Make == for associative arrays test for equality, not identity. _aaEq was added to runtime/internal/aaA.d which forwards to TypeInfo_AssociativeArray.equals in genobj.d. On the codegen side, DtoAAEquals was added to gen/aa.cpp and is called from EqualExp::toElem in gen/toir.cpp. I assume that the frontend will produce an error if == is used on associative arrays of different type. This fixes DMD bug 1429.

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);
    }
}