Let's take the nVidia Fermi Compute Architecture. It says:
The first Fermi based GPU, implemented with 3.0 billion transistors, features up to 512 CUDA cores. A CUDA core executes a floating point or integer instruction per clock for a thread. The 512 CUDA cores are organized in 16 SMs of 32 cores each.
[...]
Each CUDA processor has a fully pipelined integer arithmetic logic unit (ALU) and floating point unit (FPU).
[...]
In Fermi, the newly designed integer ALU supports full 32-bit precision for all instructions, consistent with standard programming language requirements. The integer ALU is also optimized to efficiently support 64-bit and extended precision operations. V
From what I know, and what is unclear for me, is that GPUs execute the threads in so called warps, each warp consists of ~32 threads. Each warp is assigned to only one core (is that true?). So does that mean, that each of the 32 cores of a single SM is a SIMD processor, where a single instruction handles 32 data portions ? If so, then why we say there are 32 threads in a warp, not a single SIMD thread? Why cores are sometimes referred to as scalar processors, not vector processors ?