3 ms·
486 ALU stuff is mostly 1 cycles as well (other than shifts, MUL and DIV, and all the weird stuff like AAD), as well as stores and loads. Taken conditional jump
by vardump 4y ago
486 ALU stuff is mostly 1 cycles as well (other than shifts, MUL and DIV, and all the weird stuff like AAD), as well as stores and loads. Taken conditional jumps are 3 cycles, non-taken 1 cycle, so loop unrolling helps a lot on 486.
You can approach 0.8 IPC on 486, assuming you know about AGI stalls and other quirks.
General 486-era C-compiler produced code, though, would be lucky to hit 0.4 IPC.
- dmitrygr 4y agoI was taking intel's 80486 promo materials at face value. Plus 486 ALU may be 1-cycle but loads and stores are not 2-cycle like they are for C-M0 so it'll still lose :)
- vardump 4y agoAt least this page says 486 stores and loads are 1 cycle: https://zsmith.co/intel_m.php#mov https://zsmith.co/intel_m.php#mov But it's been over 25 years since I last wrote asm for a 486 CPU.