[Bug tree-optimization/113372] wrong code with _BitInt() arithmetics at -O1

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113372

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #11)
> So the key would be to make the object live again after a CLOBBER when such
> address SSA name is used (but before any other explicit mention appears)?
> 
> The current algorithm relies on explitic mentions appearing, one original
> idea was to turn those explicit mentions (or BLOCK starts) into
> start-of-live CLOBBERs, but even that was shown to be not enough.
> 
> But yes, if we want to try to mitigate the problems somewhat without
> doing a full solution then possibly even just looking at SSA defs
> when POINTER_TYPE and the def is an ADDR_EXPR might work (in the
> visit_* callbacks of the walk_stmt_load_store_addr_ops), no propagation
> needed at all (basically just undo CSE virtually here for the simple
> cases).

It couldn't be limited to just POINTER_TYPE, because it mostly is actually
pointer-sized unsigned integer from IVOPTs, but yes, even without full
propagation I think all the testcases I've mentioned could be solved by just
doing the short walks in PHI arguments or other SSA_NAME uses (only PR111422
needs the latter).
For this PR, we'd need to visit for ivtmp.40_3 uses in PHI args the def-stmt:
  ivtmp.40_3 = (unsigned long) &MEM <unsigned long[100]> [(void *)&bitint.6 +
8B];
for PR90348 ivtmp.32_28's def-stmt:
  ivtmp.32_28 = (unsigned long) &in;
for PR110115 ivtmp.27_2's def-stmt:
  ivtmp.27_2 = (unsigned long) &h;
fpr PR111422 _44's def-stmt:
  _44 = &g + _43;
So, if you think it is ok to use just a small hack rather than full propagation
(which could even handle const/pure calls perhaps if they return pointer or
pointer-sized integer), I can implement that too.  Even the full propagation
wouldn't handle everything of course, but could handle more than the small hack
(which would need to be limited to just say 4 def-stmts and wouldn't try to
look through PHIs).