Support for architectures without hardware interlocks

[Eric Botcazou]

> I've worked on a gcc target that was porting an architecture without
> hardware interlock support. Basically, you need to emit nop operations
> to avoid possible hw conflicts. At the moment, this was done by
> patching the gcc scheduler to do so, Another issue to keep is to check
> for hardware conflicts across basic-block boundaries. And not the
> last, is to prohibit/avoid any instruction stream modification after
> scheduler (e.g., peephole optimizations etc.).

That's an overly complex approach, this usually can be done in a simpler way 
with a machine-specific pass that runs at the end of the RTL pipeline.

-- 
Eric Botcazou