func cgenFnCall(node *Node, ops *x64.OpcodeList) {
// Check function
fn, ok := node.sym.(*Function)
if !ok {
panic(fmt.Sprintf("Unknown symbol: %v, node: %v", node.sym, node))
}
switch fn.fnName {
default:
ops.CALL(fn.Rva())
case printlnFuncName:
cgenPrintCall(node, ops)
}
}
func cgenPrintCall(node *Node, ops *x64.OpcodeList) {
// Get symbol
fn, ok := node.sym.(*Function)
if !ok {
panic(fmt.Sprintf("Unknown symbol: %v", node.sym))
}
// Push the base/frame pointer register value onto stack and overwrite base/frame pointer register to point to
// the top of stack. This stack pointer can now be modified by us and restored at the end of the function to its
// previous state
// TODO: commented out as we must inline this call
// ops.PUSH(x64.Rbp)
// ops.MOV(x64.Rbp, x64.Rsp)
// Push values onto stack (string RVA & length)
str, ok := node.stats[0].sym.(*StringLiteralSymbol)
if !ok {
panic(fmt.Sprintf("print function parameter not string literal! - %v", str))
}
ops.PUSHI(str.Rva())
ops.PUSHI(uint32(len(str.Val())))
// Call print
ops.CALL(fn.Rva())
// Clean up stack by overwriting the stack pointer register with the base/frame pointer register. This discards
// the two values we pushed onto the stack. Then pop the old base/frame pointer value off the stack & back into
// the base/frame pointer register. This restores the caller's stack.
// TODO: on x64 we should use 'leave' instruction
// ops.MOV(x64.Rsp, x64.Rbp)
// ops.POP(x64.Rbp)
// ops.RET()
}