/* Perform doloop optimizations
- Copyright (C) 2004 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005 Free Software Foundation, Inc.
Based on code by Michael P. Hayes (m.hayes@elec.canterbury.ac.nz)
This file is part of GCC.
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. */
+Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA. */
#include "config.h"
#include "system.h"
#include "cfgloop.h"
#include "output.h"
#include "params.h"
+#include "target.h"
/* This module is used to modify loops with a determinable number of
iterations to use special low-overhead looping instructions.
/* Return the loop termination condition for PATTERN or zero
if it is not a decrement and branch jump insn. */
-static rtx
+rtx
doloop_condition_get (rtx pattern)
{
rtx cmp;
rtx inc;
rtx reg;
+ rtx inc_src;
rtx condition;
/* The canonical doloop pattern we expect is:
(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. */
+ 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. */
if (GET_CODE (pattern) != PARALLEL)
return 0;
inc = XVECEXP (pattern, 0, 1);
/* Check for (set (reg) (something)). */
- if (GET_CODE (inc) != SET || ! REG_P (SET_DEST (inc)))
+ if (GET_CODE (inc) != SET)
return 0;
-
- /* Extract loop counter register. */
reg = SET_DEST (inc);
+ if (! REG_P (reg))
+ return 0;
+
+ /* Check if something = (plus (reg) (const_int -1)).
+ On IA-64, this decrement is wrapped in an if_then_else. */
+ inc_src = SET_SRC (inc);
+ if (GET_CODE (inc_src) == IF_THEN_ELSE)
+ inc_src = XEXP (inc_src, 1);
+ if (GET_CODE (inc_src) != PLUS
+ || XEXP (inc_src, 0) != reg
+ || XEXP (inc_src, 1) != constm1_rtx)
+ return 0;
/* Check for (set (pc) (if_then_else (condition)
(label_ref (label))
/* 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)
+ /* We expect a GE or NE comparison with 0 or 1. */
+ if ((GET_CODE (condition) != GE
+ && GET_CODE (condition) != NE)
+ || (XEXP (condition, 1) != const0_rtx
+ && XEXP (condition, 1) != const1_rtx))
return 0;
- if (XEXP (condition, 0) == reg)
- return condition;
-
- if (GET_CODE (XEXP (condition, 0)) == PLUS
- && XEXP (XEXP (condition, 0), 0) == reg)
+ if ((XEXP (condition, 0) == reg)
+ || (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
insn != NEXT_INSN (BB_END (bb));
insn = NEXT_INSN (insn))
{
- /* A called function may clobber any special registers required for
- low-overhead looping. */
- if (CALL_P (insn))
+ /* Different targets have different necessities for low-overhead
+ looping. Call the back end for each instruction within the loop
+ to let it decide whether the insn prohibits a low-overhead loop.
+ It will then return the cause for it to emit to the dump file. */
+ const char * invalid = targetm.invalid_within_doloop (insn);
+ if (invalid)
{
if (dump_file)
- fprintf (dump_file, "Doloop: Function call in loop.\n");
- result = false;
- goto cleanup;
- }
-
- /* Some targets (eg, PPC) use the count register for branch on table
- instructions. ??? This should be a target specific check. */
- if (JUMP_P (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");
+ fprintf (dump_file, "Doloop: %s\n", invalid);
result = false;
goto cleanup;
}
{
case NE:
/* Currently only NE tests against zero and one are supported. */
- if (XEXP (condition, 1) == const1_rtx)
+ noloop = XEXP (condition, 1);
+ if (noloop != const0_rtx)
{
+ gcc_assert (noloop == 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 ();
+ gcc_assert (XEXP (condition, 1) == const0_rtx);
noloop = constm1_rtx;
/* Abort if an invalid doloop pattern has been generated. */
default:
- abort ();
+ gcc_unreachable ();
}
if (increment_count)
/* 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);
- EDGE_SUCC (preheader, 0)->flags &= ~EDGE_FALLTHRU;
- cnt = EDGE_SUCC (preheader, 0)->count;
- EDGE_SUCC (preheader, 0)->probability = 0;
- EDGE_SUCC (preheader, 0)->count = 0;
- irr = EDGE_SUCC (preheader, 0)->flags & EDGE_IRREDUCIBLE_LOOP;
+ single_succ_edge (preheader)->flags &= ~EDGE_FALLTHRU;
+ cnt = single_succ_edge (preheader)->count;
+ single_succ_edge (preheader)->probability = 0;
+ single_succ_edge (preheader)->count = 0;
+ irr = single_succ_edge (preheader)->flags & EDGE_IRREDUCIBLE_LOOP;
te = make_edge (preheader, new_preheader, EDGE_FALLTHRU | irr);
te->probability = REG_BR_PROB_BASE;
te->count = cnt;
for (ass = XEXP (ass, 1); ass; ass = XEXP (ass, 1))
{
bb = loop_split_edge_with (te, NULL_RTX);
- te = EDGE_SUCC (bb, 0);
+ te = single_succ_edge (bb);
add_test (XEXP (ass, 0), bb, set_zero);
make_edge (bb, set_zero, irr);
}
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