diff --git a/src/cmd/compile/internal/ssa/gen/PPC64.rules b/src/cmd/compile/internal/ssa/gen/PPC64.rules
index 8e42bae215..ccca72a416 100644
--- a/src/cmd/compile/internal/ssa/gen/PPC64.rules
+++ b/src/cmd/compile/internal/ssa/gen/PPC64.rules
@@ -848,6 +848,7 @@
 (ADDconst [c] (SUBFCconst [d] x)) && is32Bit(c+d) => (SUBFCconst [c+d] x)
 (NEG (ADDconst [c] x)) && is32Bit(-c) => (SUBFCconst [-c] x)
 (NEG (SUBFCconst [c] x)) && is32Bit(-c) => (ADDconst [-c] x)
+(NEG (SUB x y)) => (SUB y x)
 
 // Use register moves instead of stores and loads to move int<=>float values
 // Common with math Float64bits, Float64frombits
@@ -1087,7 +1088,7 @@
 ((CMP|CMPW|CMPU|CMPWU) x y) && canonLessThan(x,y) => (InvertFlags ((CMP|CMPW|CMPU|CMPWU) y x))
 
 // ISEL auxInt values 0=LT 1=GT 2=EQ   arg2 ? arg0 : arg1
-// ISEL auxInt values 4=GE 5=LE 6=NE   arg2 ? arg1 : arg0
+// ISEL auxInt values 4=GE 5=LE 6=NE   !arg2 ? arg1 : arg0
 // ISELB special case where arg0, arg1 values are 0, 1
 
 (Equal cmp) => (ISELB [2] (MOVDconst [1]) cmp)
@@ -1138,6 +1139,9 @@
 (ISEL [n] x y (InvertFlags bool)) && n%4 == 0 => (ISEL [n+1] x y bool)
 (ISEL [n] x y (InvertFlags bool)) && n%4 == 1 => (ISEL [n-1] x y bool)
 (ISEL [n] x y (InvertFlags bool)) && n%4 == 2 => (ISEL [n] x y bool)
+(XORconst [1] (ISELB [6] (MOVDconst [1]) cmp)) => (ISELB [2] (MOVDconst [1]) cmp)
+(XORconst [1] (ISELB [5] (MOVDconst [1]) cmp)) => (ISELB [1] (MOVDconst [1]) cmp)
+(XORconst [1] (ISELB [4] (MOVDconst [1]) cmp)) => (ISELB [0] (MOVDconst [1]) cmp)
 
 // A particular pattern seen in cgo code:
 (AND (MOVDconst [c]) x:(MOVBZload _ _)) => (ANDconst [c&0xFF] x)
diff --git a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
index ff9ce64e18..42775fa3c2 100644
--- a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
+++ b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go
@@ -396,7 +396,7 @@ func init() {
 		{name: "CMPWUconst", argLength: 1, reg: gp1cr, asm: "CMPWU", aux: "Int32", typ: "Flags"},
 
 		// ISEL auxInt values 0=LT 1=GT 2=EQ   arg2 ? arg0 : arg1
-		// ISEL auxInt values 4=GE 5=LE 6=NE   arg2 ? arg1 : arg0
+		// ISEL auxInt values 4=GE 5=LE 6=NE   !arg2 ? arg1 : arg0
 		// ISELB special case where arg0, arg1 values are 0, 1 for boolean result
 		{name: "ISEL", argLength: 3, reg: crgp21, asm: "ISEL", aux: "Int32", typ: "Int32"},  // see above
 		{name: "ISELB", argLength: 2, reg: crgp11, asm: "ISEL", aux: "Int32", typ: "Int32"}, // see above
diff --git a/src/cmd/compile/internal/ssa/rewritePPC64.go b/src/cmd/compile/internal/ssa/rewritePPC64.go
index 1e6624e906..ea1c1fa60a 100644
--- a/src/cmd/compile/internal/ssa/rewritePPC64.go
+++ b/src/cmd/compile/internal/ssa/rewritePPC64.go
@@ -11372,6 +11372,18 @@ func rewriteValuePPC64_OpPPC64NEG(v *Value) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (NEG (SUB x y))
+	// result: (SUB y x)
+	for {
+		if v_0.Op != OpPPC64SUB {
+			break
+		}
+		y := v_0.Args[1]
+		x := v_0.Args[0]
+		v.reset(OpPPC64SUB)
+		v.AddArg2(y, x)
+		return true
+	}
 	return false
 }
 func rewriteValuePPC64_OpPPC64NOR(v *Value) bool {
@@ -13912,6 +13924,8 @@ func rewriteValuePPC64_OpPPC64XOR(v *Value) bool {
 }
 func rewriteValuePPC64_OpPPC64XORconst(v *Value) bool {
 	v_0 := v.Args[0]
+	b := v.Block
+	typ := &b.Func.Config.Types
 	// match: (XORconst [c] (XORconst [d] x))
 	// result: (XORconst [c^d] x)
 	for {
@@ -13936,6 +13950,60 @@ func rewriteValuePPC64_OpPPC64XORconst(v *Value) bool {
 		v.copyOf(x)
 		return true
 	}
+	// match: (XORconst [1] (ISELB [6] (MOVDconst [1]) cmp))
+	// result: (ISELB [2] (MOVDconst [1]) cmp)
+	for {
+		if auxIntToInt64(v.AuxInt) != 1 || v_0.Op != OpPPC64ISELB || auxIntToInt32(v_0.AuxInt) != 6 {
+			break
+		}
+		cmp := v_0.Args[1]
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpPPC64MOVDconst || auxIntToInt64(v_0_0.AuxInt) != 1 {
+			break
+		}
+		v.reset(OpPPC64ISELB)
+		v.AuxInt = int32ToAuxInt(2)
+		v0 := b.NewValue0(v.Pos, OpPPC64MOVDconst, typ.Int64)
+		v0.AuxInt = int64ToAuxInt(1)
+		v.AddArg2(v0, cmp)
+		return true
+	}
+	// match: (XORconst [1] (ISELB [5] (MOVDconst [1]) cmp))
+	// result: (ISELB [1] (MOVDconst [1]) cmp)
+	for {
+		if auxIntToInt64(v.AuxInt) != 1 || v_0.Op != OpPPC64ISELB || auxIntToInt32(v_0.AuxInt) != 5 {
+			break
+		}
+		cmp := v_0.Args[1]
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpPPC64MOVDconst || auxIntToInt64(v_0_0.AuxInt) != 1 {
+			break
+		}
+		v.reset(OpPPC64ISELB)
+		v.AuxInt = int32ToAuxInt(1)
+		v0 := b.NewValue0(v.Pos, OpPPC64MOVDconst, typ.Int64)
+		v0.AuxInt = int64ToAuxInt(1)
+		v.AddArg2(v0, cmp)
+		return true
+	}
+	// match: (XORconst [1] (ISELB [4] (MOVDconst [1]) cmp))
+	// result: (ISELB [0] (MOVDconst [1]) cmp)
+	for {
+		if auxIntToInt64(v.AuxInt) != 1 || v_0.Op != OpPPC64ISELB || auxIntToInt32(v_0.AuxInt) != 4 {
+			break
+		}
+		cmp := v_0.Args[1]
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpPPC64MOVDconst || auxIntToInt64(v_0_0.AuxInt) != 1 {
+			break
+		}
+		v.reset(OpPPC64ISELB)
+		v.AuxInt = int32ToAuxInt(0)
+		v0 := b.NewValue0(v.Pos, OpPPC64MOVDconst, typ.Int64)
+		v0.AuxInt = int64ToAuxInt(1)
+		v.AddArg2(v0, cmp)
+		return true
+	}
 	return false
 }
 func rewriteValuePPC64_OpPanicBounds(v *Value) bool {