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final.c (shorten_branches): When optimizing...

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* final.c (shorten_branches): When optimizing, start with small
        length and increase from there, and don't decrease lengths.

Co-Authored-By: Richard Sandiford <rdsandiford@googlemail.com>

From-SVN: r192634
This commit is contained in:
Joern Rennecke 2012-10-20 13:46:07 +00:00 • committed by Joern Rennecke
parent 8e38384964
commit f6df08e637
2 changed files with 39 additions and 10 deletions
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3
gcc/ChangeLog
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@ -7,6 +7,9 @@
(steal_delay_list_from_target): Use copy_delay_slot_insn.
(fill_slots_from_thread, fill_simple_delay_slots): Likewise.
* final.c (shorten_branches): When optimizing, start with small
length and increase from there, and don't decrease lengths.
2012-10-19 Jan Hubicka <jh@suse.cz>
* builtins.def (BUILT_IN_UNREACHABLE): Make ATTR_CONST_NORETURN_NOTHROW_LEAF_LIST.

46
gcc/final.c
View file

@ -1009,6 +1009,13 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
align_tab[i] = seq;
}
}
/* When optimizing, we start assuming minimum length, and keep increasing
lengths as we find the need for this, till nothing changes.
When not optimizing, we start assuming maximum lengths, and
do a single pass to update the lengths. */
bool increasing = optimize != 0;
#ifdef CASE_VECTOR_SHORTEN_MODE
if (optimize)
{
@ -1062,11 +1069,16 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
flags.min_after_base = min > rel;
flags.max_after_base = max > rel;
ADDR_DIFF_VEC_FLAGS (pat) = flags;
if (increasing)
PUT_MODE (pat, CASE_VECTOR_SHORTEN_MODE (0, 0, pat));
}
}
#endif /* CASE_VECTOR_SHORTEN_MODE */
/* Compute initial lengths, addresses, and varying flags for each insn. */
int (*length_fun) (rtx) = increasing ? insn_min_length : insn_default_length;
for (insn_current_address = 0, insn = first;
insn != 0;
insn_current_address += insn_lengths[uid], insn = NEXT_INSN (insn))
@ -1117,6 +1129,8 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
#else
const_delay_slots = 0;
#endif
int (*inner_length_fun) (rtx)
= const_delay_slots ? length_fun : insn_default_length;
/* Inside a delay slot sequence, we do not do any branch shortening
if the shortening could change the number of delay slots
of the branch. */
@ -1131,7 +1145,7 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
inner_length = (asm_insn_count (PATTERN (inner_insn))
* insn_default_length (inner_insn));
else
inner_length = insn_default_length (inner_insn);
inner_length = inner_length_fun (inner_insn);
insn_lengths[inner_uid] = inner_length;
if (const_delay_slots)
@ -1149,7 +1163,7 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
}
else if (GET_CODE (body) != USE && GET_CODE (body) != CLOBBER)
{
insn_lengths[uid] = insn_default_length (insn);
insn_lengths[uid] = length_fun (insn);
varying_length[uid] = insn_variable_length_p (insn);
}
@ -1220,6 +1234,7 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
rtx prev;
int rel_align = 0;
addr_diff_vec_flags flags;
enum machine_mode vec_mode;
/* Avoid automatic aggregate initialization. */
flags = ADDR_DIFF_VEC_FLAGS (body);
@ -1298,9 +1313,12 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
else
max_addr += align_fuzz (max_lab, rel_lab, 0, 0);
}
PUT_MODE (body, CASE_VECTOR_SHORTEN_MODE (min_addr - rel_addr,
max_addr - rel_addr,
body));
vec_mode = CASE_VECTOR_SHORTEN_MODE (min_addr - rel_addr,
max_addr - rel_addr, body);
if (!increasing
|| (GET_MODE_SIZE (vec_mode)
>= GET_MODE_SIZE (GET_MODE (body))))
PUT_MODE (body, vec_mode);
if (JUMP_TABLES_IN_TEXT_SECTION
|| readonly_data_section == text_section)
{
@ -1362,10 +1380,15 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
if (inner_length != insn_lengths[inner_uid])
{
insn_lengths[inner_uid] = inner_length;
something_changed = 1;
if (!increasing || inner_length > insn_lengths[inner_uid])
{
insn_lengths[inner_uid] = inner_length;
something_changed = 1;
}
else
inner_length = insn_lengths[inner_uid];
}
insn_current_address += insn_lengths[inner_uid];
insn_current_address += inner_length;
new_length += inner_length;
}
}
@ -1382,14 +1405,17 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
insn_current_address += (new_length - tmp_length);
#endif
if (new_length != insn_lengths[uid])
if (new_length != insn_lengths[uid]
&& (!increasing || new_length > insn_lengths[uid]))
{
insn_lengths[uid] = new_length;
something_changed = 1;
}
else
insn_current_address += insn_lengths[uid] - new_length;
}
/* For a non-optimizing compile, do only a single pass. */
if (!optimize)
if (!increasing)
break;
}