The idea here, is that you do not simply set a target operating system
or architecture, but have a setting for all things different between the
operating systems. Knowledge about the name and habits of the operating
system is left to the frontend.
(We may want to provide a small support library in the future to share
the triple parsing and OS -> settings code between multiple frontends).

This reverts commit 5165321c.

lower_highlevel() is used by x10i.
Also, I'd argue we should rather deprecate lower_highlevel_graph
instead.

be: Factorise the code to emit an asm node and use a callback for each backend to output the operands.

Both functions do the same and the former is used way less.

create_compilerlib_entity() does it already, so it is not necessary to do it again in replace_with_call().

If this Conv is inserted, then the existing Conv becomes a nop.
So let the existing Conv handle the conversion.

Strange casts may cause that a Load ends up with a method entity to load from.

This prevented optimizing x < 0 ? -1 : 0, when the result is unsigned.

The same test is done by an enclosing if.

This simplifies to understand the pattern when reading the code.

It is a sign extension when the operand is signed, not just when both the operand and the result are signed.

This prevents accidently hitting a Switch, though this code can only handle Cond.
This code probably is older than the Cond-Switch schism and later tests removed switch-like Conds.