/* Loop unswitching for GNU compiler.
- Copyright (C) 2002 Free Software Foundation, Inc.
+ Copyright (C) 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010
+ Free Software Foundation, Inc.
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 2, or (at your option) any later
+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
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-02111-1307, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "tm.h"
#include "rtl.h"
#include "hard-reg-set.h"
+#include "obstack.h"
#include "basic-block.h"
#include "cfgloop.h"
#include "cfglayout.h"
containing subloops would not be very large compared to complications
with handling this case. */
-static struct loop *unswitch_loop PARAMS ((struct loops *,
- struct loop *, basic_block));
-static void unswitch_single_loop PARAMS ((struct loops *, struct loop *,
- rtx, int));
-static bool may_unswitch_on_p PARAMS ((struct loops *, basic_block,
- struct loop *, basic_block *));
-static rtx reversed_condition PARAMS ((rtx));
+static struct loop *unswitch_loop (struct loop *, basic_block, rtx, rtx);
+static void unswitch_single_loop (struct loop *, rtx, int);
+static rtx may_unswitch_on (basic_block, struct loop *, rtx *);
-/* Main entry point. Perform loop unswitching on all suitable LOOPS. */
+/* Prepare a sequence comparing OP0 with OP1 using COMP and jumping to LABEL if
+ true, with probability PROB. If CINSN is not NULL, it is the insn to copy
+ in order to create a jump. */
+
+rtx
+compare_and_jump_seq (rtx op0, rtx op1, enum rtx_code comp, rtx label, int prob,
+ rtx cinsn)
+{
+ rtx seq, jump, cond;
+ enum machine_mode mode;
+
+ mode = GET_MODE (op0);
+ if (mode == VOIDmode)
+ mode = GET_MODE (op1);
+
+ start_sequence ();
+ if (GET_MODE_CLASS (mode) == MODE_CC)
+ {
+ /* A hack -- there seems to be no easy generic way how to make a
+ conditional jump from a ccmode comparison. */
+ gcc_assert (cinsn);
+ cond = XEXP (SET_SRC (pc_set (cinsn)), 0);
+ gcc_assert (GET_CODE (cond) == comp);
+ gcc_assert (rtx_equal_p (op0, XEXP (cond, 0)));
+ gcc_assert (rtx_equal_p (op1, XEXP (cond, 1)));
+ emit_jump_insn (copy_insn (PATTERN (cinsn)));
+ jump = get_last_insn ();
+ JUMP_LABEL (jump) = JUMP_LABEL (cinsn);
+ LABEL_NUSES (JUMP_LABEL (jump))++;
+ redirect_jump (jump, label, 0);
+ }
+ else
+ {
+ gcc_assert (!cinsn);
+
+ op0 = force_operand (op0, NULL_RTX);
+ op1 = force_operand (op1, NULL_RTX);
+ do_compare_rtx_and_jump (op0, op1, comp, 0,
+ mode, NULL_RTX, NULL_RTX, label, -1);
+ jump = get_last_insn ();
+ JUMP_LABEL (jump) = label;
+ LABEL_NUSES (label)++;
+ }
+ add_reg_note (jump, REG_BR_PROB, GEN_INT (prob));
+
+ seq = get_insns ();
+ end_sequence ();
+
+ return seq;
+}
+
+/* Main entry point. Perform loop unswitching on all suitable loops. */
void
-unswitch_loops (loops)
- struct loops *loops;
+unswitch_loops (void)
{
- int i, num;
+ loop_iterator li;
struct loop *loop;
/* Go through inner loops (only original ones). */
- num = loops->num;
-
- for (i = 1; i < num; i++)
- {
- /* Removed loop? */
- loop = loops->parray[i];
- if (!loop)
- continue;
-
- if (loop->inner)
- continue;
- unswitch_single_loop (loops, loop, NULL_RTX, 0);
+ FOR_EACH_LOOP (li, loop, LI_ONLY_INNERMOST)
+ {
+ unswitch_single_loop (loop, NULL_RTX, 0);
#ifdef ENABLE_CHECKING
- verify_dominators (loops->cfg.dom);
- verify_loop_structure (loops);
+ verify_dominators (CDI_DOMINATORS);
+ verify_loop_structure ();
#endif
}
+
+ iv_analysis_done ();
}
/* Checks whether we can unswitch LOOP on condition at end of BB -- one of its
- basic blocks (for what it means see comments below). List of basic blocks
- inside LOOP is provided in BODY to save time. */
-static bool
-may_unswitch_on_p (loops, bb, loop, body)
- struct loops *loops;
- basic_block bb;
- struct loop *loop;
- basic_block *body;
+ basic blocks (for what it means see comments below). In case condition
+ compares loop invariant cc mode register, return the jump in CINSN. */
+
+static rtx
+may_unswitch_on (basic_block bb, struct loop *loop, rtx *cinsn)
{
- rtx test;
+ rtx test, at, op[2], stest;
+ struct rtx_iv iv;
unsigned i;
+ enum machine_mode mode;
/* BB must end in a simple conditional jump. */
- if (!bb->succ || !bb->succ->succ_next || bb->succ->succ_next->succ_next)
- return false;
- if (!any_condjump_p (bb->end))
- return false;
+ if (EDGE_COUNT (bb->succs) != 2)
+ return NULL_RTX;
+ if (!any_condjump_p (BB_END (bb)))
+ return NULL_RTX;
/* With branches inside loop. */
- if (!flow_bb_inside_loop_p (loop, bb->succ->dest)
- || !flow_bb_inside_loop_p (loop, bb->succ->succ_next->dest))
- return false;
+ if (!flow_bb_inside_loop_p (loop, EDGE_SUCC (bb, 0)->dest)
+ || !flow_bb_inside_loop_p (loop, EDGE_SUCC (bb, 1)->dest))
+ return NULL_RTX;
/* It must be executed just once each iteration (because otherwise we
are unable to update dominator/irreducible loop information correctly). */
- if (!just_once_each_iteration_p (loops, loop, bb))
- return false;
+ if (!just_once_each_iteration_p (loop, bb))
+ return NULL_RTX;
- /* Condition must be invariant. We use just a stupid test of invariantness
- of the condition: all used regs must not be modified inside loop body. */
- test = get_condition (bb->end, NULL);
+ /* Condition must be invariant. */
+ test = get_condition (BB_END (bb), &at, true, false);
if (!test)
- return false;
+ return NULL_RTX;
- for (i = 0; i < loop->num_nodes; i++)
- if (modified_between_p (test, body[i]->head, NEXT_INSN (body[i]->end)))
- return false;
+ for (i = 0; i < 2; i++)
+ {
+ op[i] = XEXP (test, i);
- return true;
+ if (CONSTANT_P (op[i]))
+ continue;
+
+ if (!iv_analyze (at, op[i], &iv))
+ return NULL_RTX;
+ if (iv.step != const0_rtx
+ || iv.first_special)
+ return NULL_RTX;
+
+ op[i] = get_iv_value (&iv, const0_rtx);
+ }
+
+ mode = GET_MODE (op[0]);
+ if (mode == VOIDmode)
+ mode = GET_MODE (op[1]);
+ if (GET_MODE_CLASS (mode) == MODE_CC)
+ {
+ if (at != BB_END (bb))
+ return NULL_RTX;
+
+ if (!rtx_equal_p (op[0], XEXP (test, 0))
+ || !rtx_equal_p (op[1], XEXP (test, 1)))
+ return NULL_RTX;
+
+ *cinsn = BB_END (bb);
+ return test;
+ }
+
+ stest = simplify_gen_relational (GET_CODE (test), SImode,
+ mode, op[0], op[1]);
+ if (stest == const0_rtx
+ || stest == const_true_rtx)
+ return stest;
+
+ return canon_condition (gen_rtx_fmt_ee (GET_CODE (test), SImode,
+ op[0], op[1]));
}
/* Reverses CONDition; returns NULL if we cannot. */
-static rtx
-reversed_condition (cond)
- rtx cond;
+rtx
+reversed_condition (rtx cond)
{
enum rtx_code reversed;
reversed = reversed_comparison_code (cond, NULL);
number of unswitchings done; do not allow it to grow too much, it is too
easy to create example on that the code would grow exponentially. */
static void
-unswitch_single_loop (loops, loop, cond_checked, num)
- struct loops *loops;
- struct loop *loop;
- rtx cond_checked;
- int num;
+unswitch_single_loop (struct loop *loop, rtx cond_checked, int num)
{
- basic_block *bbs, bb;
+ basic_block *bbs;
struct loop *nloop;
unsigned i;
- int true_first;
- rtx cond, rcond, conds, rconds, acond, split_before;
- int always_true;
- int always_false;
+ rtx cond, rcond = NULL_RTX, conds, rconds, acond, cinsn;
int repeat;
edge e;
/* Do not unswitch too much. */
if (num > PARAM_VALUE (PARAM_MAX_UNSWITCH_LEVEL))
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file, ";; Not unswitching anymore, hit max level\n");
+ if (dump_file)
+ fprintf (dump_file, ";; Not unswitching anymore, hit max level\n");
return;
}
/* Only unswitch innermost loops. */
if (loop->inner)
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file, ";; Not unswitching, not innermost loop\n");
+ if (dump_file)
+ fprintf (dump_file, ";; Not unswitching, not innermost loop\n");
return;
}
-
+
/* We must be able to duplicate loop body. */
if (!can_duplicate_loop_p (loop))
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file, ";; Not unswitching, can't duplicate loop\n");
+ if (dump_file)
+ fprintf (dump_file, ";; Not unswitching, can't duplicate loop\n");
return;
}
/* The loop should not be too large, to limit code growth. */
if (num_loop_insns (loop) > PARAM_VALUE (PARAM_MAX_UNSWITCH_INSNS))
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file, ";; Not unswitching, loop too big\n");
+ if (dump_file)
+ fprintf (dump_file, ";; Not unswitching, loop too big\n");
return;
}
-
+
/* Do not unswitch in cold areas. */
- if (!maybe_hot_bb_p (loop->header))
+ if (optimize_loop_for_size_p (loop))
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file, ";; Not unswitching, not hot area\n");
+ if (dump_file)
+ fprintf (dump_file, ";; Not unswitching, not hot area\n");
return;
}
-
+
/* Nor if the loop usually does not roll. */
if (expected_loop_iterations (loop) < 1)
{
- if (rtl_dump_file)
- fprintf (rtl_dump_file, ";; Not unswitching, loop iterations < 1\n");
+ if (dump_file)
+ fprintf (dump_file, ";; Not unswitching, loop iterations < 1\n");
return;
}
do
{
repeat = 0;
-
+ cinsn = NULL_RTX;
+
/* Find a bb to unswitch on. */
bbs = get_loop_body (loop);
+ iv_analysis_loop_init (loop);
for (i = 0; i < loop->num_nodes; i++)
- if (may_unswitch_on_p (loops, bbs[i], loop, bbs))
+ if ((cond = may_unswitch_on (bbs[i], loop, &cinsn)))
break;
if (i == loop->num_nodes)
return;
}
- if (!(cond = get_condition (bbs[i]->end, &split_before)))
- abort ();
- rcond = reversed_condition (cond);
-
- /* Check whether the result can be predicted. */
- always_true = 0;
- always_false = 0;
- for (acond = cond_checked; acond; acond = XEXP (acond, 1))
+ if (cond != const0_rtx
+ && cond != const_true_rtx)
{
- if (rtx_equal_p (cond, XEXP (acond, 0)))
- {
- always_true = 1;
- break;
- }
- if (rtx_equal_p (rcond, XEXP (acond, 0)))
- {
- always_false = 1;
- break;
- }
+ rcond = reversed_condition (cond);
+ if (rcond)
+ rcond = canon_condition (rcond);
+
+ /* Check whether the result can be predicted. */
+ for (acond = cond_checked; acond; acond = XEXP (acond, 1))
+ simplify_using_condition (XEXP (acond, 0), &cond, NULL);
}
- if (always_true)
+ if (cond == const_true_rtx)
{
/* Remove false path. */
- for (e = bbs[i]->succ; !(e->flags & EDGE_FALLTHRU); e = e->succ_next);
- remove_path (loops, e);
+ e = FALLTHRU_EDGE (bbs[i]);
+ remove_path (e);
free (bbs);
repeat = 1;
}
- else if (always_false)
+ else if (cond == const0_rtx)
{
/* Remove true path. */
- for (e = bbs[i]->succ; e->flags & EDGE_FALLTHRU; e = e->succ_next);
- remove_path (loops, e);
+ e = BRANCH_EDGE (bbs[i]);
+ remove_path (e);
free (bbs);
repeat = 1;
}
} while (repeat);
-
+
/* We found the condition we can unswitch on. */
conds = alloc_EXPR_LIST (0, cond, cond_checked);
if (rcond)
else
rconds = cond_checked;
- /* Separate condition in a single basic block. */
- bb = split_loop_bb (loops, bbs[i], PREV_INSN (split_before))->dest;
- free (bbs);
- true_first = !(bb->succ->flags & EDGE_FALLTHRU);
- if (rtl_dump_file)
- fprintf (rtl_dump_file, ";; Unswitching loop\n");
+ if (dump_file)
+ fprintf (dump_file, ";; Unswitching loop\n");
/* Unswitch the loop on this condition. */
- nloop = unswitch_loop (loops, loop, bb);
- if (!nloop)
- abort ();
+ nloop = unswitch_loop (loop, bbs[i], cond, cinsn);
+ gcc_assert (nloop);
/* Invoke itself on modified loops. */
- unswitch_single_loop (loops, nloop, true_first ? conds : rconds, num + 1);
- unswitch_single_loop (loops, loop, true_first ? rconds : conds, num + 1);
+ unswitch_single_loop (nloop, rconds, num + 1);
+ unswitch_single_loop (loop, conds, num + 1);
free_EXPR_LIST_node (conds);
if (rcond)
free_EXPR_LIST_node (rconds);
+
+ free (bbs);
}
/* Unswitch a LOOP w.r. to given basic block UNSWITCH_ON. We only support
unswitching of innermost loops. UNSWITCH_ON must be executed in every
- iteration, i.e. it must dominate LOOP latch, and should only contain code
- for the condition we unswitch on. Returns NULL if impossible, new
- loop otherwise. */
+ iteration, i.e. it must dominate LOOP latch. COND is the condition
+ determining which loop is entered. Returns NULL if impossible, new loop
+ otherwise. The new loop is entered if COND is true. If CINSN is not
+ NULL, it is the insn in that COND is compared. */
+
static struct loop *
-unswitch_loop (loops, loop, unswitch_on)
- struct loops *loops;
- struct loop *loop;
- basic_block unswitch_on;
+unswitch_loop (struct loop *loop, basic_block unswitch_on, rtx cond, rtx cinsn)
{
- edge entry, latch_edge;
- basic_block switch_bb, unswitch_on_alt, src;
+ edge entry, latch_edge, true_edge, false_edge, e;
+ basic_block switch_bb, unswitch_on_alt;
struct loop *nloop;
- sbitmap zero_bitmap;
- int irred_flag;
+ int irred_flag, prob;
+ rtx seq;
/* Some sanity checking. */
- if (!flow_bb_inside_loop_p (loop, unswitch_on))
- abort ();
- if (!unswitch_on->succ || !unswitch_on->succ->succ_next ||
- unswitch_on->succ->succ_next->succ_next)
- abort ();
- if (!just_once_each_iteration_p (loops, loop, unswitch_on))
- abort ();
- if (loop->inner)
- abort ();
- if (!flow_bb_inside_loop_p (loop, unswitch_on->succ->dest))
- abort ();
- if (!flow_bb_inside_loop_p (loop, unswitch_on->succ->succ_next->dest))
- abort ();
-
- /* Will we be able to perform redirection? */
- if (!any_condjump_p (unswitch_on->end))
- return NULL;
- if (!cfg_layout_can_duplicate_bb_p (unswitch_on))
- return NULL;
+ gcc_assert (flow_bb_inside_loop_p (loop, unswitch_on));
+ gcc_assert (EDGE_COUNT (unswitch_on->succs) == 2);
+ gcc_assert (just_once_each_iteration_p (loop, unswitch_on));
+ gcc_assert (!loop->inner);
+ gcc_assert (flow_bb_inside_loop_p (loop, EDGE_SUCC (unswitch_on, 0)->dest));
+ gcc_assert (flow_bb_inside_loop_p (loop, EDGE_SUCC (unswitch_on, 1)->dest));
entry = loop_preheader_edge (loop);
-
+
/* Make a copy. */
- src = entry->src;
irred_flag = entry->flags & EDGE_IRREDUCIBLE_LOOP;
entry->flags &= ~EDGE_IRREDUCIBLE_LOOP;
- zero_bitmap = sbitmap_alloc (2);
- sbitmap_zero (zero_bitmap);
- if (!duplicate_loop_to_header_edge (loop, entry, loops, 1,
- zero_bitmap, NULL, NULL, NULL, 0))
+ if (!duplicate_loop_to_header_edge (loop, entry, 1,
+ NULL, NULL, NULL, 0))
return NULL;
- free (zero_bitmap);
entry->flags |= irred_flag;
/* Record the block with condition we unswitch on. */
- unswitch_on_alt = unswitch_on->rbi->copy;
+ unswitch_on_alt = get_bb_copy (unswitch_on);
+ true_edge = BRANCH_EDGE (unswitch_on_alt);
+ false_edge = FALLTHRU_EDGE (unswitch_on);
+ latch_edge = single_succ_edge (get_bb_copy (loop->latch));
+
+ /* Create a block with the condition. */
+ prob = true_edge->probability;
+ switch_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
+ seq = compare_and_jump_seq (XEXP (cond, 0), XEXP (cond, 1), GET_CODE (cond),
+ block_label (true_edge->dest),
+ prob, cinsn);
+ emit_insn_after (seq, BB_END (switch_bb));
+ e = make_edge (switch_bb, true_edge->dest, 0);
+ e->probability = prob;
+ e->count = latch_edge->count * prob / REG_BR_PROB_BASE;
+ e = make_edge (switch_bb, FALLTHRU_EDGE (unswitch_on)->dest, EDGE_FALLTHRU);
+ e->probability = false_edge->probability;
+ e->count = latch_edge->count * (false_edge->probability) / REG_BR_PROB_BASE;
- /* Make a copy of the block containing the condition; we will use
- it as switch to decide which loop we want to use. */
- switch_bb = cfg_layout_duplicate_bb (unswitch_on, NULL);
if (irred_flag)
{
switch_bb->flags |= BB_IRREDUCIBLE_LOOP;
- switch_bb->succ->flags |= EDGE_IRREDUCIBLE_LOOP;
- switch_bb->succ->succ_next->flags |= EDGE_IRREDUCIBLE_LOOP;
+ EDGE_SUCC (switch_bb, 0)->flags |= EDGE_IRREDUCIBLE_LOOP;
+ EDGE_SUCC (switch_bb, 1)->flags |= EDGE_IRREDUCIBLE_LOOP;
}
else
{
switch_bb->flags &= ~BB_IRREDUCIBLE_LOOP;
- switch_bb->succ->flags &= ~EDGE_IRREDUCIBLE_LOOP;
- switch_bb->succ->succ_next->flags &= ~EDGE_IRREDUCIBLE_LOOP;
+ EDGE_SUCC (switch_bb, 0)->flags &= ~EDGE_IRREDUCIBLE_LOOP;
+ EDGE_SUCC (switch_bb, 1)->flags &= ~EDGE_IRREDUCIBLE_LOOP;
}
- add_to_dominance_info (loops->cfg.dom, switch_bb);
- unswitch_on->rbi->copy = unswitch_on_alt;
/* Loopify from the copy of LOOP body, constructing the new loop. */
- for (latch_edge = loop->latch->rbi->copy->succ;
- latch_edge->dest != loop->header;
- latch_edge = latch_edge->succ_next);
- nloop = loopify (loops, latch_edge,
- loop->header->rbi->copy->pred, switch_bb);
-
- /* Remove branches that are now unreachable in new loops. We rely on the
- fact that cfg_layout_duplicate_bb reverses list of edges. */
- remove_path (loops, unswitch_on->succ);
- remove_path (loops, unswitch_on_alt->succ);
-
- /* One of created loops do not have to be subloop of the outer loop now,
- so fix its placement in loop data structure. */
- fix_loop_placement (loop);
- fix_loop_placement (nloop);
+ nloop = loopify (latch_edge,
+ single_pred_edge (get_bb_copy (loop->header)), switch_bb,
+ BRANCH_EDGE (switch_bb), FALLTHRU_EDGE (switch_bb), true,
+ prob, REG_BR_PROB_BASE - prob);
+
+ /* Remove branches that are now unreachable in new loops. */
+ remove_path (true_edge);
+ remove_path (false_edge);
+
+ /* Preserve the simple loop preheaders. */
+ split_edge (loop_preheader_edge (loop));
+ split_edge (loop_preheader_edge (nloop));
return nloop;
}
OSDN Git Service
