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 b;

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

struct S
{
    int i;
    float[4] f;
}

void main()
{
    S s;
    int i = s.i;
    int* p = &s.i;
    *p = 42;
    printf("%d == %d\n", *p, s.i);

    float* f = &s.f[0];
    printf("%f == %f\n", *f, s.f[0]);
    *f = 3.1415;
    printf("%f == %f\n", *f, s.f[0]);
    s.f[0] = 123.456;
    printf("%f == %f\n", *f, s.f[0]);
}