/* Perform doloop optimizations
- Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation,
+ Inc.
Based on code by Michael P. Hayes (m.hayes@elec.canterbury.ac.nz)
This file is part of GCC.
if it is not a decrement and branch jump insn. */
rtx
-doloop_condition_get (rtx pattern)
+doloop_condition_get (rtx doloop_pat)
{
rtx cmp;
rtx inc;
rtx reg;
rtx inc_src;
rtx condition;
+ rtx pattern;
- /* The canonical doloop pattern we expect is:
+ /* The canonical doloop pattern we expect has one of the following
+ forms:
- (parallel [(set (pc) (if_then_else (condition)
- (label_ref (label))
- (pc)))
- (set (reg) (plus (reg) (const_int -1)))
- (additional clobbers and uses)])
+ 1) (parallel [(set (pc) (if_then_else (condition)
+ (label_ref (label))
+ (pc)))
+ (set (reg) (plus (reg) (const_int -1)))
+ (additional clobbers and uses)])
- Some targets (IA-64) wrap the set of the loop counter in
- an if_then_else too.
+ The branch must be the first entry of the parallel (also required
+ by jump.c), and the second entry of the parallel must be a set of
+ the loop counter register. Some targets (IA-64) wrap the set of
+ the loop counter in an if_then_else too.
- In summary, the branch must be the first entry of the
- parallel (also required by jump.c), and the second
- entry of the parallel must be a set of the loop counter
- register. */
+ 2) (set (reg) (plus (reg) (const_int -1))
+ (set (pc) (if_then_else (reg != 0)
+ (label_ref (label))
+ (pc))). */
+
+ pattern = PATTERN (doloop_pat);
if (GET_CODE (pattern) != PARALLEL)
- return 0;
+ {
+ rtx cond;
+
+ /* We expect the decrement to immediately precede the branch. */
+
+ if ((PREV_INSN (doloop_pat) == NULL_RTX)
+ || !INSN_P (PREV_INSN (doloop_pat)))
+ return 0;
- cmp = XVECEXP (pattern, 0, 0);
- inc = XVECEXP (pattern, 0, 1);
+ cmp = pattern;
+ inc = PATTERN (PREV_INSN (doloop_pat));
+ /* We expect the condition to be of the form (reg != 0) */
+ cond = XEXP (SET_SRC (cmp), 0);
+ if (GET_CODE (cond) != NE || XEXP (cond, 1) != const0_rtx)
+ return 0;
+
+ }
+ else
+ {
+ cmp = XVECEXP (pattern, 0, 0);
+ inc = XVECEXP (pattern, 0, 1);
+ }
/* Check for (set (reg) (something)). */
if (GET_CODE (inc) != SET)
if ((XEXP (condition, 0) == reg)
|| (GET_CODE (XEXP (condition, 0)) == PLUS
&& XEXP (XEXP (condition, 0), 0) == reg))
+ {
+ if (GET_CODE (pattern) != PARALLEL)
+ /* The second form we expect:
+
+ (set (reg) (plus (reg) (const_int -1))
+ (set (pc) (if_then_else (reg != 0)
+ (label_ref (label))
+ (pc))).
+
+ is equivalent to the following:
+
+ (parallel [(set (pc) (if_then_else (reg != 1)
+ (label_ref (label))
+ (pc)))
+ (set (reg) (plus (reg) (const_int -1)))
+ (additional clobbers and uses)])
+
+ So we return that form instead.
+ */
+ condition = gen_rtx_fmt_ee (NE, VOIDmode, inc_src, const1_rtx);
+
return condition;
+ }
/* ??? If a machine uses a funny comparison, we could return a
canonicalized form here. */
JUMP_LABEL (jump) = label;
/* The jump is supposed to handle an unlikely special case. */
- REG_NOTES (jump)
- = gen_rtx_EXPR_LIST (REG_BR_PROB,
- const0_rtx, REG_NOTES (jump));
+ add_reg_note (jump, REG_BR_PROB, const0_rtx);
+
LABEL_NUSES (label)++;
make_edge (bb, dest, (*e)->flags & ~EDGE_FALLTHRU);
describes the loop, DESC describes the number of iterations of the
loop, and DOLOOP_INSN is the low-overhead looping insn to emit at the
end of the loop. CONDITION is the condition separated from the
- DOLOOP_SEQ. COUNT is the number of iterations of the LOOP. */
+ DOLOOP_SEQ. COUNT is the number of iterations of the LOOP.
+ ZERO_EXTEND_P says to zero extend COUNT after the increment of it to
+ word_mode from FROM_MODE. */
static void
doloop_modify (struct loop *loop, struct niter_desc *desc,
- rtx doloop_seq, rtx condition, rtx count)
+ rtx doloop_seq, rtx condition, rtx count,
+ bool zero_extend_p, enum machine_mode from_mode)
{
rtx counter_reg;
rtx tmp, noloop = NULL_RTX;
bool increment_count;
basic_block loop_end = desc->out_edge->src;
enum machine_mode mode;
+ rtx true_prob_val;
jump_insn = BB_END (loop_end);
fputs (" iterations).\n", dump_file);
}
+ /* Get the probability of the original branch. If it exists we would
+ need to update REG_BR_PROB of the new jump_insn. */
+ true_prob_val = find_reg_note (jump_insn, REG_BR_PROB, NULL_RTX);
+
/* Discard original jump to continue loop. The original compare
result may still be live, so it cannot be discarded explicitly. */
delete_insn (jump_insn);
}
if (increment_count)
- count = simplify_gen_binary (PLUS, mode, count, const1_rtx);
+ count = simplify_gen_binary (PLUS, from_mode, count, const1_rtx);
+
+ if (zero_extend_p)
+ count = simplify_gen_unary (ZERO_EXTEND, word_mode,
+ count, from_mode);
/* Insert initialization of the count register into the loop header. */
start_sequence ();
/* Add a REG_NONNEG note if the actual or estimated maximum number
of iterations is non-negative. */
if (nonneg)
+ add_reg_note (jump_insn, REG_NONNEG, NULL_RTX);
+
+ /* Update the REG_BR_PROB note. */
+ if (true_prob_val)
{
- REG_NOTES (jump_insn)
- = gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX, REG_NOTES (jump_insn));
+ /* Seems safer to use the branch probability. */
+ add_reg_note (jump_insn, REG_BR_PROB,
+ GEN_INT (desc->in_edge->probability));
}
}
struct niter_desc *desc;
unsigned word_mode_size;
unsigned HOST_WIDE_INT word_mode_max;
+ bool zero_extend_p = false;
if (dump_file)
fprintf (dump_file, "Doloop: Processing loop %d.\n", loop->num);
max_cost
= COSTS_N_INSNS (PARAM_VALUE (PARAM_MAX_ITERATIONS_COMPUTATION_COST));
- if (rtx_cost (desc->niter_expr, SET) > max_cost)
+ if (rtx_cost (desc->niter_expr, SET, optimize_loop_for_speed_p (loop))
+ > max_cost)
{
if (dump_file)
fprintf (dump_file,
{
if (word_mode_size > GET_MODE_BITSIZE (mode))
{
- count = simplify_gen_unary (ZERO_EXTEND, word_mode,
- count, mode);
+ zero_extend_p = true;
iterations = simplify_gen_unary (ZERO_EXTEND, word_mode,
iterations, mode);
iterations_max = simplify_gen_unary (ZERO_EXTEND, word_mode,
{
while (NEXT_INSN (doloop_pat) != NULL_RTX)
doloop_pat = NEXT_INSN (doloop_pat);
- if (JUMP_P (doloop_pat))
- doloop_pat = PATTERN (doloop_pat);
- else
+ if (!JUMP_P (doloop_pat))
doloop_pat = NULL_RTX;
}
return false;
}
- doloop_modify (loop, desc, doloop_seq, condition, count);
+ doloop_modify (loop, desc, doloop_seq, condition, count,
+ zero_extend_p, mode);
return true;
}