1152 lines
31 KiB
C
1152 lines
31 KiB
C
/* Loop distribution.
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Copyright (C) 2006, 2007, 2008 Free Software Foundation, Inc.
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Contributed by Georges-Andre Silber <Georges-Andre.Silber@ensmp.fr>
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and Sebastian Pop <sebastian.pop@amd.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 it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 3, or (at your option) any
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later version.
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GCC is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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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/* This pass performs loop distribution: for example, the loop
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|DO I = 2, N
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| A(I) = B(I) + C
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| D(I) = A(I-1)*E
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|ENDDO
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is transformed to
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|DOALL I = 2, N
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| A(I) = B(I) + C
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|ENDDO
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|DOALL I = 2, N
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| D(I) = A(I-1)*E
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|ENDDO
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This pass uses an RDG, Reduced Dependence Graph built on top of the
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data dependence relations. The RDG is then topologically sorted to
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obtain a map of information producers/consumers based on which it
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generates the new loops. */
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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 "target.h"
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#include "rtl.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 "tree-dump.h"
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#include "timevar.h"
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#include "cfgloop.h"
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#include "expr.h"
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#include "optabs.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 "lambda.h"
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#include "langhooks.h"
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#include "tree-vectorizer.h"
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/* If bit I is not set, it means that this node represents an
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operation that has already been performed, and that should not be
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performed again. This is the subgraph of remaining important
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computations that is passed to the DFS algorithm for avoiding to
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include several times the same stores in different loops. */
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static bitmap remaining_stmts;
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/* A node of the RDG is marked in this bitmap when it has as a
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predecessor a node that writes to memory. */
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static bitmap upstream_mem_writes;
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/* Update the PHI nodes of NEW_LOOP. NEW_LOOP is a duplicate of
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ORIG_LOOP. */
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static void
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update_phis_for_loop_copy (struct loop *orig_loop, struct loop *new_loop)
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{
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tree new_ssa_name;
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gimple_stmt_iterator si_new, si_orig;
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edge orig_loop_latch = loop_latch_edge (orig_loop);
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edge orig_entry_e = loop_preheader_edge (orig_loop);
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edge new_loop_entry_e = loop_preheader_edge (new_loop);
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/* Scan the phis in the headers of the old and new loops
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(they are organized in exactly the same order). */
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for (si_new = gsi_start_phis (new_loop->header),
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si_orig = gsi_start_phis (orig_loop->header);
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!gsi_end_p (si_new) && !gsi_end_p (si_orig);
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gsi_next (&si_new), gsi_next (&si_orig))
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{
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tree def;
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gimple phi_new = gsi_stmt (si_new);
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gimple phi_orig = gsi_stmt (si_orig);
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/* Add the first phi argument for the phi in NEW_LOOP (the one
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associated with the entry of NEW_LOOP) */
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def = PHI_ARG_DEF_FROM_EDGE (phi_orig, orig_entry_e);
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add_phi_arg (phi_new, def, new_loop_entry_e);
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/* Add the second phi argument for the phi in NEW_LOOP (the one
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associated with the latch of NEW_LOOP) */
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def = PHI_ARG_DEF_FROM_EDGE (phi_orig, orig_loop_latch);
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if (TREE_CODE (def) == SSA_NAME)
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{
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new_ssa_name = get_current_def (def);
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if (!new_ssa_name)
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/* This only happens if there are no definitions inside the
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loop. Use the phi_result in this case. */
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new_ssa_name = PHI_RESULT (phi_new);
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}
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else
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/* Could be an integer. */
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new_ssa_name = def;
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add_phi_arg (phi_new, new_ssa_name, loop_latch_edge (new_loop));
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}
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}
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/* Return a copy of LOOP placed before LOOP. */
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static struct loop *
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copy_loop_before (struct loop *loop)
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{
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struct loop *res;
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edge preheader = loop_preheader_edge (loop);
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if (!single_exit (loop))
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return NULL;
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initialize_original_copy_tables ();
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res = slpeel_tree_duplicate_loop_to_edge_cfg (loop, preheader);
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free_original_copy_tables ();
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if (!res)
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return NULL;
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update_phis_for_loop_copy (loop, res);
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rename_variables_in_loop (res);
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return res;
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}
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/* Creates an empty basic block after LOOP. */
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static void
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create_bb_after_loop (struct loop *loop)
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{
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edge exit = single_exit (loop);
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if (!exit)
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return;
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split_edge (exit);
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}
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/* Generate code for PARTITION from the code in LOOP. The loop is
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copied when COPY_P is true. All the statements not flagged in the
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PARTITION bitmap are removed from the loop or from its copy. The
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statements are indexed in sequence inside a basic block, and the
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basic blocks of a loop are taken in dom order. Returns true when
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the code gen succeeded. */
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static bool
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generate_loops_for_partition (struct loop *loop, bitmap partition, bool copy_p)
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{
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unsigned i, x;
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gimple_stmt_iterator bsi;
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basic_block *bbs;
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if (copy_p)
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{
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loop = copy_loop_before (loop);
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create_preheader (loop, CP_SIMPLE_PREHEADERS);
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create_bb_after_loop (loop);
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}
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if (loop == NULL)
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return false;
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/* Remove stmts not in the PARTITION bitmap. The order in which we
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visit the phi nodes and the statements is exactly as in
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stmts_from_loop. */
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bbs = get_loop_body_in_dom_order (loop);
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for (x = 0, i = 0; i < loop->num_nodes; i++)
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{
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basic_block bb = bbs[i];
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for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi);)
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if (!bitmap_bit_p (partition, x++))
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remove_phi_node (&bsi, true);
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else
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gsi_next (&bsi);
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for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi);)
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if (gimple_code (gsi_stmt (bsi)) != GIMPLE_LABEL
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&& !bitmap_bit_p (partition, x++))
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gsi_remove (&bsi, false);
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else
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gsi_next (&bsi);
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mark_virtual_ops_in_bb (bb);
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}
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free (bbs);
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return true;
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}
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/* Generate a call to memset. Return true when the operation succeeded. */
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static bool
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generate_memset_zero (gimple stmt, tree op0, tree nb_iter,
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gimple_stmt_iterator bsi)
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{
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tree t, nb_bytes, addr_base;
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bool res = false;
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gimple_seq stmts = NULL, stmt_list = NULL;
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gimple fn_call;
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tree mem, fndecl, fntype, fn;
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gimple_stmt_iterator i;
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ssa_op_iter iter;
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struct data_reference *dr = XCNEW (struct data_reference);
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nb_bytes = fold_build2 (MULT_EXPR, TREE_TYPE (nb_iter),
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nb_iter, TYPE_SIZE_UNIT (TREE_TYPE (op0)));
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nb_bytes = force_gimple_operand (nb_bytes, &stmts, true, NULL);
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gimple_seq_add_seq (&stmt_list, stmts);
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DR_STMT (dr) = stmt;
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DR_REF (dr) = op0;
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dr_analyze_innermost (dr);
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/* Test for a positive stride, iterating over every element. */
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if (integer_zerop (fold_build2 (MINUS_EXPR, integer_type_node, DR_STEP (dr),
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TYPE_SIZE_UNIT (TREE_TYPE (op0)))))
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addr_base = fold_build2 (PLUS_EXPR, TREE_TYPE (DR_BASE_ADDRESS (dr)),
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DR_BASE_ADDRESS (dr),
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size_binop (PLUS_EXPR,
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DR_OFFSET (dr), DR_INIT (dr)));
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/* Test for a negative stride, iterating over every element. */
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else if (integer_zerop (fold_build2 (PLUS_EXPR, integer_type_node,
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TYPE_SIZE_UNIT (TREE_TYPE (op0)),
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DR_STEP (dr))))
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{
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addr_base = size_binop (PLUS_EXPR, DR_OFFSET (dr), DR_INIT (dr));
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addr_base = fold_build2 (MINUS_EXPR, sizetype, addr_base, nb_bytes);
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addr_base = force_gimple_operand (addr_base, &stmts, true, NULL);
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gimple_seq_add_seq (&stmt_list, stmts);
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addr_base = fold_build2 (POINTER_PLUS_EXPR,
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TREE_TYPE (DR_BASE_ADDRESS (dr)),
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DR_BASE_ADDRESS (dr), addr_base);
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}
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else
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goto end;
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mem = force_gimple_operand (addr_base, &stmts, true, NULL);
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gimple_seq_add_seq (&stmt_list, stmts);
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fndecl = implicit_built_in_decls [BUILT_IN_MEMSET];
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fntype = TREE_TYPE (fndecl);
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fn = build1 (ADDR_EXPR, build_pointer_type (fntype), fndecl);
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fn_call = gimple_build_call (fn, 3, mem, integer_zero_node, nb_bytes);
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gimple_seq_add_stmt (&stmt_list, fn_call);
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for (i = gsi_start (stmt_list); !gsi_end_p (i); gsi_next (&i))
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{
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gimple s = gsi_stmt (i);
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update_stmt_if_modified (s);
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FOR_EACH_SSA_TREE_OPERAND (t, s, iter, SSA_OP_VIRTUAL_DEFS)
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{
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if (TREE_CODE (t) == SSA_NAME)
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t = SSA_NAME_VAR (t);
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mark_sym_for_renaming (t);
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}
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}
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/* Mark also the uses of the VDEFS of STMT to be renamed. */
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FOR_EACH_SSA_TREE_OPERAND (t, stmt, iter, SSA_OP_VIRTUAL_DEFS)
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{
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if (TREE_CODE (t) == SSA_NAME)
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{
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gimple s;
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imm_use_iterator imm_iter;
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FOR_EACH_IMM_USE_STMT (s, imm_iter, t)
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update_stmt (s);
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t = SSA_NAME_VAR (t);
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}
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mark_sym_for_renaming (t);
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}
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gsi_insert_seq_after (&bsi, stmt_list, GSI_CONTINUE_LINKING);
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res = true;
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if (dump_file && (dump_flags & TDF_DETAILS))
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fprintf (dump_file, "generated memset zero\n");
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end:
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free_data_ref (dr);
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return res;
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}
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/* Tries to generate a builtin function for the instructions of LOOP
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pointed to by the bits set in PARTITION. Returns true when the
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operation succeeded. */
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static bool
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generate_builtin (struct loop *loop, bitmap partition, bool copy_p)
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{
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bool res = false;
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unsigned i, x = 0;
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basic_block *bbs;
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gimple write = NULL;
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tree op0, op1;
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gimple_stmt_iterator bsi;
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tree nb_iter = number_of_exit_cond_executions (loop);
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if (!nb_iter || nb_iter == chrec_dont_know)
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return false;
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bbs = get_loop_body_in_dom_order (loop);
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for (i = 0; i < loop->num_nodes; i++)
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{
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basic_block bb = bbs[i];
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for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
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x++;
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for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
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{
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gimple stmt = gsi_stmt (bsi);
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if (bitmap_bit_p (partition, x++)
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&& is_gimple_assign (stmt)
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&& !is_gimple_reg (gimple_assign_lhs (stmt)))
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{
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/* Don't generate the builtins when there are more than
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one memory write. */
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if (write != NULL)
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goto end;
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write = stmt;
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}
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}
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}
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if (!write)
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goto end;
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op0 = gimple_assign_lhs (write);
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op1 = gimple_assign_rhs1 (write);
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if (!(TREE_CODE (op0) == ARRAY_REF
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|| TREE_CODE (op0) == INDIRECT_REF))
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goto end;
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/* The new statements will be placed before LOOP. */
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bsi = gsi_last_bb (loop_preheader_edge (loop)->src);
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if (gimple_assign_rhs_code (write) == INTEGER_CST
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&& (integer_zerop (op1) || real_zerop (op1)))
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res = generate_memset_zero (write, op0, nb_iter, bsi);
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/* If this is the last partition for which we generate code, we have
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to destroy the loop. */
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if (res && !copy_p)
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{
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unsigned nbbs = loop->num_nodes;
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basic_block src = loop_preheader_edge (loop)->src;
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basic_block dest = single_exit (loop)->dest;
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make_edge (src, dest, EDGE_FALLTHRU);
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set_immediate_dominator (CDI_DOMINATORS, dest, src);
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cancel_loop_tree (loop);
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for (i = 0; i < nbbs; i++)
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delete_basic_block (bbs[i]);
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}
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end:
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free (bbs);
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return res;
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}
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/* Generates code for PARTITION. For simple loops, this function can
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generate a built-in. */
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static bool
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generate_code_for_partition (struct loop *loop, bitmap partition, bool copy_p)
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{
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if (generate_builtin (loop, partition, copy_p))
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return true;
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return generate_loops_for_partition (loop, partition, copy_p);
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}
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/* Returns true if the node V of RDG cannot be recomputed. */
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static bool
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rdg_cannot_recompute_vertex_p (struct graph *rdg, int v)
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{
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if (RDG_MEM_WRITE_STMT (rdg, v))
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return true;
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return false;
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}
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/* Returns true when the vertex V has already been generated in the
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current partition (V is in PROCESSED), or when V belongs to another
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partition and cannot be recomputed (V is not in REMAINING_STMTS). */
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static inline bool
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already_processed_vertex_p (bitmap processed, int v)
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{
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return (bitmap_bit_p (processed, v)
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|| !bitmap_bit_p (remaining_stmts, v));
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}
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/* Returns NULL when there is no anti-dependence among the successors
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of vertex V, otherwise returns the edge with the anti-dep. */
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static struct graph_edge *
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has_anti_dependence (struct vertex *v)
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{
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struct graph_edge *e;
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if (v->succ)
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for (e = v->succ; e; e = e->succ_next)
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if (RDGE_TYPE (e) == anti_dd)
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return e;
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return NULL;
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}
|
|
|
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/* Returns true when V has an anti-dependence edge among its successors. */
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|
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static bool
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predecessor_has_mem_write (struct graph *rdg, struct vertex *v)
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{
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struct graph_edge *e;
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if (v->pred)
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for (e = v->pred; e; e = e->pred_next)
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if (bitmap_bit_p (upstream_mem_writes, e->src)
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/* Don't consider flow channels: a write to memory followed
|
|
by a read from memory. These channels allow the split of
|
|
the RDG in different partitions. */
|
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&& !RDG_MEM_WRITE_STMT (rdg, e->src))
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return true;
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|
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return false;
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}
|
|
|
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/* Initializes the upstream_mem_writes bitmap following the
|
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information from RDG. */
|
|
|
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static void
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mark_nodes_having_upstream_mem_writes (struct graph *rdg)
|
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{
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int v, x;
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bitmap seen = BITMAP_ALLOC (NULL);
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for (v = rdg->n_vertices - 1; v >= 0; v--)
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if (!bitmap_bit_p (seen, v))
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{
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unsigned i;
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VEC (int, heap) *nodes = VEC_alloc (int, heap, 3);
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bool has_upstream_mem_write_p = false;
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|
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graphds_dfs (rdg, &v, 1, &nodes, false, NULL);
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|
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for (i = 0; VEC_iterate (int, nodes, i, x); i++)
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{
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if (bitmap_bit_p (seen, x))
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continue;
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|
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bitmap_set_bit (seen, x);
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|
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if (RDG_MEM_WRITE_STMT (rdg, x)
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|| predecessor_has_mem_write (rdg, &(rdg->vertices[x]))
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/* In anti dependences the read should occur before
|
|
the write, this is why both the read and the write
|
|
should be placed in the same partition. */
|
|
|| has_anti_dependence (&(rdg->vertices[x])))
|
|
{
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has_upstream_mem_write_p = true;
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bitmap_set_bit (upstream_mem_writes, x);
|
|
}
|
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}
|
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|
|
VEC_free (int, heap, nodes);
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|
}
|
|
}
|
|
|
|
/* Returns true when vertex u has a memory write node as a predecessor
|
|
in RDG. */
|
|
|
|
static bool
|
|
has_upstream_mem_writes (int u)
|
|
{
|
|
return bitmap_bit_p (upstream_mem_writes, u);
|
|
}
|
|
|
|
static void rdg_flag_vertex_and_dependent (struct graph *, int, bitmap, bitmap,
|
|
bitmap, bool *);
|
|
|
|
/* Flag all the uses of U. */
|
|
|
|
static void
|
|
rdg_flag_all_uses (struct graph *rdg, int u, bitmap partition, bitmap loops,
|
|
bitmap processed, bool *part_has_writes)
|
|
{
|
|
struct graph_edge *e;
|
|
|
|
for (e = rdg->vertices[u].succ; e; e = e->succ_next)
|
|
if (!bitmap_bit_p (processed, e->dest))
|
|
{
|
|
rdg_flag_vertex_and_dependent (rdg, e->dest, partition, loops,
|
|
processed, part_has_writes);
|
|
rdg_flag_all_uses (rdg, e->dest, partition, loops, processed,
|
|
part_has_writes);
|
|
}
|
|
}
|
|
|
|
/* Flag the uses of U stopping following the information from
|
|
upstream_mem_writes. */
|
|
|
|
static void
|
|
rdg_flag_uses (struct graph *rdg, int u, bitmap partition, bitmap loops,
|
|
bitmap processed, bool *part_has_writes)
|
|
{
|
|
ssa_op_iter iter;
|
|
use_operand_p use_p;
|
|
struct vertex *x = &(rdg->vertices[u]);
|
|
gimple stmt = RDGV_STMT (x);
|
|
struct graph_edge *anti_dep = has_anti_dependence (x);
|
|
|
|
/* Keep in the same partition the destination of an antidependence,
|
|
because this is a store to the exact same location. Putting this
|
|
in another partition is bad for cache locality. */
|
|
if (anti_dep)
|
|
{
|
|
int v = anti_dep->dest;
|
|
|
|
if (!already_processed_vertex_p (processed, v))
|
|
rdg_flag_vertex_and_dependent (rdg, v, partition, loops,
|
|
processed, part_has_writes);
|
|
}
|
|
|
|
if (gimple_code (stmt) != GIMPLE_PHI)
|
|
{
|
|
FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_VIRTUAL_USES)
|
|
{
|
|
tree use = USE_FROM_PTR (use_p);
|
|
|
|
if (TREE_CODE (use) == SSA_NAME)
|
|
{
|
|
gimple def_stmt = SSA_NAME_DEF_STMT (use);
|
|
int v = rdg_vertex_for_stmt (rdg, def_stmt);
|
|
|
|
if (v >= 0
|
|
&& !already_processed_vertex_p (processed, v))
|
|
rdg_flag_vertex_and_dependent (rdg, v, partition, loops,
|
|
processed, part_has_writes);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (is_gimple_assign (stmt) && has_upstream_mem_writes (u))
|
|
{
|
|
tree op0 = gimple_assign_lhs (stmt);
|
|
|
|
/* Scalar channels don't have enough space for transmitting data
|
|
between tasks, unless we add more storage by privatizing. */
|
|
if (is_gimple_reg (op0))
|
|
{
|
|
use_operand_p use_p;
|
|
imm_use_iterator iter;
|
|
|
|
FOR_EACH_IMM_USE_FAST (use_p, iter, op0)
|
|
{
|
|
int v = rdg_vertex_for_stmt (rdg, USE_STMT (use_p));
|
|
|
|
if (!already_processed_vertex_p (processed, v))
|
|
rdg_flag_vertex_and_dependent (rdg, v, partition, loops,
|
|
processed, part_has_writes);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Flag V from RDG as part of PARTITION, and also flag its loop number
|
|
in LOOPS. */
|
|
|
|
static void
|
|
rdg_flag_vertex (struct graph *rdg, int v, bitmap partition, bitmap loops,
|
|
bool *part_has_writes)
|
|
{
|
|
struct loop *loop;
|
|
|
|
if (bitmap_bit_p (partition, v))
|
|
return;
|
|
|
|
loop = loop_containing_stmt (RDG_STMT (rdg, v));
|
|
bitmap_set_bit (loops, loop->num);
|
|
bitmap_set_bit (partition, v);
|
|
|
|
if (rdg_cannot_recompute_vertex_p (rdg, v))
|
|
{
|
|
*part_has_writes = true;
|
|
bitmap_clear_bit (remaining_stmts, v);
|
|
}
|
|
}
|
|
|
|
/* Flag in the bitmap PARTITION the vertex V and all its predecessors.
|
|
Also flag their loop number in LOOPS. */
|
|
|
|
static void
|
|
rdg_flag_vertex_and_dependent (struct graph *rdg, int v, bitmap partition,
|
|
bitmap loops, bitmap processed,
|
|
bool *part_has_writes)
|
|
{
|
|
unsigned i;
|
|
VEC (int, heap) *nodes = VEC_alloc (int, heap, 3);
|
|
int x;
|
|
|
|
bitmap_set_bit (processed, v);
|
|
rdg_flag_uses (rdg, v, partition, loops, processed, part_has_writes);
|
|
graphds_dfs (rdg, &v, 1, &nodes, false, remaining_stmts);
|
|
rdg_flag_vertex (rdg, v, partition, loops, part_has_writes);
|
|
|
|
for (i = 0; VEC_iterate (int, nodes, i, x); i++)
|
|
if (!already_processed_vertex_p (processed, x))
|
|
rdg_flag_vertex_and_dependent (rdg, x, partition, loops, processed,
|
|
part_has_writes);
|
|
|
|
VEC_free (int, heap, nodes);
|
|
}
|
|
|
|
/* Initialize CONDS with all the condition statements from the basic
|
|
blocks of LOOP. */
|
|
|
|
static void
|
|
collect_condition_stmts (struct loop *loop, VEC (gimple, heap) **conds)
|
|
{
|
|
unsigned i;
|
|
edge e;
|
|
VEC (edge, heap) *exits = get_loop_exit_edges (loop);
|
|
|
|
for (i = 0; VEC_iterate (edge, exits, i, e); i++)
|
|
{
|
|
gimple cond = last_stmt (e->src);
|
|
|
|
if (cond)
|
|
VEC_safe_push (gimple, heap, *conds, cond);
|
|
}
|
|
|
|
VEC_free (edge, heap, exits);
|
|
}
|
|
|
|
/* Add to PARTITION all the exit condition statements for LOOPS
|
|
together with all their dependent statements determined from
|
|
RDG. */
|
|
|
|
static void
|
|
rdg_flag_loop_exits (struct graph *rdg, bitmap loops, bitmap partition,
|
|
bitmap processed, bool *part_has_writes)
|
|
{
|
|
unsigned i;
|
|
bitmap_iterator bi;
|
|
VEC (gimple, heap) *conds = VEC_alloc (gimple, heap, 3);
|
|
|
|
EXECUTE_IF_SET_IN_BITMAP (loops, 0, i, bi)
|
|
collect_condition_stmts (get_loop (i), &conds);
|
|
|
|
while (!VEC_empty (gimple, conds))
|
|
{
|
|
gimple cond = VEC_pop (gimple, conds);
|
|
int v = rdg_vertex_for_stmt (rdg, cond);
|
|
bitmap new_loops = BITMAP_ALLOC (NULL);
|
|
|
|
if (!already_processed_vertex_p (processed, v))
|
|
rdg_flag_vertex_and_dependent (rdg, v, partition, new_loops, processed,
|
|
part_has_writes);
|
|
|
|
EXECUTE_IF_SET_IN_BITMAP (new_loops, 0, i, bi)
|
|
if (!bitmap_bit_p (loops, i))
|
|
{
|
|
bitmap_set_bit (loops, i);
|
|
collect_condition_stmts (get_loop (i), &conds);
|
|
}
|
|
|
|
BITMAP_FREE (new_loops);
|
|
}
|
|
}
|
|
|
|
/* Flag all the nodes of RDG containing memory accesses that could
|
|
potentially belong to arrays already accessed in the current
|
|
PARTITION. */
|
|
|
|
static void
|
|
rdg_flag_similar_memory_accesses (struct graph *rdg, bitmap partition,
|
|
bitmap loops, bitmap processed,
|
|
VEC (int, heap) **other_stores)
|
|
{
|
|
bool foo;
|
|
unsigned i, n;
|
|
int j, k, kk;
|
|
bitmap_iterator ii;
|
|
struct graph_edge *e;
|
|
|
|
EXECUTE_IF_SET_IN_BITMAP (partition, 0, i, ii)
|
|
if (RDG_MEM_WRITE_STMT (rdg, i)
|
|
|| RDG_MEM_READS_STMT (rdg, i))
|
|
{
|
|
for (j = 0; j < rdg->n_vertices; j++)
|
|
if (!bitmap_bit_p (processed, j)
|
|
&& (RDG_MEM_WRITE_STMT (rdg, j)
|
|
|| RDG_MEM_READS_STMT (rdg, j))
|
|
&& rdg_has_similar_memory_accesses (rdg, i, j))
|
|
{
|
|
/* Flag first the node J itself, and all the nodes that
|
|
are needed to compute J. */
|
|
rdg_flag_vertex_and_dependent (rdg, j, partition, loops,
|
|
processed, &foo);
|
|
|
|
/* When J is a read, we want to coalesce in the same
|
|
PARTITION all the nodes that are using J: this is
|
|
needed for better cache locality. */
|
|
rdg_flag_all_uses (rdg, j, partition, loops, processed, &foo);
|
|
|
|
/* Remove from OTHER_STORES the vertex that we flagged. */
|
|
if (RDG_MEM_WRITE_STMT (rdg, j))
|
|
for (k = 0; VEC_iterate (int, *other_stores, k, kk); k++)
|
|
if (kk == j)
|
|
{
|
|
VEC_unordered_remove (int, *other_stores, k);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If the node I has two uses, then keep these together in the
|
|
same PARTITION. */
|
|
for (n = 0, e = rdg->vertices[i].succ; e; e = e->succ_next, n++);
|
|
|
|
if (n > 1)
|
|
rdg_flag_all_uses (rdg, i, partition, loops, processed, &foo);
|
|
}
|
|
}
|
|
|
|
/* Returns a bitmap in which all the statements needed for computing
|
|
the strongly connected component C of the RDG are flagged, also
|
|
including the loop exit conditions. */
|
|
|
|
static bitmap
|
|
build_rdg_partition_for_component (struct graph *rdg, rdgc c,
|
|
bool *part_has_writes,
|
|
VEC (int, heap) **other_stores)
|
|
{
|
|
int i, v;
|
|
bitmap partition = BITMAP_ALLOC (NULL);
|
|
bitmap loops = BITMAP_ALLOC (NULL);
|
|
bitmap processed = BITMAP_ALLOC (NULL);
|
|
|
|
for (i = 0; VEC_iterate (int, c->vertices, i, v); i++)
|
|
if (!already_processed_vertex_p (processed, v))
|
|
rdg_flag_vertex_and_dependent (rdg, v, partition, loops, processed,
|
|
part_has_writes);
|
|
|
|
/* Also iterate on the array of stores not in the starting vertices,
|
|
and determine those vertices that have some memory affinity with
|
|
the current nodes in the component: these are stores to the same
|
|
arrays, i.e. we're taking care of cache locality. */
|
|
rdg_flag_similar_memory_accesses (rdg, partition, loops, processed,
|
|
other_stores);
|
|
|
|
rdg_flag_loop_exits (rdg, loops, partition, processed, part_has_writes);
|
|
|
|
BITMAP_FREE (processed);
|
|
BITMAP_FREE (loops);
|
|
return partition;
|
|
}
|
|
|
|
/* Free memory for COMPONENTS. */
|
|
|
|
static void
|
|
free_rdg_components (VEC (rdgc, heap) *components)
|
|
{
|
|
int i;
|
|
rdgc x;
|
|
|
|
for (i = 0; VEC_iterate (rdgc, components, i, x); i++)
|
|
{
|
|
VEC_free (int, heap, x->vertices);
|
|
free (x);
|
|
}
|
|
}
|
|
|
|
/* Build the COMPONENTS vector with the strongly connected components
|
|
of RDG in which the STARTING_VERTICES occur. */
|
|
|
|
static void
|
|
rdg_build_components (struct graph *rdg, VEC (int, heap) *starting_vertices,
|
|
VEC (rdgc, heap) **components)
|
|
{
|
|
int i, v;
|
|
bitmap saved_components = BITMAP_ALLOC (NULL);
|
|
int n_components = graphds_scc (rdg, NULL);
|
|
VEC (int, heap) **all_components = XNEWVEC (VEC (int, heap) *, n_components);
|
|
|
|
for (i = 0; i < n_components; i++)
|
|
all_components[i] = VEC_alloc (int, heap, 3);
|
|
|
|
for (i = 0; i < rdg->n_vertices; i++)
|
|
VEC_safe_push (int, heap, all_components[rdg->vertices[i].component], i);
|
|
|
|
for (i = 0; VEC_iterate (int, starting_vertices, i, v); i++)
|
|
{
|
|
int c = rdg->vertices[v].component;
|
|
|
|
if (!bitmap_bit_p (saved_components, c))
|
|
{
|
|
rdgc x = XCNEW (struct rdg_component);
|
|
x->num = c;
|
|
x->vertices = all_components[c];
|
|
|
|
VEC_safe_push (rdgc, heap, *components, x);
|
|
bitmap_set_bit (saved_components, c);
|
|
}
|
|
}
|
|
|
|
for (i = 0; i < n_components; i++)
|
|
if (!bitmap_bit_p (saved_components, i))
|
|
VEC_free (int, heap, all_components[i]);
|
|
|
|
free (all_components);
|
|
BITMAP_FREE (saved_components);
|
|
}
|
|
|
|
/* Aggregate several components into a useful partition that is
|
|
registered in the PARTITIONS vector. Partitions will be
|
|
distributed in different loops. */
|
|
|
|
static void
|
|
rdg_build_partitions (struct graph *rdg, VEC (rdgc, heap) *components,
|
|
VEC (int, heap) **other_stores,
|
|
VEC (bitmap, heap) **partitions, bitmap processed)
|
|
{
|
|
int i;
|
|
rdgc x;
|
|
bitmap partition = BITMAP_ALLOC (NULL);
|
|
|
|
for (i = 0; VEC_iterate (rdgc, components, i, x); i++)
|
|
{
|
|
bitmap np;
|
|
bool part_has_writes = false;
|
|
int v = VEC_index (int, x->vertices, 0);
|
|
|
|
if (bitmap_bit_p (processed, v))
|
|
continue;
|
|
|
|
np = build_rdg_partition_for_component (rdg, x, &part_has_writes,
|
|
other_stores);
|
|
bitmap_ior_into (partition, np);
|
|
bitmap_ior_into (processed, np);
|
|
BITMAP_FREE (np);
|
|
|
|
if (part_has_writes)
|
|
{
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
{
|
|
fprintf (dump_file, "ldist useful partition:\n");
|
|
dump_bitmap (dump_file, partition);
|
|
}
|
|
|
|
VEC_safe_push (bitmap, heap, *partitions, partition);
|
|
partition = BITMAP_ALLOC (NULL);
|
|
}
|
|
}
|
|
|
|
/* Add the nodes from the RDG that were not marked as processed, and
|
|
that are used outside the current loop. These are scalar
|
|
computations that are not yet part of previous partitions. */
|
|
for (i = 0; i < rdg->n_vertices; i++)
|
|
if (!bitmap_bit_p (processed, i)
|
|
&& rdg_defs_used_in_other_loops_p (rdg, i))
|
|
VEC_safe_push (int, heap, *other_stores, i);
|
|
|
|
/* If there are still statements left in the OTHER_STORES array,
|
|
create other components and partitions with these stores and
|
|
their dependences. */
|
|
if (VEC_length (int, *other_stores) > 0)
|
|
{
|
|
VEC (rdgc, heap) *comps = VEC_alloc (rdgc, heap, 3);
|
|
VEC (int, heap) *foo = VEC_alloc (int, heap, 3);
|
|
|
|
rdg_build_components (rdg, *other_stores, &comps);
|
|
rdg_build_partitions (rdg, comps, &foo, partitions, processed);
|
|
|
|
VEC_free (int, heap, foo);
|
|
free_rdg_components (comps);
|
|
}
|
|
|
|
/* If there is something left in the last partition, save it. */
|
|
if (bitmap_count_bits (partition) > 0)
|
|
VEC_safe_push (bitmap, heap, *partitions, partition);
|
|
else
|
|
BITMAP_FREE (partition);
|
|
}
|
|
|
|
/* Dump to FILE the PARTITIONS. */
|
|
|
|
static void
|
|
dump_rdg_partitions (FILE *file, VEC (bitmap, heap) *partitions)
|
|
{
|
|
int i;
|
|
bitmap partition;
|
|
|
|
for (i = 0; VEC_iterate (bitmap, partitions, i, partition); i++)
|
|
debug_bitmap_file (file, partition);
|
|
}
|
|
|
|
/* Debug PARTITIONS. */
|
|
extern void debug_rdg_partitions (VEC (bitmap, heap) *);
|
|
|
|
void
|
|
debug_rdg_partitions (VEC (bitmap, heap) *partitions)
|
|
{
|
|
dump_rdg_partitions (stderr, partitions);
|
|
}
|
|
|
|
/* Generate code from STARTING_VERTICES in RDG. Returns the number of
|
|
distributed loops. */
|
|
|
|
static int
|
|
ldist_gen (struct loop *loop, struct graph *rdg,
|
|
VEC (int, heap) *starting_vertices)
|
|
{
|
|
int i, nbp;
|
|
VEC (rdgc, heap) *components = VEC_alloc (rdgc, heap, 3);
|
|
VEC (bitmap, heap) *partitions = VEC_alloc (bitmap, heap, 3);
|
|
VEC (int, heap) *other_stores = VEC_alloc (int, heap, 3);
|
|
bitmap partition, processed = BITMAP_ALLOC (NULL);
|
|
|
|
remaining_stmts = BITMAP_ALLOC (NULL);
|
|
upstream_mem_writes = BITMAP_ALLOC (NULL);
|
|
|
|
for (i = 0; i < rdg->n_vertices; i++)
|
|
{
|
|
bitmap_set_bit (remaining_stmts, i);
|
|
|
|
/* Save in OTHER_STORES all the memory writes that are not in
|
|
STARTING_VERTICES. */
|
|
if (RDG_MEM_WRITE_STMT (rdg, i))
|
|
{
|
|
int v;
|
|
unsigned j;
|
|
bool found = false;
|
|
|
|
for (j = 0; VEC_iterate (int, starting_vertices, j, v); j++)
|
|
if (i == v)
|
|
{
|
|
found = true;
|
|
break;
|
|
}
|
|
|
|
if (!found)
|
|
VEC_safe_push (int, heap, other_stores, i);
|
|
}
|
|
}
|
|
|
|
mark_nodes_having_upstream_mem_writes (rdg);
|
|
rdg_build_components (rdg, starting_vertices, &components);
|
|
rdg_build_partitions (rdg, components, &other_stores, &partitions,
|
|
processed);
|
|
BITMAP_FREE (processed);
|
|
nbp = VEC_length (bitmap, partitions);
|
|
|
|
if (nbp <= 1)
|
|
goto ldist_done;
|
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
dump_rdg_partitions (dump_file, partitions);
|
|
|
|
for (i = 0; VEC_iterate (bitmap, partitions, i, partition); i++)
|
|
if (!generate_code_for_partition (loop, partition, i < nbp - 1))
|
|
goto ldist_done;
|
|
|
|
rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
|
|
update_ssa (TODO_update_ssa_only_virtuals | TODO_update_ssa);
|
|
|
|
ldist_done:
|
|
|
|
BITMAP_FREE (remaining_stmts);
|
|
BITMAP_FREE (upstream_mem_writes);
|
|
|
|
for (i = 0; VEC_iterate (bitmap, partitions, i, partition); i++)
|
|
BITMAP_FREE (partition);
|
|
|
|
VEC_free (int, heap, other_stores);
|
|
VEC_free (bitmap, heap, partitions);
|
|
free_rdg_components (components);
|
|
return nbp;
|
|
}
|
|
|
|
/* Distributes the code from LOOP in such a way that producer
|
|
statements are placed before consumer statements. When STMTS is
|
|
NULL, performs the maximal distribution, if STMTS is not NULL,
|
|
tries to separate only these statements from the LOOP's body.
|
|
Returns the number of distributed loops. */
|
|
|
|
static int
|
|
distribute_loop (struct loop *loop, VEC (gimple, heap) *stmts)
|
|
{
|
|
bool res = false;
|
|
struct graph *rdg;
|
|
gimple s;
|
|
unsigned i;
|
|
VEC (int, heap) *vertices;
|
|
|
|
if (loop->num_nodes > 2)
|
|
{
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
fprintf (dump_file,
|
|
"FIXME: Loop %d not distributed: it has more than two basic blocks.\n",
|
|
loop->num);
|
|
|
|
return res;
|
|
}
|
|
|
|
rdg = build_rdg (loop);
|
|
|
|
if (!rdg)
|
|
{
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
fprintf (dump_file,
|
|
"FIXME: Loop %d not distributed: failed to build the RDG.\n",
|
|
loop->num);
|
|
|
|
return res;
|
|
}
|
|
|
|
vertices = VEC_alloc (int, heap, 3);
|
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
dump_rdg (dump_file, rdg);
|
|
|
|
for (i = 0; VEC_iterate (gimple, stmts, i, s); i++)
|
|
{
|
|
int v = rdg_vertex_for_stmt (rdg, s);
|
|
|
|
if (v >= 0)
|
|
{
|
|
VEC_safe_push (int, heap, vertices, v);
|
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
fprintf (dump_file,
|
|
"ldist asked to generate code for vertex %d\n", v);
|
|
}
|
|
}
|
|
|
|
res = ldist_gen (loop, rdg, vertices);
|
|
VEC_free (int, heap, vertices);
|
|
free_rdg (rdg);
|
|
|
|
return res;
|
|
}
|
|
|
|
/* Distribute all loops in the current function. */
|
|
|
|
static unsigned int
|
|
tree_loop_distribution (void)
|
|
{
|
|
struct loop *loop;
|
|
loop_iterator li;
|
|
int nb_generated_loops = 0;
|
|
|
|
FOR_EACH_LOOP (li, loop, 0)
|
|
{
|
|
VEC (gimple, heap) *work_list = VEC_alloc (gimple, heap, 3);
|
|
|
|
/* With the following working list, we're asking distribute_loop
|
|
to separate the stores of the loop: when dependences allow,
|
|
it will end on having one store per loop. */
|
|
stores_from_loop (loop, &work_list);
|
|
|
|
/* A simple heuristic for cache locality is to not split stores
|
|
to the same array. Without this call, an unrolled loop would
|
|
be split into as many loops as unroll factor, each loop
|
|
storing in the same array. */
|
|
remove_similar_memory_refs (&work_list);
|
|
|
|
nb_generated_loops = distribute_loop (loop, work_list);
|
|
|
|
if (dump_file && (dump_flags & TDF_DETAILS))
|
|
{
|
|
if (nb_generated_loops > 1)
|
|
fprintf (dump_file, "Loop %d distributed: split to %d loops.\n",
|
|
loop->num, nb_generated_loops);
|
|
else
|
|
fprintf (dump_file, "Loop %d is the same.\n", loop->num);
|
|
}
|
|
|
|
verify_loop_structure ();
|
|
|
|
VEC_free (gimple, heap, work_list);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static bool
|
|
gate_tree_loop_distribution (void)
|
|
{
|
|
return flag_tree_loop_distribution != 0;
|
|
}
|
|
|
|
struct gimple_opt_pass pass_loop_distribution =
|
|
{
|
|
{
|
|
GIMPLE_PASS,
|
|
"ldist", /* name */
|
|
gate_tree_loop_distribution, /* gate */
|
|
tree_loop_distribution, /* execute */
|
|
NULL, /* sub */
|
|
NULL, /* next */
|
|
0, /* static_pass_number */
|
|
TV_TREE_LOOP_DISTRIBUTION, /* tv_id */
|
|
PROP_cfg | PROP_ssa, /* properties_required */
|
|
0, /* properties_provided */
|
|
0, /* properties_destroyed */
|
|
0, /* todo_flags_start */
|
|
TODO_dump_func | TODO_verify_loops /* todo_flags_finish */
|
|
}
|
|
};
|