[LLVMdev] The nsw story

[Paul Robinson]

On Thu, Dec 1, 2011 at 9:37 AM, David A. Greene <greened at obbligato.org>wrote:

> Dan Gohman <gohman at apple.com> writes:
>
> > Prohibiting poison values from propogating through memory would mean
> > that the reg2mem pass would no longer be a semantics-preserving pass.
>
> Or it means you couldn't demote those values.


If reg2mem is constructing spill slots, or address-not-taken locals, I could
see classifying those as okay-to-poison. You would not want statics or
globals
or pointer-addressed memory to be poisonable, as those should be treated
as being observable locations.

So, it's not really "all of memory" that could be poisoned, only these
compiler-generated things.

Pogo
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