[LLVMdev] Available code-generation parallism

[Chris Lattner]

On Nov 3, 2008, at 3:55 PM, heisenbug wrote:
> What about "inventing" pseudo-constants (which point to the right
> thing) and build the piece of IR with them. When done, grab mutex and
> RAUW it in. Alternatively, submit to a privileged thread that performs
> the RAUW.
> The trick is to prepare the def/use chain(s) to a degree that the
> mutex is only held a minimal time. If only IR-builder threads are
> running concurrently there is no danger that a real constant vanishes,
> leaving behind a stale reference from a pseudo-constant.

That could work.  It would also have to be done for global values as  
well, and inline asm objects etc.  However, I don't see any show- 
stoppers.  The implementation could be tricky, but a nice property of  
your approach is that the single threaded case could be made  
particularly fast (instead of doing atomic ops or locking always).

-Chris