https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95558
Bug ID: 95558
Summary: Invalid IPA optimizations based on weak definition
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: bugdal at aerifal dot cx
Target Milestone: ---
Created attachment 48689
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48689&action=edit
test case
Here is a case that came up in WIP code on musl libc, where I wanted to provide
a weak dummy definition for functionality that would optionally be replaced by
a strong definition elsewhere at ld time. I've been looking for some plausible
explanation aside from an IPA bug, like interaction with UB, but I can't find
any.
In the near-minimal test case here, the function reclaim() still has all of the
logic it should, but reclaim_gaps gets optimized down to a nop.
What seems to be happening is that the dummy weak definition does not leak into
its direct caller via IPA optimizations, but does leak to the caller's caller.
