On 06/06/2013 04:52 PM, Richard Biener wrote: > + /* We cannot optimize away a static used in multiple functions (as > + might happen in C++). */ > + && !DECL_NONLOCAL(var) > > it may also happen trivially with inlining. Which means a local pass can > never > "remove" vars safely.
This is why the pass isn't run if cgraph_function_possibly_inlined_p. Tested by remove-local-statics-14b.c. > In theory we have IPA reference which tries to figure out whether a local > static > is read and/or written to (and from where). It's of course quite early > analysis > where FRE may not yet have optimized out all reads. > > But the trivial dead local static store elimination would simply eliminate > all write-only and !TREE_ADDRESSABLE vars (and statements storing > to it). > > For some reason this must be not enough so you write that local > analysis code. > > Thus - I'm asking you to double-check a trivial implementation using > the IPA reference result and double-check the issue with inlining > introducing out-of-current-function uses. I'm not sure what you're asking for here. The IPA passes seem to run much before PRE, and if you need an example why that's too early, try the remove-local-statics-7.c testcase. Bernd
