// genConv generates constraints for the conversion operation conv.
func (a *analysis) genConv(conv *ssa.Convert, cgn *cgnode) {
res := a.valueNode(conv)
if res == 0 {
return // result is non-pointerlike
}
tSrc := conv.X.Type()
tDst := conv.Type()
switch utSrc := tSrc.Underlying().(type) {
case *types.Slice:
// []byte/[]rune -> string?
return
case *types.Pointer:
// *T -> unsafe.Pointer?
if tDst.Underlying() == tUnsafePtr {
return // we don't model unsafe aliasing (unsound)
}
case *types.Basic:
switch tDst.Underlying().(type) {
case *types.Pointer:
// Treat unsafe.Pointer->*T conversions like
// new(T) and create an unaliased object.
if utSrc == tUnsafePtr {
obj := a.addNodes(mustDeref(tDst), "unsafe.Pointer conversion")
a.endObject(obj, cgn, conv)
a.addressOf(tDst, res, obj)
return
}
case *types.Slice:
// string -> []byte/[]rune (or named aliases)?
if utSrc.Info()&types.IsString != 0 {
obj := a.addNodes(sliceToArray(tDst), "convert")
a.endObject(obj, cgn, conv)
a.addressOf(tDst, res, obj)
return
}
case *types.Basic:
// All basic-to-basic type conversions are no-ops.
// This includes uintptr<->unsafe.Pointer conversions,
// which we (unsoundly) ignore.
return
}
}
panic(fmt.Sprintf("illegal *ssa.Convert %s -> %s: %s", tSrc, tDst, conv.Parent()))
}
func (f *Function) ConvertFromTo(instr *ssa.Convert, fromOpType, toOpType InstrOpType, fromXmm, toXmm XmmData) (string, *Error) {
asm := ""
ctx := context{f, instr}
a, from, err := f.LoadValueSimple(instr, instr.X)
if err != nil {
return "", err
} else {
asm += a
}
a1, to := f.allocIdentReg(instr, f.Ident(instr), f.Ident(instr).size())
asm += a1
a, tmp := f.allocReg(instr, DATA_REG, sizeInt())
asm += a
fromType :=
OpDataType{
op: fromOpType,
InstrData: InstrData{signed: signed(instr.X.Type()), size: f.sizeof(instr.X)},
xmmvariant: fromXmm}
toType :=
OpDataType{
op: toOpType,
InstrData: InstrData{signed: signed(instr.Type()), size: f.sizeof(instr)},
xmmvariant: toXmm}
// round uint64 to nearest int64 before converting to float32/float64
if isUint(instr.X.Type()) && f.sizeof(instr.X) == 8 && isFloat(instr.Type()) {
var floatSize uint
if isFloat32(instr.Type()) {
floatSize = 32
} else if isFloat64(instr.Type()) {
floatSize = 64
} else {
ice("converting from uint64 to float")
}
asm += f.ConvertUint64ToFloat(instr, tmp, from, to, floatSize)
} else {
asm += ConvertOp(ctx, from, fromType, to, toType, tmp)
}
toIdent := f.identifiers[instr.Name()]
if a, err := f.StoreValue(instr, toIdent, to); err != nil {
return "", err
} else {
asm += a
}
f.freeReg(from)
f.freeReg(to)
f.freeReg(tmp)
return asm, nil
}
func (f *Function) Convert(instr *ssa.Convert) (string, *Error) {
from := instr.X.Type()
to := instr.Type()
var fromType InstrOpType
var toType InstrOpType
var fromXmm XmmData
var toXmm XmmData
if isInteger(from) && isInteger(to) {
fromType = OP_DATA
toType = OP_DATA
fromXmm = XMM_INVALID
toXmm = XMM_INVALID
} else if isInteger(from) && isFloat(to) {
fromType = OP_DATA
toType = OP_XMM
fromXmm = XMM_INVALID
toXmm = GetXmmVariant(to)
} else if isFloat(from) && isInteger(to) {
fromType = OP_XMM
fromXmm = GetXmmVariant(from)
toType = OP_DATA
toXmm = XMM_INVALID
} else if isFloat(from) && isFloat(to) {
fromType = OP_XMM
fromXmm = GetXmmVariant(from)
toType = OP_XMM
toXmm = GetXmmVariant(to)
} else {
fmtstr := "Cannot convert from (%v) to (%v)"
msg := fmt.Sprintf(fmtstr, from.String(), to.String())
return ErrorMsg(msg)
}
return f.ConvertFromTo(instr, fromType, toType, fromXmm, toXmm)
}