cmd/compile/internal/ssa: note zero-width Ops

Add a bool to opInfo to indicate if an Op never results in any
instructions. This is a conservative approximation: some operations,
like Copy, may or may not generate code depending on their arguments.

I built the list by reading each arch's ssaGenValue function. Hopefully
I got them all.

Change-Id: I130b251b65f18208294e129bb7ddc3f91d57d31d
Reviewed-on: https://go-review.googlesource.com/97957Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/gen/386Ops.go

@@ -439,7 +439,7 @@ func init() {
 		// 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")}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("DX")}}, zeroWidth: true},
 		// LoweredGetCallerPC evaluates to the PC to which its "caller" will return.
 		// I.e., if f calls g "calls" getcallerpc,
 		// the result should be the PC within f that g will return to.
@@ -459,7 +459,7 @@ func init() {
 		// (particularly stack maps).  It takes a memory arg so it
 		// gets correctly ordered with respect to GC safepoints.
 		// arg0=ptr/int arg1=mem, output=int/ptr
-		{name: "MOVLconvert", argLength: 2, reg: gp11, asm: "MOVL", resultInArg0: true},
+		{name: "MOVLconvert", argLength: 2, reg: gp11, asm: "MOVL", resultInArg0: true, zeroWidth: true},
 
 		// Constant flag values. For any comparison, there are 5 possible
 		// outcomes: the three from the signed total order (<,==,>) and the

src/cmd/compile/internal/ssa/gen/AMD64Ops.go

@@ -568,7 +568,7 @@ func init() {
 		// 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")}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("DX")}}, zeroWidth: true},
 		// LoweredGetCallerPC evaluates to the PC to which its "caller" will return.
 		// I.e., if f calls g "calls" getcallerpc,
 		// the result should be the PC within f that g will return to.
@@ -588,8 +588,8 @@ func init() {
 		// (particularly stack maps).  It takes a memory arg so it
 		// gets correctly ordered with respect to GC safepoints.
 		// arg0=ptr/int arg1=mem, output=int/ptr
-		{name: "MOVQconvert", argLength: 2, reg: gp11, asm: "MOVQ", resultInArg0: true},
-		{name: "MOVLconvert", argLength: 2, reg: gp11, asm: "MOVL", resultInArg0: true}, // amd64p32 equivalent
+		{name: "MOVQconvert", argLength: 2, reg: gp11, asm: "MOVQ", resultInArg0: true, zeroWidth: true},
+		{name: "MOVLconvert", argLength: 2, reg: gp11, asm: "MOVL", resultInArg0: true, zeroWidth: true}, // amd64p32 equivalent
 
 		// Constant flag values. For any comparison, there are 5 possible
 		// outcomes: the three from the signed total order (<,==,>) and the

src/cmd/compile/internal/ssa/gen/ARM64Ops.go

@@ -217,8 +217,8 @@ func init() {
 		{name: "CLZW", argLength: 1, reg: gp11, asm: "CLZW"},       // count leading zero, 32-bit
 		{name: "VCNT", argLength: 1, reg: fp11, asm: "VCNT"},       // count set bits for each 8-bit unit and store the result in each 8-bit unit
 		{name: "VUADDLV", argLength: 1, reg: fp11, asm: "VUADDLV"}, // unsigned sum of eight bytes in a 64-bit value, zero extended to 64-bit.
-		{name: "LoweredRound32F", argLength: 1, reg: fp11, resultInArg0: true},
-		{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true},
+		{name: "LoweredRound32F", argLength: 1, reg: fp11, resultInArg0: true, zeroWidth: true},
+		{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true, zeroWidth: true},
 
 		// 3-operand, the addend comes first
 		{name: "FMADDS", argLength: 3, reg: fp31, asm: "FMADDS"},   // +arg0 + (arg1 * arg2)
@@ -459,7 +459,7 @@ func init() {
 		// 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")}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R26")}}, zeroWidth: true},
 
 		// LoweredGetCallerSP returns the SP of the caller of the current function.
 		{name: "LoweredGetCallerSP", reg: gp01, rematerializeable: true},

src/cmd/compile/internal/ssa/gen/ARMOps.go

@@ -514,7 +514,7 @@ func init() {
 		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
 		// and sorts it to the very beginning of the block to prevent other
 		// use of R7 (arm.REGCTXT, the closure pointer)
-		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R7")}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R7")}}, zeroWidth: true},
 
 		// LoweredGetCallerSP returns the SP of the caller of the current function.
 		{name: "LoweredGetCallerSP", reg: gp01, rematerializeable: true},

src/cmd/compile/internal/ssa/gen/MIPS64Ops.go

@@ -404,7 +404,7 @@ func init() {
 		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
 		// and sorts it to the very beginning of the block to prevent other
 		// use of R22 (mips.REGCTXT, the closure pointer)
-		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R22")}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R22")}}, zeroWidth: true},
 
 		// LoweredGetCallerSP returns the SP of the caller of the current function.
 		{name: "LoweredGetCallerSP", reg: gp01, rematerializeable: true},

src/cmd/compile/internal/ssa/gen/MIPSOps.go

@@ -374,7 +374,7 @@ func init() {
 		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
 		// and sorts it to the very beginning of the block to prevent other
 		// use of R22 (mips.REGCTXT, the closure pointer)
-		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R22")}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R22")}}, zeroWidth: true},
 
 		// LoweredGetCallerSP returns the SP of the caller of the current function.
 		{name: "LoweredGetCallerSP", reg: gp01, rematerializeable: true},

src/cmd/compile/internal/ssa/gen/PPC64Ops.go

@@ -316,7 +316,7 @@ func init() {
 		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
 		// and sorts it to the very beginning of the block to prevent other
 		// use of the closure pointer.
-		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{ctxt}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{ctxt}}, zeroWidth: true},
 
 		// LoweredGetCallerSP returns the SP of the caller of the current function.
 		{name: "LoweredGetCallerSP", reg: gp01, rematerializeable: true},
@@ -324,8 +324,8 @@ func init() {
 		//arg0=ptr,arg1=mem, returns void.  Faults if ptr is nil.
 		{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gp | sp | sb}, clobbers: tmp}, clobberFlags: true, nilCheck: true, faultOnNilArg0: true},
 		// Round ops to block fused-multiply-add extraction.
-		{name: "LoweredRound32F", argLength: 1, reg: fp11, resultInArg0: true},
-		{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true},
+		{name: "LoweredRound32F", argLength: 1, reg: fp11, resultInArg0: true, zeroWidth: true},
+		{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true, zeroWidth: true},
 
 		// Convert pointer to integer, takes a memory operand for ordering.
 		{name: "MOVDconvert", argLength: 2, reg: gp11, asm: "MOVD"},

src/cmd/compile/internal/ssa/gen/S390XOps.go

@@ -445,14 +445,14 @@ func init() {
 		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
 		// and sorts it to the very beginning of the block to prevent other
 		// use of R12 (the closure pointer)
-		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R12")}}},
+		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R12")}}, zeroWidth: true},
 		// arg0=ptr,arg1=mem, returns void.  Faults if ptr is nil.
 		// LoweredGetCallerSP returns the SP of the caller of the current function.
 		{name: "LoweredGetCallerSP", reg: gp01, rematerializeable: true},
 		{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{ptrsp}}, clobberFlags: true, nilCheck: true, faultOnNilArg0: true},
 		// Round ops to block fused-multiply-add extraction.
-		{name: "LoweredRound32F", argLength: 1, reg: fp11, resultInArg0: true},
-		{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true},
+		{name: "LoweredRound32F", argLength: 1, reg: fp11, resultInArg0: true, zeroWidth: true},
+		{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true, zeroWidth: true},
 
 		// LoweredWB invokes runtime.gcWriteBarrier. arg0=destptr, arg1=srcptr, arg2=mem, aux=runtime.gcWriteBarrier
 		// It saves all GP registers if necessary,

src/cmd/compile/internal/ssa/gen/genericOps.go

@@ -285,7 +285,7 @@ var genericOps = []opData{
 
 	// Data movement, max argument length for Phi is indefinite so just pick
 	// a really large number
-	{name: "Phi", argLength: -1}, // select an argument based on which predecessor block we came from
+	{name: "Phi", argLength: -1, zeroWidth: true}, // select an argument based on which predecessor block we came from
 	{name: "Copy", argLength: 1},                  // output = arg0
 	// Convert converts between pointers and integers.
 	// We have a special op for this so as to not confuse GC
@@ -311,8 +311,8 @@ var genericOps = []opData{
 	{name: "ConstSlice"},               // nil slice
 
 	// Constant-like things
-	{name: "InitMem"},                               // memory input to the function.
-	{name: "Arg", aux: "SymOff", symEffect: "Read"}, // argument to the function.  aux=GCNode of arg, off = offset in that arg.
+	{name: "InitMem", zeroWidth: true},                               // memory input to the function.
+	{name: "Arg", aux: "SymOff", symEffect: "Read", zeroWidth: true}, // argument to the function.  aux=GCNode of arg, off = offset in that arg.
 
 	// The address of a variable.  arg0 is the base pointer.
 	// If the variable is a global, the base pointer will be SB and
@@ -321,8 +321,8 @@ var genericOps = []opData{
 	// the Aux field will be a *gc.Node.
 	{name: "Addr", argLength: 1, aux: "Sym", symEffect: "Addr"}, // Address of a variable.  Arg0=SP or SB.  Aux identifies the variable.
 
-	{name: "SP"},                 // stack pointer
-	{name: "SB", typ: "Uintptr"}, // static base pointer (a.k.a. globals pointer)
+	{name: "SP", zeroWidth: true},                 // stack pointer
+	{name: "SB", typ: "Uintptr", zeroWidth: true}, // static base pointer (a.k.a. globals pointer)
 	{name: "Invalid"},                             // unused value
 
 	// Memory operations
@@ -395,7 +395,7 @@ var genericOps = []opData{
 	{name: "NilCheck", argLength: 2, typ: "Void"},        // arg0=ptr, arg1=mem. Panics if arg0 is nil. Returns void.
 
 	// Pseudo-ops
-	{name: "GetG", argLength: 1}, // runtime.getg() (read g pointer). arg0=mem
+	{name: "GetG", argLength: 1, zeroWidth: true}, // runtime.getg() (read g pointer). arg0=mem
 	{name: "GetClosurePtr"},                       // get closure pointer from dedicated register
 	{name: "GetCallerPC"},                         // for getcallerpc intrinsic
 	{name: "GetCallerSP"},                         // for getcallersp intrinsic
@@ -451,10 +451,10 @@ var genericOps = []opData{
 	// Unknown value. Used for Values whose values don't matter because they are dead code.
 	{name: "Unknown"},
 
-	{name: "VarDef", argLength: 1, aux: "Sym", typ: "Mem", symEffect: "None"}, // aux is a *gc.Node of a variable that is about to be initialized.  arg0=mem, returns mem
+	{name: "VarDef", argLength: 1, aux: "Sym", typ: "Mem", symEffect: "None", zeroWidth: true}, // aux is a *gc.Node of a variable that is about to be initialized.  arg0=mem, returns mem
 	{name: "VarKill", argLength: 1, aux: "Sym", symEffect: "None"},                             // aux is a *gc.Node of a variable that is known to be dead.  arg0=mem, returns mem
-	{name: "VarLive", argLength: 1, aux: "Sym", symEffect: "Read"},            // aux is a *gc.Node of a variable that must be kept live.  arg0=mem, returns mem
-	{name: "KeepAlive", argLength: 2, typ: "Mem"},                             // arg[0] is a value that must be kept alive until this mark.  arg[1]=mem, returns mem
+	{name: "VarLive", argLength: 1, aux: "Sym", symEffect: "Read", zeroWidth: true},            // aux is a *gc.Node of a variable that must be kept live.  arg0=mem, returns mem
+	{name: "KeepAlive", argLength: 2, typ: "Mem", zeroWidth: true},                             // arg[0] is a value that must be kept alive until this mark.  arg[1]=mem, returns mem
 
 	// Ops for breaking 64-bit operations on 32-bit architectures
 	{name: "Int64Make", argLength: 2, typ: "UInt64"}, // arg0=hi, arg1=lo
@@ -481,8 +481,8 @@ var genericOps = []opData{
 	{name: "Cvt64Fto64U", argLength: 1}, // float64 -> uint64, only used on archs that has the instruction
 
 	// pseudo-ops for breaking Tuple
-	{name: "Select0", argLength: 1}, // the first component of a tuple
-	{name: "Select1", argLength: 1}, // the second component of a tuple
+	{name: "Select0", argLength: 1, zeroWidth: true}, // the first component of a tuple
+	{name: "Select1", argLength: 1, zeroWidth: true}, // the second component of a tuple
 
 	// Atomic operations used for semantically inlining runtime/internal/atomic.
 	// Atomic loads return a new memory so that the loads are properly ordered

src/cmd/compile/internal/ssa/gen/main.go

@@ -54,6 +54,7 @@ type opData struct {
 	faultOnNilArg1    bool   // this op will fault if arg1 is nil (and aux encodes a small offset)
 	usesScratch       bool   // this op requires scratch memory space
 	hasSideEffects    bool   // for "reasons", not to be eliminated.  E.g., atomic store, #19182.
+	zeroWidth         bool   // op never translates into any machine code. example: copy, which may sometimes translate to machine code, is not zero-width.
 	symEffect         string // effect this op has on symbol in aux
 }
 
@@ -216,6 +217,9 @@ func genOp() {
 			if v.hasSideEffects {
 				fmt.Fprintln(w, "hasSideEffects: true,")
 			}
+			if v.zeroWidth {
+				fmt.Fprintln(w, "zeroWidth: true,")
+			}
 			needEffect := strings.HasPrefix(v.aux, "Sym")
 			if v.symEffect != "" {
 				if !needEffect {

src/cmd/compile/internal/ssa/op.go

@@ -35,6 +35,7 @@ type opInfo struct {
 	faultOnNilArg1    bool      // this op will fault if arg1 is nil (and aux encodes a small offset)
 	usesScratch       bool      // this op requires scratch memory space
 	hasSideEffects    bool      // for "reasons", not to be eliminated.  E.g., atomic store, #19182.
+	zeroWidth         bool      // op never translates into any machine code. example: copy, which may sometimes translate to machine code, is not zero-width.
 	symEffect         SymEffect // effect this op has on symbol in aux
 }
 

src/cmd/compile/internal/ssa/opGen.go

@@ -4396,6 +4396,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 4}, // DX
@@ -4452,6 +4453,7 @@ var opcodeTable = [...]opInfo{
 		name:         "MOVLconvert",
 		argLen:       2,
 		resultInArg0: true,
+		zeroWidth:    true,
 		asm:          x86.AMOVL,
 		reg: regInfo{
 			inputs: []inputInfo{
@@ -8310,6 +8312,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 4}, // DX
@@ -8366,6 +8369,7 @@ var opcodeTable = [...]opInfo{
 		name:         "MOVQconvert",
 		argLen:       2,
 		resultInArg0: true,
+		zeroWidth:    true,
 		asm:          x86.AMOVQ,
 		reg: regInfo{
 			inputs: []inputInfo{
@@ -8380,6 +8384,7 @@ var opcodeTable = [...]opInfo{
 		name:         "MOVLconvert",
 		argLen:       2,
 		resultInArg0: true,
+		zeroWidth:    true,
 		asm:          x86.AMOVL,
 		reg: regInfo{
 			inputs: []inputInfo{
@@ -12084,6 +12089,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 128}, // R7
@@ -12908,6 +12914,7 @@ var opcodeTable = [...]opInfo{
 		name:         "LoweredRound32F",
 		argLen:       1,
 		resultInArg0: true,
+		zeroWidth:    true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 9223372034707292160}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
@@ -12921,6 +12928,7 @@ var opcodeTable = [...]opInfo{
 		name:         "LoweredRound64F",
 		argLen:       1,
 		resultInArg0: true,
+		zeroWidth:    true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 9223372034707292160}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
@@ -14669,6 +14677,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 67108864}, // R26
@@ -16271,6 +16280,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 4194304}, // R22
@@ -17803,6 +17813,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 4194304}, // R22
@@ -19490,6 +19501,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 2048}, // R11
@@ -19523,6 +19535,7 @@ var opcodeTable = [...]opInfo{
 		name:         "LoweredRound32F",
 		argLen:       1,
 		resultInArg0: true,
+		zeroWidth:    true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 576460743713488896}, // F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26
@@ -19536,6 +19549,7 @@ var opcodeTable = [...]opInfo{
 		name:         "LoweredRound64F",
 		argLen:       1,
 		resultInArg0: true,
+		zeroWidth:    true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 576460743713488896}, // F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26
@@ -22596,6 +22610,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "LoweredGetClosurePtr",
 		argLen:    0,
+		zeroWidth: true,
 		reg: regInfo{
 			outputs: []outputInfo{
 				{0, 4096}, // R12
@@ -22628,6 +22643,7 @@ var opcodeTable = [...]opInfo{
 		name:         "LoweredRound32F",
 		argLen:       1,
 		resultInArg0: true,
+		zeroWidth:    true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 4294901760}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15
@@ -22641,6 +22657,7 @@ var opcodeTable = [...]opInfo{
 		name:         "LoweredRound64F",
 		argLen:       1,
 		resultInArg0: true,
+		zeroWidth:    true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 4294901760}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15
@@ -24094,6 +24111,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "Phi",
 		argLen:    -1,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{
@@ -24172,12 +24190,14 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "InitMem",
 		argLen:    0,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{
 		name:      "Arg",
 		auxType:   auxSymOff,
 		argLen:    0,
+		zeroWidth: true,
 		symEffect: SymRead,
 		generic:   true,
 	},
@@ -24191,11 +24211,13 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "SP",
 		argLen:    0,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{
 		name:      "SB",
 		argLen:    0,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{
@@ -24441,6 +24463,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "GetG",
 		argLen:    1,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{
@@ -24607,6 +24630,7 @@ var opcodeTable = [...]opInfo{
 		name:      "VarDef",
 		auxType:   auxSym,
 		argLen:    1,
+		zeroWidth: true,
 		symEffect: SymNone,
 		generic:   true,
 	},
@@ -24621,12 +24645,14 @@ var opcodeTable = [...]opInfo{
 		name:      "VarLive",
 		auxType:   auxSym,
 		argLen:    1,
+		zeroWidth: true,
 		symEffect: SymRead,
 		generic:   true,
 	},
 	{
 		name:      "KeepAlive",
 		argLen:    2,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{
@@ -24724,11 +24750,13 @@ var opcodeTable = [...]opInfo{
 	{
 		name:      "Select0",
 		argLen:    1,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{
 		name:      "Select1",
 		argLen:    1,
+		zeroWidth: true,
 		generic:   true,
 	},
 	{