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 alloca1;

pragma(alloca) void* alloca(uint);

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

void main()
{
    int n = 16;
    int* p = cast(int*)alloca(n*int.sizeof);
    int[] a = p[0..n];
    a[] = 0;
    foreach(i,v; a) {
        printf("a[%2d] = %d\n", i, v);
    }
}