Message 343498 - Python tracker (original) (raw)

Message343498

Author	pitrou
Recipients	benjamin.peterson, fweimer, gregory.p.smith, methane, miss-islington, nascheme, pitrou, skrah, tgrigg, twouters, vstinner
Date	2019-05-25.17:40:17
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	1558806017.21.0.26803352592.issue27987@roundup.psfhosted.org
In-reply-to

Content
Here is what I've found for (32-bit) ARM: - "long double" is 8 bytes long, so it's probably the same as "double" (see http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dai0274b/index.html) - the standard alignment for "double" is 8 bytes (see http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/IHI0042D_aapcs.pdf) And on (32-bit) x86, it looks like the standard alignment for "long double" is 4 bytes: https://www.codesynthesis.com/~boris/blog/2009/04/06/cxx-data-alignment-portability/ So I don't think there's anything to change on 32-bit Python builds if we only really care about ARM and x86 (which is restrictive, but using "long double" in C extension types is a bit of an exotic issue).

Content

Here is what I've found for (32-bit) ARM: - "long double" is 8 bytes long, so it's probably the same as "double" (see http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dai0274b/index.html) - the standard alignment for "double" is 8 bytes (see http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/IHI0042D_aapcs.pdf) And on (32-bit) x86, it looks like the standard alignment for "long double" is 4 bytes: https://www.codesynthesis.com/~boris/blog/2009/04/06/cxx-data-alignment-portability/ So I don't think there's anything to change on 32-bit Python builds *if* we only really care about ARM and x86 (which is restrictive, but using "long double" in C extension types is a bit of an exotic issue).

History
Date	User	Action	Args
2019-05-25 17:40:17	pitrou	set	recipients: + pitrou, twouters, nascheme, gregory.p.smith, vstinner, benjamin.peterson, methane, skrah, fweimer, miss-islington, tgrigg
2019-05-25 17:40:17	pitrou	set	messageid: 1558806017.21.0.26803352592.issue27987@roundup.psfhosted.org
2019-05-25 17:40:17	pitrou	link	issue27987 messages
2019-05-25 17:40:17	pitrou	create