// moveByType returns the reg->reg move instruction of the given type.
func moveByType(t ssa.Type) obj.As {
if t.IsFloat() {
// Moving the whole sse2 register is faster
// than moving just the correct low portion of it.
// There is no xmm->xmm move with 1 byte opcode,
// so use movups, which has 2 byte opcode.
return x86.AMOVUPS
} else {
switch t.Size() {
case 1:
// Avoids partial register write
return x86.AMOVL
case 2:
return x86.AMOVL
case 4:
return x86.AMOVL
case 8:
return x86.AMOVQ
case 16:
return x86.AMOVUPS // int128s are in SSE registers
default:
panic(fmt.Sprintf("bad int register width %d:%s", t.Size(), t))
}
}
}
// loadByType returns the load instruction of the given type.
func loadByType(t ssa.Type) obj.As {
// Avoid partial register write
if !t.IsFloat() && t.Size() <= 2 {
if t.Size() == 1 {
return x86.AMOVBLZX
} else {
return x86.AMOVWLZX
}
}
// Otherwise, there's no difference between load and store opcodes.
return storeByType(t)
}
// storeByType returns the store instruction of the given type.
func storeByType(t ssa.Type) obj.As {
width := t.Size()
if t.IsFloat() {
switch width {
case 4:
return x86.AMOVSS
case 8:
return x86.AMOVSD
}
} else {
switch width {
case 1:
return x86.AMOVB
case 2:
return x86.AMOVW
case 4:
return x86.AMOVL
case 8:
return x86.AMOVQ
}
}
panic("bad store type")
}