Functions used in expressions are inlined wrongly

[Cardillan]

When a function inlined by the optimizer is used in an expression repeatedly, the return value from one of the calls is lost:

def foo()
    rand(10)
end
print(foo() + foo())

compiles to

op rand __fn0retval 10 0
op add __tmp2 __tmp0 __fn0retval
print __tmp2
end

[Cardillan]

Fixed for the next release. Currently, the above code compiles to:

op rand __fn0retval 10 0
set __tmp0 __fn0retval
op rand __fn0retval 10 0
op add __tmp2 __tmp0 __fn0retval
print __tmp2
end

The first two instructions could be merged into one, but aren't, because __fn0retval is a protected variable. The most generic solution is to replace the function return variable with a normal temporary variable when inlining the call, because the protection is no longer necessary after the inlining - plus it decouples the inlined call from other call sites.

[Cardillan]

The function inliner was expanded to replace the return value variables with the receiving variable. It helps in some cases, but a return statement can still prevent the desired optimization from happening. This will be resolved separately.