},
			clobberFlags:   true,
			faultOnNilArg0: true,
			faultOnNilArg1: true,
		},

		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
		// and sorts it to the very beginning of the block to prevent other
		// use of R26 (arm64.REGCTXT, the closure pointer)
		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R26")}}, zeroWidth: true},

		// Lowering pass-throughs
		{name: "LoweredNilCheck", argLength: 2, faultOnNilArg0: true, nilCheck: true, reg: regInfo{inputs: []regMask{gpspMask}}}, // arg0=ptr,arg1=mem, returns void.  Faults if ptr is nil.
		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{regCtxt}}},                                                // scheduler ensures only at beginning of entry block

(IsNonNil ptr) => (SGTU ptr (MOVVconst [0]))
(IsInBounds idx len) => (SGTU len idx)
(IsSliceInBounds idx len) => (XOR (MOVVconst [1]) (SGTU idx len))

// pseudo-ops
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)

(If cond yes no) => (NE (MOVBUreg <typ.UInt64> cond) yes no)

// Write barrier.

(IsNonNil ptr) => (SGTU ptr (MOVWconst [0]))
(IsInBounds idx len) => (SGTU len idx)
(IsSliceInBounds idx len) => (XORconst [1] (SGTU idx len))

// pseudo-ops
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)

(If cond yes no) => (NE cond yes no)

// Write barrier.
(WB ...) => (LoweredWB ...)

// Checks
(IsNonNil ...) => (SNEZ ...)
(IsInBounds ...) => (Less64U ...)
(IsSliceInBounds ...) => (Leq64U ...)

// Trivial lowering
(NilCheck ...) => (LoweredNilCheck ...)
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)

// Write barrier.
(WB ...) => (LoweredWB ...)

// Publication barrier as intrinsic

		// Pseudo-ops
		{name: "LoweredGetG", argLength: 1, reg: gp01}, // arg0=mem
		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
		// and sorts it to the very beginning of the block to prevent other
		// use of DX (the closure pointer)
		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("DX")}}, zeroWidth: true},

(IsNonNil ptr) => (SGTU ptr (MOVVconst [0]))
(IsInBounds idx len) => (SGTU len idx)
(IsSliceInBounds idx len) => (XOR (MOVVconst [1]) (SGTU idx len))

// pseudo-ops
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)

(If cond yes no) => (NE cond yes no)

// Write barrier.
(WB ...) => (LoweredWB ...)

// Lowering calls
(StaticCall ...) => (CALLstatic ...)
(ClosureCall ...) => (CALLclosure ...)
(InterCall ...) => (CALLinter ...)
(TailCall ...) => (CALLtail ...)

// Miscellaneous
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)
(IsNonNil ptr) => (NotEqual (CMPconst [0] ptr))
(IsInBounds idx len) => (LessThan (CMPU idx len))

				return !opcodeTable[v.Op].zeroWidth
			} else {
				return v.Op == OpInitMem
			}
		}

		// Examine the prolog portion of the block to process special
		// zero-width ops such as Arg, Phi, LoweredGetClosurePtr (etc)
		// whose lifetimes begin at the block starting point. In an
		// entry block, allow for the possibility that we may see Arg
		// ops that appear _after_ other non-zero-width operations.
		// Example:

(IsSliceInBounds idx len) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPU idx len))
(NilCheck ...) => (LoweredNilCheck ...)
(GetG ...) => (LoweredGetG ...)
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)
(Addr {sym} base) => (MOVDaddr {sym} base)