From: "Maciej W. Rozycki" <macro@embecosm.com>
To: Jeff Law <jeffreyalaw@gmail.com>
Cc: gcc-patches@gcc.gnu.org, Andrew Waterman <andrew@sifive.com>,
Jim Wilson <jim.wilson.gcc@gmail.com>,
Kito Cheng <kito.cheng@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>
Subject: Re: [PATCH 26/44] RISC-V: Add `movMODEcc' implementation for generic targets
Date: Thu, 23 Nov 2023 22:16:53 +0000 (GMT) [thread overview]
Message-ID: <alpine.DEB.2.20.2311232145370.5892@tpp.orcam.me.uk> (raw)
In-Reply-To: <b0561234-6a7c-497a-8e78-476e327b24c0@gmail.com>
On Sun, 19 Nov 2023, Jeff Law wrote:
> OK. Just curious are y'all seeing significant interest in this case from
> customers or is this more a case of rounding out the implementation to cover
> all potential possibilities?
As in the cover letter: we have a case where the pipeline seems to imply
high enough a branch penalty for branchless alternatives to be worth
considering even where built from more than just a couple instructions.
We yet have to fully evaluate it for our case and it may be that these
sequences are costlier than branches after all or that the boundary lies
somewhere in between (or that we end up with Zicond also available in the
CPU RTL). However we realised that combined with `-mbranch-cost=' it
might be a useful tool for performance evaluation for other people as
well.
This, combined with the branch costing issues observed earlier and
attempted to address with 09/44, is also why I chose, conservatively, to
add the `-mmovcc' option to control this feature: we may choose to flip it
on by default for some tuning architectures or even globally at one point.
Especially as it seems like the `addMODEcc' part could be profitable for
some architectures already.
Maciej
next prev parent reply other threads:[~2023-11-23 22:16 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-19 5:35 [PATCH 00/44] RISC-V: Various if-conversion fixes and improvements Maciej W. Rozycki
2023-11-18 16:50 ` [PATCH 13/44] RISC-V/testsuite: Add branchless cases for FP cond-move operations Maciej W. Rozycki
2023-11-18 18:03 ` Jeff Law
2023-11-19 6:27 ` Maciej W. Rozycki
2023-11-19 5:37 ` Maciej W. Rozycki
2023-11-19 5:35 ` [PATCH 01/44] testsuite: Add cases for conditional-move and conditional-add operations Maciej W. Rozycki
2023-11-19 5:52 ` Kito Cheng
2023-11-20 10:16 ` Maciej W. Rozycki
2023-11-20 12:57 ` Richard Biener
2023-11-22 1:33 ` Maciej W. Rozycki
2023-11-19 5:35 ` [PATCH 02/44] RISC-V/testsuite: Add cases for integer SFB cond-move operations Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:35 ` [PATCH 03/44] RISC-V: Reorder comment on SFB patterns Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 04/44] RISC-V: Sanitise NEED_EQ_NE_P case with `riscv_emit_int_compare' Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 05/44] RISC-V: Fix `mode' usage in `riscv_expand_conditional_move' Maciej W. Rozycki
2023-11-19 5:54 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 06/44] RISC-V: Avoid repeated GET_MODE calls " Maciej W. Rozycki
2023-11-19 5:55 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 07/44] RISC-V: Use `nullptr' " Maciej W. Rozycki
2023-11-19 5:53 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 08/44] RISC-V: Simplify EQ vs NE selection " Maciej W. Rozycki
2023-11-19 5:56 ` Kito Cheng
2023-11-19 5:36 ` [PATCH 09/44] RISC-V: Rework branch costing model for if-conversion Maciej W. Rozycki
2023-11-19 18:52 ` Jeff Law
2023-11-23 18:34 ` Maciej W. Rozycki
2023-11-29 1:19 ` Jeff Law
2023-11-29 12:01 ` Maciej W. Rozycki
2023-11-19 5:37 ` [PATCH 10/44] RISC-V/testsuite: Add branched cases for integer cond-move operations Maciej W. Rozycki
2023-11-19 6:44 ` Kito Cheng
2023-11-19 5:37 ` [PATCH 11/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 6:47 ` Kito Cheng
2023-11-23 19:18 ` Maciej W. Rozycki
2023-11-19 5:37 ` [PATCH 12/44] RISC-V/testsuite: Add branched cases for FP " Maciej W. Rozycki
2023-11-19 6:48 ` Kito Cheng
2023-11-19 5:38 ` [PATCH 14/44] RISC-V: Also invert the cond-move condition for GEU and LEU Maciej W. Rozycki
2023-11-19 6:50 ` Kito Cheng
2023-11-19 5:38 ` [PATCH 15/44] RISC-V/testsuite: Add branched cases for GEU and LEU cond-move operations Maciej W. Rozycki
2023-11-19 17:42 ` Jeff Law
2023-11-19 5:38 ` [PATCH 16/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 7:22 ` Kito Cheng
2023-11-19 5:38 ` [PATCH 17/44] RISC-V: Avoid extraneous EQ or NE operation in cond-move expansion Maciej W. Rozycki
2023-11-19 17:45 ` Jeff Law
2023-11-19 5:38 ` [PATCH 18/44] RISC-V/testsuite: Add branched cases for equality cond-move operations Maciej W. Rozycki
2023-11-19 17:45 ` Jeff Law
2023-11-19 5:39 ` [PATCH 19/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 17:46 ` Jeff Law
2023-11-19 5:39 ` [PATCH 20/44] RISC-V: Also accept constants for T-Head cond-move comparison operands Maciej W. Rozycki
2023-11-19 17:48 ` Jeff Law
2023-11-19 5:39 ` [PATCH 21/44] RISC-V: Also accept constants for T-Head cond-move data input operands Maciej W. Rozycki
2023-11-19 17:50 ` Jeff Law
2023-11-19 5:40 ` [PATCH 22/44] RISC-V: Fold all the cond-move variants together Maciej W. Rozycki
2023-11-19 18:35 ` Jeff Law
2023-11-19 5:40 ` [PATCH 23/44] RISC-V/testsuite: Add branched cases for T-Head non-equality cond moves Maciej W. Rozycki
2023-11-19 17:54 ` Jeff Law
2023-11-19 5:40 ` [PATCH 24/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 17:54 ` Jeff Law
2023-11-19 5:40 ` [PATCH 25/44] RISC-V: Implement `riscv_emit_unary' helper Maciej W. Rozycki
2023-11-19 17:54 ` Jeff Law
2023-11-19 5:40 ` [PATCH 26/44] RISC-V: Add `movMODEcc' implementation for generic targets Maciej W. Rozycki
2023-11-19 18:18 ` Jeff Law
2023-11-23 22:16 ` Maciej W. Rozycki [this message]
2023-11-19 5:40 ` [PATCH 27/44] RISC-V/testsuite: Add branched cases for generic integer cond moves Maciej W. Rozycki
2023-11-19 18:18 ` Jeff Law
2023-11-19 5:41 ` [PATCH 28/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 18:19 ` Jeff Law
2023-11-19 5:41 ` [PATCH 29/44] RISC-V: Add `addMODEcc' implementation for generic targets Maciej W. Rozycki
2023-11-19 18:23 ` Jeff Law
2023-11-23 22:36 ` Maciej W. Rozycki
2023-11-19 5:41 ` [PATCH 30/44] RISC-V/testsuite: Add branched cases for generic integer cond adds Maciej W. Rozycki
2023-11-19 18:23 ` Jeff Law
2023-11-19 5:41 ` [PATCH 31/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 18:25 ` Jeff Law
2023-11-23 22:48 ` Maciej W. Rozycki
2023-11-19 5:42 ` [PATCH 32/44] RISC-V: Only use SUBREG if applicable in `riscv_expand_float_scc' Maciej W. Rozycki
2023-11-19 18:26 ` Jeff Law
2023-11-19 5:42 ` [PATCH 33/44] RISC-V: Also allow FP conditions in `riscv_expand_conditional_move' Maciej W. Rozycki
2023-11-19 18:30 ` Jeff Law
2023-11-23 22:55 ` Maciej W. Rozycki
2023-11-19 5:42 ` [PATCH 34/44] RISC-V: Provide FP conditional-branch instructions for if-conversion Maciej W. Rozycki
2023-11-19 19:42 ` Jeff Law
2023-11-23 23:26 ` Maciej W. Rozycki
2023-11-19 5:42 ` [PATCH 35/44] RISC-V: Avoid extraneous integer comparison for FP comparisons Maciej W. Rozycki
2023-11-19 19:44 ` Jeff Law
2023-11-19 5:42 ` [PATCH 36/44] RISC-V/testsuite: Add branched cases for generic FP cond moves Maciej W. Rozycki
2023-11-19 19:45 ` Jeff Law
2023-11-19 5:43 ` [PATCH 37/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 19:46 ` Jeff Law
2023-11-19 5:43 ` [PATCH 38/44] RISC-V/testsuite: Add branched cases for generic FP cond adds Maciej W. Rozycki
2023-11-19 19:46 ` Jeff Law
2023-11-19 5:43 ` [PATCH 39/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 19:47 ` Jeff Law
2023-11-19 5:43 ` [PATCH 40/44] RISC-V: Handle FP NE operator via inversion in cond-operation expansion Maciej W. Rozycki
2023-11-19 19:51 ` Jeff Law
2023-11-22 1:37 ` Maciej W. Rozycki
2023-11-19 5:43 ` [PATCH 41/44] RISC-V/testsuite: Add branched cases for FP NE cond-move operations Maciej W. Rozycki
2023-11-19 5:43 ` [PATCH 42/44] " Maciej W. Rozycki
2023-11-19 5:44 ` [PATCH 43/44] RISC-V/testsuite: Add branched cases for FP NE cond-add operation Maciej W. Rozycki
2023-11-19 5:44 ` [PATCH 44/44] RISC-V/testsuite: Add branchless " Maciej W. Rozycki
2023-11-19 5:52 ` [PATCH 00/44] RISC-V: Various if-conversion fixes and improvements Kito Cheng
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=alpine.DEB.2.20.2311232145370.5892@tpp.orcam.me.uk \
--to=macro@embecosm.com \
--cc=andrew@sifive.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=jeffreyalaw@gmail.com \
--cc=jim.wilson.gcc@gmail.com \
--cc=kito.cheng@gmail.com \
--cc=palmer@dabbelt.com \
/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).