[llvm-commits] Fix bug 12769 MCAssembler crashes with -mthumb -mcpu=cortex-a9

[Jim Grosbach]

Can you add a test case? Other than that, this looks good to me.

-Jim

On May 9, 2012, at 6:21 PM, Weiming Zhao wrote:

> Hi,
> 
> Attached is updated patch based on Tim's suggestion.
> I also updated the bugzilla as well.
> I run the test suite and unit test. No new fails.
> 
> Thanks,
> Weiming
> 
> -----Original Message-----
> From: Tim Northover [mailto:t.p.northover at gmail.com] 
> Sent: Wednesday, May 09, 2012 11:55 AM
> To: Weiming Zhao
> Cc: llvm-commits at cs.uiuc.edu
> Subject: Re: [llvm-commits] Fix bug 12769 MCAssembler crashes with -mthumb
> -mcpu=cortex-a9
> 
> Hi Weiming,
> 
> Apologies if this gets through twice. I tried earlier but the list seems to
> be eating e-mails from that address for some reason.
> 
>> This patch fixes the issue. And it also passes the test suite. For the 
>> unit tests, it doesn't create new fails. (details are in tests.tar)
> 
> In this case, I believe we actually need an R_ARM_THM_JUMP24 which will put
> the immediate into the correct bits for a Thumb unconditional branch. If you
> look at the ARM ELF ABI and the architecture reference manual you'll see
> that if a linker encountered R_ARM_THM_CALL it would put the immediate into
> bits 0-11 and 16-26, stamping all over your lovingly crafted B.W
> instruction.
> 
> We could also do with some tests for this specific issue: a examples for a
> similar case can be found in test/MC/ARM/elf-reloc-condcall.s.
> 
> Cheers.
> 
> Tim.
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