GitLab

This also allows to cleanup the finish neg/add carry flag fix code a
big.

- For equal destinations merge the switch table entries and Proj nodes
- Handle Switches with just a default Proj like Jmp nodes

- Normalize switch table now (sort + remove default entries)
- Correctly handle the case of multiple entries mapping to the same proj
  number.

- No strange split between no-phi and phi variants anymore. The phi
  variant can perform everything now.
- Repeat till we reach the fixpoint.

The were some comments in the code indicating that in case of SSA
destruction problems critical edges were not created. But we deal with
these cases anyway during SSA destruction so no need to avoid them
earlier.

This fixes backend/ia32_scheduled2.c.

This fixes opt/fehler266.c.

Other code still expects DestAM operations to have mode M.

NotMem now has two unused outputs but shares its mode and its Proj numbers
with the other DestAM operations.

Implemented for now: When the flags of one Sub or Cmp node are needed, but
the flags of another one are currently alive, invert the condition code and
avoid rematerialization.

When a Sub node is rematerialized, only its flags will be needed. In this
case, the Sub can be replaced by a Cmp and there is no need to have a
scratch register to store the Sub's result.

When a node is rematerialized because its flag result is needed, rewire
later uses of this node (but not the flags) to use the rematerialized
node's results. This reduces the lifetime of the node's results.

Now that the flag outputs of arithmetic operations are used, a node may
have multiple connections to the flag producer, but only one of these
actually reads the flags.