This meant initializing the address mode variant all over the ia32
backend, on the other hand this will be useful if we ever switch the
ia32 backend to a style without NoReg nodes (like amd64).

We only use the immediate and scale yet on ia32.

This is a bigger rewrite of stack frame handling in the backend:

- Do the stack frame type layout late, after all the spill slots have
  been created. This way we can avoid (and remove) the brittle
  frame_alloc_area().
- Standardize the meaning of stack entity offsets. After stack frame type
  layout they are relative to the stack pointer position at the beginning
  of the function.  It is all in one type now, no splitting into "arg",
  "between" and "stack_frame" type anymore.
- Generalize the stack pointer simulation code to work with a single
  callback. Represent stack state as current offset and align_padding
  number. Now that callbacks can access and modify them both we do not
  need custom code in the sparc backend anymore.
- Remove alignment specification on IncSP, only keep a ignore_align flag
  used for the last IncSP that has to remove all existing sp adjustments
  and may end up on a misaligned SP on ia32/amd64.
- Align stack by default on ia32+amd64 backends.

In case there also was a Shrs(x, 31),
CSE can be applied after instruction selection.

ia32: Simply make the fpcw caller (and callee) saved, so we do not need a special case when generating a call.

'mov $~0x80000000, %r; ror x, %r' is shorter than 'mov $0x80000000, %r; shr x, %r; not %r'.

'Or' cannot have float mode.

'mov $~1, %r; rol x, %r' is shorter than 'mov $1, %r; shl x, %r; not %r'.

At least __builtin_return_address(0) with -fomit-frame-pointer works
again (the variant with frame pointer is still broken).

This fixes backend/destam_flags3.c.

This fixes backend/duplicate_proj.c.

This fixes multiple tests with -O0.

This is done by introducing a new new_global_entity() function for
constructing globals/adding a visibility argument to new_alias_entity().

This fixes opt/fehler311.c.

We can get a proper mode for pointer-pointer from
get_reference_offset_mode().

This flag can be set on entities where the actual address isn't
known/compared against other address. This also fixes a bug where we
used the mach-o csrings section for global char arrays which need
distinct addresses.

tarval_convert_to() does not return tv_unknown or null pointer.

Just use the code present in the Cmp/Sub-optimization to see if it will
trigger.

This fixes opt/fehler304.c

This resolves problems with hidden dependencies during code selection, which cause dependency cycles and therefore fixes backend/scheduled.c.
Also it grants the code selection slightly more freedom by not arbitrarily restricting the order by stack dependencies.

be: Pass the input requirements directly to the constructors of nodes, which have a variable number of arguments.