From: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
To: Richard Earnshaw <rearnsha@arm.com>
Cc: Mircea Gherzan <mgherzan@gmail.com>,
"crossgcc@sourceware.org" <crossgcc@sourceware.org>
Subject: Re: ARM-PXA toolchain
Date: Tue, 08 Nov 2011 22:37:00 -0000 [thread overview]
Message-ID: <201111082336.24516.yann.morin.1998@anciens.enib.fr> (raw)
In-Reply-To: <4EB96479.8070708@arm.com>
Mircea, Richard, All,
On Tuesday 08 November 2011 18:18:49 Richard Earnshaw wrote:
> On 08/11/11 12:23, Mircea Gherzan wrote:
> > I can't check the coding for I can't compile a simple:
> > void my_vstmia(void)
> > {
> > __asm__("stc p11, cr8, [ip], #64");
> > __asm__("vstmia ip!, {d8 - d51}");
> > }
>
> That's a heck of a lot of double-precision registers! Perhaps you meant
> D15, not D51.
Aha! Good catch! :-)
Compiled with Mircea's original toolchain settings, and changing 'd51'
to 'd15' as spotted by Richard, I was able to compile that code snippet
(notice however the -O0 to not optimise at all):
$ arm-unknown-linux-gnueabi-gcc -march=armv7-a -mcpu=cortex-a9 \
-mfpu=vfpv3-d16 -mhard-float \
-O0 -o ess.o -c ess.c
$ arm-unknown-linux-gnueabi-objdump -d ess.o
[--SNIP--]
00000000 <my_vstmia>:
0: e52db004 push {fp} ; (str fp, [sp, #-4]!)
4: e28db000 add fp, sp, #0
8: ecac8b10 vstmia ip!, {d8-d15}
c: ecac8b10 vstmia ip!, {d8-d15}
10: e28bd000 add sp, fp, #0
14: e8bd0800 pop {fp}
18: e12fff1e bx lr
At any optimisation level, -O{s,1,2,3}, the assembly now looks like:
00000000 <my_vstmia>:
0: ecac8b10 vstmia ip!, {d8-d15}
4: ecac8b10 vstmia ip!, {d8-d15}
8: e12fff1e bx lr
So yes, the stc and the vstmia opcodes in the code snippet above are both
encoded into the same assembly instruction. But still, it does not tell
whether it's due to 'as' being smart, or the two opcodes actually being
the same in that situation...
Anyway, I would highly be surprised that eglibc would not run on non-VFP
hardware at all. So definitely, it looks (to me) like a bug in QEMU.
Regards,
Yann E. MORIN.
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next prev parent reply other threads:[~2011-11-08 22:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-06 16:28 Mircea Gherzan
2011-11-06 16:55 ` Yann E. MORIN
2011-11-06 19:46 ` Mircea Gherzan
2011-11-07 1:16 ` Yann E. MORIN
2011-11-08 12:23 ` Mircea Gherzan
2011-11-08 17:19 ` Richard Earnshaw
2011-11-08 22:37 ` Yann E. MORIN [this message]
2011-11-09 8:39 ` Mircea Gherzan
2011-11-10 20:16 ` Yann E. MORIN
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