operand_gsi (gsi, unshare_expr (cond),
+				       true, NULL, true, GSI_SAME_STMT);
+
+      /* Add the condition to aux field of the edge.  In case edge
+	 destination is a PHI node, this condition will be ANDed with
+	 block predicate to construct complete condition.  */
+      e->aux = cond;
+
+      tmp = build2 (TRUTH_AND_EXPR, boolean_type_node,
+		    unshare_expr (prev_cond), cond);
+      tmp_stmt = ifc_temp_var (boolean_type_node, tmp);
+      gsi_insert_before (gsi, tmp_stmt, GSI_SAME_STMT);
+      new_cond = gimple_assign_lhs (tmp_stmt);
     }
 
-  /* Do actual work now.  */
-  for (i = 0; i < loop->num_nodes; i++)
-    {
-      tree cond;
+  add_to_predicate_list (e->dest, new_cond);
+  return new_cond;
+}
 
-      bb = ifc_bbs [i];
+/* Return true if one of the basic block BB edge is exit of LOOP.  */
 
-      /* Update condition using predicate list.  */
-      cond = (tree) bb->aux;
+static bool
+bb_with_exit_edge_p (struct loop *loop, basic_block bb)
+{
+  edge e;
+  edge_iterator ei;
+  bool exit_edge_found = false;
 
-      /* Process all statements in this basic block.
-	 Remove conditional expression, if any, and annotate
-	 destination basic block(s) appropriately.  */
-      for (itr = gsi_start_bb (bb); !gsi_end_p (itr); /* empty */)
-	{
-	  gimple t = gsi_stmt (itr);
-	  cond = tree_if_convert_stmt (loop, t, cond, &itr);
-	  if (!gsi_end_p (itr))
-	    gsi_next (&itr);
-	}
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    if (loop_exit_edge_p (loop, e))
+      {
+	exit_edge_found = true;
+	break;
+      }
 
-      /* If current bb has only one successor, then consider it as an
-	 unconditional goto.  */
-      if (single_succ_p (bb))
-	{
-	  basic_block bb_n = single_succ (bb);
+  return exit_edge_found;
+}
 
-	  /* Successor bb inherits predicate of its predecessor.  If there
-	     is no predicate in predecessor bb, then consider successor bb
-	     as always executed.  */
-	  if (cond == NULL_TREE)
-	    cond = boolean_true_node;
+/* STMT is a GIMPLE_COND.  Update two destination's predicate list.
+   Remove COND_EXPR, if it is not the loop exit condition.  Otherwise
+   update loop exit condition appropriately.  GSI is the iterator
+   used to traverse statement list.  STMT is part of loop LOOP.  */
 
-	  add_to_predicate_list (bb_n, cond);
-	}
-    }
+static void
+tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
+			   gimple_stmt_iterator *gsi)
+{
+  tree c2;
+  edge true_edge, false_edge;
+  location_t loc = gimple_location (stmt);
+  tree c = fold_build2_loc (loc, gimple_cond_code (stmt), boolean_type_node,
+			    gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
 
-  /* Now, all statements are if-converted and basic blocks are
-     annotated appropriately.  Combine all basic block into one huge
-     basic block.  */
-  combine_blocks (loop);
+  extract_true_false_edges_from_block (gimple_bb (stmt),
+ 				       &true_edge, &false_edge);
 
-  /* clean up */
-  clean_predicate_lists (loop);
-  free (ifc_bbs);
-  ifc_bbs = NULL;
+  /* Add new condition into destination's predicate list.  */
 
-  return true;
+  /* If C is true, then TRUE_EDGE is taken.  */
+  add_to_dst_predicate_list (loop, true_edge, cond, c, gsi);
+
+  /* If C is false, then FALSE_EDGE is taken.  */
+  c2 = invert_truthvalue_loc (loc, unshare_expr (c));
+  add_to_dst_predicate_list (loop, false_edge, cond, c2, gsi);
+
+  /* Now this conditional statement is redundant.  Remove it.
+     But, do not remove exit condition!  Update exit condition
+     using new condition.  */
+  if (!bb_with_exit_edge_p (loop, gimple_bb (stmt)))
+    {
+      gsi_remove (gsi, true);
+      cond = NULL_TREE;
+    }
+  return;
 }
 
 /* If-convert stmt T which is part of LOOP.
@@ -269,47 +300,6 @@ tree_if_convert_stmt (struct loop *  loop, gimple t, tree cond,
   return cond;
 }
 
-/* STMT is a GIMPLE_COND.  Update two destination's predicate list.
-   Remove COND_EXPR, if it is not the loop exit condition.  Otherwise
-   update loop exit condition appropriately.  GSI is the iterator
-   used to traverse statement list.  STMT is part of loop LOOP.  */
-
-static void
-tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
-			   gimple_stmt_iterator *gsi)
-{
-  tree c, c2;
-  edge true_edge, false_edge;
-  location_t loc = gimple_location (stmt);
-
-  gcc_assert (gimple_code (stmt) == GIMPLE_COND);
-
-  c = fold_build2_loc (loc, gimple_cond_code (stmt), boolean_type_node,
-		   gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
-
-  extract_true_false_edges_from_block (gimple_bb (stmt),
- 				       &true_edge, &false_edge);
-
-  /* Add new condition into destination's predicate list.  */
-
-  /* If C is true, then TRUE_EDGE is taken.  */
-  add_to_dst_predicate_list (loop, true_edge, cond, c, gsi);
-
-  /* If C is false, then FALSE_EDGE is taken.  */
-  c2 = invert_truthvalue_loc (loc, unshare_expr (c));
-  add_to_dst_predicate_list (loop, false_edge, cond, c2, gsi);
-
-  /* Now this conditional statement is redundant.  Remove it.
-     But, do not remove exit condition!  Update exit condition
-     using new condition.  */
-  if (!bb_with_exit_edge_p (loop, gimple_bb (stmt)))
-    {
-      gsi_remove (gsi, true);
-      cond = NULL_TREE;
-    }
-  return;
-}
-
 /* Return true, iff PHI is if-convertible.  PHI is part of loop LOOP
    and it belongs to basic block BB.
    PHI is not if-convertible
@@ -512,6 +502,80 @@ if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
   return true;
 }
 
+/* Return TRUE iff, all pred blocks of BB are visited.
+   Bitmap VISITED keeps history of visited blocks.  */
+
+static bool
+pred_blocks_visited_p (basic_block bb, bitmap *visited)
+{
+  edge e;
+  edge_iterator ei;
+  FOR_EACH_EDGE (e, ei, bb->preds)
+    if (!bitmap_bit_p (*visited, e->src->index))
+      return false;
+
+  return true;
+}
+
+/* Get body of a LOOP in suitable order for if-conversion.  It is
+   caller's responsibility to deallocate basic block list.
+   If-conversion suitable order is, breadth first sort (BFS) order
+   with an additional constraint: select a block only if all its
+   predecessors are already selected.  */
+
+static basic_block *
+get_loop_body_in_if_conv_order (const struct loop *loop)
+{
+  basic_block *blocks, *blocks_in_bfs_order;
+  basic_block bb;
+  bitmap visited;
+  unsigned int index = 0;
+  unsigned int visited_count = 0;
+
+  gcc_assert (loop->num_nodes);
+  gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+
+  blocks = XCNEWVEC (basic_block, loop->num_nodes);
+  visited = BITMAP_ALLOC (NULL);
+
+  blocks_in_bfs_order = get_loop_body_in_bfs_order (loop);
+
+  index = 0;
+  while (index < loop->num_nodes)
+    {
+      bb = blocks_in_bfs_order [index];
+
+      if (bb->flags & BB_IRREDUCIBLE_LOOP)
+	{
+	  free (blocks_in_bfs_order);
+	  BITMAP_FREE (visited);
+	  free (blocks);
+	  return NULL;
+	}
+
+      if (!bitmap_bit_p (visited, bb->index))
+	{
+	  if (pred_blocks_visited_p (bb, &visited)
+	      || bb == loop->header)
+	    {
+	      /* This block is now visited.  */
+	      bitmap_set_bit (visited, bb->index);
+	      blocks[visited_count++] = bb;
+	    }
+	}
+
+      index++;
+
+      if (index == loop->num_nodes
+	  && visited_count != loop->num_nodes)
+	/* Not done yet.  */
+	index = 0;
+    }
+  free (blocks_in_bfs_order);
+  BITMAP_FREE (visited);
+  return blocks;
+}
+
 /* Return true, iff LOOP is if-convertible.
    LOOP is if-convertible if:
    - it is innermost,
@@ -613,65 +677,6 @@ if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
   return true;
 }
 
-/* Add condition COND into predicate list of basic block BB.  */
-
-static void
-add_to_predicate_list (basic_block bb, tree new_cond)
-{
-  tree cond = (tree) bb->aux;
-
-  if (cond)
-    cond = fold_build2_loc (EXPR_LOCATION (cond),
-			TRUTH_OR_EXPR, boolean_type_node,
-			unshare_expr (cond), new_cond);
-  else
-    cond = new_cond;
-
-  bb->aux = cond;
-}
-
-/* Add condition COND into BB's predicate list.  PREV_COND is
-   existing condition.  */
-
-static tree
-add_to_dst_predicate_list (struct loop * loop, edge e,
-			   tree prev_cond, tree cond,
-			   gimple_stmt_iterator *gsi)
-{
-  tree new_cond = NULL_TREE;
-
-  if (!flow_bb_inside_loop_p (loop, e->dest))
-    return NULL_TREE;
-
-  if (prev_cond == boolean_true_node || !prev_cond)
-    new_cond = unshare_expr (cond);
-  else
-    {
-      tree tmp;
-      gimple tmp_stmt = NULL;
-
-      prev_cond = force_gimple_operand_gsi (gsi, unshare_expr (prev_cond),
-					    true, NULL, true, GSI_SAME_STMT);
-
-      cond = force_gimple_operand_gsi (gsi, unshare_expr (cond),
-				       true, NULL, true, GSI_SAME_STMT);
-
-      /* Add the condition to aux field of the edge.  In case edge
-	 destination is a PHI node, this condition will be ANDed with
-	 block predicate to construct complete condition.  */
-      e->aux = cond;
-
-      /* new_cond == prev_cond AND cond */
-      tmp = build2 (TRUTH_AND_EXPR, boolean_type_node,
-		    unshare_expr (prev_cond), cond);
-      tmp_stmt = ifc_temp_var (boolean_type_node, tmp);
-      gsi_insert_before (gsi, tmp_stmt, GSI_SAME_STMT);
-      new_cond = gimple_assign_lhs (tmp_stmt);
-    }
-  add_to_predicate_list (e->dest, new_cond);
-  return new_cond;
-}
-
 /* During if-conversion aux field from basic block structure is used to hold
    predicate list.  Clean each basic block's predicate list for the given LOOP.
    Also clean aux field of successor edges, used to hold true and false
@@ -1015,125 +1020,85 @@ combine_blocks (struct loop *loop)
     merge_blocks (loop->header, exit_bb);
 }
 
-/* Make a new temp variable of type TYPE.  Add GIMPLE_ASSIGN to assign EXP
-   to the new variable.  */
-
-static gimple
-ifc_temp_var (tree type, tree exp)
-{
-  const char *name = "_ifc_";
-  tree var, new_name;
-  gimple stmt;
-
-  /* Create new temporary variable.  */
-  var = create_tmp_var (type, name);
-  add_referenced_var (var);
-
-  /* Build new statement to assign EXP to new variable.  */
-  stmt = gimple_build_assign (var, exp);
-
-  /* Get SSA name for the new variable and set make new statement
-     its definition statement.  */
-  new_name = make_ssa_name (var, stmt);
-  gimple_assign_set_lhs (stmt, new_name);
-  SSA_NAME_DEF_STMT (new_name) = stmt;
-  update_stmt (stmt);
-
-  return stmt;
-}
-
-
-/* Return TRUE iff, all pred blocks of BB are visited.
-   Bitmap VISITED keeps history of visited blocks.  */
+/* Main entry point.  Apply if-conversion to the LOOP.  Return true if
+   successful otherwise return false.  If false is returned then loop
+   remains unchanged.  FOR_VECTORIZER is a boolean flag.  It indicates
+   whether if-conversion is used for vectorizer or not.  If it is used
+   for vectorizer, additional checks are used. (Vectorization checks
+   are not yet implemented).  */
 
 static bool
-pred_blocks_visited_p (basic_block bb, bitmap *visited)
-{
-  edge e;
-  edge_iterator ei;
-  FOR_EACH_EDGE (e, ei, bb->preds)
-    if (!bitmap_bit_p (*visited, e->src->index))
-      return false;
-
-  return true;
-}
-
-/* Get body of a LOOP in suitable order for if-conversion.  It is
-   caller's responsibility to deallocate basic block list.
-   If-conversion suitable order is, breadth first sort (BFS) order
-   with an additional constraint: select a block only if all its
-   predecessors are already selected.  */
-
-static basic_block *
-get_loop_body_in_if_conv_order (const struct loop *loop)
+tree_if_conversion (struct loop *loop, bool for_vectorizer)
 {
-  basic_block *blocks, *blocks_in_bfs_order;
   basic_block bb;
-  bitmap visited;
-  unsigned int index = 0;
-  unsigned int visited_count = 0;
-
-  gcc_assert (loop->num_nodes);
-  gcc_assert (loop->latch != EXIT_BLOCK_PTR);
+  gimple_stmt_iterator itr;
+  unsigned int i;
 
-  blocks = XCNEWVEC (basic_block, loop->num_nodes);
-  visited = BITMAP_ALLOC (NULL);
+  ifc_bbs = NULL;
 
-  blocks_in_bfs_order = get_loop_body_in_bfs_order (loop);
+  /* If-conversion is not appropriate for all loops.  First, check if
+     loop is if-convertible or not.  */
+  if (!if_convertible_loop_p (loop, for_vectorizer))
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file,"-------------------------\n");
+      if (ifc_bbs)
+	{
+	  free (ifc_bbs);
+	  ifc_bbs = NULL;
+	}
+      free_dominance_info (CDI_POST_DOMINATORS);
+      return false;
+    }
 
-  index = 0;
-  while (index < loop->num_nodes)
+  /* Do actual work now.  */
+  for (i = 0; i < loop->num_nodes; i++)
     {
-      bb = blocks_in_bfs_order [index];
+      tree cond;
 
-      if (bb->flags & BB_IRREDUCIBLE_LOOP)
+      bb = ifc_bbs [i];
+
+      /* Update condition using predicate list.  */
+      cond = (tree) bb->aux;
+
+      /* Process all statements in this basic block.
+	 Remove conditional expression, if any, and annotate
+	 destination basic block(s) appropriately.  */
+      for (itr = gsi_start_bb (bb); !gsi_end_p (itr); /* empty */)
 	{
-	  free (blocks_in_bfs_order);
-	  BITMAP_FREE (visited);
-	  free (blocks);
-	  return NULL;
+	  gimple t = gsi_stmt (itr);
+	  cond = tree_if_convert_stmt (loop, t, cond, &itr);
+	  if (!gsi_end_p (itr))
+	    gsi_next (&itr);
 	}
 
-      if (!bitmap_bit_p (visited, bb->index))
+      /* If current bb has only one successor, then consider it as an
+	 unconditional goto.  */
+      if (single_succ_p (bb))
 	{
-	  if (pred_blocks_visited_p (bb, &visited)
-	      || bb == loop->header)
-	    {
-	      /* This block is now visited.  */
-	      bitmap_set_bit (visited, bb->index);
-	      blocks[visited_count++] = bb;
-	    }
-	}
+	  basic_block bb_n = single_succ (bb);
 
-      index++;
+	  /* Successor bb inherits predicate of its predecessor.  If there
+	     is no predicate in predecessor bb, then consider successor bb
+	     as always executed.  */
+	  if (cond == NULL_TREE)
+	    cond = boolean_true_node;
 
-      if (index == loop->num_nodes
-	  && visited_count != loop->num_nodes)
-	/* Not done yet.  */
-	index = 0;
+	  add_to_predicate_list (bb_n, cond);
+	}
     }
-  free (blocks_in_bfs_order);
-  BITMAP_FREE (visited);
-  return blocks;
-}
 
-/* Return true if one of the basic block BB edge is exit of LOOP.  */
-
-static bool
-bb_with_exit_edge_p (struct loop *loop, basic_block bb)
-{
-  edge e;
-  edge_iterator ei;
-  bool exit_edge_found = false;
+  /* Now, all statements are if-converted and basic blocks are
+     annotated appropriately.  Combine all basic block into one huge
+     basic block.  */
+  combine_blocks (loop);
 
-  FOR_EACH_EDGE (e, ei, bb->succs)
-    if (loop_exit_edge_p (loop, e))
-      {
-	exit_edge_found = true;
-	break;
-      }
+  /* clean up */
+  clean_predicate_lists (loop);
+  free (ifc_bbs);
+  ifc_bbs = NULL;
 
-  return exit_edge_found;
+  return true;
 }
 
 /* Tree if-conversion pass management.  */
-- 
1.6.3.3

From 2bbbeedd408a9617c7523d0e6962d7a6b742d3f5 Mon Sep 17 00:00:00 2001
From: Sebastian Pop <sebpop@gmail.com>
Date: Thu, 11 Mar 2010 12:07:46 -0600
Subject: [PATCH 3/3] Fix comments.

	* tree-if-conv.c: Fix indentation and comments.
---
 gcc/tree-if-conv.c |   23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 3b2386a..4fefc84 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -139,16 +139,18 @@ add_to_predicate_list (basic_block bb, tree new_cond)
 
   if (cond)
     cond = fold_build2_loc (EXPR_LOCATION (cond),
-			TRUTH_OR_EXPR, boolean_type_node,
-			unshare_expr (cond), new_cond);
+			    TRUTH_OR_EXPR, boolean_type_node,
+			    unshare_expr (cond), new_cond);
   else
     cond = new_cond;
 
   bb->aux = cond;
 }
 
-/* Add condition COND into BB's predicate list.  PREV_COND is
-   existing condition.  */
+/* And condition COND to the previous condition PREV_COND and add this
+   to the predicate list of the destination of edge E.  GSI is the
+   place where the gimplification of the resulting condition should
+   output code.  LOOP is the loop to be if-converted.  */
 
 static tree
 add_to_dst_predicate_list (struct loop *loop, edge e,
@@ -254,7 +256,7 @@ tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
    loop.  It is used here when it is required to delete current statement.  */
 
 static tree
-tree_if_convert_stmt (struct loop *  loop, gimple t, tree cond,
+tree_if_convert_stmt (struct loop *loop, gimple t, tree cond,
 		      gimple_stmt_iterator *gsi)
 {
   if (dump_file && (dump_flags & TDF_DETAILS))
@@ -872,8 +874,8 @@ replace_phi_with_cond_gimple_assign_stmt (gimple phi, tree cond,
     }
 }
 
-/* Process phi nodes for the given  LOOP.  Replace phi nodes with cond
-   modify expr.  */
+/* Process phi nodes for the given LOOP.  Replace phi nodes with
+   conditional modify expressions.  */
 
 static void
 process_phi_nodes (struct loop *loop)
@@ -882,7 +884,6 @@ process_phi_nodes (struct loop *loop)
   unsigned int orig_loop_num_nodes = loop->num_nodes;
   unsigned int i;
 
-  /* Replace phi nodes with cond. modify expr.  */
   for (i = 1; i < orig_loop_num_nodes; i++)
     {
       gimple phi;
@@ -897,7 +898,7 @@ process_phi_nodes (struct loop *loop)
       phi_gsi = gsi_start_phis (bb);
       gsi = gsi_after_labels (bb);
 
-      /* BB has two predecessors. Using predecessor's aux field, set
+      /* BB has two predecessors.  Using predecessor's aux field, set
 	 appropriate condition for the PHI node replacement.  */
       if (!gsi_end_p (phi_gsi))
 	true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
@@ -914,8 +915,8 @@ process_phi_nodes (struct loop *loop)
   return;
 }
 
-/* Combine all basic block from the given LOOP into one or two super
-   basic block.  Replace PHI nodes with conditional modify expression.  */
+/* Combine all the basic blocks from LOOP into one or two super basic
+   blocks.  Replace PHI nodes with conditional modify expressions.  */
 
 static void
 combine_blocks (struct loop *loop)
-- 
1.6.3.3


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]