[LLVMdev] LLVM 2.6 and Aggregate Return Values: 64 bit

John Criswell criswell at uiuc.edu
Wed Jan 20 07:35:22 PST 2010

Duncan Sands wrote:
> Hi John,
>> How well does LLVM 2.6 support aggregate return values for 64 bit 
>> targets?  I'm currently working on 64 bit Mac OS X and 64 bit Linux.  
>> Are there any known problems or limitations?
> on x86-64 it depends on what you are returning, but for example you
> should be able to return a 128 bit integer fine,
Just to make sure I understand, if the size of the aggregate return 
value is 128 bits or less, then it should work.  Correct?
>  but anything more
> will cause the code generator blow up.
By "blow up," do you mean that the code generator will fail to generate 
code at all (e.g., it will hit an assertion) or do you mean that the 
code generator will generate incorrect code?  I am seeing the latter in 
my code, and I currently suspect it's a code generator bug (though I 
could be wrong).

-- John T.

>   This limitation has been
> removed in the development version.
> Ciao,
> Duncan.

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