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From: "gjl at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/66511] [avr] whole-byte shifts not optimized away for uint64_t Date: Sat, 27 Jun 2015 18:07:00 -0000 [thread overview] Message-ID: <bug-66511-4-VfdgnrgJJE@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-66511-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66511 --- Comment #1 from Georg-Johann Lay <gjl at gcc dot gnu.org> --- (In reply to Matthijs Kooijman from comment #0) > I haven't found a readily available 5.x package yet to test. It's the same. > As you can see, the versions operating on 64 bit values preserve the > 8-bit shift (which is very inefficient on AVR), while the versions > running on 32 bit values simply copy the right registers. Lib functions are used because users complained about bloated 64-bit arithmetic. Notice that indide these 64-bit shift functions byte-shifts are used. > The foo32_16 function still has some useless instructions (r27 and r26 > are not part of the return value, not sure why these are set) but that > is probably an unrelated problem. Yes. > I've marked this with component "target", since I think these > optimizations are avr-specific (or at least not applicable to bigger > architectures).
next prev parent reply other threads:[~2015-06-27 18:07 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-06-11 14:49 [Bug target/66511] New: " matthijs at stdin dot nl 2015-06-27 17:52 ` [Bug target/66511] " gjl at gcc dot gnu.org 2015-06-27 18:07 ` gjl at gcc dot gnu.org [this message] 2015-08-02 11:42 ` matthijs at stdin dot nl 2015-08-13 20:56 ` gjl at gcc dot gnu.org 2023-04-16 12:51 ` roger at nextmovesoftware dot com 2023-04-16 17:27 ` klaus.doldinger64 at googlemail dot com
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