Devtoolset-9 fixes #841
Devtoolset-9 fixes #841
Conversation
GCC 9 will warn if using memcopy to overwrite the memory area of a non-POD class. The warning is correct, but in these cases, we know that these classes are POD so we can proceed and indicate the intent with a void* cast.
| memcpy(points.data(), mayaRawPoints, numVertices * sizeof(float) * 3); | ||
| memcpy((void*)points.data(), mayaRawPoints, numVertices * sizeof(float) * 3); |
There was a problem hiding this comment.
It often makes me a little uneasy to see void* casts, so this feels a little bit dirty to me. Seems like the compiler would be able to produce better code with more type information rather than less.
points.data() will yield a GfVec3f*, and you could then use another data() call on that to get a float*. I think I'd also use std::copy instead of memcpy and let the compiler figure out the most efficient implementation.
So with that, I'd suggest something like this:
std::copy(mayaRawPoints, mayaRawPoints + numVertices * GfVec3f::dimension, points.data()->data());There was a problem hiding this comment.
Using cdata() on the std::vector turns it into a GfVec3f C pointer, then using ->data would turn it into a full C float pointer. I do not see how the C++ compiler could optimize std::copy given raw C pointers.
Can we meet in the middle? By reshaping the source raw float* into a GfVec3f pointer, then we can use an optimized C++ constructor and skip the zero-fill we had previously.
| memcpy(&points[i], &pointsa[i], 3*sizeof(float)); | ||
| memcpy((void*)&points[i], &pointsa[i], 3*sizeof(float)); |
There was a problem hiding this comment.
Same suggestion as above, but here I think I'd also remove the loops and include the array size in the range being copied?
I'm not really familiar with this code, so I'm not sure why we're initializing the values in one structure and then copying them into another. This is also just test code though, so maybe we don't care all that much.
There was a problem hiding this comment.
Yes, I think we can skip the intermediates and the copy as well.
GCC 9 will warn if using memcopy to overwrite the memory area of a non-POD class. The warning is correct, but in these cases, we know that these classes are POD so we can proceed and indicate the intent with a void* cast.