alt Hacker News32-bit barrel shifters consume significant area and RISC-V was developed to support resource constrained low cost embedded hardware in a minimal ISA implementation.
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adgjlsfhk1 • last Tuesday at 11:20 PM
IIUC this is a lot less true in the modern era. Even with 24nm transistors (the cheapest transistor last time I checked), modern microcontrollers have a fairly big transistor budget for the core (since 80+% of the transistors are going to sram anyway).
jacquesm • last Tuesday at 10:55 PM
You can save a lot of silicon by doing 8 or 16 bit shifters and then doing the rest at the code generation level. Not having any seems really anemic to me.
torginus • yesterday at 9:25 AM
It was the case even 15 years ago when Cortex M0/M3 really started to get traction, that the processor area of ARM cores was small enough to not make a difference in practice.
The 32-bit ARM architecture included a barrel shifter as part of its basic design, as in every instruction had a shift field.
If a CPU built in 1985 with a grand total of 26 000 transistors could afford it, I am pretty sure that anything built in this century could afford it too.