CODEWITHSUNDEEP
cuda
tnknepp
tnknepp

Reputation: 6253

Did CUDA programming change from C to C++?

Before I dive too deep into CUDA programming I need to orient myself. The NVIDIA CUDA programming guides made a distinct change from referring to "CUDA C" to "CUDA C++" between versions 10.1 and 10.2. Since this was a minor version change, I suspect it is just semantics. I compared sample code from pre-10.1 and post-10.2 and found no difference...though that doesn't mean there is no difference. Was there a more subtle programming paradigm shift between these versions?

Here's my suspicion: CUDA has always been an extension of C++, not C, but everyone has referred to it as CUDA C because the we don't take advantage of the OOP offered by C++ when writing CUDA code. Is that a fair assessment?

Upvotes: 5

Views: 1181

Answers (1)

Robert Crovella
Robert Crovella

Reputation: 151799

I think your assessment is reasonable conjecture. People are sometimes imprecise in their references to C and C++, and so CUDA probably hasn't been very rigorous here either. There is some history though that suggests to me this is not purely hand-waving.

CUDA started out as largely a C-style realization, but over time added C++ style features. Certainly by CUDA 4.0 (circa 2010) if not before, there were plenty of C++ style features.

Lately, CUDA drops the reference to C but claims compliance to a particular C++ ISO standard, subject to various enumerated restrictions and limitations.

The CUDA compiler, nvcc, behaves by default like a C++ style compiler (so, for example, using C++ style mangling), and will by default invoke the host-code C++ compiler (e.g. g++) not the host code C compiler (e.g. gcc) when passing off host code to be compiled.

As you point out, a programmer can use the C++ language syntactically in a very similar way to C usage (e.g. without the use of classes, to pick one example). This is also true for CUDA C++.

It's not possible to build Rome in a day, and so CUDA development has proceeded in various areas at various rates. For example, one stated limitation of CUDA is that elements of the standard library (std::) are not necessarily supported in device code. However various CUDA developers are working to gradually fill in this gap with the libcu++ evolution.

Upvotes: 8

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