[llvm-commits] Source register same as write-back base

[Jakob Stoklund Olesen]

On Apr 11, 2011, at 2:27 PM, Johnny Chen wrote:

> Hi Joe,
> 
> I've CCed llvm-commit.  Hopefully the backend folks can help you out!
> Thanks.
> 
> On Apr 11, 2011, at 2:20 PM, Joe Abbey wrote:
> 
>> Johnny,
>>  
>> I saw your changelist which adds a check to the disassembly of ARM instructions.
>>  
>> I’m currently trying to debug how the register allocation works to produce:
>>  
>> str r3, [r3], #4
>>  
>> My assembler is complaining that:
>>  
>> libtest-libstl.so.bc:46025: Warning: source register same as write-back base
>>  
>> And it should because as you (and ARM) note, this is UNPREDICTABLE.

Is this the same situation as the armV5 MUL instructions where the documents say it is unpredictable, but all existing hardware implementations behave correctly?

Which architecture revisions have this constraint?

/jakob