cmd/compile: fix PPC64.rules for LoweredMove

A recent performance improvement for PPC64.rules introduced a
regression for the case where the size of a move is <= 8 bytes
and the value used in the offset field of the instruction is not
aligned correctly for the instruction. In the cases where this happened,
the assembler was not detecting the incorrect offset and still generated
the instruction even though it was invalid.

This fix changes the PPC64.rules for the moves that are now failing
to include the correct alignment checks, along some additional testcases
for gc/ssa for the failing alignments.

I will add a fix to the assembler to detect incorrect offsets in
another CL.

This fixes #19907

Change-Id: I3d327ce0ea6afed884725b1824f9217cef2fe6bf
Reviewed-on: https://go-review.googlesource.com/40290Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
Reviewed-by: David Chase <drchase@google.com>

src/cmd/compile/internal/gc/testdata/copy.go

@@ -656,6 +656,108 @@ func testCopy1041() {
 	}
 }
 
+//go:noinline
+func tu2copy_ssa(docopy bool, data [2]byte, x *[2]byte) {
+	if docopy {
+		*x = data
+	}
+}
+func testUnalignedCopy2() {
+	var a [2]byte
+	t2 := [2]byte{2, 3}
+	tu2copy_ssa(true, t2, &a)
+	want2 := [2]byte{2, 3}
+	if a != want2 {
+		fmt.Printf("tu2copy got=%v, want %v\n", a, want2)
+		failed = true
+	}
+}
+
+//go:noinline
+func tu3copy_ssa(docopy bool, data [3]byte, x *[3]byte) {
+	if docopy {
+		*x = data
+	}
+}
+func testUnalignedCopy3() {
+	var a [3]byte
+	t3 := [3]byte{3, 4, 5}
+	tu3copy_ssa(true, t3, &a)
+	want3 := [3]byte{3, 4, 5}
+	if a != want3 {
+		fmt.Printf("tu3copy got=%v, want %v\n", a, want3)
+		failed = true
+	}
+}
+
+//go:noinline
+func tu4copy_ssa(docopy bool, data [4]byte, x *[4]byte) {
+	if docopy {
+		*x = data
+	}
+}
+func testUnalignedCopy4() {
+	var a [4]byte
+	t4 := [4]byte{4, 5, 6, 7}
+	tu4copy_ssa(true, t4, &a)
+	want4 := [4]byte{4, 5, 6, 7}
+	if a != want4 {
+		fmt.Printf("tu4copy got=%v, want %v\n", a, want4)
+		failed = true
+	}
+}
+
+//go:noinline
+func tu5copy_ssa(docopy bool, data [5]byte, x *[5]byte) {
+	if docopy {
+		*x = data
+	}
+}
+func testUnalignedCopy5() {
+	var a [5]byte
+	t5 := [5]byte{5, 6, 7, 8, 9}
+	tu5copy_ssa(true, t5, &a)
+	want5 := [5]byte{5, 6, 7, 8, 9}
+	if a != want5 {
+		fmt.Printf("tu5copy got=%v, want %v\n", a, want5)
+		failed = true
+	}
+}
+
+//go:noinline
+func tu6copy_ssa(docopy bool, data [6]byte, x *[6]byte) {
+	if docopy {
+		*x = data
+	}
+}
+func testUnalignedCopy6() {
+	var a [6]byte
+	t6 := [6]byte{6, 7, 8, 9, 10, 11}
+	tu6copy_ssa(true, t6, &a)
+	want6 := [6]byte{6, 7, 8, 9, 10, 11}
+	if a != want6 {
+		fmt.Printf("tu6copy got=%v, want %v\n", a, want6)
+		failed = true
+	}
+}
+
+//go:noinline
+func tu7copy_ssa(docopy bool, data [7]byte, x *[7]byte) {
+	if docopy {
+		*x = data
+	}
+}
+func testUnalignedCopy7() {
+	var a [7]byte
+	t7 := [7]byte{7, 8, 9, 10, 11, 12, 13}
+	tu7copy_ssa(true, t7, &a)
+	want7 := [7]byte{7, 8, 9, 10, 11, 12, 13}
+	if a != want7 {
+		fmt.Printf("tu7copy got=%v, want %v\n", a, want7)
+		failed = true
+	}
+}
+
 var failed bool
 
 func main() {
@@ -690,6 +792,12 @@ func main() {
 	testCopy1039()
 	testCopy1040()
 	testCopy1041()
+	testUnalignedCopy2()
+	testUnalignedCopy3()
+	testUnalignedCopy4()
+	testUnalignedCopy5()
+	testUnalignedCopy6()
+	testUnalignedCopy7()
 	if failed {
 		panic("failed")
 	}

src/cmd/compile/internal/gc/testdata/gen/copyGen.go

@@ -20,6 +20,8 @@ import (
 
 var sizes = [...]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 23, 24, 25, 31, 32, 33, 63, 64, 65, 1023, 1024, 1025, 1024 + 7, 1024 + 8, 1024 + 9, 1024 + 15, 1024 + 16, 1024 + 17}
 
+var usizes = [...]int{2, 3, 4, 5, 6, 7}
+
 func main() {
 	w := new(bytes.Buffer)
 	fmt.Fprintf(w, "// run\n")
@@ -66,12 +68,45 @@ func main() {
 		fmt.Fprintf(w, "}\n")
 	}
 
+	for _, s := range usizes {
+		// function being tested
+		fmt.Fprintf(w, "//go:noinline\n")
+		fmt.Fprintf(w, "func tu%dcopy_ssa(docopy bool, data [%d]byte, x *[%d]byte) {\n", s, s, s)
+		fmt.Fprintf(w, "  if docopy {\n")
+		fmt.Fprintf(w, "    *x = data\n")
+		fmt.Fprintf(w, "  }\n")
+		fmt.Fprintf(w, "}\n")
+
+		// testing harness
+		fmt.Fprintf(w, "func testUnalignedCopy%d() {\n", s)
+		fmt.Fprintf(w, "  var a [%d]byte\n", s)
+		fmt.Fprintf(w, "  t%d := [%d]byte{", s, s)
+		for i := 0; i < s; i++ {
+			fmt.Fprintf(w, " %d,", s+i)
+		}
+		fmt.Fprintf(w, "}\n")
+		fmt.Fprintf(w, "  tu%dcopy_ssa(true, t%d, &a)\n", s, s)
+		fmt.Fprintf(w, "  want%d := [%d]byte{", s, s)
+		for i := 0; i < s; i++ {
+			fmt.Fprintf(w, " %d,", s+i)
+		}
+		fmt.Fprintf(w, "}\n")
+		fmt.Fprintf(w, "  if a != want%d {\n", s)
+		fmt.Fprintf(w, "    fmt.Printf(\"tu%dcopy got=%%v, want %%v\\n\", a, want%d)\n", s, s)
+		fmt.Fprintf(w, "    failed=true\n")
+		fmt.Fprintf(w, "  }\n")
+		fmt.Fprintf(w, "}\n")
+	}
+
 	// boilerplate at end
 	fmt.Fprintf(w, "var failed bool\n")
 	fmt.Fprintf(w, "func main() {\n")
 	for _, s := range sizes {
 		fmt.Fprintf(w, "  testCopy%d()\n", s)
 	}
+	for _, s := range usizes {
+		fmt.Fprintf(w, "  testUnalignedCopy%d()\n", s)
+	}
 	fmt.Fprintf(w, "  if failed {\n")
 	fmt.Fprintf(w, "    panic(\"failed\")\n")
 	fmt.Fprintf(w, "  }\n")

src/cmd/compile/internal/ssa/gen/PPC64.rules

@@ -554,51 +554,37 @@
 (Zero [s] ptr mem) -> (LoweredZero [s] ptr mem)
 
 // moves
+// Only the MOVD and MOVW instructions require 4 byte
+// alignment in the offset field.  The other MOVx instructions
+// allow any alignment.
 (Move [0] _ _ mem) -> mem
 (Move [1] dst src mem) -> (MOVBstore dst (MOVBZload src mem) mem)
 (Move [2] dst src mem) ->
         (MOVHstore dst (MOVHZload src mem) mem)
-(Move [4] {t} dst src mem) && t.(Type).Alignment()%4 == 0 ->
-	(MOVWstore dst (MOVWload src mem) mem)
-(Move [4] {t} dst src mem) && t.(Type).Alignment()%2 == 0 ->
-	(MOVHstore [2] dst (MOVHZload [2] src mem)
-		(MOVHstore dst (MOVHZload src mem) mem))
 (Move [4] dst src mem) ->
-	(MOVBstore [3] dst (MOVBZload [3] src mem)
-		(MOVBstore [2] dst (MOVBZload [2] src mem)
-			(MOVBstore [1] dst (MOVBZload [1] src mem)
-				(MOVBstore dst (MOVBZload src mem) mem))))
-
-(Move [8] {t} dst src mem) && t.(Type).Alignment()%8 == 0 ->
-	(MOVDstore dst (MOVDload src mem) mem)
+	(MOVWstore dst (MOVWZload src mem) mem)
+// MOVD for load and store must have offsets that are multiple of 4
 (Move [8] {t} dst src mem) && t.(Type).Alignment()%4 == 0 ->
+	(MOVDstore dst (MOVDload src mem) mem)
+(Move [8] dst src mem) ->
 	(MOVWstore [4] dst (MOVWZload [4] src mem)
 		(MOVWstore dst (MOVWZload src mem) mem))
-(Move [8] {t} dst src mem) && t.(Type).Alignment()%2 == 0 ->
-	(MOVHstore [6] dst (MOVHZload [6] src mem)
-		(MOVHstore [4] dst (MOVHZload [4] src mem)
-			(MOVHstore [2] dst (MOVHZload [2] src mem)
-				(MOVHstore dst (MOVHZload src mem) mem))))
-
 (Move [3] dst src mem) ->
         (MOVBstore [2] dst (MOVBZload [2] src mem)
                 (MOVHstore dst (MOVHload src mem) mem))
-(Move [4] dst src mem) ->
-        (MOVWstore dst (MOVWload src mem) mem)
 (Move [5] dst src mem) ->
         (MOVBstore [4] dst (MOVBZload [4] src mem)
-                (MOVWstore dst (MOVWload src mem) mem))
+                (MOVWstore dst (MOVWZload src mem) mem))
 (Move [6] dst src mem) ->
         (MOVHstore [4] dst (MOVHZload [4] src mem)
-                (MOVWstore dst (MOVWload src mem) mem))
+                (MOVWstore dst (MOVWZload src mem) mem))
 (Move [7] dst src mem) ->
         (MOVBstore [6] dst (MOVBZload [6] src mem)
                 (MOVHstore [4] dst (MOVHZload [4] src mem)
-                        (MOVWstore dst (MOVWload src mem) mem)))
-(Move [8] dst src mem) ->
-        (MOVDstore dst (MOVDload src mem) mem)
+                        (MOVWstore dst (MOVWZload src mem) mem)))
 
-// Large move uses a loop
+// Large move uses a loop. Since the address is computed and the
+// offset is zero, any alignment can be used.
 (Move [s] dst src mem) && s > 8 ->
         (LoweredMove [s] dst src mem)
 

src/cmd/compile/internal/ssa/rewritePPC64.go

@@ -3739,64 +3739,9 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v.AddArg(mem)
 		return true
 	}
-	// match: (Move [4] {t} dst src mem)
-	// cond: t.(Type).Alignment()%4 == 0
-	// result: (MOVWstore dst (MOVWload src mem) mem)
-	for {
-		if v.AuxInt != 4 {
-			break
-		}
-		t := v.Aux
-		dst := v.Args[0]
-		src := v.Args[1]
-		mem := v.Args[2]
-		if !(t.(Type).Alignment()%4 == 0) {
-			break
-		}
-		v.reset(OpPPC64MOVWstore)
-		v.AddArg(dst)
-		v0 := b.NewValue0(v.Pos, OpPPC64MOVWload, types.Int32)
-		v0.AddArg(src)
-		v0.AddArg(mem)
-		v.AddArg(v0)
-		v.AddArg(mem)
-		return true
-	}
-	// match: (Move [4] {t} dst src mem)
-	// cond: t.(Type).Alignment()%2 == 0
-	// result: (MOVHstore [2] dst (MOVHZload [2] src mem) 		(MOVHstore dst (MOVHZload src mem) mem))
-	for {
-		if v.AuxInt != 4 {
-			break
-		}
-		t := v.Aux
-		dst := v.Args[0]
-		src := v.Args[1]
-		mem := v.Args[2]
-		if !(t.(Type).Alignment()%2 == 0) {
-			break
-		}
-		v.reset(OpPPC64MOVHstore)
-		v.AuxInt = 2
-		v.AddArg(dst)
-		v0 := b.NewValue0(v.Pos, OpPPC64MOVHZload, types.UInt16)
-		v0.AuxInt = 2
-		v0.AddArg(src)
-		v0.AddArg(mem)
-		v.AddArg(v0)
-		v1 := b.NewValue0(v.Pos, OpPPC64MOVHstore, TypeMem)
-		v1.AddArg(dst)
-		v2 := b.NewValue0(v.Pos, OpPPC64MOVHZload, types.UInt16)
-		v2.AddArg(src)
-		v2.AddArg(mem)
-		v1.AddArg(v2)
-		v1.AddArg(mem)
-		v.AddArg(v1)
-		return true
-	}
 	// match: (Move [4] dst src mem)
 	// cond:
-	// result: (MOVBstore [3] dst (MOVBZload [3] src mem) 		(MOVBstore [2] dst (MOVBZload [2] src mem) 			(MOVBstore [1] dst (MOVBZload [1] src mem) 				(MOVBstore dst (MOVBZload src mem) mem))))
+	// result: (MOVWstore dst (MOVWZload src mem) mem)
 	for {
 		if v.AuxInt != 4 {
 			break
@@ -3804,44 +3749,17 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		dst := v.Args[0]
 		src := v.Args[1]
 		mem := v.Args[2]
-		v.reset(OpPPC64MOVBstore)
-		v.AuxInt = 3
+		v.reset(OpPPC64MOVWstore)
 		v.AddArg(dst)
-		v0 := b.NewValue0(v.Pos, OpPPC64MOVBZload, types.UInt8)
-		v0.AuxInt = 3
+		v0 := b.NewValue0(v.Pos, OpPPC64MOVWZload, types.UInt32)
 		v0.AddArg(src)
 		v0.AddArg(mem)
 		v.AddArg(v0)
-		v1 := b.NewValue0(v.Pos, OpPPC64MOVBstore, TypeMem)
-		v1.AuxInt = 2
-		v1.AddArg(dst)
-		v2 := b.NewValue0(v.Pos, OpPPC64MOVBZload, types.UInt8)
-		v2.AuxInt = 2
-		v2.AddArg(src)
-		v2.AddArg(mem)
-		v1.AddArg(v2)
-		v3 := b.NewValue0(v.Pos, OpPPC64MOVBstore, TypeMem)
-		v3.AuxInt = 1
-		v3.AddArg(dst)
-		v4 := b.NewValue0(v.Pos, OpPPC64MOVBZload, types.UInt8)
-		v4.AuxInt = 1
-		v4.AddArg(src)
-		v4.AddArg(mem)
-		v3.AddArg(v4)
-		v5 := b.NewValue0(v.Pos, OpPPC64MOVBstore, TypeMem)
-		v5.AddArg(dst)
-		v6 := b.NewValue0(v.Pos, OpPPC64MOVBZload, types.UInt8)
-		v6.AddArg(src)
-		v6.AddArg(mem)
-		v5.AddArg(v6)
-		v5.AddArg(mem)
-		v3.AddArg(v5)
-		v1.AddArg(v3)
-		v.AddArg(v1)
+		v.AddArg(mem)
 		return true
 	}
 	// match: (Move [8] {t} dst src mem)
-	// cond: t.(Type).Alignment()%8 == 0
+	// cond: t.(Type).Alignment()%4 == 0
 	// result: (MOVDstore dst (MOVDload src mem) mem)
 	for {
 		if v.AuxInt != 8 {
@@ -3851,7 +3769,7 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		dst := v.Args[0]
 		src := v.Args[1]
 		mem := v.Args[2]
-		if !(t.(Type).Alignment()%8 == 0) {
+		if !(t.(Type).Alignment()%4 == 0) {
 			break
 		}
 		v.reset(OpPPC64MOVDstore)
@@ -3863,20 +3781,16 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v.AddArg(mem)
 		return true
 	}
-	// match: (Move [8] {t} dst src mem)
-	// cond: t.(Type).Alignment()%4 == 0
+	// match: (Move [8] dst src mem)
+	// cond:
 	// result: (MOVWstore [4] dst (MOVWZload [4] src mem) 		(MOVWstore dst (MOVWZload src mem) mem))
 	for {
 		if v.AuxInt != 8 {
 			break
 		}
-		t := v.Aux
 		dst := v.Args[0]
 		src := v.Args[1]
 		mem := v.Args[2]
-		if !(t.(Type).Alignment()%4 == 0) {
-			break
-		}
 		v.reset(OpPPC64MOVWstore)
 		v.AuxInt = 4
 		v.AddArg(dst)
@@ -3895,56 +3809,6 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v.AddArg(v1)
 		return true
 	}
-	// match: (Move [8] {t} dst src mem)
-	// cond: t.(Type).Alignment()%2 == 0
-	// result: (MOVHstore [6] dst (MOVHZload [6] src mem) 		(MOVHstore [4] dst (MOVHZload [4] src mem) 			(MOVHstore [2] dst (MOVHZload [2] src mem) 				(MOVHstore dst (MOVHZload src mem) mem))))
-	for {
-		if v.AuxInt != 8 {
-			break
-		}
-		t := v.Aux
-		dst := v.Args[0]
-		src := v.Args[1]
-		mem := v.Args[2]
-		if !(t.(Type).Alignment()%2 == 0) {
-			break
-		}
-		v.reset(OpPPC64MOVHstore)
-		v.AuxInt = 6
-		v.AddArg(dst)
-		v0 := b.NewValue0(v.Pos, OpPPC64MOVHZload, types.UInt16)
-		v0.AuxInt = 6
-		v0.AddArg(src)
-		v0.AddArg(mem)
-		v.AddArg(v0)
-		v1 := b.NewValue0(v.Pos, OpPPC64MOVHstore, TypeMem)
-		v1.AuxInt = 4
-		v1.AddArg(dst)
-		v2 := b.NewValue0(v.Pos, OpPPC64MOVHZload, types.UInt16)
-		v2.AuxInt = 4
-		v2.AddArg(src)
-		v2.AddArg(mem)
-		v1.AddArg(v2)
-		v3 := b.NewValue0(v.Pos, OpPPC64MOVHstore, TypeMem)
-		v3.AuxInt = 2
-		v3.AddArg(dst)
-		v4 := b.NewValue0(v.Pos, OpPPC64MOVHZload, types.UInt16)
-		v4.AuxInt = 2
-		v4.AddArg(src)
-		v4.AddArg(mem)
-		v3.AddArg(v4)
-		v5 := b.NewValue0(v.Pos, OpPPC64MOVHstore, TypeMem)
-		v5.AddArg(dst)
-		v6 := b.NewValue0(v.Pos, OpPPC64MOVHZload, types.UInt16)
-		v6.AddArg(src)
-		v6.AddArg(mem)
-		v5.AddArg(v6)
-		v5.AddArg(mem)
-		v3.AddArg(v5)
-		v1.AddArg(v3)
-		v.AddArg(v1)
-		return true
-	}
 	// match: (Move [3] dst src mem)
 	// cond:
 	// result: (MOVBstore [2] dst (MOVBZload [2] src mem)                 (MOVHstore dst (MOVHload src mem) mem))
@@ -3973,28 +3837,9 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v.AddArg(v1)
 		return true
 	}
-	// match: (Move [4] dst src mem)
-	// cond:
-	// result: (MOVWstore dst (MOVWload src mem) mem)
-	for {
-		if v.AuxInt != 4 {
-			break
-		}
-		dst := v.Args[0]
-		src := v.Args[1]
-		mem := v.Args[2]
-		v.reset(OpPPC64MOVWstore)
-		v.AddArg(dst)
-		v0 := b.NewValue0(v.Pos, OpPPC64MOVWload, types.Int32)
-		v0.AddArg(src)
-		v0.AddArg(mem)
-		v.AddArg(v0)
-		v.AddArg(mem)
-		return true
-	}
 	// match: (Move [5] dst src mem)
 	// cond:
-	// result: (MOVBstore [4] dst (MOVBZload [4] src mem)                 (MOVWstore dst (MOVWload src mem) mem))
+	// result: (MOVBstore [4] dst (MOVBZload [4] src mem)                 (MOVWstore dst (MOVWZload src mem) mem))
 	for {
 		if v.AuxInt != 5 {
 			break
@@ -4012,7 +3857,7 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v.AddArg(v0)
 		v1 := b.NewValue0(v.Pos, OpPPC64MOVWstore, TypeMem)
 		v1.AddArg(dst)
-		v2 := b.NewValue0(v.Pos, OpPPC64MOVWload, types.Int32)
+		v2 := b.NewValue0(v.Pos, OpPPC64MOVWZload, types.UInt32)
 		v2.AddArg(src)
 		v2.AddArg(mem)
 		v1.AddArg(v2)
@@ -4022,7 +3867,7 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 	}
 	// match: (Move [6] dst src mem)
 	// cond:
-	// result: (MOVHstore [4] dst (MOVHZload [4] src mem)                 (MOVWstore dst (MOVWload src mem) mem))
+	// result: (MOVHstore [4] dst (MOVHZload [4] src mem)                 (MOVWstore dst (MOVWZload src mem) mem))
 	for {
 		if v.AuxInt != 6 {
 			break
@@ -4040,7 +3885,7 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v.AddArg(v0)
 		v1 := b.NewValue0(v.Pos, OpPPC64MOVWstore, TypeMem)
 		v1.AddArg(dst)
-		v2 := b.NewValue0(v.Pos, OpPPC64MOVWload, types.Int32)
+		v2 := b.NewValue0(v.Pos, OpPPC64MOVWZload, types.UInt32)
 		v2.AddArg(src)
 		v2.AddArg(mem)
 		v1.AddArg(v2)
@@ -4050,7 +3895,7 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 	}
 	// match: (Move [7] dst src mem)
 	// cond:
-	// result: (MOVBstore [6] dst (MOVBZload [6] src mem)                 (MOVHstore [4] dst (MOVHZload [4] src mem)                         (MOVWstore dst (MOVWload src mem) mem)))
+	// result: (MOVBstore [6] dst (MOVBZload [6] src mem)                 (MOVHstore [4] dst (MOVHZload [4] src mem)                         (MOVWstore dst (MOVWZload src mem) mem)))
 	for {
 		if v.AuxInt != 7 {
 			break
@@ -4076,7 +3921,7 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v1.AddArg(v2)
 		v3 := b.NewValue0(v.Pos, OpPPC64MOVWstore, TypeMem)
 		v3.AddArg(dst)
-		v4 := b.NewValue0(v.Pos, OpPPC64MOVWload, types.Int32)
+		v4 := b.NewValue0(v.Pos, OpPPC64MOVWZload, types.UInt32)
 		v4.AddArg(src)
 		v4.AddArg(mem)
 		v3.AddArg(v4)
@@ -4085,25 +3930,6 @@ func rewriteValuePPC64_OpMove(v *Value) bool {
 		v.AddArg(v1)
 		return true
 	}
-	// match: (Move [8] dst src mem)
-	// cond:
-	// result: (MOVDstore dst (MOVDload src mem) mem)
-	for {
-		if v.AuxInt != 8 {
-			break
-		}
-		dst := v.Args[0]
-		src := v.Args[1]
-		mem := v.Args[2]
-		v.reset(OpPPC64MOVDstore)
-		v.AddArg(dst)
-		v0 := b.NewValue0(v.Pos, OpPPC64MOVDload, types.Int64)
-		v0.AddArg(src)
-		v0.AddArg(mem)
-		v.AddArg(v0)
-		v.AddArg(mem)
-		return true
-	}
 	// match: (Move [s] dst src mem)
 	// cond: s > 8
 	// result: (LoweredMove [s] dst src mem)