Thread: Apple M1 SoC
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Old 2020-11-29, 21:00   #19
ewmayer
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Sep 2002
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Laurent PMed me results of a clang/llvm Mlucas build attempt. Most of the source files compiled fine, but there is a subset which failed, all due to clang reporting "error: inline assembly requires more registers than available" for the same macro, which is a particularly register-greedy one - the clobber list for the Arm64 ASIMD version of it shows 12 of 16 GPRs and 25 of 32 vector-regs used. I am look into it to see if there is some straightforward way to reduce the number of registers used - alas the compiler didn't include any detail in the error message about the precise *type* of registers clang it needed more of.

The same macro has built fine on Arm64/ASIMD in the past using GCC, so this appears to be something related to Clang optimizations and/or the OS.
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