When it comes to comparison to SYCL, HIP is much closer to the spirit of SYCL than ROCm is. Both aim to help writing a single codebase that'll run across multiple hardwares. For now though, the trajectory of SYCL appears much more promising to me than HIP. HIP is already split in two parts for CPU and GPU, which is baffling, and neither part seems to receive much love from AMD.
SYCL can get pretty much equivalent performance in Kernels to eg. CUDA. Try looking at SYCL performance papers on Arxiv. Eg. see [1].
That isn't to say that SYCL code is optimised on every platform without tweaking - you do still need to put effort into target specific optimizations to get the best performance, like you would in the CUDA or HIP.
> Why drop ROCm (used on the world's largest supercomputer?)
Some of the world's largest super-computers / HPC applications do use SYCL for AMD! The application I'm most aware of for this is GROMACS. As to why? - because having 3 version of the same code using different programming APIs is a big maintenance burden.
The fact that GROMACS is unwilling to drop CUDA support to stand fully behind SYCL is very telling.
> Banding together with Intel to support SYCL would in my opinion
Except that Intel has more control over SYCL and has repeatedly hurt AMD products with anticompetitive behavior in the past. Why would AMD permit their software to be controlled be a competitor?
AMD is executing with ROCm NOW, with multiple Top500 supercomputer wins and deployment in major cloud vendors with MI300X. Yes, the software needs to improve, but the practice of throwing out software to start over is not a good strategy.
AMD has far more momentum in the data center than INTC at present.