[LLVMdev] error: instruction requires: thumb2

[Jim Grosbach]

Sure. Use legal ARM mode syntax for the instruction.

Specifically, there is no offset immediate for the ARM mode LDREX instruction. It's illegal syntax to supply one, even if it's zero.

-Jim

On Aug 16, 2012, at 2:36 PM, Lei Zhao <leizhao833 at gmail.com> wrote:

> It works. But a follow-up question: why do I have to compile it to thumb mode in order to pass the compilation? Is there a way to make it compile to regular arm mode? Thanks.
> 
> - Lei
> 
> On Aug 16, 2012, at 4:00 PM, Eli Friedman wrote:
> 
>> On Thu, Aug 16, 2012 at 12:55 PM, Lei Zhao <leizhao833 at gmail.com> wrote:
>>> Hi Everybody,
>>> 
>>> I recently did a cross-compiling using clang (built with host=x86, target=arm) with the following command:
>>> 
>>>> clang -march=armv7-a -mfloat-abi=soft -ccc-host-triple arm-none-linux-gnueabi -integrated-as main.c -o main.o -c
>>> 
>>> and get error message:
>>> 
>>> -------------------------------------------------------
>>> main.c:9:9: error: instruction requires: thumb2
>>>       "ldrex %[oldValue], [%[ptr], #0]\n" // oldValue = *ptr
>>>       ^
>>> <inline asm>:1:2: note: instantiated into assembly here
>>>       ldrex r6, [r4, #0]
>>>       ^
>>> main.c:11:3: error: instruction requires: thumb2
>>>       "strexeq %[failed], %[newValue], [%[ptr], #0]\n"
>>>        ^
>>> <inline asm>:3:1: note: instantiated into assembly here
>>> strexeq r5, lr, [r4, #0]
>>> ^
>>> 2 errors generated.
>>> -------------------------------------------------------
>>> 
>>> In the main.c, some ARM assembly are embedded which contains instructions ldrex, strexeq. I don't know what the message suggests since the cpu specified does support thumb2. Could someone help? Thanks.
>> 
>> Try "-mthumb".
>> 
>> -Eli
> 
> 
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