On 05/07/12 19:11, Andrew MacLeod wrote:
On 05/07/2012 07:04 PM, Aldy Hernandez wrote:
Andrew suggested the correct fix was to add a new pass that was able
to do some ?? flow sensitive data flow analysis ?? that could discover
these unreachable paths and insert the 0 phis at the start of the
blocks automatically. But that seemed like far too much work,
considering how long it's taken me to get this far ;-).
Wait, no. I didn't suggest writing an entire generic pass was the
correct fix for you... I said that this was a technique that a generic
pass which identified this sort of flow sensitive data flow info could
use to work within the CFG. Simply zeroing out uses of the load in PHI
nodes on paths it has determined are not actually reachable by that
value, and you were suppose to integrate just the bits of that technique
that you required.. just replace any uses of your LSM temporary with 0.
I never intended you should write an entire pass...
Ah, well in that case, I've already done that. Well I don't do it on
any path, just in the loop header, and things propagate down from there
quite nicely :).
Aldy
