Craig Topper 278578744a [X86] Handle SETB_C32r/SETB_C64r in flag copy lowering the same way we handle SBB ...

Previously we took the restored flag in a GPR, extended it 32 or 64 bits. Then used as an input to a sub from 0. This requires creating a zero extend and creating a 0.

This patch changes this to just use an ADD with 255 to restore the carry flag and keep the SETB_C32r/SETB_C64r. Exactly like we handle SBB which is what SETB becomes.

Differential Revision: https://reviews.llvm.org/D74152

2020-02-07 10:31:19 -08:00

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