MatCat.OpenSource/8sa1-gcc
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

(unroll_loops): Set local_regno only if set_dominates_use returns true.

Browse Source 
(unroll_loops): Set local_regno only if set_dominates_use
returns true.
(set_dominates_use): New function.

From-SVN: r12917
This commit is contained in:
Jim Wilson 1996-10-08 14:51:09 -07:00
parent a7c1916aea
commit 1fe33d17b9
1 changed files with 84 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

85
gcc/unroll.c
View File

@ -743,12 +743,37 @@ unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
if (copy_start == loop_start)
copy_start_luid++;
/* If a pseudo's lifetime is entirely contained within this loop, then we
can use a different pseudo in each unrolled copy of the loop. This
results in better code. */
for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
if (regno_first_uid[j] > 0 && regno_first_uid[j] <= max_uid_for_loop
&& uid_luid[regno_first_uid[j]] >= copy_start_luid
&& regno_last_uid[j] > 0 && regno_last_uid[j] <= max_uid_for_loop
&& uid_luid[regno_last_uid[j]] <= copy_end_luid)
local_regno[j] = 1;
{
/* However, we must also check for loop-carried dependencies.
If the value the pseudo has at the end of iteration X is
used by iteration X+1, then we can not use a different pseudo
for each unrolled copy of the loop. */
/* A pseudo is safe if regno_first_uid is a set, and this
set dominates all instructions from regno_first_uid to
regno_last_uid. */
/* ??? This check is simplistic. We would get better code if
this check was more sophisticated. */
if (set_dominates_use (j, regno_first_uid[j], regno_last_uid[j],
copy_start, copy_end))
local_regno[j] = 1;
if (loop_dump_stream)
{
if (local_regno[j])
fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
else
fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
j);
}
}
}
/* If this loop requires exit tests when unrolled, check to see if we
@ -3510,3 +3535,61 @@ remap_split_bivs (x)
}
return x;
}
/* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
return 0. COPY_START is where we can start looking for the insns
FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
insns.
If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
must dominate LAST_UID.
If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
may not dominate LAST_UID.
If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
must dominate LAST_UID. */
int
set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
int regno;
int first_uid;
int last_uid;
rtx copy_start;
rtx copy_end;
{
int passed_jump = 0;
rtx p = NEXT_INSN (copy_start);
while (INSN_UID (p) != first_uid)
{
if (GET_CODE (p) == JUMP_INSN)
passed_jump= 1;
/* Could not find FIRST_UID. */
if (p == copy_end)
return 0;
p = NEXT_INSN (p);
}
/* Verify that FIRST_UID is an insn that entirely sets REGNO. */
if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
|| ! dead_or_set_regno_p (p, regno))
return 0;
/* FIRST_UID is always executed. */
if (passed_jump == 0)
return 1;
while (INSN_UID (p) != last_uid)
{
/* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
can not be sure that FIRST_UID dominates LAST_UID. */
if (GET_CODE (p) == CODE_LABEL)
return 0;
p = NEXT_INSN (p);
}
/* FIRST_UID is always executed if LAST_UID is executed. */
return 1;
}