Date: Sun, 31 Jan 2016 16:41:11 -0800 From: Mark Millard <markmi@dsl-only.net> To: Roman Divacky <rdivacky@vlakno.cz> Cc: Nathan Whitehorn <nwhitehorn@freebsd.org>, Justin Hibbits <chmeeedalf@gmail.com>, FreeBSD Toolchain <freebsd-toolchain@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: Re: 3 quick questions about stack alignment for powerpc (32-bit) signal handlers Message-ID: <0716BE3E-B7D1-4A10-B011-C1F0245296E7@dsl-only.net> In-Reply-To: <20160131140807.GA83147@vlakno.cz> References: <517B7923-5166-42D0-8FA8-52C05F956F06@dsl-only.net> <20160131140807.GA83147@vlakno.cz>
next in thread | previous in thread | raw e-mail | index | archive | help
I have submitted Bug 206810 for this 11.0-CURRENT/clang380-import stack alignment problem for TARGET_ARCH=powerpc signal delivery. === Mark Millard markmi at dsl-only.net On 2016-Jan-31, at 6:08 AM, Roman Divacky <rdivacky at vlakno.cz> wrote: Fwiw, LLVM expect 16B aligned stack on PowerPC. On Sun, Jan 31, 2016 at 05:55:20AM -0800, Mark Millard wrote: > 3 quick FreeBSD for powerpc (32-bit) questions: > > > A) For PowerPC (32-bit) what is the stack alignment requirement by the ABI(s) that FreeBSD targets? > > B) Are signal handlers supposed to be given that alignment? > > > I ask because signal handlers are at times begin given just 4-byte alignment but clang 3.8.0 powerpc's code generation can depend on the alignment being more than 4. > > clang 3.8.0 can calculate addresses by, for example, masking in a 0x4 relative to what would need to be an aligned address with alignment 8 or more instead of adding 0x4 to a more arbitrary address. > > So far I've only seen less than 8 byte stack alignment via signal handler activity. > > > C) Which should be blamed for problems here: clang's code generation, FreeBSD's stack alignment handling for signals, or both? > > === > Mark Millard > markmi at dsl-only.net > > _______________________________________________ > freebsd-toolchain@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain > To unsubscribe, send any mail to "freebsd-toolchain-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?0716BE3E-B7D1-4A10-B011-C1F0245296E7>