# can you use \`restrict\` on data members with cudaMalloc?
**URL:** https://forums.developer.nvidia.com/t/can-you-use-restrict-on-data-members-with-cudamalloc/57365
**Category:** CUDA Programming and Performance
**Created:** [January 23, 2018, 11:24am UTC](https://forums.developer.nvidia.com/t/can-you-use-restrict-on-data-members-with-cudamalloc/57365 "2018-01-23T11:24:00Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@svennevs](https://forums.developer.nvidia.com/u/svennevs)
#### Post date: [January 23, 2018, 11:24am UTC](https://forums.developer.nvidia.com/t/can-you-use-restrict-on-data-members-with-cudamalloc/57365/1 "2018-01-23T11:24:00Z")
I am redoing some code to make sure I am taking advantage of **restrict** where applicable. For functions, it’s golden. But I’d like to also apply it to struct members, which is supposed to be valid: [http://en.cppreference.com/w/c/language/restrict#Struct\_members](http://en.cppreference.com/w/c/language/restrict#Struct_members)
However, I can’t figure out how to do this (or if it is even possible) because **cudaMalloc** needs a **void \*\***. Example
```auto
struct MyData {
float4 * __restrict__ a = nullptr;
float4 * __restrict__ b = nullptr;
static const int N = 20;
void allocate() {
cudaMalloc(
// reinterpret_cast(&a), // cannot cast away 'const' or other qualifiers
&a,
N * sizeof(float4)
);
cudaMalloc(
&b,
N * sizeof(float4)
);
}
void free() {
cudaFree(a);
cudaFree(b);
}
};
int main(void) {
MyData data;
data.allocate();
data.free();
}
```
Errors with
```auto
error: no instance of overloaded function "cudaMalloc" matches the argument list
argument types are: (float4 * __restrict__ *, unsigned long)
```
In reality I think I have all of my bases covered, the methods where **a** and **b** are actually used in functions are marked as **restrict**. I was just wondering if the above is supported, planned to be, not possible to support, etc. Thanks for any thoughts!
---
### Author:  [@cbuchner1](https://forums.developer.nvidia.com/u/cbuchner1)
#### Post date: [January 23, 2018, 3:42pm UTC](https://forums.developer.nvidia.com/t/can-you-use-restrict-on-data-members-with-cudamalloc/57365/2 "2018-01-23T15:42:41Z")
this variant builds for me with nvcc -std=c++11 -o test test.cu from the either the CUDA 7.5, 8.0 or the 9.1 toolkit.
sometimes the simplest typecasts are the best ;)
```auto
void allocate() {
cudaMalloc(
(void**)&a,
N * sizeof(float4)
);
cudaMalloc(
(void**)&b,
N * sizeof(float4)
);
}
```
---
### Author:  [@svennevs](https://forums.developer.nvidia.com/u/svennevs)
#### Post date: [January 23, 2018, 11:48pm UTC](https://forums.developer.nvidia.com/t/can-you-use-restrict-on-data-members-with-cudamalloc/57365/3 "2018-01-23T23:48:21Z")
> [@](#):
>
> sometimes the simplest typecasts are the best ;)
Indeed! I can’t believe I didn’t even try that _faceslap_. Thanks :)