Sean Anderson 726a802fda arm: Use builtins for ffs/fls ...

Since ARMv5, the clz instruction allows for efficient implementation of
ffs/fls with builtins. Until ARMv7 (with Thumb-2), this instruction is
only available in ARM mode. LTO makes it difficult to force specific
functions to be in ARM mode, as it is effectively a form of very
aggressive inlining. To work around this, fls/ffs are implemented in
assembly for ARMv5 and ARMv6 when compiling U-Boot in Thumb mode.
Overall, this saves around 75 bytes per call.

This code is synced with v5.15 of the Linux kernel.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

2023-08-17 16:39:20 -04:00

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__ffs.h

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__fls.h

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builtin-__ffs.h

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builtin-__fls.h

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builtin-ffs.h

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builtin-fls.h

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fls64.h

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fls.h

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