Пример #1
0
func (tm *llvmTypeMap) basicLLVMType(b *types.Basic) llvm.Type {
	switch b.Kind() {
	case types.Bool:
		return llvm.Int1Type()
	case types.Int8, types.Uint8:
		return llvm.Int8Type()
	case types.Int16, types.Uint16:
		return llvm.Int16Type()
	case types.Int32, types.Uint32:
		return llvm.Int32Type()
	case types.Uint, types.Int:
		return tm.inttype
	case types.Int64, types.Uint64:
		return llvm.Int64Type()
	case types.Float32:
		return llvm.FloatType()
	case types.Float64:
		return llvm.DoubleType()
	case types.UnsafePointer, types.Uintptr:
		return tm.target.IntPtrType()
	case types.Complex64:
		f32 := llvm.FloatType()
		elements := []llvm.Type{f32, f32}
		return llvm.StructType(elements, false)
	case types.Complex128:
		f64 := llvm.DoubleType()
		elements := []llvm.Type{f64, f64}
		return llvm.StructType(elements, false)
	case types.String:
		i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
		elements := []llvm.Type{i8ptr, tm.inttype}
		return llvm.StructType(elements, false)
	}
	panic(fmt.Sprint("unhandled kind: ", b.Kind))
}
Пример #2
0
func (tm *TypeMap) basicLLVMType(b *types.Basic) llvm.Type {
	switch b.Kind {
	case types.BoolKind:
		return llvm.Int1Type()
	case types.Int8Kind, types.Uint8Kind:
		return llvm.Int8Type()
	case types.Int16Kind, types.Uint16Kind:
		return llvm.Int16Type()
	case types.Int32Kind, types.Uint32Kind:
		return llvm.Int32Type()
	case types.Int64Kind, types.Uint64Kind:
		return llvm.Int64Type()
	case types.Float32Kind:
		return llvm.FloatType()
	case types.Float64Kind:
		return llvm.DoubleType()
	case types.UnsafePointerKind, types.UintptrKind,
		types.UintKind, types.IntKind:
		return tm.target.IntPtrType()
	//case Complex64: TODO
	//case Complex128:
	//case UntypedInt:
	//case UntypedFloat:
	//case UntypedComplex:
	case types.StringKind:
		i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
		elements := []llvm.Type{i8ptr, llvm.Int32Type()}
		return llvm.StructType(elements, false)
	}
	panic(fmt.Sprint("unhandled kind: ", b.Kind))
}
Пример #3
0
func (v ConstValue) LLVMValue() llvm.Value {
	typ := types.Underlying(v.Type())
	switch typ {
	case types.Int, types.Uint:
		return llvm.ConstInt(llvm.Int32Type(), uint64(v.Int64()), true)
		// TODO 32/64bit (probably wait for gc)
		//int_val := v.Val.(*big.Int)
		//if int_val.Cmp(maxBigInt32) > 0 || int_val.Cmp(minBigInt32) < 0 {
		//	panic(fmt.Sprint("const ", int_val, " overflows int"))
		//}
		//return llvm.ConstInt(v.compiler.target.IntPtrType(), uint64(v.Int64()), true)
	case types.Uint:
		return llvm.ConstInt(llvm.Int32Type(), uint64(v.Int64()), false)

	case types.Int8:
		return llvm.ConstInt(llvm.Int8Type(), uint64(v.Int64()), true)
	case types.Uint8, types.Byte:
		return llvm.ConstInt(llvm.Int8Type(), uint64(v.Int64()), false)

	case types.Int16:
		return llvm.ConstInt(llvm.Int16Type(), uint64(v.Int64()), true)
	case types.Uint16:
		return llvm.ConstInt(llvm.Int16Type(), uint64(v.Int64()), false)

	case types.Int32, types.Rune:
		return llvm.ConstInt(llvm.Int32Type(), uint64(v.Int64()), true)
	case types.Uint32:
		return llvm.ConstInt(llvm.Int32Type(), uint64(v.Int64()), false)

	case types.Int64:
		return llvm.ConstInt(llvm.Int64Type(), uint64(v.Int64()), true)
	case types.Uint64:
		return llvm.ConstInt(llvm.Int64Type(), uint64(v.Int64()), true)

	case types.Float32:
		return llvm.ConstFloat(llvm.FloatType(), float64(v.Float64()))
	case types.Float64:
		return llvm.ConstFloat(llvm.DoubleType(), float64(v.Float64()))

	case types.UnsafePointer, types.Uintptr:
		inttype := v.compiler.target.IntPtrType()
		return llvm.ConstInt(inttype, uint64(v.Int64()), false)

	case types.String:
		strval := (v.Val).(string)
		ptr := v.compiler.builder.CreateGlobalStringPtr(strval, "")
		len_ := llvm.ConstInt(llvm.Int32Type(), uint64(len(strval)), false)
		return llvm.ConstStruct([]llvm.Value{ptr, len_}, false)

	case types.Bool:
		if v := v.Val.(bool); v {
			return llvm.ConstAllOnes(llvm.Int1Type())
		}
		return llvm.ConstNull(llvm.Int1Type())
	}
	panic(fmt.Errorf("Unhandled type: %v", typ)) //v.typ.Kind))
}
Пример #4
0
func (v *LLVMValue) Convert(dsttyp types.Type) Value {
	b := v.compiler.builder

	// If it's a stack allocated value, we'll want to compare the
	// value type, not the pointer type.
	srctyp := v.typ

	// Get the underlying type, if any.
	origdsttyp := dsttyp
	dsttyp = dsttyp.Underlying()
	srctyp = srctyp.Underlying()

	// Identical (underlying) types? Just swap in the destination type.
	if types.IsIdentical(srctyp, dsttyp) {
		// A method converted to a function type without the
		// receiver is where we convert a "method value" into a
		// function.
		if srctyp, ok := srctyp.(*types.Signature); ok && srctyp.Recv() != nil {
			if dsttyp, ok := dsttyp.(*types.Signature); ok && dsttyp.Recv() == nil {
				return v.convertMethodValue(origdsttyp)
			}
		}

		// TODO avoid load here by reusing pointer value, if exists.
		return v.compiler.NewValue(v.LLVMValue(), origdsttyp)
	}

	// Both pointer types with identical underlying types? Same as above.
	if srctyp, ok := srctyp.(*types.Pointer); ok {
		if dsttyp, ok := dsttyp.(*types.Pointer); ok {
			srctyp := srctyp.Elem().Underlying()
			dsttyp := dsttyp.Elem().Underlying()
			if types.IsIdentical(srctyp, dsttyp) {
				return v.compiler.NewValue(v.LLVMValue(), origdsttyp)
			}
		}
	}

	// Convert from an interface type.
	if _, isinterface := srctyp.(*types.Interface); isinterface {
		if interface_, isinterface := dsttyp.(*types.Interface); isinterface {
			return v.mustConvertI2I(interface_)
		} else {
			return v.mustConvertI2V(origdsttyp)
		}
	}

	// Converting to an interface type.
	if interface_, isinterface := dsttyp.(*types.Interface); isinterface {
		return v.convertV2I(interface_)
	}

	byteslice := types.NewSlice(types.Typ[types.Byte])
	runeslice := types.NewSlice(types.Typ[types.Rune])

	// string ->
	if isString(srctyp) {
		// (untyped) string -> string
		// XXX should untyped strings be able to escape go/types?
		if isString(dsttyp) {
			return v.compiler.NewValue(v.LLVMValue(), origdsttyp)
		}

		// string -> []byte
		if types.IsIdentical(dsttyp, byteslice) {
			c := v.compiler
			value := v.LLVMValue()
			strdata := c.builder.CreateExtractValue(value, 0, "")
			strlen := c.builder.CreateExtractValue(value, 1, "")

			// Data must be copied, to prevent changes in
			// the byte slice from mutating the string.
			newdata := c.builder.CreateArrayMalloc(strdata.Type().ElementType(), strlen, "")
			memcpy := c.NamedFunction("runtime.memcpy", "func(uintptr, uintptr, uintptr)")
			c.builder.CreateCall(memcpy, []llvm.Value{
				c.builder.CreatePtrToInt(newdata, c.target.IntPtrType(), ""),
				c.builder.CreatePtrToInt(strdata, c.target.IntPtrType(), ""),
				strlen,
			}, "")
			strdata = newdata

			struct_ := llvm.Undef(c.types.ToLLVM(byteslice))
			struct_ = c.builder.CreateInsertValue(struct_, strdata, 0, "")
			struct_ = c.builder.CreateInsertValue(struct_, strlen, 1, "")
			struct_ = c.builder.CreateInsertValue(struct_, strlen, 2, "")
			return c.NewValue(struct_, byteslice)
		}

		// string -> []rune
		if types.IsIdentical(dsttyp, runeslice) {
			return v.stringToRuneSlice()
		}
	}

	// []byte -> string
	if types.IsIdentical(srctyp, byteslice) && isString(dsttyp) {
		c := v.compiler
		value := v.LLVMValue()
		data := c.builder.CreateExtractValue(value, 0, "")
		len := c.builder.CreateExtractValue(value, 1, "")

		// Data must be copied, to prevent changes in
		// the byte slice from mutating the string.
		newdata := c.builder.CreateArrayMalloc(data.Type().ElementType(), len, "")
		memcpy := c.NamedFunction("runtime.memcpy", "func(uintptr, uintptr, uintptr)")
		c.builder.CreateCall(memcpy, []llvm.Value{
			c.builder.CreatePtrToInt(newdata, c.target.IntPtrType(), ""),
			c.builder.CreatePtrToInt(data, c.target.IntPtrType(), ""),
			len,
		}, "")
		data = newdata

		struct_ := llvm.Undef(c.types.ToLLVM(types.Typ[types.String]))
		struct_ = c.builder.CreateInsertValue(struct_, data, 0, "")
		struct_ = c.builder.CreateInsertValue(struct_, len, 1, "")
		return c.NewValue(struct_, types.Typ[types.String])
	}

	// []rune -> string
	if types.IsIdentical(srctyp, runeslice) && isString(dsttyp) {
		return v.runeSliceToString()
	}

	// rune -> string
	if isString(dsttyp) && isInteger(srctyp) {
		return v.runeToString()
	}

	// TODO other special conversions?
	llvm_type := v.compiler.types.ToLLVM(dsttyp)

	// Unsafe pointer conversions.
	if dsttyp == types.Typ[types.UnsafePointer] { // X -> unsafe.Pointer
		if _, isptr := srctyp.(*types.Pointer); isptr {
			value := b.CreatePtrToInt(v.LLVMValue(), llvm_type, "")
			return v.compiler.NewValue(value, origdsttyp)
		} else if srctyp == types.Typ[types.Uintptr] {
			return v.compiler.NewValue(v.LLVMValue(), origdsttyp)
		}
	} else if srctyp == types.Typ[types.UnsafePointer] { // unsafe.Pointer -> X
		if _, isptr := dsttyp.(*types.Pointer); isptr {
			value := b.CreateIntToPtr(v.LLVMValue(), llvm_type, "")
			return v.compiler.NewValue(value, origdsttyp)
		} else if dsttyp == types.Typ[types.Uintptr] {
			return v.compiler.NewValue(v.LLVMValue(), origdsttyp)
		}
	}

	lv := v.LLVMValue()
	srcType := lv.Type()
	switch srcType.TypeKind() {
	case llvm.IntegerTypeKind:
		switch llvm_type.TypeKind() {
		case llvm.IntegerTypeKind:
			srcBits := srcType.IntTypeWidth()
			dstBits := llvm_type.IntTypeWidth()
			delta := srcBits - dstBits
			switch {
			case delta < 0:
				// TODO check if (un)signed, use S/ZExt accordingly.
				lv = b.CreateZExt(lv, llvm_type, "")
			case delta > 0:
				lv = b.CreateTrunc(lv, llvm_type, "")
			}
			return v.compiler.NewValue(lv, origdsttyp)
		case llvm.FloatTypeKind, llvm.DoubleTypeKind:
			if !isUnsigned(v.Type()) {
				lv = b.CreateSIToFP(lv, llvm_type, "")
			} else {
				lv = b.CreateUIToFP(lv, llvm_type, "")
			}
			return v.compiler.NewValue(lv, origdsttyp)
		}
	case llvm.DoubleTypeKind:
		switch llvm_type.TypeKind() {
		case llvm.FloatTypeKind:
			lv = b.CreateFPTrunc(lv, llvm_type, "")
			return v.compiler.NewValue(lv, origdsttyp)
		case llvm.IntegerTypeKind:
			if !isUnsigned(dsttyp) {
				lv = b.CreateFPToSI(lv, llvm_type, "")
			} else {
				lv = b.CreateFPToUI(lv, llvm_type, "")
			}
			return v.compiler.NewValue(lv, origdsttyp)
		}
	case llvm.FloatTypeKind:
		switch llvm_type.TypeKind() {
		case llvm.DoubleTypeKind:
			lv = b.CreateFPExt(lv, llvm_type, "")
			return v.compiler.NewValue(lv, origdsttyp)
		case llvm.IntegerTypeKind:
			if !isUnsigned(dsttyp) {
				lv = b.CreateFPToSI(lv, llvm_type, "")
			} else {
				lv = b.CreateFPToUI(lv, llvm_type, "")
			}
			return v.compiler.NewValue(lv, origdsttyp)
		}
	}

	// Complex -> complex. Complexes are only convertible to other
	// complexes, contant conversions aside. So we can just check the
	// source type here; given that the types are not identical
	// (checked above), we can assume the destination type is the alternate
	// complex type.
	if isComplex(srctyp) {
		var fpcast func(*Builder, llvm.Value, llvm.Type, string) llvm.Value
		var fptype llvm.Type
		if srctyp == types.Typ[types.Complex64] {
			fpcast = (*Builder).CreateFPExt
			fptype = llvm.DoubleType()
		} else {
			fpcast = (*Builder).CreateFPTrunc
			fptype = llvm.FloatType()
		}
		if fpcast != nil {
			realv := b.CreateExtractValue(lv, 0, "")
			imagv := b.CreateExtractValue(lv, 1, "")
			realv = fpcast(b, realv, fptype, "")
			imagv = fpcast(b, imagv, fptype, "")
			lv = llvm.Undef(v.compiler.types.ToLLVM(dsttyp))
			lv = b.CreateInsertValue(lv, realv, 0, "")
			lv = b.CreateInsertValue(lv, imagv, 1, "")
			return v.compiler.NewValue(lv, origdsttyp)
		}
	}

	srcstr := v.compiler.types.TypeString(v.typ)
	dststr := v.compiler.types.TypeString(origdsttyp)
	panic(fmt.Sprintf("unimplemented conversion: %s -> %s", srcstr, dststr))
}
Пример #5
0
func (v ConstValue) LLVMValue() llvm.Value {
	typ := types.Underlying(v.Type())
	if name, ok := typ.(*types.Name); ok {
		typ = name.Underlying
	}

	switch typ.(*types.Basic).Kind {
	case types.IntKind, types.UintKind:
		return llvm.ConstInt(llvm.Int32Type(), uint64(v.Int64()), true)
		// TODO 32/64bit (probably wait for gc)
		//int_val := v.Val.(*big.Int)
		//if int_val.Cmp(maxBigInt32) > 0 || int_val.Cmp(minBigInt32) < 0 {
		//	panic(fmt.Sprint("const ", int_val, " overflows int"))
		//}
		//return llvm.ConstInt(v.compiler.target.IntPtrType(), uint64(v.Int64()), true)

	case types.Int8Kind:
		return llvm.ConstInt(llvm.Int8Type(), uint64(v.Int64()), true)
	case types.Uint8Kind:
		return llvm.ConstInt(llvm.Int8Type(), uint64(v.Int64()), false)

	case types.Int16Kind:
		return llvm.ConstInt(llvm.Int16Type(), uint64(v.Int64()), true)
	case types.Uint16Kind:
		return llvm.ConstInt(llvm.Int16Type(), uint64(v.Int64()), false)

	case types.Int32Kind:
		return llvm.ConstInt(llvm.Int32Type(), uint64(v.Int64()), true)
	case types.Uint32Kind:
		return llvm.ConstInt(llvm.Int32Type(), uint64(v.Int64()), false)

	case types.Int64Kind:
		return llvm.ConstInt(llvm.Int64Type(), uint64(v.Int64()), true)
	case types.Uint64Kind:
		return llvm.ConstInt(llvm.Int64Type(), uint64(v.Int64()), false)

	case types.Float32Kind:
		return llvm.ConstFloat(llvm.FloatType(), float64(v.Float64()))
	case types.Float64Kind:
		return llvm.ConstFloat(llvm.DoubleType(), float64(v.Float64()))

	case types.Complex64Kind:
		r_, i_ := v.Complex()
		r := llvm.ConstFloat(llvm.FloatType(), r_)
		i := llvm.ConstFloat(llvm.FloatType(), i_)
		return llvm.ConstStruct([]llvm.Value{r, i}, false)
	case types.Complex128Kind:
		r_, i_ := v.Complex()
		r := llvm.ConstFloat(llvm.DoubleType(), r_)
		i := llvm.ConstFloat(llvm.DoubleType(), i_)
		return llvm.ConstStruct([]llvm.Value{r, i}, false)

	case types.UnsafePointerKind, types.UintptrKind:
		inttype := v.compiler.target.IntPtrType()
		return llvm.ConstInt(inttype, uint64(v.Int64()), false)

	case types.StringKind:
		strval := (v.Val).(string)
		strlen := len(strval)
		i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
		var ptr llvm.Value
		if strlen > 0 {
			ptr = v.compiler.builder.CreateGlobalStringPtr(strval, "")
			ptr = llvm.ConstBitCast(ptr, i8ptr)
		} else {
			ptr = llvm.ConstNull(i8ptr)
		}
		len_ := llvm.ConstInt(llvm.Int32Type(), uint64(strlen), false)
		return llvm.ConstStruct([]llvm.Value{ptr, len_}, false)

	case types.BoolKind:
		if v := v.Val.(bool); v {
			return llvm.ConstAllOnes(llvm.Int1Type())
		}
		return llvm.ConstNull(llvm.Int1Type())
	}
	panic(fmt.Errorf("Unhandled type: %v", typ)) //v.typ.Kind))
}
Пример #6
0
func (v *LLVMValue) Convert(dst_typ types.Type) Value {
	b := v.compiler.builder

	// If it's a stack allocated value, we'll want to compare the
	// value type, not the pointer type.
	src_typ := v.typ

	// Get the underlying type, if any.
	orig_dst_typ := dst_typ
	dst_typ = types.Underlying(dst_typ)
	src_typ = types.Underlying(src_typ)

	// Identical (underlying) types? Just swap in the destination type.
	if types.Identical(src_typ, dst_typ) {
		// TODO avoid load here by reusing pointer value, if exists.
		return v.compiler.NewLLVMValue(v.LLVMValue(), orig_dst_typ)
	}

	// Both pointer types with identical underlying types? Same as above.
	if src_typ, ok := src_typ.(*types.Pointer); ok {
		if dst_typ, ok := dst_typ.(*types.Pointer); ok {
			src_typ := types.Underlying(src_typ.Base)
			dst_typ := types.Underlying(dst_typ.Base)
			if types.Identical(src_typ, dst_typ) {
				return v.compiler.NewLLVMValue(v.LLVMValue(), orig_dst_typ)
			}
		}
	}

	// Convert from an interface type.
	if _, isinterface := src_typ.(*types.Interface); isinterface {
		if interface_, isinterface := dst_typ.(*types.Interface); isinterface {
			result, _ := v.convertI2I(interface_)
			return result
		} else {
			result, _ := v.convertI2V(orig_dst_typ)
			return result
		}
	}

	// Converting to an interface type.
	if interface_, isinterface := dst_typ.(*types.Interface); isinterface {
		return v.convertV2I(interface_)
	}

	// string -> []byte
	byteslice := &types.Slice{Elt: types.Byte}
	if src_typ == types.String && types.Identical(dst_typ, byteslice) {
		c := v.compiler
		value := v.LLVMValue()
		strdata := c.builder.CreateExtractValue(value, 0, "")
		strlen := c.builder.CreateExtractValue(value, 1, "")
		struct_ := llvm.Undef(c.types.ToLLVM(byteslice))
		struct_ = c.builder.CreateInsertValue(struct_, strdata, 0, "")
		struct_ = c.builder.CreateInsertValue(struct_, strlen, 1, "")
		struct_ = c.builder.CreateInsertValue(struct_, strlen, 2, "")
		return c.NewLLVMValue(struct_, byteslice)
	}

	// []byte -> string
	if types.Identical(src_typ, byteslice) && dst_typ == types.String {
		c := v.compiler
		value := v.LLVMValue()
		data := c.builder.CreateExtractValue(value, 0, "")
		len := c.builder.CreateExtractValue(value, 1, "")
		struct_ := llvm.Undef(c.types.ToLLVM(types.String))
		struct_ = c.builder.CreateInsertValue(struct_, data, 0, "")
		struct_ = c.builder.CreateInsertValue(struct_, len, 1, "")
		return c.NewLLVMValue(struct_, types.String)
	}

	// Rune to string conversion.
	if dst_typ == types.String && isIntType(src_typ) {
		return v.runeToString()
	}

	// TODO other special conversions?
	llvm_type := v.compiler.types.ToLLVM(dst_typ)

	// Unsafe pointer conversions.
	if dst_typ == types.UnsafePointer { // X -> unsafe.Pointer
		if _, isptr := src_typ.(*types.Pointer); isptr {
			value := b.CreatePtrToInt(v.LLVMValue(), llvm_type, "")
			return v.compiler.NewLLVMValue(value, orig_dst_typ)
		} else if src_typ == types.Uintptr {
			return v.compiler.NewLLVMValue(v.LLVMValue(), orig_dst_typ)
		}
	} else if src_typ == types.UnsafePointer { // unsafe.Pointer -> X
		if _, isptr := dst_typ.(*types.Pointer); isptr {
			value := b.CreateIntToPtr(v.LLVMValue(), llvm_type, "")
			return v.compiler.NewLLVMValue(value, orig_dst_typ)
		} else if dst_typ == types.Uintptr {
			return v.compiler.NewLLVMValue(v.LLVMValue(), orig_dst_typ)
		}
	}

	// FIXME select the appropriate cast here, depending on size, type (int/float)
	// and sign.
	lv := v.LLVMValue()
	srcType := lv.Type()
	switch srcType.TypeKind() { // source type
	case llvm.IntegerTypeKind:
		switch llvm_type.TypeKind() {
		case llvm.IntegerTypeKind:
			srcBits := srcType.IntTypeWidth()
			dstBits := llvm_type.IntTypeWidth()
			delta := srcBits - dstBits
			switch {
			case delta < 0:
				// TODO check if (un)signed, use S/ZExt accordingly.
				lv = b.CreateZExt(lv, llvm_type, "")
			case delta > 0:
				lv = b.CreateTrunc(lv, llvm_type, "")
			}
			return v.compiler.NewLLVMValue(lv, orig_dst_typ)
		case llvm.FloatTypeKind, llvm.DoubleTypeKind:
			if signed(v.Type()) {
				lv = b.CreateSIToFP(lv, llvm_type, "")
			} else {
				lv = b.CreateUIToFP(lv, llvm_type, "")
			}
			return v.compiler.NewLLVMValue(lv, orig_dst_typ)
		}
	case llvm.DoubleTypeKind:
		switch llvm_type.TypeKind() {
		case llvm.FloatTypeKind:
			lv = b.CreateFPTrunc(lv, llvm_type, "")
			return v.compiler.NewLLVMValue(lv, orig_dst_typ)
		case llvm.IntegerTypeKind:
			if signed(dst_typ) {
				lv = b.CreateFPToSI(lv, llvm_type, "")
			} else {
				lv = b.CreateFPToUI(lv, llvm_type, "")
			}
			return v.compiler.NewLLVMValue(lv, orig_dst_typ)
		}
	case llvm.FloatTypeKind:
		switch llvm_type.TypeKind() {
		case llvm.DoubleTypeKind:
			lv = b.CreateFPExt(lv, llvm_type, "")
			return v.compiler.NewLLVMValue(lv, orig_dst_typ)
		case llvm.IntegerTypeKind:
			if signed(dst_typ) {
				lv = b.CreateFPToSI(lv, llvm_type, "")
			} else {
				lv = b.CreateFPToUI(lv, llvm_type, "")
			}
			return v.compiler.NewLLVMValue(lv, orig_dst_typ)
		}
	}

	// Complex -> complex. Complexes are only convertible to other
	// complexes, contant conversions aside. So we can just check the
	// source type here; given that the types are not identical
	// (checked above), we can assume the destination type is the alternate
	// complex type.
	if src_typ == types.Complex64 || src_typ == types.Complex128 {
		var fpcast func(llvm.Builder, llvm.Value, llvm.Type, string) llvm.Value
		var fptype llvm.Type
		if src_typ == types.Complex64 {
			fpcast = llvm.Builder.CreateFPExt
			fptype = llvm.DoubleType()
		} else {
			fpcast = llvm.Builder.CreateFPTrunc
			fptype = llvm.FloatType()
		}
		if fpcast != nil {
			realv := b.CreateExtractValue(lv, 0, "")
			imagv := b.CreateExtractValue(lv, 1, "")
			realv = fpcast(b, realv, fptype, "")
			imagv = fpcast(b, imagv, fptype, "")
			lv = llvm.Undef(v.compiler.types.ToLLVM(dst_typ))
			lv = b.CreateInsertValue(lv, realv, 0, "")
			lv = b.CreateInsertValue(lv, imagv, 1, "")
			return v.compiler.NewLLVMValue(lv, orig_dst_typ)
		}
	}

	panic(fmt.Sprint("unimplemented conversion: ", v.typ, " -> ", orig_dst_typ))
}