Conor Dooley 7816ebc1dd RISC-V: remove decrement/increment dance in ISA string parser
While expanding on the comments in the ISA string parsing code, I
noticed that the conditional decrement of `isa` at the end of the loop
was a bit odd.
The parsing code expects that at the start of the for loop, `isa` will
point to the first character of the next unparsed extension.
However, depending on what the next extension is, this may not be true.
Unless the next extension is a multi-letter extension preceded by an
underscore, `isa` will either point to the string's null-terminator or
to the first character of the next extension, once the switch statement
has been evaluated.
Obviously incrementing `isa` at the end of the loop could cause it to
increment past the null terminator or miss a single letter extension, so
`isa` is conditionally decremented, just so that the loop can increment
it again.

It's easier to understand the code if, instead of this decrement +
increment dance, we instead use a while loop & rely on the handling of
individual extension types to leave `isa` pointing to the first
character of the next extension.
As already mentioned, this won't be the case where the following
extension is multi-letter & preceded by an underscore. To handle that,
invert the check and increment rather than decrement.
Hopefully this eliminates a "huh?!?" moment the next time somebody tries
to understand this code.

Reviewed-by: Andrew Jones <[email protected]>
Signed-off-by: Conor Dooley <[email protected]>
Reviewed-by: Sunil V L <[email protected]>
Link: https://lore.kernel.org/r/20230607-estate-left-f20faabefb89@spud
Signed-off-by: Palmer Dabbelt <[email protected]>
2023-06-21 07:45:17 -07:00
2022-09-28 09:02:20 +02:00
2023-05-07 13:34:35 -07:00
…

Linux kernel
============

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several of them using the Restructured Text markup notation.

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