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 bug24;
extern(C) int printf(char*, ...);

struct S
{
    long l;
    float f;
}

void main()
{
    S s = S(3L,2f);
    delegate {
        S t = S(4L, 1f);
        delegate {
            s.l += t.l;
            s.f += t.f;
        }();
    }();
    printf("%lu %f\n", s.l, s.f);
    assert(s.l == 7 && s.f == 3);
}