https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94988
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Last reconfirmed| |2020-05-08
Status|UNCONFIRMED |ASSIGNED
Blocks| |57359
Target Milestone|--- |11.0
Ever confirmed|0 |1
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ah, forgot to update this testcase. This is another instance of PR57359, that
is, we may not sink the store to b across the store to *b since b may point
to itself and with j == 1 we'd change
b = b + 2;
*b = x;
to
*b = x;
b = b + 2;
note there's a twist for this particular case, namely the preceeding load
of 'b' gives us knowledge about the dynamic type of 'b' which means we
could use that to assess that we _can_ exchange the stores.
But that logic is not implemented.
I'll see how to do that.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57359
[Bug 57359] store motion causes wrong code for union access at -O3
