keccak: Fix keccakf1600 implementation selection #168
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1. On macOS __builtin_cpu_init() must be called directly because otherwise it will run after select_keccakf1600_implementation(). See https://bugs.llvm.org/show_bug.cgi?id=48459. 2. Check availability of both BMI and BMI2. Some CPUs like Intel E5-2697 v2 incorrectly report BMI2 being available. Co-authored-by: yperbasis <[email protected]>
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| // This is needed on macOS because of the bug: https://bugs.llvm.org/show_bug.cgi?id=48459. | ||
| __builtin_cpu_init(); | ||
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| // Check if both BMI and BMI2 are supported. Some CPUs like Intel E5-2697 v2 incorrectly |
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Do you have some kind of bug report / errata link for this?
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No. This comes from experiments on CI.
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I can't even find any details spec of E5-2697 v2. I checks the assembly code generated by __builtin_cpu_supports("bmi2") and it looks correct. I also found a case where for some other Intel CPU it was reporting some features not actually available. That was fixed by BIOS update :)
Seems like a CPU bug, but no more information than this.
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I also found a case where for some other Intel CPU it was reporting some features not actually available. That was fixed by BIOS update :)
That sounds like a new microcode was pushed to the BIOS. The microcode must be loaded on every cold start.
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otherwise it will run after select_keccakf1600_implementation().
See https://bugs.llvm.org/show_bug.cgi?id=48459.
Intel E5-2697 v2 incorrectly report BMI2 being available.