public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/55894] No constant propagation in Intel intrinsics Date: Mon, 07 Jan 2013 14:26:00 -0000 [thread overview] Message-ID: <bug-55894-4-YOY4Y2BJME@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-55894-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55894 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-01-07 14:25:33 UTC --- The reason why it doesn't happen during combine is that the insns don't allow constants, they require loads from memory, so while the compiler is aware of the folded constant, e.g. in the g function: (insn 12 7 15 2 (set (reg/i:V2DF 21 xmm0) (subreg:V2DF (reg:V2DI 65 [ D.4526 ]) 0)) pr55894.c:16 1157 {*movv2df_internal} (expr_list:REG_DEAD (reg:V2DI 65 [ D.4526 ]) (expr_list:REG_EQUAL (const_vector:V2DF [ (const_double:DF +QNaN [+QNaN]) (const_double:DF +QNaN [+QNaN]) ]) (nil)))) it fails to match and thus isn't actually used in the code. A pass that would see you load a constant from memory, do some transformations on it which are all foldable by the compiler and transforming that into just load of a different constant could handle this (or do it in combine?), but the problem with that is that it could in theory increase the constant pool too much.
next prev parent reply other threads:[~2013-01-07 14:26 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-01-07 13:14 [Bug target/55894] New: " glisse at gcc dot gnu.org 2013-01-07 13:36 ` [Bug target/55894] " rguenth at gcc dot gnu.org 2013-01-07 13:48 ` glisse at gcc dot gnu.org 2013-01-07 14:26 ` jakub at gcc dot gnu.org [this message] 2013-01-07 20:17 ` glisse at gcc dot gnu.org 2021-12-29 4:44 ` pinskia at gcc dot gnu.org 2021-12-29 4:47 ` pinskia at gcc dot gnu.org
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=bug-55894-4-YOY4Y2BJME@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@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: linkBe 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).