[LLVMdev] Attributes & CloneFunctionInto

[Ralf Karrenberg]

Hi everybody,

for the record, I managed to work around the issue:
- create a temporary function declaration tmpFn with the type and 
attributes of the target function newFn
- remove all attributes of newFn (unintuitive: one has to use 
"newFn->setAttributes" with an empty AttributeSet)
- CloneFunctionInto(newFn, origFn, ...)
- copy attributes back from tmpFn (newFn->copyAttributesFrom(tmpFn))
- erase tmpFn

Cheers,
Ralf

On 5/15/13 5:51 PM, Ralf Karrenberg wrote:
> Hi John,
>
> thanks for the pointer. However, I'd rather avoid rolling a custom
> implementation. After all, it's not like I want to do something
> drastically different...
> I had sorted out the problem for 3.2 as well as a previous version of
> 3.3 trunk, but the API changed about a hundred times. Now as it
> apparently has stabilized, I moved to a the 3.3 release branch just to
> find that even my previous workarounds don't work anymore.
>
> I can't understand why the API of llvm::Function does not simply provide
> two functions
> - setAttribute(unsigned paramIdx, AttributeKind A) and
> - removeAttribute(unsigned paramIdx, AttributeKind A).
>
> Cheers,
> Ralf
>
> On 5/15/13 5:39 PM, John Criswell wrote:
>> On 5/15/13 10:27 AM, Ralf Karrenberg wrote:
>>> Hi,
>>>
>>> I am again struggling to find my way around the Attribute classes.
>>> What I want to do is clone a function into a declaration where some
>>> parameters may have a different alignment.
>>> CloneFunctionInto in debug mode hits an assertion which is marked with
>>> a FIXME (Attributes.cpp:673).
>>> I would be totally fine with any kind of workaround, e.g. removing all
>>> attributes from the target declaration, then cloning, and then setting
>>> the correct attributes.
>>> However, I can't find a way to modify an existing alignment *in any
>>> way* without hitting an assertion (the other one being line 727 for
>>> removeAttributes). I've also tried using addAttributes() and
>>> setAttributes() to set the alignment to 0, but this seems to be
>>> ignored...
>>
>> SAFECode clones a function to change the alignment of byval arguments.
>> You can look at the code at
>> http://llvm.org/viewvc/llvm-project/safecode/branches/release_32/lib/BaggyBoundsChecks/BaggyBoundsChecks.cpp?revision=177641&view=markup.
>>
>>
>>
>> Note that the code works with LLVM 3.2.
>>
>> -- John T.
>>
>>>
>>> Any help on this? :)
>>>
>>> Thanks,
>>> Ralf
>>> _______________________________________________
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>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
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>>
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