There is no node left that uses it.

There is no legitimate reason for an outside user to change the op of a node.
Even internally it should be used less, i.e. only for Deleted, Id and Tuple.

This fixed opt/fehler274.c.

This sort of typeless programming is bad style and deprecated.

The previous approach put the irg link into the block attributes, so
while saving memory an extra indirection was necessary. Some testing
with valgrind massif+callgrind revealed that a direct link increses peak
memory usage by ~1% while also increasing runtime by ~1%. More
importantly the code gets a bit simpler and some strange corner cases can be
removed with the direct link.

This makes our usage of PhiMs to represent the observable behaviour of
non-terminating loops more obvious.
Having an explicit loop Phi constructor also fixes problems with Phi
getting optimized before the keep edge was added.

For details see endless loops section on the homepage.

Previously a Bad node was returned which could hide problems and more
importantly you create new nodes (the BadBB) in an operation that apparently
only queries the graph.

This removes the strange entity/type duality and we get rid of union symconst_symbol.

They weren't used in a sensible way and their semantic for
non-arithmetic ops was unclear.
Also implicitely fixes a bunch of bugs where these where set but no op_index
was set at the same time.

Just state the copyright and the project the files belong to. You can
then find the COPYING file for the whole project.

Projs are always in the same block as their predecessor.

We get a clean SIGSEGV anyway, if they're not fulfilled

ir: Shuffle node macros, so functions in the header declaring the macros use the inline versions of the node functions.