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

[Jim Grosbach]

Hi Weiming,

Creating a temp file for the output is no problem; however, naming it explicitly like that won't work because it'll end up in the source directory and lit won't know how to clean it up. You can use %t instead to get a temporary file name. test/MC/MachO/ARM/nop-thumb2-padding.s has a good example in its RUN line:
@ RUN: llvm-mc -triple armv7-apple-darwin %s -filetype=obj -o %t.obj             
@ RUN: macho-dump --dump-section-data < %t.obj > %t.dump                         
@ RUN: FileCheck %s < %t.dump 

I suggest checking the actual encoded bits of the instruction and the relocation data  from the object file as well, not just the opcode. You can use separate RUN lines w/ different check prefixes if necessary to have llvm-objdump spit out the different pieces you need to look at.

-Jim

On May 10, 2012, at 12:19 PM, Weiming Zhao <weimingz at codeaurora.org> wrote:

> 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
> 
> <thumb2-uncond-branch.s>