cmd/compile: try and access last argument first in rulegen

This reduces the number of extra bounds check hints we need to
insert. For example, rather than producing:

	_ = v.Args[2]
	x := v.Args[0]
	y := v.Args[1]
	z := v.Args[2]

We now produce:

	z := v.Args[2]
	x := v.Args[0]
	y := v.Args[1]

This gets rid of about 7000 lines of code from the rewrite rules.

Change-Id: I1291cf0f82e8d035a6d65bce7dee6cedee04cbcd
Reviewed-on: https://go-review.googlesource.com/c/go/+/167397
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 66 insertions, 136 deletions

diff --git a/src/cmd/compile/internal/ssa/rewritedec64.go b/src/cmd/compile/internal/ssa/rewritedec64.go
index eef5483c30..5a143a92a7 100644
--- a/src/cmd/compile/internal/ssa/rewritedec64.go
+++ b/src/cmd/compile/internal/ssa/rewritedec64.go
@@ -143,9 +143,8 @@ func rewriteValuedec64_OpAdd64_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Add32withcarry <typ.Int32> (Int64Hi x) (Int64Hi y) (Select1 <types.TypeFlags> (Add32carry (Int64Lo x) (Int64Lo y)))) (Select0 <typ.UInt32> (Add32carry (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpAdd32withcarry, typ.Int32)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -185,9 +184,8 @@ func rewriteValuedec64_OpAnd64_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (And32 <typ.UInt32> (Int64Hi x) (Int64Hi y)) (And32 <typ.UInt32> (Int64Lo x) (Int64Lo y)))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpAnd32, typ.UInt32)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -459,9 +457,8 @@ func rewriteValuedec64_OpEq64_0(v *Value) bool {
 	// cond:
 	// result: (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Eq32 (Int64Lo x) (Int64Lo y)))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpAndB)
 		v0 := b.NewValue0(v.Pos, OpEq32, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -489,9 +486,8 @@ func rewriteValuedec64_OpGeq64_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Greater32 (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Geq32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpGreater32, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -529,9 +525,8 @@ func rewriteValuedec64_OpGeq64U_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Greater32U (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Geq32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpGreater32U, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -569,9 +564,8 @@ func rewriteValuedec64_OpGreater64_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Greater32 (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Greater32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpGreater32, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -609,9 +603,8 @@ func rewriteValuedec64_OpGreater64U_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Greater32U (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Greater32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpGreater32U, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -669,7 +662,6 @@ func rewriteValuedec64_OpInt64Lo_0(v *Value) bool {
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
 		lo := v_0.Args[1]
 		v.reset(OpCopy)
 		v.Type = lo.Type
@@ -685,9 +677,8 @@ func rewriteValuedec64_OpLeq64_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Less32 (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Leq32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpLess32, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -725,9 +716,8 @@ func rewriteValuedec64_OpLeq64U_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Less32U (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Leq32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpLess32U, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -765,9 +755,8 @@ func rewriteValuedec64_OpLess64_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Less32 (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Less32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpLess32, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -805,9 +794,8 @@ func rewriteValuedec64_OpLess64U_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Less32U (Int64Hi x) (Int64Hi y)) (AndB (Eq32 (Int64Hi x) (Int64Hi y)) (Less32U (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpLess32U, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -847,9 +835,8 @@ func rewriteValuedec64_OpLoad_0(v *Value) bool {
 	// result: (Int64Make (Load <typ.Int32> (OffPtr <typ.Int32Ptr> [4] ptr) mem) (Load <typ.UInt32> ptr mem))
 	for {
 		t := v.Type
-		_ = v.Args[1]
-		ptr := v.Args[0]
 		mem := v.Args[1]
+		ptr := v.Args[0]
 		if !(is64BitInt(t) && !config.BigEndian && t.IsSigned()) {
 			break
 		}
@@ -872,9 +859,8 @@ func rewriteValuedec64_OpLoad_0(v *Value) bool {
 	// result: (Int64Make (Load <typ.UInt32> (OffPtr <typ.UInt32Ptr> [4] ptr) mem) (Load <typ.UInt32> ptr mem))
 	for {
 		t := v.Type
-		_ = v.Args[1]
-		ptr := v.Args[0]
 		mem := v.Args[1]
+		ptr := v.Args[0]
 		if !(is64BitInt(t) && !config.BigEndian && !t.IsSigned()) {
 			break
 		}
@@ -897,9 +883,8 @@ func rewriteValuedec64_OpLoad_0(v *Value) bool {
 	// result: (Int64Make (Load <typ.Int32> ptr mem) (Load <typ.UInt32> (OffPtr <typ.UInt32Ptr> [4] ptr) mem))
 	for {
 		t := v.Type
-		_ = v.Args[1]
-		ptr := v.Args[0]
 		mem := v.Args[1]
+		ptr := v.Args[0]
 		if !(is64BitInt(t) && config.BigEndian && t.IsSigned()) {
 			break
 		}
@@ -922,9 +907,8 @@ func rewriteValuedec64_OpLoad_0(v *Value) bool {
 	// result: (Int64Make (Load <typ.UInt32> ptr mem) (Load <typ.UInt32> (OffPtr <typ.UInt32Ptr> [4] ptr) mem))
 	for {
 		t := v.Type
-		_ = v.Args[1]
-		ptr := v.Args[0]
 		mem := v.Args[1]
+		ptr := v.Args[0]
 		if !(is64BitInt(t) && config.BigEndian && !t.IsSigned()) {
 			break
 		}
@@ -979,7 +963,7 @@ func rewriteValuedec64_OpLsh16x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -987,7 +971,6 @@ func rewriteValuedec64_OpLsh16x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpLsh16x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1003,9 +986,8 @@ func rewriteValuedec64_OpLsh16x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1056,7 +1038,7 @@ func rewriteValuedec64_OpLsh32x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1064,7 +1046,6 @@ func rewriteValuedec64_OpLsh32x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpLsh32x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1080,9 +1061,8 @@ func rewriteValuedec64_OpLsh32x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1105,15 +1085,13 @@ func rewriteValuedec64_OpLsh64x16_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Lsh32x16 <typ.UInt32> hi s) (Rsh32Ux16 <typ.UInt32> lo (Sub16 <typ.UInt16> (Const16 <typ.UInt16> [32]) s))) (Lsh32x16 <typ.UInt32> lo (Sub16 <typ.UInt16> s (Const16 <typ.UInt16> [32])))) (Lsh32x16 <typ.UInt32> lo s))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpOr32, typ.UInt32)
 		v1 := b.NewValue0(v.Pos, OpOr32, typ.UInt32)
@@ -1156,15 +1134,13 @@ func rewriteValuedec64_OpLsh64x32_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Lsh32x32 <typ.UInt32> hi s) (Rsh32Ux32 <typ.UInt32> lo (Sub32 <typ.UInt32> (Const32 <typ.UInt32> [32]) s))) (Lsh32x32 <typ.UInt32> lo (Sub32 <typ.UInt32> s (Const32 <typ.UInt32> [32])))) (Lsh32x32 <typ.UInt32> lo s))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpOr32, typ.UInt32)
 		v1 := b.NewValue0(v.Pos, OpOr32, typ.UInt32)
@@ -1235,7 +1211,7 @@ func rewriteValuedec64_OpLsh64x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1243,7 +1219,6 @@ func rewriteValuedec64_OpLsh64x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpLsh64x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1259,9 +1234,8 @@ func rewriteValuedec64_OpLsh64x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1284,15 +1258,13 @@ func rewriteValuedec64_OpLsh64x8_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Lsh32x8 <typ.UInt32> hi s) (Rsh32Ux8 <typ.UInt32> lo (Sub8 <typ.UInt8> (Const8 <typ.UInt8> [32]) s))) (Lsh32x8 <typ.UInt32> lo (Sub8 <typ.UInt8> s (Const8 <typ.UInt8> [32])))) (Lsh32x8 <typ.UInt32> lo s))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpOr32, typ.UInt32)
 		v1 := b.NewValue0(v.Pos, OpOr32, typ.UInt32)
@@ -1363,7 +1335,7 @@ func rewriteValuedec64_OpLsh8x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1371,7 +1343,6 @@ func rewriteValuedec64_OpLsh8x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpLsh8x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1387,9 +1358,8 @@ func rewriteValuedec64_OpLsh8x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1412,9 +1382,8 @@ func rewriteValuedec64_OpMul64_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Add32 <typ.UInt32> (Mul32 <typ.UInt32> (Int64Lo x) (Int64Hi y)) (Add32 <typ.UInt32> (Mul32 <typ.UInt32> (Int64Hi x) (Int64Lo y)) (Select0 <typ.UInt32> (Mul32uhilo (Int64Lo x) (Int64Lo y))))) (Select1 <typ.UInt32> (Mul32uhilo (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpAdd32, typ.UInt32)
 		v1 := b.NewValue0(v.Pos, OpMul32, typ.UInt32)
@@ -1482,9 +1451,8 @@ func rewriteValuedec64_OpNeq64_0(v *Value) bool {
 	// cond:
 	// result: (OrB (Neq32 (Int64Hi x) (Int64Hi y)) (Neq32 (Int64Lo x) (Int64Lo y)))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpOrB)
 		v0 := b.NewValue0(v.Pos, OpNeq32, typ.Bool)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -1512,9 +1480,8 @@ func rewriteValuedec64_OpOr64_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Or32 <typ.UInt32> (Int64Hi x) (Int64Hi y)) (Or32 <typ.UInt32> (Int64Lo x) (Int64Lo y)))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpOr32, typ.UInt32)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -1570,7 +1537,7 @@ func rewriteValuedec64_OpRsh16Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1578,7 +1545,6 @@ func rewriteValuedec64_OpRsh16Ux64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh16Ux32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1594,9 +1560,8 @@ func rewriteValuedec64_OpRsh16Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1650,7 +1615,7 @@ func rewriteValuedec64_OpRsh16x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1658,7 +1623,6 @@ func rewriteValuedec64_OpRsh16x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh16x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1674,9 +1638,8 @@ func rewriteValuedec64_OpRsh16x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1727,7 +1690,7 @@ func rewriteValuedec64_OpRsh32Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1735,7 +1698,6 @@ func rewriteValuedec64_OpRsh32Ux64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh32Ux32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1751,9 +1713,8 @@ func rewriteValuedec64_OpRsh32Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1805,7 +1766,7 @@ func rewriteValuedec64_OpRsh32x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1813,7 +1774,6 @@ func rewriteValuedec64_OpRsh32x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh32x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -1829,9 +1789,8 @@ func rewriteValuedec64_OpRsh32x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -1854,15 +1813,13 @@ func rewriteValuedec64_OpRsh64Ux16_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Rsh32Ux16 <typ.UInt32> hi s) (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Rsh32Ux16 <typ.UInt32> lo s) (Lsh32x16 <typ.UInt32> hi (Sub16 <typ.UInt16> (Const16 <typ.UInt16> [32]) s))) (Rsh32Ux16 <typ.UInt32> hi (Sub16 <typ.UInt16> s (Const16 <typ.UInt16> [32])))))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpRsh32Ux16, typ.UInt32)
 		v0.AddArg(hi)
@@ -1905,15 +1862,13 @@ func rewriteValuedec64_OpRsh64Ux32_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Rsh32Ux32 <typ.UInt32> hi s) (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Rsh32Ux32 <typ.UInt32> lo s) (Lsh32x32 <typ.UInt32> hi (Sub32 <typ.UInt32> (Const32 <typ.UInt32> [32]) s))) (Rsh32Ux32 <typ.UInt32> hi (Sub32 <typ.UInt32> s (Const32 <typ.UInt32> [32])))))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpRsh32Ux32, typ.UInt32)
 		v0.AddArg(hi)
@@ -1984,7 +1939,7 @@ func rewriteValuedec64_OpRsh64Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -1992,7 +1947,6 @@ func rewriteValuedec64_OpRsh64Ux64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh64Ux32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -2008,9 +1962,8 @@ func rewriteValuedec64_OpRsh64Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -2033,15 +1986,13 @@ func rewriteValuedec64_OpRsh64Ux8_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Rsh32Ux8 <typ.UInt32> hi s) (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Rsh32Ux8 <typ.UInt32> lo s) (Lsh32x8 <typ.UInt32> hi (Sub8 <typ.UInt8> (Const8 <typ.UInt8> [32]) s))) (Rsh32Ux8 <typ.UInt32> hi (Sub8 <typ.UInt8> s (Const8 <typ.UInt8> [32])))))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpRsh32Ux8, typ.UInt32)
 		v0.AddArg(hi)
@@ -2084,15 +2035,13 @@ func rewriteValuedec64_OpRsh64x16_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Rsh32x16 <typ.UInt32> hi s) (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Rsh32Ux16 <typ.UInt32> lo s) (Lsh32x16 <typ.UInt32> hi (Sub16 <typ.UInt16> (Const16 <typ.UInt16> [32]) s))) (And32 <typ.UInt32> (Rsh32x16 <typ.UInt32> hi (Sub16 <typ.UInt16> s (Const16 <typ.UInt16> [32]))) (Zeromask (ZeroExt16to32 (Rsh16Ux32 <typ.UInt16> s (Const32 <typ.UInt32> [5])))))))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpRsh32x16, typ.UInt32)
 		v0.AddArg(hi)
@@ -2147,15 +2096,13 @@ func rewriteValuedec64_OpRsh64x32_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Rsh32x32 <typ.UInt32> hi s) (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Rsh32Ux32 <typ.UInt32> lo s) (Lsh32x32 <typ.UInt32> hi (Sub32 <typ.UInt32> (Const32 <typ.UInt32> [32]) s))) (And32 <typ.UInt32> (Rsh32x32 <typ.UInt32> hi (Sub32 <typ.UInt32> s (Const32 <typ.UInt32> [32]))) (Zeromask (Rsh32Ux32 <typ.UInt32> s (Const32 <typ.UInt32> [5]))))))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpRsh32x32, typ.UInt32)
 		v0.AddArg(hi)
@@ -2246,7 +2193,7 @@ func rewriteValuedec64_OpRsh64x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -2254,7 +2201,6 @@ func rewriteValuedec64_OpRsh64x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh64x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -2270,9 +2216,8 @@ func rewriteValuedec64_OpRsh64x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -2295,15 +2240,13 @@ func rewriteValuedec64_OpRsh64x8_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Rsh32x8 <typ.UInt32> hi s) (Or32 <typ.UInt32> (Or32 <typ.UInt32> (Rsh32Ux8 <typ.UInt32> lo s) (Lsh32x8 <typ.UInt32> hi (Sub8 <typ.UInt8> (Const8 <typ.UInt8> [32]) s))) (And32 <typ.UInt32> (Rsh32x8 <typ.UInt32> hi (Sub8 <typ.UInt8> s (Const8 <typ.UInt8> [32]))) (Zeromask (ZeroExt8to32 (Rsh8Ux32 <typ.UInt8> s (Const32 <typ.UInt32> [5])))))))
 	for {
-		_ = v.Args[1]
+		s := v.Args[1]
 		v_0 := v.Args[0]
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
-		hi := v_0.Args[0]
 		lo := v_0.Args[1]
-		s := v.Args[1]
+		hi := v_0.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpRsh32x8, typ.UInt32)
 		v0.AddArg(hi)
@@ -2386,7 +2329,7 @@ func rewriteValuedec64_OpRsh8Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -2394,7 +2337,6 @@ func rewriteValuedec64_OpRsh8Ux64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh8Ux32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -2410,9 +2352,8 @@ func rewriteValuedec64_OpRsh8Ux64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -2466,7 +2407,7 @@ func rewriteValuedec64_OpRsh8x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
+		lo := v_1.Args[1]
 		v_1_0 := v_1.Args[0]
 		if v_1_0.Op != OpConst32 {
 			break
@@ -2474,7 +2415,6 @@ func rewriteValuedec64_OpRsh8x64_0(v *Value) bool {
 		if v_1_0.AuxInt != 0 {
 			break
 		}
-		lo := v_1.Args[1]
 		v.reset(OpRsh8x32)
 		v.AddArg(x)
 		v.AddArg(lo)
@@ -2490,9 +2430,8 @@ func rewriteValuedec64_OpRsh8x64_0(v *Value) bool {
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
+		hi := v_1.Args[0]
 		if !(hi.Op != OpConst32) {
 			break
 		}
@@ -2562,16 +2501,14 @@ func rewriteValuedec64_OpStore_0(v *Value) bool {
 	// result: (Store {hi.Type} (OffPtr <hi.Type.PtrTo()> [4] dst) hi (Store {lo.Type} dst lo mem))
 	for {
 		t := v.Aux
-		_ = v.Args[2]
+		mem := v.Args[2]
 		dst := v.Args[0]
 		v_1 := v.Args[1]
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
-		mem := v.Args[2]
+		hi := v_1.Args[0]
 		if !(t.(*types.Type).Size() == 8 && !config.BigEndian) {
 			break
 		}
@@ -2595,16 +2532,14 @@ func rewriteValuedec64_OpStore_0(v *Value) bool {
 	// result: (Store {lo.Type} (OffPtr <lo.Type.PtrTo()> [4] dst) lo (Store {hi.Type} dst hi mem))
 	for {
 		t := v.Aux
-		_ = v.Args[2]
+		mem := v.Args[2]
 		dst := v.Args[0]
 		v_1 := v.Args[1]
 		if v_1.Op != OpInt64Make {
 			break
 		}
-		_ = v_1.Args[1]
-		hi := v_1.Args[0]
 		lo := v_1.Args[1]
-		mem := v.Args[2]
+		hi := v_1.Args[0]
 		if !(t.(*types.Type).Size() == 8 && config.BigEndian) {
 			break
 		}
@@ -2632,9 +2567,8 @@ func rewriteValuedec64_OpSub64_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Sub32withcarry <typ.Int32> (Int64Hi x) (Int64Hi y) (Select1 <types.TypeFlags> (Sub32carry (Int64Lo x) (Int64Lo y)))) (Select0 <typ.UInt32> (Sub32carry (Int64Lo x) (Int64Lo y))))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpSub32withcarry, typ.Int32)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)
@@ -2676,7 +2610,6 @@ func rewriteValuedec64_OpTrunc64to16_0(v *Value) bool {
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
 		lo := v_0.Args[1]
 		v.reset(OpTrunc32to16)
 		v.AddArg(lo)
@@ -2693,7 +2626,6 @@ func rewriteValuedec64_OpTrunc64to32_0(v *Value) bool {
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
 		lo := v_0.Args[1]
 		v.reset(OpCopy)
 		v.Type = lo.Type
@@ -2711,7 +2643,6 @@ func rewriteValuedec64_OpTrunc64to8_0(v *Value) bool {
 		if v_0.Op != OpInt64Make {
 			break
 		}
-		_ = v_0.Args[1]
 		lo := v_0.Args[1]
 		v.reset(OpTrunc32to8)
 		v.AddArg(lo)
@@ -2726,9 +2657,8 @@ func rewriteValuedec64_OpXor64_0(v *Value) bool {
 	// cond:
 	// result: (Int64Make (Xor32 <typ.UInt32> (Int64Hi x) (Int64Hi y)) (Xor32 <typ.UInt32> (Int64Lo x) (Int64Lo y)))
 	for {
-		_ = v.Args[1]
-		x := v.Args[0]
 		y := v.Args[1]
+		x := v.Args[0]
 		v.reset(OpInt64Make)
 		v0 := b.NewValue0(v.Pos, OpXor32, typ.UInt32)
 		v1 := b.NewValue0(v.Pos, OpInt64Hi, typ.UInt32)