> More complex instructions that combine multiple processing steps would help, it seems that the core RISC-V community is opposed to that idea out of purely ideological reasons
Thats not true, the Scalar Efficiency SIG is currently working on such an extension.
I remember last year (?) Quancomm proposing an ISA extension that brings ARM-like addressing modes and paired stores to RISC-V, and the community reaction being very negative. Happy to hear that there are now initiatives to streamline these proposals and make RISC-V a better fit for high-performance CPUs. I am looking forward to future developments!
The negative responses were, because Qualcomm wanted to remove the C extension from the application profiles.
Qualcomm prefered a strict 32-bit instruction set, with potentially 64 bit naturally aligned instructions. RISC-V is designed for 16, 32, 48, 64 bit instructions that are 16 bit aligned, and retroactively changing that wouldn't have been a good decision. Both sides of the argument agreed that both options are resonable and don't hinder high performance designs.
Qualcomm seems to have accepted this now, as they e.g. proposes 48 bit instructions with larger immediats.