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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [gcc/] [graphite-blocking.c] - Blame information for rev 280

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1 280 jeremybenn
/* Heuristics and transform for loop blocking and strip mining on
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   polyhedral representation.
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   Copyright (C) 2009 Free Software Foundation, Inc.
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   Contributed by Sebastian Pop <sebastian.pop@amd.com> and
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   Pranav Garg  <pranav.garg2107@gmail.com>.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3.  If not see
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<http://www.gnu.org/licenses/>.  */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "ggc.h"
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#include "tree.h"
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#include "rtl.h"
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#include "output.h"
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#include "basic-block.h"
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#include "diagnostic.h"
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#include "tree-flow.h"
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#include "toplev.h"
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#include "tree-dump.h"
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#include "timevar.h"
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#include "cfgloop.h"
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#include "tree-chrec.h"
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#include "tree-data-ref.h"
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#include "tree-scalar-evolution.h"
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#include "tree-pass.h"
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#include "domwalk.h"
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#include "value-prof.h"
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#include "pointer-set.h"
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#include "gimple.h"
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#include "params.h"
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#ifdef HAVE_cloog
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#include "cloog/cloog.h"
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#include "ppl_c.h"
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#include "sese.h"
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#include "graphite-ppl.h"
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#include "graphite.h"
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#include "graphite-poly.h"
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/* Strip mines with a factor STRIDE the scattering (time) dimension
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   around PBB at depth TIME_DEPTH.
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   The following example comes from the wiki page:
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   http://gcc.gnu.org/wiki/Graphite/Strip_mine
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   The strip mine of a loop with a tile of 64 can be obtained with a
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   scattering function as follows:
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   $ cat ./albert_strip_mine.cloog
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   # language: C
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   c
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   # parameter {n | n >= 0}
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   1 3
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   #  n  1
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   1  1  0
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   1
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   n
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   1 # Number of statements:
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   1
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   # {i | 0 <= i <= n}
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   2 4
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   #  i  n   1
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   1  1  0   0
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   1 -1  1   0
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   1
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   i
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   1 # Scattering functions
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   3 6
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   #  NEW  OLD    i    n    1
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   1  -64    0    1    0    0
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   1   64    0   -1    0   63
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   1
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   NEW  OLD
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   #the output of CLooG is like this:
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   #$ cloog ./albert_strip_mine.cloog
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   # for (NEW=0;NEW<=floord(n,64);NEW++) {
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   #   for (OLD=max(64*NEW,0);OLD<=min(64*NEW+63,n);OLD++) {
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   #     S1(i = OLD) ;
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   #   }
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   # }
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*/
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static bool
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pbb_strip_mine_time_depth (poly_bb_p pbb, int time_depth, int stride)
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{
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  ppl_dimension_type iter, dim, strip;
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  ppl_Polyhedron_t res = PBB_TRANSFORMED_SCATTERING (pbb);
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  /* STRIP is the dimension that iterates with stride STRIDE.  */
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  /* ITER is the dimension that enumerates single iterations inside
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     one strip that has at most STRIDE iterations.  */
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  strip = time_depth;
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  iter = strip + 2;
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  psct_add_scattering_dimension (pbb, strip);
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  psct_add_scattering_dimension (pbb, strip + 1);
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  ppl_Polyhedron_space_dimension (res, &dim);
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  /* Lower bound of the striped loop.  */
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  {
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    ppl_Constraint_t new_cstr;
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    ppl_Linear_Expression_t expr;
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    ppl_new_Linear_Expression_with_dimension (&expr, dim);
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    ppl_set_coef (expr, strip, -1 * stride);
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    ppl_set_coef (expr, iter, 1);
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    ppl_new_Constraint (&new_cstr, expr, PPL_CONSTRAINT_TYPE_GREATER_OR_EQUAL);
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    ppl_delete_Linear_Expression (expr);
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    ppl_Polyhedron_add_constraint (res, new_cstr);
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    ppl_delete_Constraint (new_cstr);
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  }
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  /* Upper bound of the striped loop.  */
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  {
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    ppl_Constraint_t new_cstr;
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    ppl_Linear_Expression_t expr;
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    ppl_new_Linear_Expression_with_dimension (&expr, dim);
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    ppl_set_coef (expr, strip, stride);
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    ppl_set_coef (expr, iter, -1);
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    ppl_set_inhomogeneous (expr, stride - 1);
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    ppl_new_Constraint (&new_cstr, expr, PPL_CONSTRAINT_TYPE_GREATER_OR_EQUAL);
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    ppl_delete_Linear_Expression (expr);
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    ppl_Polyhedron_add_constraint (res, new_cstr);
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    ppl_delete_Constraint (new_cstr);
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  }
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  /* Static scheduling for ITER level.
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     This is mandatory to keep the 2d + 1 canonical scheduling format.  */
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  {
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    ppl_Constraint_t new_cstr;
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    ppl_Linear_Expression_t expr;
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    ppl_new_Linear_Expression_with_dimension (&expr, dim);
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    ppl_set_coef (expr, strip + 1, 1);
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    ppl_set_inhomogeneous (expr, 0);
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    ppl_new_Constraint (&new_cstr, expr, PPL_CONSTRAINT_TYPE_EQUAL);
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    ppl_delete_Linear_Expression (expr);
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    ppl_Polyhedron_add_constraint (res, new_cstr);
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    ppl_delete_Constraint (new_cstr);
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  }
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  return true;
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}
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/* Returns true when strip mining with STRIDE of the loop around PBB
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   at DEPTH is profitable.  */
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static bool
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pbb_strip_mine_profitable_p (poly_bb_p pbb,
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                             graphite_dim_t depth,
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                             int stride)
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{
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  Value niter, strip_stride;
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  bool res;
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  value_init (strip_stride);
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  value_init (niter);
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  value_set_si (strip_stride, stride);
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  pbb_number_of_iterations_at_time (pbb, psct_dynamic_dim (pbb, depth), niter);
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  res = value_gt (niter, strip_stride);
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  value_clear (strip_stride);
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  value_clear (niter);
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  return res;
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}
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/* Strip-mines all the loops of LST that are considered profitable to
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   strip-mine.  Return true if it did strip-mined some loops.  */
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static bool
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lst_do_strip_mine_loop (lst_p lst, int depth)
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{
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  int i;
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  lst_p l;
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  int stride = PARAM_VALUE (PARAM_LOOP_BLOCK_TILE_SIZE);
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  poly_bb_p pbb;
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209
  if (!lst)
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    return false;
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212
  if (LST_LOOP_P (lst))
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    {
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      bool res = false;
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      for (i = 0; VEC_iterate (lst_p, LST_SEQ (lst), i, l); i++)
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        res |= lst_do_strip_mine_loop (l, depth);
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      return res;
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    }
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  pbb = LST_PBB (lst);
223
  return pbb_strip_mine_time_depth (pbb, psct_dynamic_dim (pbb, depth),
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                                    stride);
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}
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/* Strip-mines all the loops of LST that are considered profitable to
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   strip-mine.  Return true if it did strip-mined some loops.  */
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static bool
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lst_do_strip_mine (lst_p lst)
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{
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  int i;
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  lst_p l;
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  bool res = false;
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  int stride = PARAM_VALUE (PARAM_LOOP_BLOCK_TILE_SIZE);
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  int depth;
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  if (!lst
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      || !LST_LOOP_P (lst))
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    return false;
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  for (i = 0; VEC_iterate (lst_p, LST_SEQ (lst), i, l); i++)
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    res |= lst_do_strip_mine (l);
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  depth = lst_depth (lst);
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  if (depth >= 0
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      && pbb_strip_mine_profitable_p (LST_PBB (lst_find_first_pbb (lst)),
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                                      depth, stride))
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    {
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      res |= lst_do_strip_mine_loop (lst, lst_depth (lst));
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      lst_add_loop_under_loop (lst);
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    }
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  return res;
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}
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/* Strip mines all the loops in SCOP.  Nothing profitable in all this:
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   this is just a driver function.  */
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bool
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scop_do_strip_mine (scop_p scop)
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{
264
  bool transform_done = false;
265
 
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  store_scattering (scop);
267
 
268
  transform_done = lst_do_strip_mine (SCOP_TRANSFORMED_SCHEDULE (scop));
269
 
270
  if (!transform_done)
271
    return false;
272
 
273
  if (!graphite_legal_transform (scop))
274
    {
275
      restore_scattering (scop);
276
      return false;
277
    }
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279
  return transform_done;
280
}
281
 
282
/* Loop blocks all the loops in SCOP.  Returns true when we manage to
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   block some loops.  */
284
 
285
bool
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scop_do_block (scop_p scop)
287
{
288
  bool strip_mined = false;
289
  bool interchanged = false;
290
 
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  store_scattering (scop);
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293
  strip_mined = lst_do_strip_mine (SCOP_TRANSFORMED_SCHEDULE (scop));
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  interchanged = scop_do_interchange (scop);
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  /* If we don't interchange loops, then the strip mine is not
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     profitable, and the transform is not a loop blocking.  */
298
  if (!interchanged
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      || !graphite_legal_transform (scop))
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    {
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      restore_scattering (scop);
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      return false;
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    }
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  else if (strip_mined && interchanged
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           && dump_file && (dump_flags & TDF_DETAILS))
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    fprintf (dump_file, "SCoP will be loop blocked.\n");
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  return strip_mined || interchanged;
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}
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#endif

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