Functions
static struct loop *	tree_unswitch_loop (struct loop *, basic_block, tree)
static bool	tree_unswitch_single_loop (struct loop *, int)
static tree	tree_may_unswitch_on (basic_block, struct loop *)
unsigned int	tree_ssa_unswitch_loops ()
static tree	tree_may_unswitch_on ()
static tree	simplify_using_entry_checks ()
static bool	tree_unswitch_single_loop ()

Function Documentation

static tree simplify_using_entry_checks ( )

static

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).

References edge_def::flags, gimple_cond_code(), gimple_cond_lhs(), gimple_cond_rhs(), last_stmt(), loop_preheader_edge(), operand_equal_p(), single_pred_edge(), single_pred_p(), and edge_def::src.

Referenced by tree_unswitch_single_loop().

static tree tree_may_unswitch_on	(	basic_block	,
		struct loop *
	)

static

Referenced by tree_unswitch_single_loop().

static tree tree_may_unswitch_on ( )

static

Checks whether we can unswitch LOOP on condition at end of BB -- one of its
   basic blocks (for what it means see comments below).

References flow_bb_inside_loop_p(), gimple_bb(), gimple_cond_code(), gimple_cond_false_p(), gimple_cond_lhs(), gimple_cond_rhs(), gimple_cond_true_p(), and last_stmt().

unsigned int tree_ssa_unswitch_loops ( void )

Main entry point.  Perform loop unswitching on all suitable loops.

References changed, dump_file, dump_flags, eni_size_weights, estimated_loop_iterations_int(), HOST_WIDE_INT, LI_ONLY_INNERMOST, loop::num, optimize_loop_for_size_p(), tree_num_loop_insns(), and tree_unswitch_single_loop().

Referenced by tree_ssa_loop_unswitch().

static struct loop * tree_unswitch_loop	(	struct loop *	loop,
		basic_block	unswitch_on,
		tree	cond
	)

staticread

@verbatim Loop unswitching.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see http://www.gnu.org/licenses/.

This file implements the loop unswitching, i.e. transformation of loops like

   while (A)
     {
       if (inv)
         B;

       X;

       if (!inv)
         C;
     }

   where inv is the loop invariant, into

   if (inv)
     {
       while (A)
         {
           B;
           X;
         }
     }
   else
     {
       while (A)
         {
           X;
           C;
         }
     }

   Inv is considered invariant iff the values it compares are both invariant;
   tree-ssa-loop-im.c ensures that all the suitable conditions are in this
   shape.

Unswitch a LOOP w.r. to given basic block UNSWITCH_ON.  We only support
   unswitching of innermost loops.  COND is the condition determining which
   loop is entered -- the new loop is entered if COND is true.  Returns NULL
   if impossible, new loop otherwise.

References extract_true_false_edges_from_block(), flow_bb_inside_loop_p(), loop::inner, loop_version(), edge_def::probability, basic_block_def::succs, and unshare_expr().

Referenced by tree_unswitch_single_loop().

static bool tree_unswitch_single_loop	(	struct loop *	,
		int
	)

static

Referenced by tree_ssa_unswitch_loops(), and tree_unswitch_single_loop().

static bool tree_unswitch_single_loop ( )

static

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.

References changed, edge_def::dest, dump_file, dump_flags, edge_def::flags, basic_block_def::flags, free(), free_original_copy_tables(), get_loop_body(), gimple_cond_false_p(), gimple_cond_set_condition_from_tree(), gimple_cond_true_p(), initialize_original_copy_tables(), integer_nonzerop(), integer_zerop(), last_stmt(), basic_block_def::loop_father, loop::num_nodes, simplify_using_entry_checks(), basic_block_def::succs, tree_may_unswitch_on(), tree_unswitch_loop(), tree_unswitch_single_loop(), update_ssa(), update_stmt(), and worklist.

Functions

Function Documentation