On Wed, Feb 02, 2022 at 03:42:48PM +0100, Richard Biener via Gcc-patches wrote:
> This adds a flag to CONSTRUCTOR nodes indicating that for
> clobbers this marks the end-of-life of storage as opposed to
> just ending the lifetime of the object that occupied it.
> The dangling pointer diagnostics uses CLOBBERs but is confused
> by those emitted by the C++ frontend for example which emits
> them for the second purpose at the start of CTORs. The issue
> is also appearant for aarch64 in PR104092.
I think many further build_clobber calls actually should build
those EOL clobbers, I think we'd need to go through them one by one and see
what kind of clobber it is.
E.g. I think all of omp-low.cc build_clobber calls are like that.
C++ FE indeed emits some clobbers at the start of ctors with
-flifetime-dse=2, but others e.g. at the end of dtors, dunno about those,
though maybe the object doesn't go out of scope at that point yet.
What about expansion and tree-ssa-live.cc, should those keep doing
what it does and not ignore clobbers that aren't CLOBBER_MARKS_EOL?
Jakub
