libc/string/memset.c: Use unsigned long for stores

[arichardson]

Summary

While most 64-bit architectures have an assembly implementation of this
file, RISC-V does not. As we now store 8 bytes instead of 4 it should speed
up RISC-V.

[jrtc27]

Would (u)intptr_t make more sense so it's faster on CHERI? Doesn't make a difference upstream but does to us.

[arichardson]

In D29536#662074, @jrtc27 wrote:

Would (u)intptr_t make more sense so it's faster on CHERI? Doesn't make a difference upstream but does to us.

I thought about that, but that would require additional changes to create an all-ones capability register.

[jrtc27]

In D29536#662083, @arichardson wrote:

In D29536#662074, @jrtc27 wrote:

Would (u)intptr_t make more sense so it's faster on CHERI? Doesn't make a difference upstream but does to us.

I thought about that, but that would require additional changes to create an all-ones capability register.

Oh, right, memset not bzero, never mind then

[arichardson]

ping?

[kib]

lib/libc/string/memset.c

91

Did you considered lowering 3 to e.g. 2?

[arichardson]

lib/libc/string/memset.c

91

This might make sense but I feel uncomfortable making that change without benchmarks.

[arichardson]

Drop #undef and add a TODO comment for the threshold

[arichardson]

Fix TODO comment