Date: Fri, 23 Dec 2011 23:56:42 +0000 From: Alexander Best <arundel@freebsd.org> To: freebsd-current@freebsd.org Cc: freebsd-arch@freebsd.org Subject: [rfc] removing -mpreferred-stack-boundary=2 flag for i386? Message-ID: <20111223235642.GA37495@freebsd.org>
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hi there, is -mpreferred-stack-boundary=2 really necessary for i386 builds any longer? i built GENERIC (including modules) with and without that flag. the results are: 1654496 bytes with the flag set vs. 1654952 bytes with the flag unset the gcc(1) man page states the following: " This extra alignment does consume extra stack space, and generally increases code size. Code that is sensitive to stack space usage, such as embedded systems and operating system kernels, may want to reduce the preferred alignment to -mpreferred-stack-boundary=2. " the comment in sys/conf/kern.mk however sorta suggests that the default alignment of 4 bytes might improve performance. cheers. alex
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