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re PR rtl-optimization/38449 (delay branch scheduling follows REG_CROSSING_JUMP jumps indiscriminately)

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PR rtl-optimization/38449:
        * hooks.c (hook_bool_const_rtx_const_rtx_true): New function.
        * hooks.h (hook_bool_const_rtx_const_rtx_true): Declare.
        * target.def: Merge in definitions and documentation for
        TARGET_CAN_FOLLOW_JUMP.
        * doc/tm.texi.in: Add documentation locations for the above.
        * doc/tm.texi: Regenerate.
        * reorg.c (follow_jumps): New parameters jump and crossing.
        Changed all callers.

From-SVN: r191878
This commit is contained in:
Joern Rennecke 2012-09-30 19:25:49 +00:00 committed by Joern Rennecke
parent f84992b001
commit 4b4de898c9
7 changed files with 69 additions and 8 deletions
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12
gcc/ChangeLog
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@ -1,3 +1,15 @@
2012-09-30 Joern Rennecke <joern.rennecke@embecosm.com>
PR rtl-optimization/38449:
* hooks.c (hook_bool_const_rtx_const_rtx_true): New function.
* hooks.h (hook_bool_const_rtx_const_rtx_true): Declare.
* target.def: Merge in definitions and documentation for
TARGET_CAN_FOLLOW_JUMP.
* doc/tm.texi.in: Add documentation locations for the above.
* doc/tm.texi: Regenerate.
* reorg.c (follow_jumps): New parameters jump and crossing.
Changed all callers.
2012-09-30 Eric Botcazou <ebotcazou@adacore.com>
* reorg.c (relax_delay_slots): Use delay_insn consistently.

4
gcc/doc/tm.texi
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@ -10958,6 +10958,10 @@ filling of delay slots can result in branches being redirected, and this
may in turn cause a branch offset to overflow.
@end defmac
@deftypefn {Target Hook} bool TARGET_CAN_FOLLOW_JUMP (const_rtx @var{follower}, const_rtx @var{followee})
FOLLOWER and FOLLOWEE are JUMP_INSN instructions; return true if FOLLOWER may be modified to follow FOLLOWEE; false, if it can't. For example, on some targets, certain kinds of branches can't be made to follow through a hot/cold partitioning.
@end deftypefn
@deftypefn {Target Hook} bool TARGET_COMMUTATIVE_P (const_rtx @var{x}, int @var{outer_code})
This target hook returns @code{true} if @var{x} is considered to be commutative.
Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider

2
gcc/doc/tm.texi.in
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@ -10814,6 +10814,8 @@ filling of delay slots can result in branches being redirected, and this
may in turn cause a branch offset to overflow.
@end defmac
@hook TARGET_CAN_FOLLOW_JUMP
@hook TARGET_COMMUTATIVE_P
This target hook returns @code{true} if @var{x} is considered to be commutative.
Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider

8
gcc/hooks.c
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@ -117,6 +117,14 @@ hook_bool_mode_rtx_true (enum machine_mode mode ATTRIBUTE_UNUSED,
return true;
}
/* Generic hook that takes (rtx, rtx) and returns true. */
bool
hook_bool_const_rtx_const_rtx_true (const_rtx follower ATTRIBUTE_UNUSED,
const_rtx followee ATTRIBUTE_UNUSED)
{
return true;
}
/* Generic hook that takes (enum machine_mode, unsigned HOST_WIDE_INT)
and returns false. */
bool

1
gcc/hooks.h
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@ -36,6 +36,7 @@ extern bool hook_bool_mode_const_rtx_false (enum machine_mode, const_rtx);
extern bool hook_bool_mode_const_rtx_true (enum machine_mode, const_rtx);
extern bool hook_bool_mode_rtx_false (enum machine_mode, rtx);
extern bool hook_bool_mode_rtx_true (enum machine_mode, rtx);
extern bool hook_bool_const_rtx_const_rtx_true (const_rtx, const_rtx);
extern bool hook_bool_mode_uhwi_false (enum machine_mode,
unsigned HOST_WIDE_INT);
extern bool hook_bool_tree_false (tree);

39
gcc/reorg.c
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@ -2494,22 +2494,25 @@ fill_simple_delay_slots (int non_jumps_p)
#endif
}
/* Follow any unconditional jump at LABEL;
/* Follow any unconditional jump at LABEL, for the purpose of redirecting JUMP;
return the ultimate label reached by any such chain of jumps.
Return a suitable return rtx if the chain ultimately leads to a
return instruction.
If LABEL is not followed by a jump, return LABEL.
If the chain loops or we can't find end, return LABEL,
since that tells caller to avoid changing the insn. */
since that tells caller to avoid changing the insn.
If the returned label is obtained by following a REG_CROSSING_JUMP
jump, set *CROSSING to true, otherwise set it to false. */
static rtx
follow_jumps (rtx label)
follow_jumps (rtx label, rtx jump, bool *crossing)
{
rtx insn;
rtx next;
rtx value = label;
int depth;
*crossing = false;
if (ANY_RETURN_P (label))
return label;
for (depth = 0;
@ -2537,6 +2540,11 @@ follow_jumps (rtx label)
|| GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
break;
if (!targetm.can_follow_jump (jump, insn))
break;
if (!*crossing)
*crossing
= find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX) != NULL_RTX;
value = this_label;
}
if (depth == 10)
@ -2984,6 +2992,7 @@ fill_slots_from_thread (rtx insn, rtx condition, rtx thread,
if (new_thread != thread)
{
rtx label;
bool crossing = false;
gcc_assert (thread_if_true);
@ -2991,7 +3000,7 @@ fill_slots_from_thread (rtx insn, rtx condition, rtx thread,
&& redirect_with_delay_list_safe_p (insn,
JUMP_LABEL (new_thread),
delay_list))
new_thread = follow_jumps (JUMP_LABEL (new_thread));
new_thread = follow_jumps (JUMP_LABEL (new_thread), insn, &crossing);
if (ANY_RETURN_P (new_thread))
label = find_end_label (new_thread);
@ -3001,7 +3010,11 @@ fill_slots_from_thread (rtx insn, rtx condition, rtx thread,
label = get_label_before (new_thread);
if (label)
reorg_redirect_jump (insn, label);
{
reorg_redirect_jump (insn, label);
if (crossing)
set_unique_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX);
}
}
return delay_list;
@ -3347,6 +3360,7 @@ relax_delay_slots (rtx first)
for (insn = first; insn; insn = next)
{
rtx other;
bool crossing;
next = next_active_insn (insn);
@ -3357,7 +3371,9 @@ relax_delay_slots (rtx first)
&& (condjump_p (insn) || condjump_in_parallel_p (insn))
&& !ANY_RETURN_P (target_label = JUMP_LABEL (insn)))
{
target_label = skip_consecutive_labels (follow_jumps (target_label));
target_label
= skip_consecutive_labels (follow_jumps (target_label, insn,
&crossing));
if (ANY_RETURN_P (target_label))
target_label = find_end_label (target_label);
@ -3369,7 +3385,11 @@ relax_delay_slots (rtx first)
}
if (target_label && target_label != JUMP_LABEL (insn))
reorg_redirect_jump (insn, target_label);
{
reorg_redirect_jump (insn, target_label);
if (crossing)
set_unique_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX);
}
/* See if this jump conditionally branches around an unconditional
jump. If so, invert this jump and point it to the target of the
@ -3503,7 +3523,8 @@ relax_delay_slots (rtx first)
/* If this jump goes to another unconditional jump, thread it, but
don't convert a jump into a RETURN here. */
trial = skip_consecutive_labels (follow_jumps (target_label));
trial = skip_consecutive_labels (follow_jumps (target_label, delay_insn,
&crossing));
if (ANY_RETURN_P (trial))
trial = find_end_label (trial);
@ -3512,6 +3533,8 @@ relax_delay_slots (rtx first)
{
reorg_redirect_jump (delay_insn, trial);
target_label = trial;
if (crossing)
set_unique_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX);
}
/* If the first insn at TARGET_LABEL is redundant with a previous

11
gcc/target.def
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@ -1350,6 +1350,17 @@ DEFHOOK
bool, (void),
hook_bool_void_false)
/* True if FOLLOWER may be modified to follow FOLLOWEE. */
DEFHOOK
(can_follow_jump,
"FOLLOWER and FOLLOWEE are JUMP_INSN instructions;\
return true if FOLLOWER may be modified to follow FOLLOWEE;\
false, if it can't.\
For example, on some targets, certain kinds of branches can't be made to\
follow through a hot/cold partitioning.",
bool, (const_rtx follower, const_rtx followee),
hook_bool_const_rtx_const_rtx_true)
/* Return a register class for which branch target register
optimizations should be applied. */
DEFHOOK