[LLVMdev] Unknown or runtime type in function definition?

[Daniel Dunbar]

On Fri, Apr 9, 2010 at 3:11 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
> On Fri, Apr 9, 2010 at 2:11 PM, Bueno, Denis <denbuen at sandia.gov> wrote:
>> Hello all,
>>
>> I'm trying to understand a bit of LLVM IR syntax.  I have a function
>> definition which looks like this in IR:
>>
>>    define void @foo(%1* ptr) { ...
>>
>> The C code for foo has a definition that looks like:
>>
>>    typedef struct bar_struct bar;
>>    ... Definition of struct bar_struct ...
>>    void foo(bar *ptr) { ...
>>
>> I can't whittle down a convenient test source file just now; but I'm trying
>> to understand what the syntax of the 'define' above means -- specifically,
>> what does it mean for a parameter to have type '%1*'?  What is the semantics
>> here?  Inside the body of @foo, there is an SSA variable %1 -- is that
>> variable related to the %1 in the type of the parameter?  (It doesn't seem
>> to be, which is why I ask.)
>
> In that context, %1 refers to an unnamed struct; whether %1 refers to
> a type or a value is determined by the context.  Short example which
> should help:

FWIW, I personally regard this as a bug not a feature. It doesn't make
the IR any easier to read.

 - Daniel

>
> %0 = type { i32, float, float, double }
> define i32 @a(%0*) {
> entry:
>  getelementptr %0* %0, i32 0, i32 0
>  load i32* %1
>  ret i32 %2
> }
>
> -Eli
>
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