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doloop.c: Removed.

Browse source 
* doloop.c: Removed.
	* loop-doloop.c: New file.
	* Makefile.in (doloop.o): Remove.
	(loop-doloop.o): New.
	* cfgloop.h (get_loop_level, doloop_optimize_loops): Declare.
	* cfgloopanal.c (get_loop_level): New function.
	* loop-iv.c (iv_number_of_iterations): Handle case when loop
	is leaved immediatelly.
	* loop.c (strength_reduce): Do not call doloop optimization.
	* loop.h (LOOP_BCT): Removed.
	* passes.c (rest_of_handle_loop_optimize): Do not use LOOP_BCT.
	(rest_of_handle_loop2): Call doloop_optimize_loops.
	(rest_of_compilation): Test for optimizations moved to
	rest_of_handle_loop2.

From-SVN: r79625
This commit is contained in:
Zdenek Dvorak 2004-03-18 17:42:34 +01:00 • committed by Zdenek Dvorak
parent 327e534343
commit 689ba89dd8
10 changed files with 612 additions and 912 deletions
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17
gcc/ChangeLog
View file

@ -1,3 +1,20 @@
2004-03-18 Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz>
* doloop.c: Removed.
* loop-doloop.c: New file.
* Makefile.in (doloop.o): Remove.
(loop-doloop.o): New.
* cfgloop.h (get_loop_level, doloop_optimize_loops): Declare.
* cfgloopanal.c (get_loop_level): New function.
* loop-iv.c (iv_number_of_iterations): Handle case when loop
is leaved immediatelly.
* loop.c (strength_reduce): Do not call doloop optimization.
* loop.h (LOOP_BCT): Removed.
* passes.c (rest_of_handle_loop_optimize): Do not use LOOP_BCT.
(rest_of_handle_loop2): Call doloop_optimize_loops.
(rest_of_compilation): Test for optimizations moved to
rest_of_handle_loop2.
2004-03-17 Fariborz Jahanian <fjahanian@apple.com>
* config/rs6000/rs6000.c (rs6000_stack_info): correct reg_size

8
gcc/Makefile.in
View file

@ -849,7 +849,7 @@ OBJS-common = \
cfg.o cfganal.o cfgbuild.o cfgcleanup.o cfglayout.o cfgloop.o \
cfgloopanal.o cfgloopmanip.o loop-init.o loop-unswitch.o loop-unroll.o \
cfgrtl.o combine.o conflict.o convert.o coverage.o cse.o cselib.o \
dbxout.o debug.o df.o diagnostic.o dojump.o doloop.o dominance.o \
dbxout.o debug.o df.o diagnostic.o dojump.o dominance.o loop-doloop.o \
dwarf2asm.o dwarf2out.o emit-rtl.o except.o explow.o loop-iv.o \
expmed.o expr.o final.o flow.o fold-const.o function.o gcse.o \
genrtl.o ggc-common.o global.o graph.o gtype-desc.o \
@ -1702,9 +1702,9 @@ loop.o : loop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) flags.h $(L
insn-config.h $(REGS_H) hard-reg-set.h $(RECOG_H) $(EXPR_H) \
real.h $(PREDICT_H) $(BASIC_BLOCK_H) function.h cfgloop.h \
toplev.h varray.h except.h cselib.h $(OPTABS_H) $(TM_P_H) $(GGC_H)
doloop.o : doloop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) flags.h \
$(LOOP_H) $(EXPR_H) hard-reg-set.h $(BASIC_BLOCK_H) $(TM_P_H) toplev.h \
cfgloop.h
loop-doloop.o : loop-doloop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
$(RTL_H) flags.h $(EXPR_H) hard-reg-set.h $(BASIC_BLOCK_H) $(TM_P_H) \
toplev.h cfgloop.h output.h $(PARAMS_H)
unroll.o : unroll.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) insn-config.h \
function.h $(INTEGRATE_H) $(REGS_H) $(RECOG_H) flags.h $(EXPR_H) $(LOOP_H) toplev.h \
hard-reg-set.h varray.h $(BASIC_BLOCK_H) $(TM_P_H) $(PREDICT_H) $(PARAMS_H) \

2
gcc/cfgloop.h
View file

@ -247,6 +247,7 @@ extern bool flow_bb_inside_loop_p (const struct loop *, const basic_block);
extern struct loop * find_common_loop (struct loop *, struct loop *);
extern int num_loop_insns (struct loop *);
extern int average_num_loop_insns (struct loop *);
extern unsigned get_loop_level (const struct loop *);
/* Loops & cfg manipulation. */
extern basic_block *get_loop_body (const struct loop *);
@ -417,3 +418,4 @@ enum
};
extern void unroll_and_peel_loops (struct loops *, int);
extern void doloop_optimize_loops (struct loops *);

17
gcc/cfgloopanal.c
View file

@ -457,3 +457,20 @@ expected_loop_iterations (const struct loop *loop)
return (freq_latch + freq_in - 1) / freq_in;
}
}
/* Returns the maximum level of nesting of subloops of LOOP. */
unsigned
get_loop_level (const struct loop *loop)
{
const struct loop *ploop;
unsigned mx = 0, l;
for (ploop = loop->inner; ploop; ploop = ploop->next)
{
l = get_loop_level (ploop);
if (l >= mx)
mx = l + 1;
}
return mx;
}

883
gcc/doloop.c
View file

@ -1,883 +0,0 @@
/* Perform doloop optimizations
Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004
Free Software Foundation, Inc.
Contributed by Michael P. Hayes (m.hayes@elec.canterbury.ac.nz)
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
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "flags.h"
#include "expr.h"
#include "loop.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "toplev.h"
#include "tm_p.h"
#include "cfgloop.h"
/* This module is used to modify loops with a determinable number of
iterations to use special low-overhead looping instructions.
It first validates whether the loop is well behaved and has a
determinable number of iterations (either at compile or run-time).
It then modifies the loop to use a low-overhead looping pattern as
follows:
1. A pseudo register is allocated as the loop iteration counter.
2. The number of loop iterations is calculated and is stored
in the loop counter.
3. At the end of the loop, the jump insn is replaced by the
doloop_end pattern. The compare must remain because it might be
used elsewhere. If the loop-variable or condition register are
used elsewhere, they will be eliminated by flow.
4. An optional doloop_begin pattern is inserted at the top of the
loop.
*/
#ifdef HAVE_doloop_end
static rtx doloop_condition_get (rtx);
static unsigned HOST_WIDE_INT doloop_iterations_max (const struct loop_info *,
enum machine_mode, int);
static int doloop_valid_p (const struct loop *, rtx);
static int doloop_modify (const struct loop *, rtx, rtx, rtx, rtx, rtx);
static int doloop_modify_runtime (const struct loop *, rtx, rtx, rtx,
enum machine_mode, rtx);
/* Return the loop termination condition for PATTERN or zero
if it is not a decrement and branch jump insn. */
static rtx
doloop_condition_get (rtx pattern)
{
rtx cmp;
rtx inc;
rtx reg;
rtx condition;
/* The canonical doloop pattern we expect is:
(parallel [(set (pc) (if_then_else (condition)
(label_ref (label))
(pc)))
(set (reg) (plus (reg) (const_int -1)))
(additional clobbers and uses)])
Some machines (IA-64) make the decrement conditional on
the condition as well, so we don't bother verifying the
actual decrement. 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. */
if (GET_CODE (pattern) != PARALLEL)
return 0;
cmp = XVECEXP (pattern, 0, 0);
inc = XVECEXP (pattern, 0, 1);
/* Check for (set (reg) (something)). */
if (GET_CODE (inc) != SET || ! REG_P (SET_DEST (inc)))
return 0;
/* Extract loop counter register. */
reg = SET_DEST (inc);
/* Check for (set (pc) (if_then_else (condition)
(label_ref (label))
(pc))). */
if (GET_CODE (cmp) != SET
|| SET_DEST (cmp) != pc_rtx
|| GET_CODE (SET_SRC (cmp)) != IF_THEN_ELSE
|| GET_CODE (XEXP (SET_SRC (cmp), 1)) != LABEL_REF
|| XEXP (SET_SRC (cmp), 2) != pc_rtx)
return 0;
/* Extract loop termination condition. */
condition = XEXP (SET_SRC (cmp), 0);
if ((GET_CODE (condition) != GE && GET_CODE (condition) != NE)
|| GET_CODE (XEXP (condition, 1)) != CONST_INT)
return 0;
if (XEXP (condition, 0) == reg)
return condition;
if (GET_CODE (XEXP (condition, 0)) == PLUS
&& XEXP (XEXP (condition, 0), 0) == reg)
return condition;
/* ??? If a machine uses a funny comparison, we could return a
canonicalised form here. */
return 0;
}
/* Return an estimate of the maximum number of loop iterations for the
loop specified by LOOP or zero if the loop is not normal.
MODE is the mode of the iteration count and NONNEG is nonzero if
the iteration count has been proved to be non-negative. */
static unsigned HOST_WIDE_INT
doloop_iterations_max (const struct loop_info *loop_info,
enum machine_mode mode, int nonneg)
{
unsigned HOST_WIDE_INT n_iterations_max;
enum rtx_code code;
rtx min_value;
rtx max_value;
HOST_WIDE_INT abs_inc;
int neg_inc;
neg_inc = 0;
abs_inc = INTVAL (loop_info->increment);
if (abs_inc < 0)
{
abs_inc = -abs_inc;
neg_inc = 1;
}
if (neg_inc)
{
code = swap_condition (loop_info->comparison_code);
min_value = loop_info->final_equiv_value;
max_value = loop_info->initial_equiv_value;
}
else
{
code = loop_info->comparison_code;
min_value = loop_info->initial_equiv_value;
max_value = loop_info->final_equiv_value;
}
/* Since the loop has a VTOP, we know that the initial test will be
true and thus the value of max_value should be greater than the
value of min_value. Thus the difference should always be positive
and the code must be LT, LE, LTU, LEU, or NE. Otherwise the loop is
not normal, e.g., `for (i = 0; i < 10; i--)'. */
switch (code)
{
case LTU:
case LEU:
{
unsigned HOST_WIDE_INT umax;
unsigned HOST_WIDE_INT umin;
if (GET_CODE (min_value) == CONST_INT)
umin = INTVAL (min_value);
else
umin = 0;
if (GET_CODE (max_value) == CONST_INT)
umax = INTVAL (max_value);
else
umax = ((unsigned) 2 << (GET_MODE_BITSIZE (mode) - 1)) - 1;
n_iterations_max = umax - umin;
break;
}
case LT:
case LE:
{
HOST_WIDE_INT smax;
HOST_WIDE_INT smin;
if (GET_CODE (min_value) == CONST_INT)
smin = INTVAL (min_value);
else
smin = -((unsigned) 1 << (GET_MODE_BITSIZE (mode) - 1));
if (GET_CODE (max_value) == CONST_INT)
smax = INTVAL (max_value);
else
smax = ((unsigned) 1 << (GET_MODE_BITSIZE (mode) - 1)) - 1;
n_iterations_max = smax - smin;
break;
}
case NE:
if (GET_CODE (min_value) == CONST_INT
&& GET_CODE (max_value) == CONST_INT)
n_iterations_max = INTVAL (max_value) - INTVAL (min_value);
else
/* We need to conservatively assume that we might have the maximum
number of iterations without any additional knowledge. */
n_iterations_max = ((unsigned) 2 << (GET_MODE_BITSIZE (mode) - 1)) - 1;
break;
default:
return 0;
}
n_iterations_max /= abs_inc;
/* If we know that the iteration count is non-negative then adjust
n_iterations_max if it is so large that it appears negative. */
if (nonneg
&& n_iterations_max > ((unsigned) 1 << (GET_MODE_BITSIZE (mode) - 1)))
n_iterations_max = ((unsigned) 1 << (GET_MODE_BITSIZE (mode) - 1)) - 1;
return n_iterations_max;
}
/* Return nonzero if the loop specified by LOOP is suitable for
the use of special low-overhead looping instructions. */
static int
doloop_valid_p (const struct loop *loop, rtx jump_insn)
{
const struct loop_info *loop_info = LOOP_INFO (loop);
/* The loop must have a conditional jump at the end. */
if (! any_condjump_p (jump_insn)
|| ! onlyjump_p (jump_insn))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Invalid jump at loop end.\n");
return 0;
}
/* Give up if a loop has been completely unrolled. */
if (loop_info->n_iterations == loop_info->unroll_number)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Loop completely unrolled.\n");
return 0;
}
/* The loop must have a single exit target. A break or return
statement within a loop will generate multiple loop exits.
Another example of a loop that currently generates multiple exit
targets is for (i = 0; i < (foo ? 8 : 4); i++) { }. */
if (loop_info->has_multiple_exit_targets || loop->exit_count)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Loop has multiple exit targets.\n");
return 0;
}
/* An indirect jump may jump out of the loop. */
if (loop_info->has_indirect_jump)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Indirect jump in function.\n");
return 0;
}
/* A called function may clobber any special registers required for
low-overhead looping. */
if (loop_info->has_call)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Function call in loop.\n");
return 0;
}
/* Some targets (eg, PPC) use the count register for branch on table
instructions. ??? This should be a target specific check. */
if (loop_info->has_tablejump)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Computed branch in the loop.\n");
return 0;
}
if (! loop_info->increment)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Could not determine iteration info.\n");
return 0;
}
if (GET_CODE (loop_info->increment) != CONST_INT)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Increment not an integer constant.\n");
return 0;
}
/* There is no guarantee that a NE loop will terminate if the
absolute increment is not unity. ??? We could compute this
condition at run-time and have an additional jump around the loop
to ensure an infinite loop. */
if (loop_info->comparison_code == NE
&& !loop_info->preconditioned
&& INTVAL (loop_info->increment) != -1
&& INTVAL (loop_info->increment) != 1)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: NE loop with non-unity increment.\n");
return 0;
}
/* Check for loops that may not terminate under special conditions. */
if (! loop_info->n_iterations
&& ((loop_info->comparison_code == LEU
&& INTVAL (loop_info->increment) > 0)
|| (loop_info->comparison_code == GEU
&& INTVAL (loop_info->increment) < 0)
|| (loop_info->comparison_code == LTU
&& INTVAL (loop_info->increment) > 1)
|| (loop_info->comparison_code == GTU
&& INTVAL (loop_info->increment) < -1)))
{
/* If the comparison is LEU and the comparison value is UINT_MAX
then the loop will not terminate. Similarly, if the
comparison code is GEU and the comparison value is 0, the
loop will not terminate.
If the absolute increment is not 1, the loop can be infinite
even with LTU/GTU, e.g. for (i = 3; i > 0; i -= 2)
Note that with LE and GE, the loop behavior is undefined
(C++ standard section 5 clause 5) if an overflow occurs, say
between INT_MAX and INT_MAX + 1. We thus don't have to worry
about these two cases.
??? We could compute these conditions at run-time and have a
additional jump around the loop to ensure an infinite loop.
However, it is very unlikely that this is the intended
behavior of the loop and checking for these rare boundary
conditions would pessimize all other code.
If the loop is executed only a few times an extra check to
restart the loop could use up most of the benefits of using a
count register loop. Note however, that normally, this
restart branch would never execute, so it could be predicted
well by the CPU. We should generate the pessimistic code by
default, and have an option, e.g. -funsafe-loops that would
enable count-register loops in this case. */
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Possible infinite iteration case ignored.\n");
}
return 1;
}
/* Modify the loop to use the low-overhead looping insn where LOOP
describes the loop, ITERATIONS is an RTX containing the desired
number of loop iterations, ITERATIONS_MAX is a CONST_INT specifying
the maximum number of loop iterations, and DOLOOP_INSN is the
low-overhead looping insn to emit at the end of the loop. This
returns nonzero if it was successful. */
static int
doloop_modify (const struct loop *loop, rtx iterations, rtx iterations_max,
rtx doloop_seq, rtx start_label, rtx condition)
{
rtx counter_reg;
rtx count;
rtx sequence;
rtx jump_insn;
int nonneg = 0;
int decrement_count;
jump_insn = prev_nonnote_insn (loop->end);
if (loop_dump_stream)
{
fprintf (loop_dump_stream, "Doloop: Inserting doloop pattern (");
if (GET_CODE (iterations) == CONST_INT)
fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
INTVAL (iterations));
else
fputs ("runtime", loop_dump_stream);
fputs (" iterations).", loop_dump_stream);
}
/* Emit the label that will delimit the top of the loop.
This has to be done before the delete_insn call below, to prevent
delete_insn from deleting too much. */
emit_label_after (start_label, loop->top ? loop->top : loop->start);
LABEL_NUSES (start_label)++;
/* Discard original jump to continue loop. The original compare
result may still be live, so it cannot be discarded explicitly. */
delete_related_insns (jump_insn);
counter_reg = XEXP (condition, 0);
if (GET_CODE (counter_reg) == PLUS)
counter_reg = XEXP (counter_reg, 0);
start_sequence ();
count = iterations;
decrement_count = 0;
switch (GET_CODE (condition))
{
case NE:
/* Currently only NE tests against zero and one are supported. */
if (XEXP (condition, 1) == const0_rtx)
decrement_count = 1;
else if (XEXP (condition, 1) != const1_rtx)
abort ();
break;
case GE:
/* Currently only GE tests against zero are supported. */
if (XEXP (condition, 1) != const0_rtx)
abort ();
/* The iteration count needs decrementing for a GE test. */
decrement_count = 1;
/* Determine if the iteration counter will be non-negative.
Note that the maximum value loaded is iterations_max - 1. */
if ((unsigned HOST_WIDE_INT) INTVAL (iterations_max)
<= ((unsigned) 1 << (GET_MODE_BITSIZE (GET_MODE (counter_reg)) - 1)))
nonneg = 1;
break;
/* Abort if an invalid doloop pattern has been generated. */
default:
abort ();
}
if (decrement_count)
{
if (GET_CODE (count) == CONST_INT)
count = GEN_INT (INTVAL (count) - 1);
else
count = expand_simple_binop (GET_MODE (counter_reg), MINUS,
count, const1_rtx,
0, 0, OPTAB_LIB_WIDEN);
}
/* Insert initialization of the count register into the loop header. */
convert_move (counter_reg, count, 1);
sequence = get_insns ();
end_sequence ();
emit_insn_before (sequence, loop->start);
/* Some targets (eg, C4x) need to initialize special looping
registers. */
#ifdef HAVE_doloop_begin
{
rtx init;
init = gen_doloop_begin (counter_reg,
GET_CODE (iterations) == CONST_INT
? iterations : const0_rtx, iterations_max,
GEN_INT (loop->level));
if (init)
{
start_sequence ();
emit_insn (init);
sequence = get_insns ();
end_sequence ();
emit_insn_after (sequence, loop->start);
}
}
#endif
/* Insert the new low-overhead looping insn. */
emit_jump_insn_before (doloop_seq, loop->end);
jump_insn = prev_nonnote_insn (loop->end);
JUMP_LABEL (jump_insn) = start_label;
/* Add a REG_NONNEG note if the actual or estimated maximum number
of iterations is non-negative. */
if (nonneg)
{
REG_NOTES (jump_insn)
= gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX, REG_NOTES (jump_insn));
}
return 1;
}
/* Handle the more complex case, where the bounds are not known at
compile time. In this case we generate a run_time calculation of
the number of iterations. We rely on the existence of a run-time
guard to ensure that the loop executes at least once, i.e.,
initial_value obeys the loop comparison condition. If a guard is
not present, we emit one. The loop to modify is described by LOOP.
ITERATIONS_MAX is a CONST_INT specifying the estimated maximum
number of loop iterations. DOLOOP_INSN is the low-overhead looping
insn to insert. Returns nonzero if loop successfully modified. */
static int
doloop_modify_runtime (const struct loop *loop, rtx iterations_max,
rtx doloop_seq, rtx start_label,
enum machine_mode mode, rtx condition)
{
const struct loop_info *loop_info = LOOP_INFO (loop);
HOST_WIDE_INT abs_inc;
HOST_WIDE_INT abs_loop_inc;
int neg_inc;
rtx diff;
rtx sequence;
rtx iterations;
rtx initial_value;
rtx final_value;
rtx increment;
int unsigned_p;
enum rtx_code comparison_code;
increment = loop_info->increment;
initial_value = loop_info->initial_value;
final_value = loop_info->final_value;
neg_inc = 0;
abs_inc = INTVAL (increment);
if (abs_inc < 0)
{
abs_inc = -abs_inc;
neg_inc = 1;
}
comparison_code = loop_info->comparison_code;
unsigned_p = (comparison_code == LTU
|| comparison_code == LEU
|| comparison_code == GTU
|| comparison_code == GEU
|| comparison_code == NE);
/* The number of iterations (prior to any loop unrolling) is given by:
n = (abs (final - initial) + abs_inc - 1) / abs_inc.
However, it is possible for the summation to overflow, and a
safer method is:
n = abs (final - initial) / abs_inc;
n += (abs (final - initial) % abs_inc) != 0;
But when abs_inc is a power of two, the summation won't overflow
except in cases where the loop never terminates. So we don't
need to use this more costly calculation.
If the loop has been unrolled, the full calculation is
t1 = abs_inc * unroll_number; increment per loop
n = (abs (final - initial) + abs_inc - 1) / t1; full loops
n += (abs (final - initial) + abs_inc - 1) % t1) >= abs_inc;
partial loop
which works out to be equivalent to
n = (abs (final - initial) + t1 - 1) / t1;
In the case where the loop was preconditioned, a few iterations
may have been executed earlier; but 'initial' was adjusted as they
were executed, so we don't need anything special for that case here.
As above, when t1 is a power of two we don't need to worry about
overflow.
The division and modulo operations can be avoided by requiring
that the increment is a power of 2 (precondition_loop_p enforces
this requirement). Nevertheless, the RTX_COSTS should be checked
to see if a fast divmod is available. */
start_sequence ();
/* abs (final - initial) */
diff = expand_simple_binop (mode, MINUS,
copy_rtx (neg_inc ? initial_value : final_value),
copy_rtx (neg_inc ? final_value : initial_value),
NULL_RTX, unsigned_p, OPTAB_LIB_WIDEN);
/* Some code transformations can result in code akin to
tmp = i + 1;
...
goto scan_start;
top:
tmp = tmp + 1;
scan_start:
i = tmp;
if (i < n) goto top;
We'll have already detected this form of loop in scan_loop,
and set loop->top and loop->scan_start appropriately.
In this situation, we skip the increment the first time through
the loop, which results in an incorrect estimate of the number
of iterations. Adjust the difference to compensate. */
/* ??? Logically, it would seem this belongs in loop_iterations.
However, this causes regressions e.g. on x86 execute/20011008-3.c,
so I do not believe we've properly characterized the exact nature
of the problem. In the meantime, this fixes execute/20011126-2.c
on ia64 and some Ada front end miscompilation on ppc. */
if (loop->scan_start)
{
rtx iteration_var = loop_info->iteration_var;
struct loop_ivs *ivs = LOOP_IVS (loop);
struct iv_class *bl;
if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == BASIC_INDUCT)
bl = REG_IV_CLASS (ivs, REGNO (iteration_var));
else if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == GENERAL_INDUCT)
{
struct induction *v = REG_IV_INFO (ivs, REGNO (iteration_var));
bl = REG_IV_CLASS (ivs, REGNO (v->src_reg));
}
else
/* Iteration var must be an induction variable to get here. */
abort ();
if (INSN_UID (bl->biv->insn) < max_uid_for_loop
&& INSN_LUID (bl->biv->insn) < INSN_LUID (loop->scan_start))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Basic induction var skips initial incr.\n");
diff = expand_simple_binop (mode, PLUS, diff, GEN_INT (abs_inc),
diff, unsigned_p, OPTAB_LIB_WIDEN);
}
}
abs_loop_inc = abs_inc * loop_info->unroll_number;
if (abs_loop_inc != 1)
{
int shift_count;
shift_count = exact_log2 (abs_loop_inc);
if (shift_count < 0)
abort ();
/* (abs (final - initial) + abs_inc * unroll_number - 1) */
diff = expand_simple_binop (GET_MODE (diff), PLUS,
diff, GEN_INT (abs_loop_inc - 1),
diff, 1, OPTAB_LIB_WIDEN);
/* (abs (final - initial) + abs_inc * unroll_number - 1)
/ (abs_inc * unroll_number) */
diff = expand_simple_binop (GET_MODE (diff), LSHIFTRT,
diff, GEN_INT (shift_count),
diff, 1, OPTAB_LIB_WIDEN);
}
iterations = diff;
/* If there is a NOTE_INSN_LOOP_VTOP, we have a `for' or `while'
style loop, with a loop exit test at the start. Thus, we can
assume that the loop condition was true when the loop was
entered.
`do-while' loops require special treatment since the exit test is
not executed before the start of the loop. We need to determine
if the loop will terminate after the first pass and to limit the
iteration count to one if necessary. */
if (! loop->vtop)
{
if (loop_dump_stream)
fprintf (loop_dump_stream, "Doloop: Do-while loop.\n");
/* A `do-while' loop must iterate at least once. For code like
i = initial; do { ... } while (++i < final);
we will calculate a bogus iteration count if initial > final.
So detect this and set the iteration count to 1.
Note that if the loop has been unrolled, then the loop body
is guaranteed to execute at least once. Also, when the
comparison is NE, our calculated count will be OK. */
if (loop_info->unroll_number == 1 && comparison_code != NE)
{
rtx label;
/* Emit insns to test if the loop will immediately
terminate and to set the iteration count to 1 if true. */
label = gen_label_rtx();
emit_cmp_and_jump_insns (copy_rtx (initial_value),
copy_rtx (loop_info->comparison_value),
comparison_code, NULL_RTX, mode, 0,
label);
JUMP_LABEL (get_last_insn ()) = label;
LABEL_NUSES (label)++;
emit_move_insn (iterations, const1_rtx);
emit_label (label);
}
}
sequence = get_insns ();
end_sequence ();
emit_insn_before (sequence, loop->start);
return doloop_modify (loop, iterations, iterations_max, doloop_seq,
start_label, condition);
}
/* This is the main entry point. Process loop described by LOOP
validating that the loop is suitable for conversion to use a low
overhead looping instruction, replacing the jump insn where
suitable. We distinguish between loops with compile-time bounds
and those with run-time bounds. Information from LOOP is used to
compute the number of iterations and to determine whether the loop
is a candidate for this optimization. Returns nonzero if loop
successfully modified. */
int
doloop_optimize (const struct loop *loop)
{
struct loop_info *loop_info = LOOP_INFO (loop);
rtx initial_value;
rtx final_value;
rtx increment;
rtx jump_insn;
enum machine_mode mode;
unsigned HOST_WIDE_INT n_iterations;
unsigned HOST_WIDE_INT n_iterations_max;
rtx doloop_seq, doloop_pat, doloop_reg;
rtx iterations;
rtx iterations_max;
rtx start_label;
rtx condition;
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Processing loop %d, enclosed levels %d.\n",
loop->num, loop->level);
jump_insn = prev_nonnote_insn (loop->end);
/* Check that loop is a candidate for a low-overhead looping insn. */
if (! doloop_valid_p (loop, jump_insn))
return 0;
/* Determine if the loop can be safely, and profitably,
preconditioned. While we don't precondition the loop in a loop
unrolling sense, this test ensures that the loop is well behaved
and that the increment is a constant integer. */
if (! precondition_loop_p (loop, &initial_value, &final_value,
&increment, &mode))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Cannot precondition loop.\n");
return 0;
}
/* Determine or estimate the maximum number of loop iterations. */
n_iterations = loop_info->n_iterations;
if (n_iterations)
{
/* This is the simple case where the initial and final loop
values are constants. */
n_iterations_max = n_iterations;
}
else
{
int nonneg = find_reg_note (jump_insn, REG_NONNEG, 0) != 0;
/* This is the harder case where the initial and final loop
values may not be constants. */
n_iterations_max = doloop_iterations_max (loop_info, mode, nonneg);
if (! n_iterations_max)
{
/* We have something like `for (i = 0; i < 10; i--)'. */
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Not normal loop.\n");
return 0;
}
}
/* Account for loop unrolling in the iteration count. This will
have no effect if loop_iterations could not determine the number
of iterations. */
n_iterations /= loop_info->unroll_number;
n_iterations_max /= loop_info->unroll_number;
if (n_iterations && n_iterations < 3)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Too few iterations (%ld) to be profitable.\n",
(long int) n_iterations);
return 0;
}
iterations = GEN_INT (n_iterations);
iterations_max = GEN_INT (n_iterations_max);
/* Generate looping insn. If the pattern FAILs then give up trying
to modify the loop since there is some aspect the back-end does
not like. */
start_label = gen_label_rtx ();
doloop_reg = gen_reg_rtx (mode);
doloop_seq = gen_doloop_end (doloop_reg, iterations, iterations_max,
GEN_INT (loop->level), start_label);
if (! doloop_seq && mode != word_mode)
{
PUT_MODE (doloop_reg, word_mode);
doloop_seq = gen_doloop_end (doloop_reg, iterations, iterations_max,
GEN_INT (loop->level), start_label);
}
if (! doloop_seq)
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Target unwilling to use doloop pattern!\n");
return 0;
}
/* If multiple instructions were created, the last must be the
jump instruction. Also, a raw define_insn may yield a plain
pattern. */
doloop_pat = doloop_seq;
if (INSN_P (doloop_pat))
{
while (NEXT_INSN (doloop_pat) != NULL_RTX)
doloop_pat = NEXT_INSN (doloop_pat);
if (GET_CODE (doloop_pat) == JUMP_INSN)
doloop_pat = PATTERN (doloop_pat);
else
doloop_pat = NULL_RTX;
}
if (! doloop_pat
|| ! (condition = doloop_condition_get (doloop_pat)))
{
if (loop_dump_stream)
fprintf (loop_dump_stream,
"Doloop: Unrecognizable doloop pattern!\n");
return 0;
}
if (n_iterations != 0)
/* Handle the simpler case, where we know the iteration count at
compile time. */
return doloop_modify (loop, iterations, iterations_max, doloop_seq,
start_label, condition);
else
/* Handle the harder case, where we must add additional runtime tests. */
return doloop_modify_runtime (loop, iterations_max, doloop_seq,
start_label, mode, condition);
}
#endif /* HAVE_doloop_end */

553
gcc/loop-doloop.c Normal file
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@ -0,0 +1,553 @@
/* Perform doloop optimizations
Copyright (C) 2004 Free Software Foundation, Inc.
Based on code by Michael P. Hayes (m.hayes@elec.canterbury.ac.nz)
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
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "flags.h"
#include "expr.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "toplev.h"
#include "tm_p.h"
#include "cfgloop.h"
#include "output.h"
#include "params.h"
/* This module is used to modify loops with a determinable number of
iterations to use special low-overhead looping instructions.
It first validates whether the loop is well behaved and has a
determinable number of iterations (either at compile or run-time).
It then modifies the loop to use a low-overhead looping pattern as
follows:
1. A pseudo register is allocated as the loop iteration counter.
2. The number of loop iterations is calculated and is stored
in the loop counter.
3. At the end of the loop, the jump insn is replaced by the
doloop_end pattern. The compare must remain because it might be
used elsewhere. If the loop-variable or condition register are
used elsewhere, they will be eliminated by flow.
4. An optional doloop_begin pattern is inserted at the top of the
loop.
TODO The optimization should only performed when either the biv used for exit
condition is unused at all except for the exit test, or if we do not have to
change its value, since otherwise we have to add a new induction variable,
which usually will not pay up (unless the cost of the doloop pattern is
somehow extremely lower than the cost of compare & jump, or unless the bct
register cannot be used for anything else but doloop -- ??? detect these
cases). */
#ifdef HAVE_doloop_end
/* Return the loop termination condition for PATTERN or zero
if it is not a decrement and branch jump insn. */
static rtx
doloop_condition_get (rtx pattern)
{
rtx cmp;
rtx inc;
rtx reg;
rtx condition;
/* The canonical doloop pattern we expect is:
(parallel [(set (pc) (if_then_else (condition)
(label_ref (label))
(pc)))
(set (reg) (plus (reg) (const_int -1)))
(additional clobbers and uses)])
Some machines (IA-64) make the decrement conditional on
the condition as well, so we don't bother verifying the
actual decrement. 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. */
if (GET_CODE (pattern) != PARALLEL)
return 0;
cmp = XVECEXP (pattern, 0, 0);
inc = XVECEXP (pattern, 0, 1);
/* Check for (set (reg) (something)). */
if (GET_CODE (inc) != SET || ! REG_P (SET_DEST (inc)))
return 0;
/* Extract loop counter register. */
reg = SET_DEST (inc);
/* Check for (set (pc) (if_then_else (condition)
(label_ref (label))
(pc))). */
if (GET_CODE (cmp) != SET
|| SET_DEST (cmp) != pc_rtx
|| GET_CODE (SET_SRC (cmp)) != IF_THEN_ELSE
|| GET_CODE (XEXP (SET_SRC (cmp), 1)) != LABEL_REF
|| XEXP (SET_SRC (cmp), 2) != pc_rtx)
return 0;
/* Extract loop termination condition. */
condition = XEXP (SET_SRC (cmp), 0);
if ((GET_CODE (condition) != GE && GET_CODE (condition) != NE)
|| GET_CODE (XEXP (condition, 1)) != CONST_INT)
return 0;
if (XEXP (condition, 0) == reg)
return condition;
if (GET_CODE (XEXP (condition, 0)) == PLUS
&& XEXP (XEXP (condition, 0), 0) == reg)
return condition;
/* ??? If a machine uses a funny comparison, we could return a
canonicalised form here. */
return 0;
}
/* Return nonzero if the loop specified by LOOP is suitable for
the use of special low-overhead looping instructions. DESC
describes the number of iterations of the loop. */
static bool
doloop_valid_p (struct loop *loop, struct niter_desc *desc)
{
basic_block *body = get_loop_body (loop), bb;
rtx insn;
unsigned i;
/* Check for loops that may not terminate under special conditions. */
if (!desc->simple_p
|| desc->assumptions
|| desc->infinite)
{
/* There are some cases that would require a special attention.
For example if the comparison is LEU and the comparison value
is UINT_MAX then the loop will not terminate. Similarly, if the
comparison code is GEU and the comparison value is 0, the
loop will not terminate.
If the absolute increment is not 1, the loop can be infinite
even with LTU/GTU, e.g. for (i = 3; i > 0; i -= 2)
??? We could compute these conditions at run-time and have a
additional jump around the loop to ensure an infinite loop.
However, it is very unlikely that this is the intended
behavior of the loop and checking for these rare boundary
conditions would pessimize all other code.
If the loop is executed only a few times an extra check to
restart the loop could use up most of the benefits of using a
count register loop. Note however, that normally, this
restart branch would never execute, so it could be predicted
well by the CPU. We should generate the pessimistic code by
default, and have an option, e.g. -funsafe-loops that would
enable count-register loops in this case. */
if (dump_file)
fprintf (dump_file, "Doloop: Possible infinite iteration case.\n");
return false;
}
for (i = 0; i < loop->num_nodes; i++)
{
bb = body[i];
for (insn = BB_HEAD (bb);
insn != NEXT_INSN (BB_END (bb));
insn = NEXT_INSN (insn))
{
/* A called function may clobber any special registers required for
low-overhead looping. */
if (GET_CODE (insn) == CALL_INSN)
{
if (dump_file)
fprintf (dump_file, "Doloop: Function call in loop.\n");
return false;
}
/* Some targets (eg, PPC) use the count register for branch on table
instructions. ??? This should be a target specific check. */
if (GET_CODE (insn) == JUMP_INSN
&& (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
|| GET_CODE (PATTERN (insn)) == ADDR_VEC))
{
if (dump_file)
fprintf (dump_file, "Doloop: Computed branch in the loop.\n");
return false;
}
}
}
free (body);
return true;
}
/* Adds test of COND jumping to DEST to the end of BB. */
static void
add_test (rtx cond, basic_block bb, basic_block dest)
{
rtx seq, jump, label;
enum machine_mode mode;
rtx op0 = XEXP (cond, 0), op1 = XEXP (cond, 1);
enum rtx_code code = GET_CODE (cond);
mode = GET_MODE (XEXP (cond, 0));
if (mode == VOIDmode)
mode = GET_MODE (XEXP (cond, 1));
start_sequence ();
op0 = force_operand (op0, NULL_RTX);
op1 = force_operand (op1, NULL_RTX);
label = block_label (dest);
do_compare_rtx_and_jump (op0, op1, code, 0, mode, NULL_RTX, NULL_RTX, label);
jump = get_last_insn ();
JUMP_LABEL (jump) = label;
/* The jump is supposed to handle an unlikely special case. */
REG_NOTES (jump)
= gen_rtx_EXPR_LIST (REG_BR_PROB,
GEN_INT (0), REG_NOTES (jump));
LABEL_NUSES (label)++;
seq = get_insns ();
end_sequence ();
emit_insn_after (seq, BB_END (bb));
}
/* Modify the loop to use the low-overhead looping insn where LOOP
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. */
static void
doloop_modify (struct loop *loop, struct niter_desc *desc,
rtx doloop_seq, rtx condition)
{
rtx counter_reg;
rtx count, tmp, noloop = NULL_RTX;
rtx sequence;
rtx jump_insn;
rtx jump_label;
int nonneg = 0, irr;
bool increment_count;
basic_block loop_end = desc->out_edge->src;
jump_insn = BB_END (loop_end);
if (dump_file)
{
fprintf (dump_file, "Doloop: Inserting doloop pattern (");
if (desc->const_iter)
fprintf (dump_file, HOST_WIDEST_INT_PRINT_DEC, desc->niter);
else
fputs ("runtime", dump_file);
fputs (" iterations).\n", dump_file);
}
/* Discard original jump to continue loop. The original compare
result may still be live, so it cannot be discarded explicitly. */
delete_insn (jump_insn);
counter_reg = XEXP (condition, 0);
if (GET_CODE (counter_reg) == PLUS)
counter_reg = XEXP (counter_reg, 0);
count = desc->niter_expr;
increment_count = false;
switch (GET_CODE (condition))
{
case NE:
/* Currently only NE tests against zero and one are supported. */
if (XEXP (condition, 1) == const1_rtx)
{
increment_count = true;
noloop = const1_rtx;
}
else if (XEXP (condition, 1) == const0_rtx)
noloop = const0_rtx;
else
abort ();
break;
case GE:
/* Currently only GE tests against zero are supported. */
if (XEXP (condition, 1) != const0_rtx)
abort ();
noloop = constm1_rtx;
/* The iteration count does not need incrementing for a GE test. */
increment_count = false;
/* Determine if the iteration counter will be non-negative.
Note that the maximum value loaded is iterations_max - 1. */
if (desc->niter_max
<= ((unsigned HOST_WIDEST_INT) 1
<< (GET_MODE_BITSIZE (GET_MODE (counter_reg)) - 1)))
nonneg = 1;
break;
/* Abort if an invalid doloop pattern has been generated. */
default:
abort ();
}
if (increment_count)
count = simplify_gen_binary (PLUS, desc->mode, count, const1_rtx);
/* Insert initialization of the count register into the loop header. */
start_sequence ();
tmp = force_operand (count, counter_reg);
convert_move (counter_reg, tmp, 1);
sequence = get_insns ();
end_sequence ();
emit_insn_after (sequence, BB_END (loop_preheader_edge (loop)->src));
if (desc->noloop_assumptions)
{
rtx ass = desc->noloop_assumptions;
basic_block preheader = loop_preheader_edge (loop)->src;
basic_block set_zero
= loop_split_edge_with (loop_preheader_edge (loop), NULL_RTX);
basic_block new_preheader
= loop_split_edge_with (loop_preheader_edge (loop), NULL_RTX);
basic_block bb;
edge te;
gcov_type cnt;
/* Expand the condition testing the assumptions and if it does not pass,
reset the count register to 0. */
add_test (XEXP (ass, 0), preheader, set_zero);
preheader->succ->flags &= ~EDGE_FALLTHRU;
cnt = preheader->succ->count;
preheader->succ->probability = 0;
preheader->succ->count = 0;
irr = preheader->succ->flags & EDGE_IRREDUCIBLE_LOOP;
te = make_edge (preheader, new_preheader, EDGE_FALLTHRU | irr);
te->probability = REG_BR_PROB_BASE;
te->count = cnt;
set_immediate_dominator (CDI_DOMINATORS, new_preheader, preheader);
set_zero->count = 0;
set_zero->frequency = 0;
for (ass = XEXP (ass, 1); ass; ass = XEXP (ass, 1))
{
bb = loop_split_edge_with (te, NULL_RTX);
te = bb->succ;
add_test (XEXP (ass, 0), bb, set_zero);
make_edge (bb, set_zero, irr);
}
start_sequence ();
convert_move (counter_reg, noloop, 0);
sequence = get_insns ();
end_sequence ();
emit_insn_after (sequence, BB_END (set_zero));
}
/* Some targets (eg, C4x) need to initialize special looping
registers. */
#ifdef HAVE_doloop_begin
{
rtx init;
unsigned level = get_loop_level (loop) + 1;
init = gen_doloop_begin (counter_reg,
desc->const_iter ? desc->niter_expr : const0_rtx,
desc->niter_max,
GEN_INT (level));
if (init)
{
start_sequence ();
emit_insn (init);
sequence = get_insns ();
end_sequence ();
emit_insn_after (sequence, BB_END (loop_preheader_edge (loop)->src));
}
}
#endif
/* Insert the new low-overhead looping insn. */
emit_jump_insn_after (doloop_seq, BB_END (loop_end));
jump_insn = BB_END (loop_end);
jump_label = block_label (desc->in_edge->dest);
JUMP_LABEL (jump_insn) = jump_label;
LABEL_NUSES (jump_label)++;
/* Ensure the right fallthru edge is marked, for case we have reversed
the condition. */
desc->in_edge->flags &= ~EDGE_FALLTHRU;
desc->out_edge->flags |= EDGE_FALLTHRU;
/* Add a REG_NONNEG note if the actual or estimated maximum number
of iterations is non-negative. */
if (nonneg)
{
REG_NOTES (jump_insn)
= gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX, REG_NOTES (jump_insn));
}
}
/* Process loop described by LOOP validating that the loop is suitable for
conversion to use a low overhead looping instruction, replacing the jump
insn where suitable. Returns true if the loop was successfully
modified. */
static bool
doloop_optimize (struct loop *loop)
{
enum machine_mode mode;
rtx doloop_seq, doloop_pat, doloop_reg;
rtx iterations;
rtx iterations_max;
rtx start_label;
rtx condition;
unsigned level, est_niter;
struct niter_desc *desc;
if (dump_file)
fprintf (dump_file, "Doloop: Processing loop %d.\n", loop->num);
iv_analysis_loop_init (loop);
/* Find the simple exit of a LOOP. */
desc = get_simple_loop_desc (loop);
/* Check that loop is a candidate for a low-overhead looping insn. */
if (!doloop_valid_p (loop, desc))
{
if (dump_file)
fprintf (dump_file,
"Doloop: The loop is not suitable.\n");
return false;
}
mode = desc->mode;
est_niter = 3;
if (desc->const_iter)
est_niter = desc->niter;
/* If the estimate on number of iterations is reliable (comes from profile
feedback), use it. Do not use it normally, since the expected number
of iterations of an unrolled loop is 2. */
if (loop->header->count)
est_niter = expected_loop_iterations (loop);
if (est_niter < 3)
{
if (dump_file)
fprintf (dump_file,
"Doloop: Too few iterations (%u) to be profitable.\n",
est_niter);
return false;
}
iterations = desc->const_iter ? desc->niter_expr : const0_rtx;
iterations_max = GEN_INT (desc->niter_max);
level = get_loop_level (loop) + 1;
/* Generate looping insn. If the pattern FAILs then give up trying
to modify the loop since there is some aspect the back-end does
not like. */
start_label = block_label (desc->in_edge->dest);
doloop_reg = gen_reg_rtx (mode);
doloop_seq = gen_doloop_end (doloop_reg, iterations, iterations_max,
GEN_INT (level), start_label);
if (! doloop_seq && mode != word_mode)
{
PUT_MODE (doloop_reg, word_mode);
doloop_seq = gen_doloop_end (doloop_reg, iterations, iterations_max,
GEN_INT (level), start_label);
}
if (! doloop_seq)
{
if (dump_file)
fprintf (dump_file,
"Doloop: Target unwilling to use doloop pattern!\n");
return false;
}
/* If multiple instructions were created, the last must be the
jump instruction. Also, a raw define_insn may yield a plain
pattern. */
doloop_pat = doloop_seq;
if (INSN_P (doloop_pat))
{
while (NEXT_INSN (doloop_pat) != NULL_RTX)
doloop_pat = NEXT_INSN (doloop_pat);
if (GET_CODE (doloop_pat) == JUMP_INSN)
doloop_pat = PATTERN (doloop_pat);
else
doloop_pat = NULL_RTX;
}
if (! doloop_pat
|| ! (condition = doloop_condition_get (doloop_pat)))
{
if (dump_file)
fprintf (dump_file, "Doloop: Unrecognizable doloop pattern!\n");
return false;
}
doloop_modify (loop, desc, doloop_seq, condition);
return true;
}
/* This is the main entry point. Process all LOOPS using doloop_optimize. */
void
doloop_optimize_loops (struct loops *loops)
{
unsigned i;
struct loop *loop;
for (i = 1; i < loops->num; i++)
{
loop = loops->parray[i];
if (!loop)
continue;
doloop_optimize (loop);
}
iv_analysis_done ();
#ifdef ENABLE_CHECKING
verify_dominators (CDI_DOMINATORS);
verify_loop_structure (loops);
#endif
}
#endif /* HAVE_doloop_end */

4
gcc/loop-iv.c
View file

@ -2281,6 +2281,10 @@ iv_number_of_iterations (struct loop *loop, rtx insn, rtx condition,
simplify_using_initial_values (loop, IOR, &desc->infinite);
simplify_using_initial_values (loop, NIL, &desc->niter_expr);
if (desc->noloop_assumptions
&& XEXP (desc->noloop_assumptions, 0) == const_true_rtx)
goto zero_iter;
if (GET_CODE (desc->niter_expr) == CONST_INT)
{
unsigned HOST_WIDEST_INT val = INTVAL (desc->niter_expr);

17
gcc/loop.c
View file

@ -5352,23 +5352,6 @@ strength_reduce (struct loop *loop, int flags)
&& unrolled_insn_copies <= insn_count))
unroll_loop (loop, insn_count, 1);
#ifdef HAVE_doloop_end
if (HAVE_doloop_end && (flags & LOOP_BCT) && flag_branch_on_count_reg)
doloop_optimize (loop);
#endif /* HAVE_doloop_end */
/* In case number of iterations is known, drop branch prediction note
in the branch. Do that only in second loop pass, as loop unrolling
may change the number of iterations performed. */
if (flags & LOOP_BCT)
{
unsigned HOST_WIDE_INT n
= loop_info->n_iterations / loop_info->unroll_number;
if (n > 1)
predict_insn (prev_nonnote_insn (loop->end), PRED_LOOP_ITERATIONS,
REG_BR_PROB_BASE - REG_BR_PROB_BASE / n);
}
if (loop_dump_stream)
fprintf (loop_dump_stream, "\n");

5
gcc/loop.h
View file

@ -26,9 +26,8 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
/* Flags passed to loop_optimize. */
#define LOOP_UNROLL 1
#define LOOP_BCT 2
#define LOOP_PREFETCH 4
#define LOOP_AUTO_UNROLL 8
#define LOOP_PREFETCH 2
#define LOOP_AUTO_UNROLL 4
/* Get the loop info pointer of a loop. */
#define LOOP_INFO(LOOP) ((struct loop_info *) (LOOP)->aux)

18
gcc/passes.c
View file

@ -1456,7 +1456,7 @@ rest_of_handle_loop_optimize (tree decl, rtx insns)
reg_scan (insns, max_reg_num (), 1);
}
cleanup_barriers ();
loop_optimize (insns, dump_file, do_unroll | LOOP_BCT | do_prefetch);
loop_optimize (insns, dump_file, do_unroll | do_prefetch);
/* Loop can create trivially dead instructions. */
delete_trivially_dead_insns (insns, max_reg_num ());
@ -1476,6 +1476,12 @@ rest_of_handle_loop2 (tree decl, rtx insns)
struct loops *loops;
basic_block bb;
if (!flag_unswitch_loops
&& !flag_peel_loops
&& !flag_unroll_loops
&& !flag_branch_on_count_reg)
return;
timevar_push (TV_LOOP);
open_dump_file (DFI_loop2, decl);
if (dump_file)
@ -1498,6 +1504,11 @@ rest_of_handle_loop2 (tree decl, rtx insns)
(flag_unroll_loops ? UAP_UNROLL : 0) |
(flag_unroll_all_loops ? UAP_UNROLL_ALL : 0));
#ifdef HAVE_doloop_end
if (flag_branch_on_count_reg && HAVE_doloop_end)
doloop_optimize_loops (loops);
#endif /* HAVE_doloop_end */
loop_optimizer_finalize (loops, dump_file);
}
@ -1776,10 +1787,7 @@ rest_of_compilation (tree decl)
if (flag_tracer)
rest_of_handle_tracer (decl, insns);
if (optimize > 0
&& (flag_unswitch_loops
|| flag_peel_loops
|| flag_unroll_loops))
if (optimize > 0)
rest_of_handle_loop2 (decl, insns);
if (flag_web)