A lot of it is about having shorter versions for frequently used instructions. E.g. compare and branch is just one instruction on RISC-V. More complex instructions simply are not used frequently so their ability to reduce code size isn't as big as people think.
In addition RISC-V has twice as many registers as ARM-32 Cortex-A9, which the particular CoreMark was comparing against. Also a different ABI conventions reduce the number of instructions spent on saving and restoring registers. E.g. RISC-V has certain registers marked as saved, temporary, arguments etc.
Then of course for RISC-V it isn't expensive to support compressed instructions. You use the same decoder not different modes and different decoders like ARM. Just 400 gates to implement, so it is kind of a no-brainer.
If comparing SPEC CPU2006 benchmark code using GCC compiler then uncompressed RISC-V vs uncompressed ARM is basically the same. Compressed RISC-V and compressed ARM is basically the same. The latter beats x86 by about 26%.
Uncompressed RISC-V is just 8% bigger than x86. So I would say in general RISC-V is paying a very small price for its simplicity. One could say there is a benefit in being able to learn from past mistakes.
In addition RISC-V has twice as many registers as ARM-32 Cortex-A9, which the particular CoreMark was comparing against. Also a different ABI conventions reduce the number of instructions spent on saving and restoring registers. E.g. RISC-V has certain registers marked as saved, temporary, arguments etc.
Then of course for RISC-V it isn't expensive to support compressed instructions. You use the same decoder not different modes and different decoders like ARM. Just 400 gates to implement, so it is kind of a no-brainer.
If comparing SPEC CPU2006 benchmark code using GCC compiler then uncompressed RISC-V vs uncompressed ARM is basically the same. Compressed RISC-V and compressed ARM is basically the same. The latter beats x86 by about 26%.
Uncompressed RISC-V is just 8% bigger than x86. So I would say in general RISC-V is paying a very small price for its simplicity. One could say there is a benefit in being able to learn from past mistakes.