// Absorb flag constants into SETxx ops.
((SETEQ|SETLE|SETGE|SETBE|SETAE) (FlagEQ))     => (MOVLconst [1])
((SETNE|SETL|SETG|SETB|SETA)     (FlagEQ))     => (MOVLconst [0])
((SETNE|SETL|SETLE|SETB|SETBE)   (FlagLT_ULT)) => (MOVLconst [1])
((SETEQ|SETG|SETGE|SETA|SETAE)   (FlagLT_ULT)) => (MOVLconst [0])
((SETNE|SETL|SETLE|SETA|SETAE)   (FlagLT_UGT)) => (MOVLconst [1])
((SETEQ|SETG|SETGE|SETB|SETBE)   (FlagLT_UGT)) => (MOVLconst [0])

// func checkASM() bool
TEXT ·checkASM(SB),NOSPLIT,$0-1
	// check that masks<>(SB) and shifts<>(SB) are aligned to 16-byte
	MOVQ	$masks<>(SB), AX
	MOVQ	$shifts<>(SB), BX
	ORQ	BX, AX
	TESTQ	$15, AX
	SETEQ	ret+0(FP)
	RET

// these are arguments to pshufb. They move data down from
// the high bytes of the register to the low bytes of the register.
// index is how many bytes to move.