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Matt Turner
de5a4687c0
find_zero_ne_all () searches for a zero byte in X1 or a byte that differs between X1 and X2. A caller that knows X2 contains no NUL byte does not need the zero test, since a NUL byte in X1 already differs from every byte of X2. Add find_ne_all (), which searches for inequality alone, to the generic implementation and to each target that provides its own string-fza.h. Dropping the zero test makes it cheaper than find_zero_ne_all () on every target. Return the difference unreduced wherever index_first () and index_last () come from the generic string-fzi.h, which uses stdc_trailing_zeros () and stdc_leading_zeros () and so only needs to know which byte holds the first or the last set bit. That covers armv6t2, powerpc and riscv with the bitmap extensions, as well as the generic implementation. Only the generic one tests HAVE_BITOPTS_WORKING, since its fallback ctzb () and clzb () isolate a single bit and expect it at 0x80; the target masks are already incompatible with that fallback and cannot use it either way. riscv without the bitmap extensions takes its string-fza.h from the generic implementation while defining its own index_first () and index_last (), which tested bit 7 of each byte. Test the whole byte instead, so that they accept the unreduced difference. alpha keeps a reduced form, its find_t being a cmpbge mask of one bit per byte throughout. Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>