diff --git a/src/cmd/compile/internal/amd64/ssa.go b/src/cmd/compile/internal/amd64/ssa.go
index 0c9d12620af..fadac162820 100644
--- a/src/cmd/compile/internal/amd64/ssa.go
+++ b/src/cmd/compile/internal/amd64/ssa.go
@@ -1866,7 +1866,7 @@ func spillArgReg(pp *objw.Progs, p *obj.Prog, f *ssa.Func, t *types.Type, reg in
 func simdReg(v *ssa.Value) int16 {
 	t := v.Type
 	if !t.IsSIMD() {
-		panic("simdReg: not a simd type")
+		base.Fatalf("simdReg: not a simd type; v=%s, b=b%d, f=%s", v.LongString(), v.Block.ID, v.Block.Func.Name)
 	}
 	switch t.Size() {
 	case 8:
diff --git a/src/cmd/compile/internal/ssagen/intrinsics.go b/src/cmd/compile/internal/ssagen/intrinsics.go
index 660047df1f2..73e84077fd2 100644
--- a/src/cmd/compile/internal/ssagen/intrinsics.go
+++ b/src/cmd/compile/internal/ssagen/intrinsics.go
@@ -1684,6 +1684,34 @@ func opLen3Imm8(op ssa.Op, t *types.Type, offset int) func(s *state, n *ir.CallE
 	}
 }
 
+func opLen2Imm8_2I(op ssa.Op, t *types.Type, offset int) func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
+	return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
+		if args[1].Op == ssa.OpConst8 {
+			return s.newValue2I(op, t, args[2].AuxInt<<int64(offset), args[0], args[1])
+		}
+		plainPanicSimdImm(s)
+		// Even though this default call is unreachable semantically,
+		// it has to return something, otherwise the compiler will try to generate
+		// default codes which might lead to a FwdRef being put at the entry block
+		// triggering a compiler panic.
+		return s.newValue2I(op, t, 0, args[0], args[1])
+	}
+}
+
+func opLen3Imm8_2I(op ssa.Op, t *types.Type, offset int) func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
+	return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
+		if args[1].Op == ssa.OpConst8 {
+			return s.newValue3I(op, t, args[2].AuxInt<<int64(offset), args[0], args[1], args[3])
+		}
+		plainPanicSimdImm(s)
+		// Even though this default call is unreachable semantically,
+		// it has to return something, otherwise the compiler will try to generate
+		// default codes which might lead to a FwdRef being put at the entry block
+		// triggering a compiler panic.
+		return s.newValue3I(op, t, 0, args[0], args[1], args[3])
+	}
+}
+
 func opLen4Imm8(op ssa.Op, t *types.Type, offset int) func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 	return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
 		if args[1].Op == ssa.OpConst8 {
diff --git a/src/cmd/compile/internal/ssagen/simdintrinsics.go b/src/cmd/compile/internal/ssagen/simdintrinsics.go
index 87c1327f162..a7f9b9d8a34 100644
--- a/src/cmd/compile/internal/ssagen/simdintrinsics.go
+++ b/src/cmd/compile/internal/ssagen/simdintrinsics.go
@@ -262,12 +262,12 @@ func simdIntrinsics(addF func(pkg, fn string, b intrinsicBuilder, archFamilies .
 	addF(simdPackage, "Float64x2.FusedMultiplySubAdd", opLen3(ssa.OpFusedMultiplySubAddFloat64x2, types.TypeVec128), sys.AMD64)
 	addF(simdPackage, "Float64x4.FusedMultiplySubAdd", opLen3(ssa.OpFusedMultiplySubAddFloat64x4, types.TypeVec256), sys.AMD64)
 	addF(simdPackage, "Float64x8.FusedMultiplySubAdd", opLen3(ssa.OpFusedMultiplySubAddFloat64x8, types.TypeVec512), sys.AMD64)
-	addF(simdPackage, "Uint8x16.GaloisFieldAffineTransform", opLen2Imm8(ssa.OpGaloisFieldAffineTransformUint8x16, types.TypeVec128, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x32.GaloisFieldAffineTransform", opLen2Imm8(ssa.OpGaloisFieldAffineTransformUint8x32, types.TypeVec256, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x64.GaloisFieldAffineTransform", opLen2Imm8(ssa.OpGaloisFieldAffineTransformUint8x64, types.TypeVec512, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x16.GaloisFieldAffineTransformInversed", opLen2Imm8(ssa.OpGaloisFieldAffineTransformInversedUint8x16, types.TypeVec128, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x32.GaloisFieldAffineTransformInversed", opLen2Imm8(ssa.OpGaloisFieldAffineTransformInversedUint8x32, types.TypeVec256, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x64.GaloisFieldAffineTransformInversed", opLen2Imm8(ssa.OpGaloisFieldAffineTransformInversedUint8x64, types.TypeVec512, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x16.GaloisFieldAffineTransform", opLen2Imm8_2I(ssa.OpGaloisFieldAffineTransformUint8x16, types.TypeVec128, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x32.GaloisFieldAffineTransform", opLen2Imm8_2I(ssa.OpGaloisFieldAffineTransformUint8x32, types.TypeVec256, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x64.GaloisFieldAffineTransform", opLen2Imm8_2I(ssa.OpGaloisFieldAffineTransformUint8x64, types.TypeVec512, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x16.GaloisFieldAffineTransformInversed", opLen2Imm8_2I(ssa.OpGaloisFieldAffineTransformInversedUint8x16, types.TypeVec128, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x32.GaloisFieldAffineTransformInversed", opLen2Imm8_2I(ssa.OpGaloisFieldAffineTransformInversedUint8x32, types.TypeVec256, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x64.GaloisFieldAffineTransformInversed", opLen2Imm8_2I(ssa.OpGaloisFieldAffineTransformInversedUint8x64, types.TypeVec512, 0), sys.AMD64)
 	addF(simdPackage, "Uint8x16.GaloisFieldMul", opLen2(ssa.OpGaloisFieldMulUint8x16, types.TypeVec128), sys.AMD64)
 	addF(simdPackage, "Uint8x32.GaloisFieldMul", opLen2(ssa.OpGaloisFieldMulUint8x32, types.TypeVec256), sys.AMD64)
 	addF(simdPackage, "Uint8x64.GaloisFieldMul", opLen2(ssa.OpGaloisFieldMulUint8x64, types.TypeVec512), sys.AMD64)
@@ -627,12 +627,12 @@ func simdIntrinsics(addF func(pkg, fn string, b intrinsicBuilder, archFamilies .
 	addF(simdPackage, "Float64x2.MaskedFusedMultiplySubAdd", opLen4(ssa.OpMaskedFusedMultiplySubAddFloat64x2, types.TypeVec128), sys.AMD64)
 	addF(simdPackage, "Float64x4.MaskedFusedMultiplySubAdd", opLen4(ssa.OpMaskedFusedMultiplySubAddFloat64x4, types.TypeVec256), sys.AMD64)
 	addF(simdPackage, "Float64x8.MaskedFusedMultiplySubAdd", opLen4(ssa.OpMaskedFusedMultiplySubAddFloat64x8, types.TypeVec512), sys.AMD64)
-	addF(simdPackage, "Uint8x16.MaskedGaloisFieldAffineTransform", opLen3Imm8(ssa.OpMaskedGaloisFieldAffineTransformUint8x16, types.TypeVec128, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x32.MaskedGaloisFieldAffineTransform", opLen3Imm8(ssa.OpMaskedGaloisFieldAffineTransformUint8x32, types.TypeVec256, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x64.MaskedGaloisFieldAffineTransform", opLen3Imm8(ssa.OpMaskedGaloisFieldAffineTransformUint8x64, types.TypeVec512, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x16.MaskedGaloisFieldAffineTransformInversed", opLen3Imm8(ssa.OpMaskedGaloisFieldAffineTransformInversedUint8x16, types.TypeVec128, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x32.MaskedGaloisFieldAffineTransformInversed", opLen3Imm8(ssa.OpMaskedGaloisFieldAffineTransformInversedUint8x32, types.TypeVec256, 0), sys.AMD64)
-	addF(simdPackage, "Uint8x64.MaskedGaloisFieldAffineTransformInversed", opLen3Imm8(ssa.OpMaskedGaloisFieldAffineTransformInversedUint8x64, types.TypeVec512, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x16.MaskedGaloisFieldAffineTransform", opLen3Imm8_2I(ssa.OpMaskedGaloisFieldAffineTransformUint8x16, types.TypeVec128, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x32.MaskedGaloisFieldAffineTransform", opLen3Imm8_2I(ssa.OpMaskedGaloisFieldAffineTransformUint8x32, types.TypeVec256, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x64.MaskedGaloisFieldAffineTransform", opLen3Imm8_2I(ssa.OpMaskedGaloisFieldAffineTransformUint8x64, types.TypeVec512, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x16.MaskedGaloisFieldAffineTransformInversed", opLen3Imm8_2I(ssa.OpMaskedGaloisFieldAffineTransformInversedUint8x16, types.TypeVec128, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x32.MaskedGaloisFieldAffineTransformInversed", opLen3Imm8_2I(ssa.OpMaskedGaloisFieldAffineTransformInversedUint8x32, types.TypeVec256, 0), sys.AMD64)
+	addF(simdPackage, "Uint8x64.MaskedGaloisFieldAffineTransformInversed", opLen3Imm8_2I(ssa.OpMaskedGaloisFieldAffineTransformInversedUint8x64, types.TypeVec512, 0), sys.AMD64)
 	addF(simdPackage, "Uint8x16.MaskedGaloisFieldMul", opLen3(ssa.OpMaskedGaloisFieldMulUint8x16, types.TypeVec128), sys.AMD64)
 	addF(simdPackage, "Uint8x32.MaskedGaloisFieldMul", opLen3(ssa.OpMaskedGaloisFieldMulUint8x32, types.TypeVec256), sys.AMD64)
 	addF(simdPackage, "Uint8x64.MaskedGaloisFieldMul", opLen3(ssa.OpMaskedGaloisFieldMulUint8x64, types.TypeVec512), sys.AMD64)
diff --git a/src/simd/stubs_amd64.go b/src/simd/stubs_amd64.go
index e589378c72f..f0db32a07d1 100644
--- a/src/simd/stubs_amd64.go
+++ b/src/simd/stubs_amd64.go
@@ -1430,56 +1430,56 @@ func (x Float64x8) FusedMultiplySubAdd(y Float64x8, z Float64x8) Float64x8
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8):
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEQB, CPU Feature: AVX512EVEX
-func (x Uint8x16) GaloisFieldAffineTransform(b uint8, y Uint64x2) Uint8x16
+func (x Uint8x16) GaloisFieldAffineTransform(y Uint64x2, b uint8) Uint8x16
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8):
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEQB, CPU Feature: AVX512EVEX
-func (x Uint8x32) GaloisFieldAffineTransform(b uint8, y Uint64x4) Uint8x32
+func (x Uint8x32) GaloisFieldAffineTransform(y Uint64x4, b uint8) Uint8x32
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8):
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEQB, CPU Feature: AVX512EVEX
-func (x Uint8x64) GaloisFieldAffineTransform(b uint8, y Uint64x8) Uint8x64
+func (x Uint8x64) GaloisFieldAffineTransform(y Uint64x8, b uint8) Uint8x64
 
 /* GaloisFieldAffineTransformInversed */
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8),
 // with x inversed with reduction polynomial x^8 + x^4 + x^3 + x + 1:
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEINVQB, CPU Feature: AVX512EVEX
-func (x Uint8x16) GaloisFieldAffineTransformInversed(b uint8, y Uint64x2) Uint8x16
+func (x Uint8x16) GaloisFieldAffineTransformInversed(y Uint64x2, b uint8) Uint8x16
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8),
 // with x inversed with reduction polynomial x^8 + x^4 + x^3 + x + 1:
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEINVQB, CPU Feature: AVX512EVEX
-func (x Uint8x32) GaloisFieldAffineTransformInversed(b uint8, y Uint64x4) Uint8x32
+func (x Uint8x32) GaloisFieldAffineTransformInversed(y Uint64x4, b uint8) Uint8x32
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8),
 // with x inversed with reduction polynomial x^8 + x^4 + x^3 + x + 1:
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEINVQB, CPU Feature: AVX512EVEX
-func (x Uint8x64) GaloisFieldAffineTransformInversed(b uint8, y Uint64x8) Uint8x64
+func (x Uint8x64) GaloisFieldAffineTransformInversed(y Uint64x8, b uint8) Uint8x64
 
 /* GaloisFieldMul */
 
@@ -3573,56 +3573,56 @@ func (x Float64x8) MaskedFusedMultiplySubAdd(y Float64x8, z Float64x8, u Mask64x
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8):
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEQB, CPU Feature: AVX512EVEX
-func (x Uint8x16) MaskedGaloisFieldAffineTransform(b uint8, y Uint64x2, m Mask8x16) Uint8x16
+func (x Uint8x16) MaskedGaloisFieldAffineTransform(y Uint64x2, b uint8, m Mask8x16) Uint8x16
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8):
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEQB, CPU Feature: AVX512EVEX
-func (x Uint8x32) MaskedGaloisFieldAffineTransform(b uint8, y Uint64x4, m Mask8x32) Uint8x32
+func (x Uint8x32) MaskedGaloisFieldAffineTransform(y Uint64x4, b uint8, m Mask8x32) Uint8x32
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8):
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEQB, CPU Feature: AVX512EVEX
-func (x Uint8x64) MaskedGaloisFieldAffineTransform(b uint8, y Uint64x8, m Mask8x64) Uint8x64
+func (x Uint8x64) MaskedGaloisFieldAffineTransform(y Uint64x8, b uint8, m Mask8x64) Uint8x64
 
 /* MaskedGaloisFieldAffineTransformInversed */
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8),
 // with x inversed with reduction polynomial x^8 + x^4 + x^3 + x + 1:
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEINVQB, CPU Feature: AVX512EVEX
-func (x Uint8x16) MaskedGaloisFieldAffineTransformInversed(b uint8, y Uint64x2, m Mask8x16) Uint8x16
+func (x Uint8x16) MaskedGaloisFieldAffineTransformInversed(y Uint64x2, b uint8, m Mask8x16) Uint8x16
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8),
 // with x inversed with reduction polynomial x^8 + x^4 + x^3 + x + 1:
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEINVQB, CPU Feature: AVX512EVEX
-func (x Uint8x32) MaskedGaloisFieldAffineTransformInversed(b uint8, y Uint64x4, m Mask8x32) Uint8x32
+func (x Uint8x32) MaskedGaloisFieldAffineTransformInversed(y Uint64x4, b uint8, m Mask8x32) Uint8x32
 
 // GaloisFieldAffineTransform computes an affine transformation in GF(2^8),
 // with x inversed with reduction polynomial x^8 + x^4 + x^3 + x + 1:
 // x is a vector of 8-bit vectors, with each adjacent 8 as a group; y is a vector of 8x8 1-bit matrixes;
-// imm is an 8-bit vector. The affine transformation is y * x + imm, with each element of y
+// b is an 8-bit vector. The affine transformation is y * x + b, with each element of y
 // corresponding to a group of 8 elements in x.
 //
 // Asm: VGF2P8AFFINEINVQB, CPU Feature: AVX512EVEX
-func (x Uint8x64) MaskedGaloisFieldAffineTransformInversed(b uint8, y Uint64x8, m Mask8x64) Uint8x64
+func (x Uint8x64) MaskedGaloisFieldAffineTransformInversed(y Uint64x8, b uint8, m Mask8x64) Uint8x64
 
 /* MaskedGaloisFieldMul */