[llvm-dev] How to implement function pointer?

[Philip Pfaffe via llvm-dev]

Hi Yafei,

a Value whose type is a FunctionType _is_ a function pointer. You use
FunctionType::get to create such a type given the return type and the
argument types. Or you call foo->getType() if foo is a Function* :)

Cheers,
Philip

On Tue, Feb 26, 2019 at 12:41 PM Yafei Liu <yfliu at mobvoi.com> wrote:

> Hi Philip,
> Isn't function pointer a pointer first? I checked  FunctionType and still
> have no idea about how to do this, can you show me which api in
> FunctionType should I use?
>
> On Tue, Feb 26, 2019 at 7:18 PM Philip Pfaffe <philip.pfaffe at gmail.com>
> wrote:
>
>> Hi Yafei,
>>
>> you're looking for the [FunctionType](
>> http://llvm.org/doxygen/classllvm_1_1FunctionType.html).
>>
>> Cheers,
>> Philip
>>
>> On Tue, Feb 26, 2019 at 11:15 AM Yafei Liu via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hi, I'm learning to use llvm api to generate IR code, I got two good
>>> tutorials, https://llvm.org/docs/tutorial/ and
>>> https://www.ibm.com/developerworks/library/os-createcompilerllvm1/index.html,
>>> but non of those showed how to implement a function pointer(or at least
>>> there is but I didn't find out).
>>>
>>> For example I got a c style code like this:
>>>
>>> int foo(int i) {
>>>   return ++i;
>>> }
>>>
>>> int (*p)(int);
>>>
>>> int main() {
>>>   p = foo;
>>>   p(3);
>>> }
>>>
>>> I turn it into IR code and found the sytex of a function pointer is:
>>> @p = global i32 (i32)* null, align 8
>>> I tried play with llvm::PointerType but I cannot get the sytex, so could
>>> anyone teach me how to do this?
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>
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