// coerceSlice takes a slice of one element type and coerces it to a
// slice of another.
func (c *compiler) coerceSlice(src llvm.Value, dsttyp llvm.Type) llvm.Value {
dst := llvm.Undef(dsttyp)
srcmem := c.builder.CreateExtractValue(src, 0, "")
srclen := c.builder.CreateExtractValue(src, 1, "")
srccap := c.builder.CreateExtractValue(src, 2, "")
dstmemtyp := dsttyp.StructElementTypes()[0]
dstmem := c.builder.CreateBitCast(srcmem, dstmemtyp, "")
dst = c.builder.CreateInsertValue(dst, dstmem, 0, "")
dst = c.builder.CreateInsertValue(dst, srclen, 1, "")
dst = c.builder.CreateInsertValue(dst, srccap, 2, "")
return dst
}
func (tm *TypeMap) makeSlice(values []llvm.Value, slicetyp llvm.Type) llvm.Value {
ptrtyp := slicetyp.StructElementTypes()[0]
var globalptr llvm.Value
if len(values) > 0 {
array := llvm.ConstArray(ptrtyp.ElementType(), values)
globalptr = llvm.AddGlobal(tm.module, array.Type(), "")
globalptr.SetInitializer(array)
globalptr = llvm.ConstBitCast(globalptr, ptrtyp)
} else {
globalptr = llvm.ConstNull(ptrtyp)
}
len_ := llvm.ConstInt(tm.inttype, uint64(len(values)), false)
slice := llvm.ConstNull(slicetyp)
slice = llvm.ConstInsertValue(slice, globalptr, []uint32{0})
slice = llvm.ConstInsertValue(slice, len_, []uint32{1})
slice = llvm.ConstInsertValue(slice, len_, []uint32{2})
return slice
}
func (c *compiler) VisitAppend(expr *ast.CallExpr) Value {
// TODO handle ellpisis arg
s := c.VisitExpr(expr.Args[0])
elem := c.VisitExpr(expr.Args[1])
appendName := "runtime.sliceappend"
appendFun := c.module.NamedFunction(appendName)
uintptrTyp := c.target.IntPtrType()
var i8slice llvm.Type
if appendFun.IsNil() {
i8slice = c.types.ToLLVM(&types.Slice{Elt: types.Int8})
args := []llvm.Type{uintptrTyp, i8slice, i8slice}
appendFunTyp := llvm.FunctionType(i8slice, args, false)
appendFun = llvm.AddFunction(c.module.Module, appendName, appendFunTyp)
} else {
i8slice = appendFun.Type().ReturnType()
}
i8ptr := i8slice.StructElementTypes()[0]
// Coerce first argument into an []int8.
a_ := s.LLVMValue()
sliceTyp := a_.Type()
a := c.coerceSlice(a_, i8slice)
// Construct a fresh []int8 for the temporary slice.
b_ := elem.LLVMValue()
one := llvm.ConstInt(llvm.Int32Type(), 1, false)
mem := c.builder.CreateAlloca(elem.LLVMValue().Type(), "")
c.builder.CreateStore(b_, mem)
b := llvm.Undef(i8slice)
b = c.builder.CreateInsertValue(b, c.builder.CreateBitCast(mem, i8ptr, ""), 0, "")
b = c.builder.CreateInsertValue(b, one, 1, "")
b = c.builder.CreateInsertValue(b, one, 2, "")
// Call runtime function, then coerce the result.
runtimeTyp := c.types.ToRuntime(s.Type())
runtimeTyp = c.builder.CreatePtrToInt(runtimeTyp, uintptrTyp, "")
args := []llvm.Value{runtimeTyp, a, b}
result := c.builder.CreateCall(appendFun, args, "")
return c.NewLLVMValue(c.coerceSlice(result, sliceTyp), s.Type())
}