[tuples] Tuplify invariant motion

[Aldy Hernandez]

>>>>> "Zdenek" == Zdenek Dvorak <rakdver@kam.mff.cuni.cz> writes:

 > Hi,
 > this patch enables lcSSA form creation and tuplifies lim, as well as
 > fixing a few things to make it work:

 > 1) gimple_could_trap_p is factored out of tree_could_trap_p.
 > 2) the remove_eh_info argument of gsi_remove is renamed to make it
 >    clear that it really means "do not destroy anything permanent,
 >    I am going to reinsert this statement elsewhere"; and we now
 >    do not free the operands of the statement if this argument is false.
 > 3) gimple_find_edge_insert_loc is made to use gsi_last_bb, so that
 >    commit_edge_insertions updates stmt->basic block mapping correctly

 > The patch causes one misscompilation (gcc.c-torture/execute/pr34176.c)
 > in the testsuite (virtual operands are wrong, making lim perform an
 > illegal transformation).  I will try to fix this, but I would like to
 > commit the bulk of the patch now (possibly with lim disabled, if
 > preferable) in order to avoid having to fix conflicts with other
 > changes.  OK?

Ok, provided you look into the misscompilation :).

Thanks.
Aldy