Re-enable Neon dot on unknown chipsets (Armv7), improve Unisoc vendor detection #342
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JacobSzwejbka
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larryliu0820
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In #265, I disabled Neon dot product instructions on certain Unisoc chipsets due to sporadic SIGILL crashes. This reduced the occurance substantially, but we still saw some crashes on Unisoc phones. I tracked this down to cpuinfo vendor detection failing on some phones due to conflicting Unisoc and Spreadtrum vendor info and thus not hitting the check. I disabled neondot on all unknown chipsets on armv7 in #300, based on the (faulty) assumption that major chipsets would not be considered to have an unknown vendor.
That assumption was not correct, so I've refined the check in this PR to resolve the ambiguity in vendor detection and re-enabling neon dot instructions on unknown chipsets in armv7 mode. This should resolve the issue for unisoc phones and undo any perf regression for non-Unisoc devices.