[PATCH v9 06/12] riscv: prevent compressed instructions in alternatives

Philipp Tomsich philipp.tomsich at vrull.eu
Wed Apr 13 02:09:07 PDT 2022


On Wed, 13 Apr 2022 at 05:03, Heiko Stuebner <heiko at sntech.de> wrote:
>
> Instructions are opportunistically compressed by the RISC-V assembler
> when possible, but in alternatives-blocks both the old and new content
> need to be the same size, so having the toolchain do somewhat random
> optimizations will cause strange side-effects like
> "attempt to move .org backwards" compile-time errors.
>
> Already a simple "and" used in alternatives assembly will cause these
> mismatched code sizes.
>
> So prevent compressed instructions to be generated in alternatives-
> code and use option-push and -pop to only limit this to the relevant
> code blocks
>
> Signed-off-by: Heiko Stuebner <heiko at sntech.de>
> Reviewed-by: Christoph Hellwig <hch at lst.de>

Reviewed-by: Philipp Tomsich <philipp.tomsich at vrull.eu>



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