[LLVMdev] [Patch] Let MC/ELF generate Thumb/Thumb-2 are properly

[Koan-Sin Tan]

Jim, 

Thanks, I'll do it accordingly.

Sent from my iPhone

On May 13, 2011, at 11:04 PM, Jim Grosbach <grosbach at apple.com> wrote:

> Hi Koan,
> 
> In general, this looks OK to me. Please split the patch into separate pieces, one for each issue you're addressing, though. From your description, it sounds like this should be 4 patches. That way we have a cleaner revision history in svn.
> 
> -Jim
> 
> On May 12, 2011, at 10:42 PM, Koan-Sin Tan wrote:
> 
>> Hi,
>> 
>> We are trying to use clang as a drop-in replacement for the gcc come with
>> Android NDK. I found that MC/ELF doesn't not handle Thumb functions properly,
>> e.g., bit 0 of the function name in the .symtab is not set to 1, and some thumb
>> instructions are not generated correctly, e.g., the addresses for tBL/tBLX are
>> not calculated right.
>> 
>> With that attached patch, we can compile and run some (not all) Android
>> NDK samples without problem.
>> 
>> The attached initial patch
>> 1. sets bit 0 of the function address of thumb function in .symtab
>>  ("T is 1 if the target symbol S has type STT_FUNC and the
>>  symbol addresses a Thumb instruction ;it is 0 otherwise."
>>  from "ELF for the ARM Architecture" 4.7.1.2)
>> 
>> 2. fixes target address tBL and tBLX
>> 3. sets relocation type of tBL/tBLX to R_ARM_THM_CALL
>>   (4.7.1.6)
>> 4. adds some attributes to attribute section when cpu is "xscale"
>>  (this is what used in Android NDK, when architecture is ARMv5)
>> 
>> --
>> // koan-sin tan
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