(F(MADD|NMADD|MSUB|NMSUB)S neg:(FNEGS x) y z) && neg.Uses == 1 => (F(NMSUB|MSUB|NMADD|MADD)S x y z)
(F(MADD|NMADD|MSUB|NMSUB)S x y neg:(FNEGS z)) && neg.Uses == 1 => (F(MSUB|NMSUB|MADD|NMADD)S x y z)
(F(MADD|NMADD|MSUB|NMSUB)D neg:(FNEGD x) y z) && neg.Uses == 1 => (F(NMSUB|MSUB|NMADD|MADD)D x y z)

		{name: "SUB", argLength: 2, reg: gp21, asm: "SUB"},                                                 // arg0-arg1
		{name: "SUBCC", argLength: 2, reg: gp21, asm: "SUBCC", typ: "(Int,Flags)"},                         // arg0-arg1 sets CC
		{name: "SUBFCconst", argLength: 1, reg: gp11cxer, asm: "SUBC", aux: "Int64"},                       // auxInt - arg0 (carry is ignored)

		}
	}

	// Clone should make a copy of bSub, since bSub is just part of b and so is in the arena.
	bSub := b[1:3]
	bSubCopy := UserArenaClone(bSub)
	if unsafe.Pointer(&bSub[0]) == unsafe.Pointer(&bSubCopy[0]) {
		t.Errorf("Clone did not make a copy: %#v -> %#v", bSub, bSubCopy)
	}
	if len(bSub) != len(bSubCopy) {
		t.Errorf("Clone made an incorrect copy (bad length): %d -> %d", len(bSub), len(bSubCopy))
	} else {

		// F extension.
		{name: "FADDS", argLength: 2, reg: fp21, asm: "FADDS", commutative: true, typ: "Float32"},                                           // arg0 + arg1
		{name: "FSUBS", argLength: 2, reg: fp21, asm: "FSUBS", commutative: false, typ: "Float32"},                                          // arg0 - arg1

	AFMULCC
	AFMULS
	AFMULSCC
	AFNABS
	AFNABSCC
	AFNEG
	AFNEGCC
	AFNMADD
	AFNMADDCC
	AFNMADDS
	AFNMADDSCC
	AFNMSUB
	AFNMSUBCC
	AFNMSUBS
	AFNMSUBSCC
	AFRSP
	AFRSPCC
	AFSUB
	AFSUBCC
	AFSUBS
	AFSUBSCC
	AISEL
	AMOVMW
	ALBAR
	ALHAR
	ALSW
	ALWAR
	ALWSYNC
	AMOVDBR
	AMOVWBR
	AMOVB
	AMOVBU
	AMOVBZ
	AMOVBZU
	AMOVH
	AMOVHBR
	AMOVHU

	// This is the same heuristic that libpng uses, although the filters are attempted in order of
	// estimated most likely to be minimal (ftUp, ftPaeth, ftNone, ftSub, ftAverage), rather than
	// in their enumeration order (ftNone, ftSub, ftUp, ftAverage, ftPaeth).
	cdat0 := cr[0][1:]
	cdat1 := cr[1][1:]
	cdat2 := cr[2][1:]
	cdat3 := cr[3][1:]
	cdat4 := cr[4][1:]
	pdat := pr[1:]
	n := len(cdat0)

	ASLTI
	ASLTIU
	AANDI
	AORI
	AXORI
	ASLLI
	ASRLI
	ASRAI
	ALUI
	AAUIPC
	AADD
	ASLT
	ASLTU
	AAND
	AOR
	AXOR
	ASLL
	ASRL
	ASUB
	ASRA

	// 2.5: Control Transfer Instructions
	AJAL
	AJALR
	ABEQ
	ABNE
	ABLT
	ABLTU
	ABGE
	ABGEU

	// 2.6: Load and Store Instructions
	ALW
	ALWU
	ALH
	ALHU

	SRL	X6, X5, X7				// b3d36200
	SRL	X5, X6					// 33535300
	SRL	$1, X5, X6				// 13d31200
	SRL	$1, X5					// 93d21200

	SUB	X6, X5, X7				// b3836240
	SUB	X5, X6					// 33035340
	SUB	$-2047, X5, X6				// 1383f27f
	SUB	$2048, X5, X6				// 13830280
	SUB	$-2047, X5				// 9382f27f
	SUB	$2048, X5				// 93820280

	SRA	X6, X5, X7				// b3d36240
	SRA	X5, X6					// 33535340
	SRA	$1, X5, X6				// 13d31240

		return &inst{0x33, 0x5, 0x0, 0, 0x0}
	case ASRLI:
		return &inst{0x13, 0x5, 0x0, 0, 0x0}
	case ASRLIW:
		return &inst{0x1b, 0x5, 0x0, 0, 0x0}
	case ASRLW:
		return &inst{0x3b, 0x5, 0x0, 0, 0x0}
	case ASUB:
		return &inst{0x33, 0x0, 0x0, 1024, 0x20}
	case ASUBW:
		return &inst{0x3b, 0x0, 0x0, 1024, 0x20}
	case ASW:
		return &inst{0x23, 0x2, 0x0, 0, 0x0}
	case AWFI:
		return &inst{0x73, 0x0, 0x5, 261, 0x8}

				p.From.Offset = 0
			}
		}
	}

	switch p.As {
	// Rewrite SUB constants into ADD.
	case ASUBC:
		if p.From.Type == obj.TYPE_CONST {
			p.From.Offset = -p.From.Offset
			p.As = AADDC
		}

	case ASUBCCC:
		if p.From.Type == obj.TYPE_CONST {
			p.From.Offset = -p.From.Offset
			p.As = AADDCCC
		}

	case ASUB:
		if p.From.Type != obj.TYPE_CONST {
			break
		}