This commit is contained in:
parent
6df8046a37
commit
d44b58ed57
@ -1,48 +1,46 @@
|
|||||||
From 839bc42772ba7af66af3bd16efed4a69511312ae Mon Sep 17 00:00:00 2001
|
From 5729ffad4db78b26f0d1f658a9fd695be5970550 Mon Sep 17 00:00:00 2001
|
||||||
From: Segher Boessenkool <segher@kernel.crashing.org>
|
From: Richard Biener <rguenther@suse.de>
|
||||||
Date: Wed, 27 Mar 2024 14:09:52 +0000
|
Date: Wed, 3 Apr 2024 12:58:26 +0200
|
||||||
Subject: [PATCH] combine: Don't combine if I2 does not change
|
Subject: [PATCH] rtl-optimization/101523 - avoid re-combine after noop 2->2
|
||||||
|
combination
|
||||||
To: gcc-patches@gcc.gnu.org
|
To: gcc-patches@gcc.gnu.org
|
||||||
|
|
||||||
In some cases combine will "combine" an I2 and I3, but end up putting
|
The following avoids re-walking and re-combining the instructions
|
||||||
exactly the same thing back as I2 as was there before. This is never
|
between i2 and i3 when the pattern of i2 doesn't change.
|
||||||
progress, so we shouldn't do it, it will lead to oscillating behaviour
|
|
||||||
and the like.
|
|
||||||
|
|
||||||
If we want to canonicalise things, that's fine, but this is not the
|
|
||||||
way to do it.
|
|
||||||
|
|
||||||
2024-03-27 Segher Boessenkool <segher@kernel.crashing.org>
|
|
||||||
|
|
||||||
PR rtl-optimization/101523
|
PR rtl-optimization/101523
|
||||||
* combine.cc (try_combine): Don't do a 2-insn combination if
|
* combine.cc (try_combine): When the pattern of i2 doesn't
|
||||||
it does not in fact change I2.
|
change do not re-start combining at i2 or an earlier insn which
|
||||||
|
had links or notes added.
|
||||||
---
|
---
|
||||||
gcc/combine.cc | 11 +++++++++++
|
gcc/combine.cc | 7 +++++++
|
||||||
1 file changed, 11 insertions(+)
|
1 file changed, 7 insertions(+)
|
||||||
|
|
||||||
diff --git a/gcc/combine.cc b/gcc/combine.cc
|
diff --git a/gcc/combine.cc b/gcc/combine.cc
|
||||||
index a4479f8d836..745391016d0 100644
|
index a4479f8d836..ff25752cac4 100644
|
||||||
--- a/gcc/combine.cc
|
--- a/gcc/combine.cc
|
||||||
+++ b/gcc/combine.cc
|
+++ b/gcc/combine.cc
|
||||||
@@ -4186,6 +4186,17 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
|
@@ -4186,6 +4186,10 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
|
||||||
adjust_for_new_dest (i3);
|
adjust_for_new_dest (i3);
|
||||||
}
|
}
|
||||||
|
|
||||||
+ /* If I2 didn't change, this is not a combination (but a simplification or
|
+ bool i2_unchanged = false;
|
||||||
+ canonicalisation with context), which should not be done here. Doing
|
|
||||||
+ it here explodes the algorithm. Don't. */
|
|
||||||
+ if (rtx_equal_p (newi2pat, PATTERN (i2)))
|
+ if (rtx_equal_p (newi2pat, PATTERN (i2)))
|
||||||
+ {
|
+ i2_unchanged = true;
|
||||||
+ if (dump_file)
|
|
||||||
+ fprintf (dump_file, "i2 didn't change, not doing this\n");
|
|
||||||
+ undo_all ();
|
|
||||||
+ return 0;
|
|
||||||
+ }
|
|
||||||
+
|
+
|
||||||
/* We now know that we can do this combination. Merge the insns and
|
/* We now know that we can do this combination. Merge the insns and
|
||||||
update the status of registers and LOG_LINKS. */
|
update the status of registers and LOG_LINKS. */
|
||||||
|
|
||||||
|
@@ -4752,6 +4756,9 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
|
||||||
|
combine_successes++;
|
||||||
|
undo_commit ();
|
||||||
|
|
||||||
|
+ if (i2_unchanged)
|
||||||
|
+ return i3;
|
||||||
|
+
|
||||||
|
rtx_insn *ret = newi2pat ? i2 : i3;
|
||||||
|
if (added_links_insn && DF_INSN_LUID (added_links_insn) < DF_INSN_LUID (ret))
|
||||||
|
ret = added_links_insn;
|
||||||
--
|
--
|
||||||
2.35.3
|
2.35.3
|
||||||
|
|
||||||
|
@ -1,5 +1,5 @@
|
|||||||
-------------------------------------------------------------------
|
-------------------------------------------------------------------
|
||||||
Thu Mar 28 06:55:18 UTC 2024 - Richard Biener <rguenther@suse.com>
|
Thu Apr 4 07:43:17 UTC 2024 - Richard Biener <rguenther@suse.com>
|
||||||
|
|
||||||
- Add gcc13-pr101523.patch to avoid combine spending too much
|
- Add gcc13-pr101523.patch to avoid combine spending too much
|
||||||
compile-time and memory doing nothing on s390x. [boo#1188441]
|
compile-time and memory doing nothing on s390x. [boo#1188441]
|
||||||
|
Loading…
Reference in New Issue
Block a user