[phobos] std.parallelism's unit tests randomly hang on win32

[Walter Bright]

On 5/1/2011 12:44 PM, David Simcha wrote:
> Update:  The segfaults on Linux64 are also being caused by the low order bit 
> corruption bug.  Whenever I look at the chain of pointer dereferences in GDB 
> by viewing the registers and disassembly on crash, the segfault is always 
> caused by dereferencing a pointer to some memory address that's clearly 
> illegal.  (On x64 user mode addresses can't have their high order bits set, 
> and the addresses being dereferenced often do.  See 
> http://en.wikipedia.org/wiki/X64#Virtual_address_space_details .)  This wild 
> pointer is obtained by dereferencing another pointer whose low order bits are 
> always equal to TaskStatus.done.  For example, if TaskStatus.done == 2, the 
> pointer might be something like 0x0000ABCD EF123402.  If TaskStatus.done == 1, 
> it will be something like 0x0000ABCD EF123401.
>

Add asserts on that pointer value going out of range, and keep working backwards 
until the point where the value goes wrong is discovered.