func newSlice(b *builder, t types.T, addr, size codegen.Ref) *ref {
ret := b.newTemp(&types.Slice{T: t})
retAddr := b.newPtr()
b.b.Arith(retAddr, nil, "&", ret.IR())
b.b.Assign(codegen.NewAddrRef(retAddr, 4, 0, false, true), addr)
b.b.Assign(codegen.NewAddrRef(retAddr, 4, 4, false, true), size)
return ret
}
func loadArray(b *builder, array *ref) (addr, n codegen.Ref, et types.T) {
base := b.newPtr()
t := array.Type()
switch t := t.(type) {
case *types.Array:
b.b.Arith(base, nil, "&", array.IR())
return base, codegen.Snum(t.N), t.T
case *types.Slice:
b.b.Arith(base, nil, "&", array.IR())
addr = codegen.NewAddrRef(base, 4, 0, false, true)
n = codegen.NewAddrRef(base, 4, 4, false, true)
return addr, n, t.T
}
panic("bug")
}
func buildField(b *builder, this codegen.Ref, field *types.Field) *ref {
retIR := codegen.NewAddrRef(
this,
field.T.Size(),
field.Offset(),
types.IsByte(field.T),
true,
)
return newAddressableRef(field.T, retIR)
}
func buildCallLen(b *builder, expr *tast.CallExpr) *ref {
args := b.buildExpr(expr.Args)
t := args.Type()
ret := b.newTemp(types.Int)
switch t := t.(type) {
case *types.Slice:
addr := b.newPtr()
b.b.Arith(addr, nil, "&", args.IR())
b.b.Assign(ret.IR(), codegen.NewAddrRef(addr, 4, 4, false, true))
return ret
case *types.Array:
b.b.Assign(ret.IR(), codegen.Num(uint32(t.N)))
return ret
}
panic("bug")
}
func buildArrayGet(b *builder, expr *tast.IndexExpr, array *ref) *ref {
index := buildArrayIndex(b, expr.Index)
base, n, et := loadArray(b, array)
checkInRange(b, index, n, "u<")
addr := b.newPtr()
b.b.Arith(addr, index, "*", codegen.Snum(arrayElementSize(et)))
b.b.Arith(addr, base, "+", addr)
size := et.Size()
retIR := codegen.NewAddrRef(
addr, // base address
size, // size
0, // dynamic offset; precalculated
types.IsByte(et), // isByte
true, // isAlign
)
return newAddressableRef(et, retIR)
}
