https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67051
Bug ID: 67051
Summary: symtab_node::equal_address_to too conservative?
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
CC: hubicka at gcc dot gnu.org
Target Milestone: ---
For
int i;
int j;
symtab_node::equal_address_to says "no" to &i == &j. This seems to be because
i and j are 'common' and decl_binds_to_current_def_p returns false.
But I don't see how a valid testcase could alias i and j in another translation
unit. Yes, they can be interposed.
Probably this is
/* TODO: Alias oracle basically assume that addresses of global variables
are different unless they are declared as alias of one to another.
We probably should be consistent and use this fact here, too, and update
alias oracle to use this predicate. */
?
This makes us fail to optimize conditionals like &i != &j
