[PATCH] D59576: [X86] Add CMPXCHG8B feature flag. Set it for all CPUs except i386/i486 including 'generic'. Disable use of CMPXCHG8B when this flag isn't set.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D59576#1437153 <https://reviews.llvm.org/D59576#1437153>, @efriedma wrote:

> Does this affect the assembler?  If so, should we also have an assembler testcase?


I shouldn't. We don't do fine grained feature control in the X86 assembler. The only AssemblerPredicates we have have are for 16/32/64 bit mode. We do block cmpxchg16b in 64-bit mode, but we shouldn't have to block cmpxchg8b anywhere.


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