222 lines
5.3 KiB
C
222 lines
5.3 KiB
C
/* 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 loop around PBB at depth
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LOOP_DEPTH. 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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0 0 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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0 0 1 -1 0 0
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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_loop_depth (poly_bb_p pbb, int loop_depth, int stride)
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{
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ppl_dimension_type iter, dim;
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ppl_Polyhedron_t res = PBB_TRANSFORMED_SCATTERING (pbb);
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ppl_dimension_type strip = psct_scattering_dim_for_loop_depth (pbb,
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loop_depth);
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psct_add_scattering_dimension (pbb, strip);
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iter = psct_iterator_dim (pbb, loop_depth);
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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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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 LOOP_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 loop_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 (pbb, loop_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 around PBB. Nothing profitable in all this:
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this is just a driver function. */
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static bool
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pbb_do_strip_mine (poly_bb_p pbb)
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{
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graphite_dim_t loop_depth;
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int stride = 64;
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bool transform_done = false;
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for (loop_depth = 0; loop_depth < pbb_dim_iter_domain (pbb); loop_depth++)
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if (pbb_strip_mine_profitable_p (pbb, loop_depth, stride))
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transform_done |= pbb_strip_mine_loop_depth (pbb, loop_depth, stride);
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return transform_done;
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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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{
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poly_bb_p pbb;
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int i;
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bool transform_done = false;
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store_scattering (scop);
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for (i = 0; VEC_iterate (poly_bb_p, SCOP_BBS (scop), i, pbb); i++)
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transform_done |= pbb_do_strip_mine (pbb);
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if (!transform_done)
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return false;
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if (!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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return true;
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}
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#endif
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