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From: "fw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/110899] RFE: Attributes preserve_most and preserve_all Date: Mon, 07 Aug 2023 13:42:57 +0000 [thread overview] Message-ID: <bug-110899-4-ZjqPnK064p@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-110899-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110899 --- Comment #5 from Florian Weimer <fw at gcc dot gnu.org> --- (In reply to Michael Matz from comment #3) > For ABIs you generally want a good mix between caller- and callee-saved > registers. The x86-64 psABI didn't do that on the SSE regs for conscious, but > meanwhile irrelevant, reasons, so my approach above tried to rectify this. > > The clang attributes seem to go against that general idea, they move all regs > (or all general regs) into being callee-saved (except, strangely for > aarch64?). This is intended for functions that are called conditionally, but rarely, such as debug logging. It's not a generally useful calling convention. > It also makes argument registers be callee-saved, which is very > unconventional. Isn't this done for the this pointer in some C++ ABIs? > Does the clang implementation take into account the various problematic > cases that arise when calling a normal function from a (say) preserve_all > function > (hint: such call can't usually be done)? How so? We need to version the __preserve_most__ attribute with the ISA level, of course.
next prev parent reply other threads:[~2023-08-07 13:42 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-08-04 13:57 [Bug target/110899] New: " elver at google dot com 2023-08-04 14:19 ` [Bug target/110899] " pinskia at gcc dot gnu.org 2023-08-07 8:38 ` rguenth at gcc dot gnu.org 2023-08-07 12:28 ` fw at gcc dot gnu.org 2023-08-07 12:55 ` matz at gcc dot gnu.org 2023-08-07 12:59 ` matz at gcc dot gnu.org 2023-08-07 13:42 ` fw at gcc dot gnu.org [this message] 2023-08-07 13:55 ` hubicka at gcc dot gnu.org 2023-08-07 15:34 ` matz at gcc dot gnu.org 2023-08-07 16:19 ` fw at gcc dot gnu.org 2023-08-07 16:24 ` matz at gcc dot gnu.org 2023-08-08 8:59 ` fw at gcc dot gnu.org 2023-08-08 12:47 ` matz at gcc dot gnu.org 2023-12-25 11:04 ` sjames at gcc dot gnu.org 2023-12-28 21:26 ` pinskia at gcc dot gnu.org
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