On Mon, May 17, 2010 at 12:01 PM, Gilles Chanteperdrix
<[email protected]> wrote:
> Jeremy Brown wrote:
>> On Mon, May 17, 2010 at 11:25 AM, Gilles Chanteperdrix
>> <[email protected]> wrote:
>>> Jeremy Brown wrote:
>>>> {standard input}: Assembler messages:
>>>> {standard input}:140: Error: selected processor does not support `rsc
>>>> r7,r7,#0'
>>>> {standard input}:159: Error: selected processor does not support `rsc
>>>> r1,r1,#0'
>>>> make: *** [libxenomai_la-timeconv.lo] Error 1
>>> Ok. Could you try and compile the following piece of code with your
>>> toolchain and show me the disassembly ?
>>>
>>> long long foo(long long x)
>>> {
>>> return -x;
>>> }
>>>
>>> --
>>> Gilles.
>>
>> Thanks for the quick reply! Here's the complete contents of foo.s:
>>
>> .syntax unified
>
> That is the key: I presume this means your compiler generates syntax
> which works both with ARM and thumb2, and rsc does not exist with
> thumb2. Note that from a performance point of view, this may not be a win.
Ah, success --- based on your note, a colleague of mine determined
that arranging to pass gcc the (undocumented) "-marm" flag enables the
compiler to build the unpatched Xenomai 2.5.3 sources from beginning
to end. For posterity, I recompiled your example code with -O2 -marm,
and appended it below.
Thank you for all of your help!
Jeremy
.arch armv7-a
.eabi_attribute 27, 3
.fpu vfpv3-d16
.eabi_attribute 20, 1
.eabi_attribute 21, 1
.eabi_attribute 23, 3
.eabi_attribute 24, 1
.eabi_attribute 25, 1
.eabi_attribute 26, 2
.eabi_attribute 30, 2
.eabi_attribute 18, 4
.file "foo.c"
.text
.align 2
.global foo
.type foo, %function
foo:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
rsbs r2, r0, #0
rsc r3, r1, #0
mov r1, r3
mov r0, r2
bx lr
.size foo, .-foo
.ident "GCC: (Ubuntu 4.4.3-4ubuntu5) 4.4.3"
.section .note.GNU-stack,"",%progbits
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