Date: Mon, 16 Feb 2004 13:12:15 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: "Juan Tumani" <jtumani55@hotmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: FreeBSD 5.2 v/s FreeBSD 4.9 MFLOPS performance (gcc3.3.3 v/sgcc2.9.5) Message-ID: <200402162112.i1GLCFMV087316@apollo.backplane.com> References: <BAY12-F357RapPBVToy00031029@hotmail.com>
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I'm surprised Bruce hasn't chimed in here yet. I guess he's tired of
repeating himself.
In 4.9, libcsu, which generates crt1.o (which is the start code for
C programs which the linker links in automatically) has this line in it:
andl $~0xf, %%esp # align stack to 16-byte boundary
So anything linked with 4.9 is going to align the stack on a
16 byte boundary no matter WHAT the kernel does.
FreeBSD-5 does not have this alignment in its crt1.o because GCC3
automatically aligns the stack on a per-procedure basis. Or at least
it is supposed to. Maybe it's broke? :-)
-Matt
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