cmd/compile: remove nil check for Zero/Move on 386, AMD64, S390X

Fixes #18003.

Change-Id: Iadcc5c424c64badecfb5fdbd4dbd9197df56182c
Reviewed-on: https://go-review.googlesource.com/33421
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -373,6 +373,7 @@ func init() {
 				clobbers: buildReg("DI CX"),
 				// Note: CX is only clobbered when dynamic linking.
 			},
+			faultOnNilArg0: true,
 		},
 
 		// arg0 = address of memory to zero
@@ -387,6 +388,7 @@ func init() {
 				inputs:   []regMask{buildReg("DI"), buildReg("CX"), buildReg("AX")},
 				clobbers: buildReg("DI CX"),
 			},
+			faultOnNilArg0: true,
 		},
 
 		{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true},                                             // call static function aux.(*gc.Sym).  arg0=mem, auxint=argsize, returns mem
@@ -409,6 +411,8 @@ func init() {
 				clobbers: buildReg("DI SI CX"), // uses CX as a temporary
 			},
 			clobberFlags:   true,
+			faultOnNilArg0: true,
+			faultOnNilArg1: true,
 		},
 
 		// arg0 = destination pointer
@@ -423,6 +427,8 @@ func init() {
 				inputs:   []regMask{buildReg("DI"), buildReg("SI"), buildReg("CX")},
 				clobbers: buildReg("DI SI CX"),
 			},
+			faultOnNilArg0: true,
+			faultOnNilArg1: true,
 		},
 
 		// (InvertFlags (CMPL a b)) == (CMPL b a)

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

@@ -422,6 +422,7 @@ func init() {
 				clobbers: buildReg("DI"),
 			},
 			clobberFlags:   true,
+			faultOnNilArg0: true,
 		},
 		{name: "MOVOconst", reg: regInfo{nil, 0, []regMask{fp}}, typ: "Int128", aux: "Int128", rematerializeable: true},
 
@@ -437,6 +438,7 @@ func init() {
 				inputs:   []regMask{buildReg("DI"), buildReg("CX"), buildReg("AX")},
 				clobbers: buildReg("DI CX"),
 			},
+			faultOnNilArg0: true,
 		},
 
 		{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true},                                             // call static function aux.(*gc.Sym).  arg0=mem, auxint=argsize, returns mem
@@ -459,6 +461,8 @@ func init() {
 				clobbers: buildReg("DI SI X0"), // uses X0 as a temporary
 			},
 			clobberFlags:   true,
+			faultOnNilArg0: true,
+			faultOnNilArg1: true,
 		},
 
 		// arg0 = destination pointer
@@ -473,6 +477,8 @@ func init() {
 				inputs:   []regMask{buildReg("DI"), buildReg("SI"), buildReg("CX")},
 				clobbers: buildReg("DI SI CX"),
 			},
+			faultOnNilArg0: true,
+			faultOnNilArg1: true,
 		},
 
 		// (InvertFlags (CMPQ a b)) == (CMPQ b a)

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

@@ -570,6 +570,8 @@ func init() {
 			},
 			clobberFlags:   true,
 			typ:            "Mem",
+			faultOnNilArg0: true,
+			faultOnNilArg1: true,
 		},
 
 		// large clear
@@ -594,6 +596,7 @@ func init() {
 			},
 			clobberFlags:   true,
 			typ:            "Mem",
+			faultOnNilArg0: true,
 		},
 	}
 

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

@@ -4074,6 +4074,7 @@ var opcodeTable = [...]opInfo{
 		name:           "DUFFZERO",
 		auxType:        auxInt64,
 		argLen:         3,
+		faultOnNilArg0: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128}, // DI
@@ -4085,6 +4086,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:           "REPSTOSL",
 		argLen:         4,
+		faultOnNilArg0: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128}, // DI
@@ -4156,6 +4158,8 @@ var opcodeTable = [...]opInfo{
 		auxType:        auxInt64,
 		argLen:         3,
 		clobberFlags:   true,
+		faultOnNilArg0: true,
+		faultOnNilArg1: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128}, // DI
@@ -4167,6 +4171,8 @@ var opcodeTable = [...]opInfo{
 	{
 		name:           "REPMOVSL",
 		argLen:         4,
+		faultOnNilArg0: true,
+		faultOnNilArg1: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128}, // DI
@@ -7066,6 +7072,7 @@ var opcodeTable = [...]opInfo{
 		auxType:        auxInt64,
 		argLen:         3,
 		clobberFlags:   true,
+		faultOnNilArg0: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128},   // DI
@@ -7088,6 +7095,7 @@ var opcodeTable = [...]opInfo{
 	{
 		name:           "REPSTOSQ",
 		argLen:         4,
+		faultOnNilArg0: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128}, // DI
@@ -7159,6 +7167,8 @@ var opcodeTable = [...]opInfo{
 		auxType:        auxInt64,
 		argLen:         3,
 		clobberFlags:   true,
+		faultOnNilArg0: true,
+		faultOnNilArg1: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128}, // DI
@@ -7170,6 +7180,8 @@ var opcodeTable = [...]opInfo{
 	{
 		name:           "REPMOVSQ",
 		argLen:         4,
+		faultOnNilArg0: true,
+		faultOnNilArg1: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 128}, // DI
@@ -19718,6 +19730,8 @@ var opcodeTable = [...]opInfo{
 		auxType:        auxInt64,
 		argLen:         4,
 		clobberFlags:   true,
+		faultOnNilArg0: true,
+		faultOnNilArg1: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 2},     // R1
@@ -19732,6 +19746,7 @@ var opcodeTable = [...]opInfo{
 		auxType:        auxInt64,
 		argLen:         3,
 		clobberFlags:   true,
+		faultOnNilArg0: true,
 		reg: regInfo{
 			inputs: []inputInfo{
 				{0, 2},     // R1

test/nilptr3.go

@@ -254,3 +254,8 @@ func f7() (*Struct, float64) {
 	p := &t.Y    // ERROR "removed nil check"
 	return t, *p // ERROR "removed nil check"
 }
+
+// make sure to remove nil check for memory move (issue #18003)
+func f8(t *[8]int) [8]int {
+	return *t // ERROR "removed nil check"
+}