// indirectFunction creates an indirect function from a
// given function and arguments, suitable for use with
// "defer" and "go".
func (c *compiler) indirectFunction(fn *LLVMValue, args []*LLVMValue) *LLVMValue {
nilarytyp := types.NewSignature(nil, nil, nil, nil, false)
if len(args) == 0 {
val := fn.LLVMValue()
ptr := c.builder.CreateExtractValue(val, 0, "")
ctx := c.builder.CreateExtractValue(val, 1, "")
fnval := llvm.Undef(c.types.ToLLVM(nilarytyp))
ptr = c.builder.CreateBitCast(ptr, fnval.Type().StructElementTypes()[0], "")
ctx = c.builder.CreateBitCast(ctx, fnval.Type().StructElementTypes()[1], "")
fnval = c.builder.CreateInsertValue(fnval, ptr, 0, "")
fnval = c.builder.CreateInsertValue(fnval, ctx, 1, "")
return c.NewValue(fnval, nilarytyp)
}
// Check if function pointer or context pointer is global/null.
fnval := fn.LLVMValue()
fnptr := fnval
var nctx int
var fnctx llvm.Value
var fnctxindex uint64
var globalfn bool
if fnptr.Type().TypeKind() == llvm.StructTypeKind {
fnptr = c.builder.CreateExtractValue(fnval, 0, "")
fnctx = c.builder.CreateExtractValue(fnval, 1, "")
globalfn = !fnptr.IsAFunction().IsNil()
if !globalfn {
nctx++
}
if !fnctx.IsNull() {
fnctxindex = uint64(nctx)
nctx++
}
} else {
// We've got a raw global function pointer. Convert to <ptr,ctx>.
fnval = llvm.ConstNull(c.types.ToLLVM(fn.Type()))
fnval = llvm.ConstInsertValue(fnval, fnptr, []uint32{0})
fn = c.NewValue(fnval, fn.Type())
fnctx = llvm.ConstExtractValue(fnval, []uint32{1})
globalfn = true
}
i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
llvmargs := make([]llvm.Value, len(args)+nctx)
llvmargtypes := make([]llvm.Type, len(args)+nctx)
for i, arg := range args {
llvmargs[i+nctx] = arg.LLVMValue()
llvmargtypes[i+nctx] = llvmargs[i+nctx].Type()
}
if !globalfn {
llvmargtypes[0] = fnptr.Type()
llvmargs[0] = fnptr
}
if !fnctx.IsNull() {
llvmargtypes[fnctxindex] = fnctx.Type()
llvmargs[fnctxindex] = fnctx
}
// TODO(axw) investigate an option for go statements
// to allocate argument structure on the stack in the
// initiator, and block until the spawned goroutine
// has loaded the arguments from it.
structtyp := llvm.StructType(llvmargtypes, false)
argstruct := c.createTypeMalloc(structtyp)
for i, llvmarg := range llvmargs {
argptr := c.builder.CreateGEP(argstruct, []llvm.Value{
llvm.ConstInt(llvm.Int32Type(), 0, false),
llvm.ConstInt(llvm.Int32Type(), uint64(i), false)}, "")
c.builder.CreateStore(llvmarg, argptr)
}
// Create a function that will take a pointer to a structure of the type
// defined above, or no parameters if there are none to pass.
fntype := llvm.FunctionType(llvm.VoidType(), []llvm.Type{argstruct.Type()}, false)
indirectfn := llvm.AddFunction(c.module.Module, "", fntype)
i8argstruct := c.builder.CreateBitCast(argstruct, i8ptr, "")
currblock := c.builder.GetInsertBlock()
c.builder.SetInsertPointAtEnd(llvm.AddBasicBlock(indirectfn, "entry"))
argstruct = indirectfn.Param(0)
newargs := make([]*LLVMValue, len(args))
for i := range llvmargs[nctx:] {
argptr := c.builder.CreateGEP(argstruct, []llvm.Value{
llvm.ConstInt(llvm.Int32Type(), 0, false),
llvm.ConstInt(llvm.Int32Type(), uint64(i+nctx), false)}, "")
newargs[i] = c.NewValue(c.builder.CreateLoad(argptr, ""), args[i].Type())
}
// Unless we've got a global function, extract the
// function pointer from the context.
if !globalfn {
fnval = llvm.Undef(fnval.Type())
fnptrptr := c.builder.CreateGEP(argstruct, []llvm.Value{
llvm.ConstInt(llvm.Int32Type(), 0, false),
llvm.ConstInt(llvm.Int32Type(), 0, false)}, "")
fnptr = c.builder.CreateLoad(fnptrptr, "")
fnval = c.builder.CreateInsertValue(fnval, fnptr, 0, "")
}
if !fnctx.IsNull() {
fnctxptr := c.builder.CreateGEP(argstruct, []llvm.Value{
llvm.ConstInt(llvm.Int32Type(), 0, false),
llvm.ConstInt(llvm.Int32Type(), fnctxindex, false)}, "")
fnctx = c.builder.CreateLoad(fnctxptr, "")
fnval = c.builder.CreateInsertValue(fnval, fnctx, 1, "")
fn = c.NewValue(fnval, fn.Type())
}
c.createCall(fn, newargs)
// Indirect function calls' return values are always ignored.
c.builder.CreateRetVoid()
c.builder.SetInsertPointAtEnd(currblock)
fnval = llvm.Undef(c.types.ToLLVM(nilarytyp))
indirectfn = c.builder.CreateBitCast(indirectfn, fnval.Type().StructElementTypes()[0], "")
fnval = c.builder.CreateInsertValue(fnval, indirectfn, 0, "")
fnval = c.builder.CreateInsertValue(fnval, i8argstruct, 1, "")
fn = c.NewValue(fnval, nilarytyp)
return fn
}