- You can now construct the lookup table separately and perform the
  lowering selectively on irgs (instead of the whole program at once)
  while reusing the lookup table.
- Simplified API a bit.
- Remove i_mapper_RuntimeCall. All users are simpler by doing the
  transformations directly instead of filling in runtime_rt
  structures...

Use the same style as the SPARC 64bit lowering, making the additional
handle_intrinsics step unnecessary now.

before_abi() callback was removed, you can simply put that code at the end
of the init() callback. custom_abi flag was removed, if a backend needs the
be_abi_introduce() stuff (formerly custom_abi == false) then it can call
it at the end of the init() callback.

The code was only working on ia32 and contains several ia32 specific
bits, so keep it in the ia32 backend for now. At least the amd64 backend
will require a different implementation of PIC.

The result of gs_matrix_gauss_seidel() never is negative.

get_tarval_uint64() checks the same.

If the solution of our eigenvalue problem results in unreasonable values
(like infinity), we now fall back to a loop-weight-based execution
frequency, or, if this is not sufficient, to a constant execution
frequency.

The backends which support rotl now match for or(shl,shr) patterns.

This makes it consistent with the rest of libFirm and avoids cases where
the non-inlined version of the functions is used inside the header by accident.

This ensures that only kept blocks get the extra weight for the keep edge.

We have to consider that less significant bits of the operands
can affect more significant bits of the operation itself.

This fixes opt/occult2.c and 177.mesa.

We should never see an Id node and Call nodes should never have mode_X.

After killing a store (e.g. if it is dead), its Store value can be killed,
if no other node uses it. We can use the code in reduce_adr_usage for that,
which also works for non-pointers.

This commit adds a new function kill_and_reduce_usage, which works for Load
and Store nodes. It kills the node and all Loads on which only the killed
node depends.

optimize_load can introduce dead stores, which are not removed, because
they have already been visited (the irg is walked from Start to End).

This commit adds a second irg walk for dead store elimination after the
other optimizations have run, and removes dead store elimination from the
first walk.