From: Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>
To: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Subject: [PATCH] simplify-rtx: Implement constant folding of SS_TRUNCATE, US_TRUNCATE
Date: Thu, 8 Jun 2023 14:56:37 +0000 [thread overview]
Message-ID: <PAXPR08MB6926C9C547D641065D6AF5379350A@PAXPR08MB6926.eurprd08.prod.outlook.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 878 bytes --]
Hi all,
This patch implements RTL constant-folding for the SS_TRUNCATE and US_TRUNCATE codes.
The semantics are a clamping operation on the argument with the min and max of the narrow mode,
followed by a truncation. The signedness of the clamp and the min/max extrema is derived from
the signedness of the saturating operation.
We have a number of instructions in aarch64 that use SS_TRUNCATE and US_TRUNCATE to represent
their operations and we have pretty thorough runtime tests in gcc.target/aarch64/advsimd-intrinsics/vqmovn*.c.
With this patch the instructions are folded away at optimisation levels and the correctness checks still
pass.
Bootstrapped and tested on aarch64-none-linux-gnu and aarch64_be-none-elf.
Ok for trunk?
Thanks,
Kyrill
gcc/ChangeLog:
* simplify-rtx.cc (simplify_const_unary_operation):
Handle US_TRUNCATE, SS_TRUNCATE.
[-- Attachment #2: s_truncate.patch --]
[-- Type: application/octet-stream, Size: 989 bytes --]
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index 276be67aa67247dd46361ab9badc46ab089d6df0..5983a06e5a8ca89c717e8648be410024147b16e6 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -2131,6 +2131,22 @@ simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
result = wide_int::from (op0, width, UNSIGNED);
break;
+ case US_TRUNCATE:
+ case SS_TRUNCATE:
+ {
+ signop sgn = code == US_TRUNCATE ? UNSIGNED : SIGNED;
+ wide_int nmax
+ = wide_int::from (wi::max_value (width, sgn),
+ GET_MODE_PRECISION (imode), sgn);
+ wide_int nmin
+ = wide_int::from (wi::min_value (width, sgn),
+ GET_MODE_PRECISION (imode), sgn);
+ result
+ = wide_int::from (op0, GET_MODE_PRECISION (imode), sgn);
+ result = wi::min (wi::max (result, nmin, sgn), nmax, sgn);
+ result = wide_int::from (result, width, sgn);
+ break;
+ }
case SIGN_EXTEND:
result = wide_int::from (op0, width, SIGNED);
break;
next reply other threads:[~2023-06-08 14:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 14:56 Kyrylo Tkachov [this message]
2023-06-09 15:11 ` Jeff Law
2023-06-09 18:08 ` Richard Sandiford
2023-06-12 10:45 ` Kyrylo Tkachov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=PAXPR08MB6926C9C547D641065D6AF5379350A@PAXPR08MB6926.eurprd08.prod.outlook.com \
--to=kyrylo.tkachov@arm.com \
--cc=gcc-patches@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).