Remove an old workaround that was kept around for ABI-compatibility on x86-64 between different LLVM versions. This means LLVM r67588 is required if you want to compile for x86-64, otherwise the backend will assert when you try to return e.g. struct { int i; char c; } from a function. (In particular, this is no longer compatible with LLVM 2.5) It also means that any code returning small structs on x86-64 will probably need to be recompiled in order to be linkable to code compiled with this change.

module tangotests.vararg4;

extern(C) int printf(char*, ...);

struct S
{
    int i;
}

void func(...)
{
    S* sp = cast(S*)_argptr;
    assert(sp.i == 42);
}

void main()
{
    printf("1st:\n");
    {
    S s = S(42);
    func(s);
    }
    printf("ok\n");

    printf("2nd:\n");
    {
    func(S(42));
    }
    printf("ok\n");
}