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

[Weiming Zhao]

Hi Jim,

Attached is the test case (test/MC/ARM/thumb2-uncond-branch.s)
Since llvm-objdump can't be piped, I have to let llvm-mc to generate a temp
file (a.out).
And if I just run llvm-mc -show-encoding, it won't cover the polemic code.

If you think this test is OK, I'll update the bugzilla as well.

Thanks,
Weiming


-----Original Message-----
From: Jim Grosbach [mailto:grosbach at apple.com] 
Sent: Wednesday, May 09, 2012 7:25 PM
To: Weiming Zhao
Cc: 'Tim Northover'; llvm-commits at cs.uiuc.edu
Subject: Re: [llvm-commits] Fix bug 12769 MCAssembler crashes with -mthumb
-mcpu=cortex-a9

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.
> <fix-12769_2.patch>_______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits

-------------- next part --------------
A non-text attachment was scrubbed...
Name: thumb2-uncond-branch.s
Type: application/octet-stream
Size: 350 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20120510/2f4c646f/attachment.obj>