phiprop: Allow for one store inbetween the load and the phi which is being used to...

phiprop: Allow for one store inbetween the load and the phi which is being used to insert [PR123120]

So phiprop has one disadvantage is that if there is store between the
phi with the addresses and the new load, phiprop will no do anything.
This means for some C++ code where you have a min of a max (or the opposite),
depending on the argument order of evaluation phiprop might do
the transformation or it might not (see tree-ssa/phiprop-3.C for examples).
So we need to allow skipping of one store inbetween the load and
where the phi is located.

Aggregates include a store when doing phiprop so we need to check
if there are also loads between the original store/load and the
store we are skipping. This can be added afterwards but I didn't
see aggregate case happening enough to make a big dent. I added
testcases (phiprop-{10,11}.c) to make sure cases where the load
would make a different shows up though.

changes since v1:
* v2: rewrite can_handle_load to avoid duplicated skipping store code.

	PR tree-optimization/123120
	PR tree-optimization/116823
gcc/ChangeLog:

	* tree-ssa-phiprop.cc (phiprop_insert_phi): Add other_vuse
	argument, use it instead of the vuse on the use_stmt.
	(can_handle_load): Add aggregate argument. Also return the vuse
	of the load/store when the insert is allowed.
	Skipping over one non-modifying store for !aggregate.
	(propagate_with_phi): Update call to can_handle_load
	and phiprop_insert_phi.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/phiprop-8.c: New test.
	* gcc.dg/tree-ssa/phiprop-9.c: New test.
	* gcc.dg/tree-ssa/phiprop-10.c: New test.
	* gcc.dg/tree-ssa/phiprop-11.c: New test.
	* gcc.dg/tree-ssa/phiprop-12.c: New test.
	* g++.dg/tree-ssa/phiprop-3.C: New test.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>