diff --git a/src/cmd/compile/internal/riscv64/ssa.go b/src/cmd/compile/internal/riscv64/ssa.go
index 9aa77c3d02..2231219579 100644
--- a/src/cmd/compile/internal/riscv64/ssa.go
+++ b/src/cmd/compile/internal/riscv64/ssa.go
@@ -294,7 +294,8 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		ssa.OpRISCV64FADDD, ssa.OpRISCV64FSUBD, ssa.OpRISCV64FMULD, ssa.OpRISCV64FDIVD,
 		ssa.OpRISCV64FEQD, ssa.OpRISCV64FNED, ssa.OpRISCV64FLTD, ssa.OpRISCV64FLED, ssa.OpRISCV64FSGNJD,
 		ssa.OpRISCV64MIN, ssa.OpRISCV64MAX, ssa.OpRISCV64MINU, ssa.OpRISCV64MAXU,
-		ssa.OpRISCV64SH1ADD, ssa.OpRISCV64SH2ADD, ssa.OpRISCV64SH3ADD:
+		ssa.OpRISCV64SH1ADD, ssa.OpRISCV64SH2ADD, ssa.OpRISCV64SH3ADD,
+		ssa.OpRISCV64CZEROEQZ, ssa.OpRISCV64CZERONEZ:
 		r := v.Reg()
 		r1 := v.Args[0].Reg()
 		r2 := v.Args[1].Reg()
diff --git a/src/cmd/compile/internal/ssa/_gen/RISCV64.rules b/src/cmd/compile/internal/ssa/_gen/RISCV64.rules
index 13a8cab3b5..296b8fc2b4 100644
--- a/src/cmd/compile/internal/ssa/_gen/RISCV64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/RISCV64.rules
@@ -859,3 +859,22 @@
 (Max64  x y) && buildcfg.GORISCV64 >= 22 => (MAX  x y)
 (Min64u x y) && buildcfg.GORISCV64 >= 22 => (MINU x y)
 (Max64u x y) && buildcfg.GORISCV64 >= 22 => (MAXU x y)
+
+// Conditional selection (note that these will only be emitted for rva23u64 and above)
+(CondSelect <t> x y cond) =>
+	(OR (CZEROEQZ <t> x (MOVBUreg <typ.UInt64> cond)) (CZERONEZ <t> y (MOVBUreg <typ.UInt64> cond)))
+(CZERO(EQ|NE)Z x (SNEZ y)) => (CZERO(EQ|NE)Z x y)
+(CZERO(EQ|NE)Z x (SEQZ y)) => (CZERO(NE|EQ)Z x y)
+(CZEROEQZ x x) => x
+(CZERONEZ x x) => (MOVDconst [0])
+(CZERO(EQ|NE)Z (MOVDconst [0]) _) => (MOVDconst [0])
+
+// Optimize conditional arithmetic operations
+(OR (CZEROEQZ <t> x cond) (CZERONEZ <t> ((ADD|SUB|OR|XOR|SUBW) x y) cond)) => ((ADD|SUB|OR|XOR|SUBW) x (CZERONEZ <t> y cond))
+(OR (CZEROEQZ <t> ((ADD|SUB|OR|XOR|SUBW) x y) cond) (CZERONEZ <t> x cond)) => ((ADD|SUB|OR|XOR|SUBW) x (CZEROEQZ <t> y cond))
+(OR x:(CZEROEQZ z cond) (CZERONEZ y:(AND z _) cond)) => (OR y x)
+(OR (CZEROEQZ x:(AND z _) cond) y:(CZERONEZ z cond)) => (OR x y)
+(OR x:(CZEROEQZ z cond) (CZERONEZ y:(ANDI <t> [c] z) cond)) => (OR y x)
+(OR (CZEROEQZ x:(ANDI <t> [c] z) cond) y:(CZERONEZ z cond)) => (OR x y)
+(OR (CZEROEQZ <t> x cond) (CZERONEZ <t> ((ADDI|ORI|XORI) [c] x) cond)) => ((ADD|OR|XOR) x (CZERONEZ <t> (MOVDconst [c]) cond))
+(OR (CZEROEQZ <t> ((ADDI|ORI|XORI) [c] x) cond) (CZERONEZ <t> x cond)) => ((ADD|OR|XOR) x (CZEROEQZ <t> (MOVDconst [c]) cond))
diff --git a/src/cmd/compile/internal/ssa/_gen/RISCV64Ops.go b/src/cmd/compile/internal/ssa/_gen/RISCV64Ops.go
index 68674211b0..cd7e8fb144 100644
--- a/src/cmd/compile/internal/ssa/_gen/RISCV64Ops.go
+++ b/src/cmd/compile/internal/ssa/_gen/RISCV64Ops.go
@@ -528,6 +528,10 @@ func init() {
 		//   ====+=============================
 		{name: "FCLASSS", argLength: 1, reg: fpgp, asm: "FCLASSS", typ: "Int64"}, // classify float32
 		{name: "FCLASSD", argLength: 1, reg: fpgp, asm: "FCLASSD", typ: "Int64"}, // classify float64
+
+		// RISC-V Integer Conditional (Zicond) operations extension
+		{name: "CZEROEQZ", argLength: 2, reg: gp21, asm: "CZEROEQZ"}, // arg1 == 0 result is 0, else arg0
+		{name: "CZERONEZ", argLength: 2, reg: gp21, asm: "CZERONEZ"}, // arg1 != 0 result is 0, else arg0
 	}
 
 	RISCV64blocks := []blockData{
diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index f039139e4a..2014f9c60f 100644
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -5356,6 +5356,8 @@ const (
 	OpRISCV64LoweredFMAXD
 	OpRISCV64FCLASSS
 	OpRISCV64FCLASSD
+	OpRISCV64CZEROEQZ
+	OpRISCV64CZERONEZ
 
 	OpS390XFADDS
 	OpS390XFADD
@@ -81426,6 +81428,34 @@ var opcodeTable = [...]opInfo{
 			},
 		},
 	},
+	{
+		name:   "CZEROEQZ",
+		argLen: 2,
+		asm:    riscv.ACZEROEQZ,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 1006632944}, // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+				{1, 1006632944}, // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+			outputs: []outputInfo{
+				{0, 1006632944}, // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+		},
+	},
+	{
+		name:   "CZERONEZ",
+		argLen: 2,
+		asm:    riscv.ACZERONEZ,
+		reg: regInfo{
+			inputs: []inputInfo{
+				{0, 1006632944}, // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+				{1, 1006632944}, // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+			outputs: []outputInfo{
+				{0, 1006632944}, // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
+			},
+		},
+	},
 
 	{
 		name:         "FADDS",
diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
index 284d88967b..1fa1cd8a48 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -133,6 +133,8 @@ func rewriteValueRISCV64(v *Value) bool {
 	case OpCom8:
 		v.Op = OpRISCV64NOT
 		return true
+	case OpCondSelect:
+		return rewriteValueRISCV64_OpCondSelect(v)
 	case OpConst16:
 		return rewriteValueRISCV64_OpConst16(v)
 	case OpConst32:
@@ -514,6 +516,10 @@ func rewriteValueRISCV64(v *Value) bool {
 		return rewriteValueRISCV64_OpRISCV64AND(v)
 	case OpRISCV64ANDI:
 		return rewriteValueRISCV64_OpRISCV64ANDI(v)
+	case OpRISCV64CZEROEQZ:
+		return rewriteValueRISCV64_OpRISCV64CZEROEQZ(v)
+	case OpRISCV64CZERONEZ:
+		return rewriteValueRISCV64_OpRISCV64CZERONEZ(v)
 	case OpRISCV64FADDD:
 		return rewriteValueRISCV64_OpRISCV64FADDD(v)
 	case OpRISCV64FADDS:
@@ -1081,6 +1087,30 @@ func rewriteValueRISCV64_OpBswap32(v *Value) bool {
 		return true
 	}
 }
+func rewriteValueRISCV64_OpCondSelect(v *Value) bool {
+	v_2 := v.Args[2]
+	v_1 := v.Args[1]
+	v_0 := v.Args[0]
+	b := v.Block
+	typ := &b.Func.Config.Types
+	// match: (CondSelect <t> x y cond)
+	// result: (OR (CZEROEQZ <t> x (MOVBUreg <typ.UInt64> cond)) (CZERONEZ <t> y (MOVBUreg <typ.UInt64> cond)))
+	for {
+		t := v.Type
+		x := v_0
+		y := v_1
+		cond := v_2
+		v.reset(OpRISCV64OR)
+		v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+		v1 := b.NewValue0(v.Pos, OpRISCV64MOVBUreg, typ.UInt64)
+		v1.AddArg(cond)
+		v0.AddArg2(x, v1)
+		v2 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+		v2.AddArg2(y, v1)
+		v.AddArg2(v0, v2)
+		return true
+	}
+}
 func rewriteValueRISCV64_OpConst16(v *Value) bool {
 	// match: (Const16 [val])
 	// result: (MOVDconst [int64(val)])
@@ -3528,6 +3558,105 @@ func rewriteValueRISCV64_OpRISCV64ANDI(v *Value) bool {
 	}
 	return false
 }
+func rewriteValueRISCV64_OpRISCV64CZEROEQZ(v *Value) bool {
+	v_1 := v.Args[1]
+	v_0 := v.Args[0]
+	// match: (CZEROEQZ x (SNEZ y))
+	// result: (CZEROEQZ x y)
+	for {
+		x := v_0
+		if v_1.Op != OpRISCV64SNEZ {
+			break
+		}
+		y := v_1.Args[0]
+		v.reset(OpRISCV64CZEROEQZ)
+		v.AddArg2(x, y)
+		return true
+	}
+	// match: (CZEROEQZ x (SEQZ y))
+	// result: (CZERONEZ x y)
+	for {
+		x := v_0
+		if v_1.Op != OpRISCV64SEQZ {
+			break
+		}
+		y := v_1.Args[0]
+		v.reset(OpRISCV64CZERONEZ)
+		v.AddArg2(x, y)
+		return true
+	}
+	// match: (CZEROEQZ x x)
+	// result: x
+	for {
+		x := v_0
+		if x != v_1 {
+			break
+		}
+		v.copyOf(x)
+		return true
+	}
+	// match: (CZEROEQZ (MOVDconst [0]) _)
+	// result: (MOVDconst [0])
+	for {
+		if v_0.Op != OpRISCV64MOVDconst || auxIntToInt64(v_0.AuxInt) != 0 {
+			break
+		}
+		v.reset(OpRISCV64MOVDconst)
+		v.AuxInt = int64ToAuxInt(0)
+		return true
+	}
+	return false
+}
+func rewriteValueRISCV64_OpRISCV64CZERONEZ(v *Value) bool {
+	v_1 := v.Args[1]
+	v_0 := v.Args[0]
+	// match: (CZERONEZ x (SNEZ y))
+	// result: (CZERONEZ x y)
+	for {
+		x := v_0
+		if v_1.Op != OpRISCV64SNEZ {
+			break
+		}
+		y := v_1.Args[0]
+		v.reset(OpRISCV64CZERONEZ)
+		v.AddArg2(x, y)
+		return true
+	}
+	// match: (CZERONEZ x (SEQZ y))
+	// result: (CZEROEQZ x y)
+	for {
+		x := v_0
+		if v_1.Op != OpRISCV64SEQZ {
+			break
+		}
+		y := v_1.Args[0]
+		v.reset(OpRISCV64CZEROEQZ)
+		v.AddArg2(x, y)
+		return true
+	}
+	// match: (CZERONEZ x x)
+	// result: (MOVDconst [0])
+	for {
+		x := v_0
+		if x != v_1 {
+			break
+		}
+		v.reset(OpRISCV64MOVDconst)
+		v.AuxInt = int64ToAuxInt(0)
+		return true
+	}
+	// match: (CZERONEZ (MOVDconst [0]) _)
+	// result: (MOVDconst [0])
+	for {
+		if v_0.Op != OpRISCV64MOVDconst || auxIntToInt64(v_0.AuxInt) != 0 {
+			break
+		}
+		v.reset(OpRISCV64MOVDconst)
+		v.AuxInt = int64ToAuxInt(0)
+		return true
+	}
+	return false
+}
 func rewriteValueRISCV64_OpRISCV64FADDD(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
@@ -6925,6 +7054,8 @@ func rewriteValueRISCV64_OpRISCV64NEGW(v *Value) bool {
 func rewriteValueRISCV64_OpRISCV64OR(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]
+	b := v.Block
+	typ := &b.Func.Config.Types
 	// match: (OR (MOVDconst [val]) x)
 	// cond: is32Bit(val)
 	// result: (ORI [val] x)
@@ -6955,6 +7086,653 @@ func rewriteValueRISCV64_OpRISCV64OR(v *Value) bool {
 		v.copyOf(x)
 		return true
 	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (ADD x y) cond))
+	// result: (ADD x (CZERONEZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64ADD {
+				continue
+			}
+			_ = v_1_0.Args[1]
+			v_1_0_0 := v_1_0.Args[0]
+			v_1_0_1 := v_1_0.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, v_1_0_0, v_1_0_1 = _i1+1, v_1_0_1, v_1_0_0 {
+				if x != v_1_0_0 {
+					continue
+				}
+				y := v_1_0_1
+				if cond != v_1.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64ADD)
+				v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+				v0.AddArg2(y, cond)
+				v.AddArg2(x, v0)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (SUB x y) cond))
+	// result: (SUB x (CZERONEZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64SUB {
+				continue
+			}
+			y := v_1_0.Args[1]
+			if x != v_1_0.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64SUB)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+			v0.AddArg2(y, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (OR x y) cond))
+	// result: (OR x (CZERONEZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64OR {
+				continue
+			}
+			_ = v_1_0.Args[1]
+			v_1_0_0 := v_1_0.Args[0]
+			v_1_0_1 := v_1_0.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, v_1_0_0, v_1_0_1 = _i1+1, v_1_0_1, v_1_0_0 {
+				if x != v_1_0_0 {
+					continue
+				}
+				y := v_1_0_1
+				if cond != v_1.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64OR)
+				v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+				v0.AddArg2(y, cond)
+				v.AddArg2(x, v0)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (XOR x y) cond))
+	// result: (XOR x (CZERONEZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64XOR {
+				continue
+			}
+			_ = v_1_0.Args[1]
+			v_1_0_0 := v_1_0.Args[0]
+			v_1_0_1 := v_1_0.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, v_1_0_0, v_1_0_1 = _i1+1, v_1_0_1, v_1_0_0 {
+				if x != v_1_0_0 {
+					continue
+				}
+				y := v_1_0_1
+				if cond != v_1.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64XOR)
+				v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+				v0.AddArg2(y, cond)
+				v.AddArg2(x, v0)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (SUBW x y) cond))
+	// result: (SUBW x (CZERONEZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64SUBW {
+				continue
+			}
+			y := v_1_0.Args[1]
+			if x != v_1_0.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64SUBW)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+			v0.AddArg2(y, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (ADD x y) cond) (CZERONEZ <t> x cond))
+	// result: (ADD x (CZEROEQZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64ADD {
+				continue
+			}
+			_ = v_0_0.Args[1]
+			v_0_0_0 := v_0_0.Args[0]
+			v_0_0_1 := v_0_0.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, v_0_0_0, v_0_0_1 = _i1+1, v_0_0_1, v_0_0_0 {
+				x := v_0_0_0
+				y := v_0_0_1
+				if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+					continue
+				}
+				_ = v_1.Args[1]
+				if x != v_1.Args[0] || cond != v_1.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64ADD)
+				v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+				v0.AddArg2(y, cond)
+				v.AddArg2(x, v0)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (SUB x y) cond) (CZERONEZ <t> x cond))
+	// result: (SUB x (CZEROEQZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64SUB {
+				continue
+			}
+			y := v_0_0.Args[1]
+			x := v_0_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			if x != v_1.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64SUB)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+			v0.AddArg2(y, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (OR x y) cond) (CZERONEZ <t> x cond))
+	// result: (OR x (CZEROEQZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64OR {
+				continue
+			}
+			_ = v_0_0.Args[1]
+			v_0_0_0 := v_0_0.Args[0]
+			v_0_0_1 := v_0_0.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, v_0_0_0, v_0_0_1 = _i1+1, v_0_0_1, v_0_0_0 {
+				x := v_0_0_0
+				y := v_0_0_1
+				if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+					continue
+				}
+				_ = v_1.Args[1]
+				if x != v_1.Args[0] || cond != v_1.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64OR)
+				v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+				v0.AddArg2(y, cond)
+				v.AddArg2(x, v0)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (XOR x y) cond) (CZERONEZ <t> x cond))
+	// result: (XOR x (CZEROEQZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64XOR {
+				continue
+			}
+			_ = v_0_0.Args[1]
+			v_0_0_0 := v_0_0.Args[0]
+			v_0_0_1 := v_0_0.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, v_0_0_0, v_0_0_1 = _i1+1, v_0_0_1, v_0_0_0 {
+				x := v_0_0_0
+				y := v_0_0_1
+				if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+					continue
+				}
+				_ = v_1.Args[1]
+				if x != v_1.Args[0] || cond != v_1.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64XOR)
+				v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+				v0.AddArg2(y, cond)
+				v.AddArg2(x, v0)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (SUBW x y) cond) (CZERONEZ <t> x cond))
+	// result: (SUBW x (CZEROEQZ <t> y cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64SUBW {
+				continue
+			}
+			y := v_0_0.Args[1]
+			x := v_0_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			if x != v_1.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64SUBW)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+			v0.AddArg2(y, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR x:(CZEROEQZ z cond) (CZERONEZ y:(AND z _) cond))
+	// result: (OR y x)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			x := v_0
+			if x.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			cond := x.Args[1]
+			z := x.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ {
+				continue
+			}
+			_ = v_1.Args[1]
+			y := v_1.Args[0]
+			if y.Op != OpRISCV64AND {
+				continue
+			}
+			y_0 := y.Args[0]
+			y_1 := y.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, y_0, y_1 = _i1+1, y_1, y_0 {
+				if z != y_0 || cond != v_1.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64OR)
+				v.AddArg2(y, x)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ x:(AND z _) cond) y:(CZERONEZ z cond))
+	// result: (OR x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if x.Op != OpRISCV64AND {
+				continue
+			}
+			x_0 := x.Args[0]
+			x_1 := x.Args[1]
+			for _i1 := 0; _i1 <= 1; _i1, x_0, x_1 = _i1+1, x_1, x_0 {
+				z := x_0
+				y := v_1
+				if y.Op != OpRISCV64CZERONEZ {
+					continue
+				}
+				_ = y.Args[1]
+				if z != y.Args[0] || cond != y.Args[1] {
+					continue
+				}
+				v.reset(OpRISCV64OR)
+				v.AddArg2(x, y)
+				return true
+			}
+		}
+		break
+	}
+	// match: (OR x:(CZEROEQZ z cond) (CZERONEZ y:(ANDI <t> [c] z) cond))
+	// result: (OR y x)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			x := v_0
+			if x.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			cond := x.Args[1]
+			z := x.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ {
+				continue
+			}
+			_ = v_1.Args[1]
+			y := v_1.Args[0]
+			if y.Op != OpRISCV64ANDI {
+				continue
+			}
+			if z != y.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64OR)
+			v.AddArg2(y, x)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ x:(ANDI <t> [c] z) cond) y:(CZERONEZ z cond))
+	// result: (OR x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if x.Op != OpRISCV64ANDI {
+				continue
+			}
+			z := x.Args[0]
+			y := v_1
+			if y.Op != OpRISCV64CZERONEZ {
+				continue
+			}
+			_ = y.Args[1]
+			if z != y.Args[0] || cond != y.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64OR)
+			v.AddArg2(x, y)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (ADDI [c] x) cond))
+	// result: (ADD x (CZERONEZ <t> (MOVDconst [c]) cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64ADDI {
+				continue
+			}
+			c := auxIntToInt64(v_1_0.AuxInt)
+			if x != v_1_0.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64ADD)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+			v1 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
+			v1.AuxInt = int64ToAuxInt(c)
+			v0.AddArg2(v1, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (ORI [c] x) cond))
+	// result: (OR x (CZERONEZ <t> (MOVDconst [c]) cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64ORI {
+				continue
+			}
+			c := auxIntToInt64(v_1_0.AuxInt)
+			if x != v_1_0.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64OR)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+			v1 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
+			v1.AuxInt = int64ToAuxInt(c)
+			v0.AddArg2(v1, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> x cond) (CZERONEZ <t> (XORI [c] x) cond))
+	// result: (XOR x (CZERONEZ <t> (MOVDconst [c]) cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			x := v_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			v_1_0 := v_1.Args[0]
+			if v_1_0.Op != OpRISCV64XORI {
+				continue
+			}
+			c := auxIntToInt64(v_1_0.AuxInt)
+			if x != v_1_0.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64XOR)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZERONEZ, t)
+			v1 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
+			v1.AuxInt = int64ToAuxInt(c)
+			v0.AddArg2(v1, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (ADDI [c] x) cond) (CZERONEZ <t> x cond))
+	// result: (ADD x (CZEROEQZ <t> (MOVDconst [c]) cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64ADDI {
+				continue
+			}
+			c := auxIntToInt64(v_0_0.AuxInt)
+			x := v_0_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			if x != v_1.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64ADD)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+			v1 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
+			v1.AuxInt = int64ToAuxInt(c)
+			v0.AddArg2(v1, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (ORI [c] x) cond) (CZERONEZ <t> x cond))
+	// result: (OR x (CZEROEQZ <t> (MOVDconst [c]) cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64ORI {
+				continue
+			}
+			c := auxIntToInt64(v_0_0.AuxInt)
+			x := v_0_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			if x != v_1.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64OR)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+			v1 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
+			v1.AuxInt = int64ToAuxInt(c)
+			v0.AddArg2(v1, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (OR (CZEROEQZ <t> (XORI [c] x) cond) (CZERONEZ <t> x cond))
+	// result: (XOR x (CZEROEQZ <t> (MOVDconst [c]) cond))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpRISCV64CZEROEQZ {
+				continue
+			}
+			t := v_0.Type
+			cond := v_0.Args[1]
+			v_0_0 := v_0.Args[0]
+			if v_0_0.Op != OpRISCV64XORI {
+				continue
+			}
+			c := auxIntToInt64(v_0_0.AuxInt)
+			x := v_0_0.Args[0]
+			if v_1.Op != OpRISCV64CZERONEZ || v_1.Type != t {
+				continue
+			}
+			_ = v_1.Args[1]
+			if x != v_1.Args[0] || cond != v_1.Args[1] {
+				continue
+			}
+			v.reset(OpRISCV64XOR)
+			v0 := b.NewValue0(v.Pos, OpRISCV64CZEROEQZ, t)
+			v1 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
+			v1.AuxInt = int64ToAuxInt(c)
+			v0.AddArg2(v1, cond)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
 	return false
 }
 func rewriteValueRISCV64_OpRISCV64ORI(v *Value) bool {
diff --git a/src/cmd/compile/internal/ssagen/intrinsics.go b/src/cmd/compile/internal/ssagen/intrinsics.go
index f6ece1fbe3..0657d5fc75 100644
--- a/src/cmd/compile/internal/ssagen/intrinsics.go
+++ b/src/cmd/compile/internal/ssagen/intrinsics.go
@@ -1612,6 +1612,10 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
 	/******** crypto/internal/constanttime ********/
 	// We implement a superset of the Select promise:
 	// Select returns x if v != 0 and y if v == 0.
+	hasCMOV := []*sys.Arch{sys.ArchAMD64, sys.ArchARM64, sys.ArchLoong64, sys.ArchPPC64, sys.ArchPPC64LE, sys.ArchWasm}
+	if cfg.goriscv64 >= 23 {
+		hasCMOV = append(hasCMOV, sys.ArchRISCV64)
+	}
 	add("crypto/internal/constanttime", "Select",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			v, x, y := args[0], args[1], args[2]
@@ -1631,8 +1635,7 @@ func initIntrinsics(cfg *intrinsicBuildConfig) {
 			check := s.newValue2(checkOp, types.Types[types.TBOOL], zero, v)
 
 			return s.newValue3(ssa.OpCondSelect, types.Types[types.TINT], x, y, check)
-		},
-		sys.ArchAMD64, sys.ArchARM64, sys.ArchLoong64, sys.ArchPPC64, sys.ArchPPC64LE, sys.ArchWasm) // all with CMOV support.
+		}, hasCMOV...) // all with CMOV support.
 	add("crypto/internal/constanttime", "boolToUint8",
 		func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 			return s.newValue1(ssa.OpCvtBoolToUint8, types.Types[types.TUINT8], args[0])
diff --git a/src/cmd/compile/internal/ssagen/intrinsics_test.go b/src/cmd/compile/internal/ssagen/intrinsics_test.go
index a85a8871e3..37058556dc 100644
--- a/src/cmd/compile/internal/ssagen/intrinsics_test.go
+++ b/src/cmd/compile/internal/ssagen/intrinsics_test.go
@@ -1204,6 +1204,7 @@ var wantIntrinsics = map[testIntrinsicKey]struct{}{
 	{"riscv64", "sync/atomic", "SwapUint32"}:                           struct{}{},
 	{"riscv64", "sync/atomic", "SwapUint64"}:                           struct{}{},
 	{"riscv64", "sync/atomic", "SwapUintptr"}:                          struct{}{},
+	{"riscv64", "crypto/internal/constanttime", "Select"}:              struct{}{},
 	{"riscv64", "crypto/internal/constanttime", "boolToUint8"}:         struct{}{},
 	{"s390x", "internal/runtime/atomic", "And"}:                        struct{}{},
 	{"s390x", "internal/runtime/atomic", "And8"}:                       struct{}{},