[LLVMdev] Problem returning aggregate struct (complex number) by value

Andrew Friedley afriedle at indiana.edu
Fri Apr 2 13:12:11 PDT 2010

Duncan Sands wrote:
> Hi Andrew,
>> %0 = type { float, float }
>> define %0 @test600() {
>> entry:
>>     ret %0 { float 4.200000e+01, float 3.500000e+01 }
>> }
>> Running that through llc, the x86-64 assembly looks like this (abbreviated):
> unfortunately the x86-64 ABI says that complex numbers are *not* passed the
> same as a struct containing two floats.  Your LLVM IR is not ABI conformant
> and thus will not interact properly with ABI conformant code, like that produced
> by llvm-gcc.

Thanks for the response.  I'm aware of that, but dont think I quite 
understand why that affects me here -- I'm using structs in all cases 
(although as an abstraction for a complex number), not actual C99 
complex.  Does LLVM just assume that I really mean C99 complex when I'm 
working with a struct of two floats?

Even so this doesn't answer my question, of what can I do to make this 
work? :)


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