Piotr Fusik 6e7312bda6 [RISCV] Select and/or/xor with certain constants to Zbb ANDN/ORN/XNOR (#120221) ...

(and X, (C<<12|0xfff)) -> (ANDN X, ~C<<12)
    (or  X, (C<<12|0xfff)) -> (ORN  X, ~C<<12)
    (xor X, (C<<12|0xfff)) -> (XNOR X, ~C<<12)

Emits better code, typically by avoiding an `ADDI HI, -1` instruction.

Co-authored-by: Craig Topper <craig.topper@sifive.com>

2024-12-19 21:38:20 +01:00

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