Normalize floating point environment on startup #38420
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yuyichao
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Nov 13, 2020
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yuyichao
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LGTM.
FWIW, I believe I tested subnormals on the ARM cores and they weren't really slower. Of course it was with cortex-a57 and things might have changed.
In #38419 we noticed that on AArch64 Darwin, processes start with the FZ and DN floating point flags set. To maintain consistency across platforms, reset these flags whenever we start julia. Not that default_nans isn't available on x86, so while we do have julia-level wrappers for the fz flag, I'm not adding any for the dn flag. The function is exported, so if somebody really needs it in some aarch64-specific code, they can ccall it.
KlausC
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Nov 14, 2020
src/processor_fallback.cpp
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| return 0; | ||
| } | ||
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| extern "C" JL_DLLEXPORT int32_t jl_set_zero_subnormals(int8_t isDefault) |
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shouldn't that be jl_set_default_nans ?
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In #38419 we noticed that on AArch64 Darwin, processes start with the
FZ and DN floating point flags set. To maintain consistency across platforms,
reset these flags whenever we start julia. Not that default_nans isn't available
on x86, so while we do have julia-level wrappers for the fz flag, I'm not
adding any for the dn flag. The function is exported, so if somebody really
needs it in some aarch64-specific code, they can ccall it.
cc @oscardssmith
Fixes #38419