Omar wrote:
1) How '>' really work, am i using it correctly or do I need to use it with another another constraint (like 'm>')?
It is usually used in the same alternative as another constraint such as 'm' or 'o', but I'm not sure if that is required. Most gcc internals stuff like this is not well documented. You just try it, and if it works fine, if it doesn't, then change it.
1.1) Which file should I load while debugging to understand how constrains are being use?
Constraints are only used by the register allocation passes, primarily regclass and reload.
2) How I limit the 'i' constraint so that only constants below or equal to 255 are allowed?
Depends on the gcc version. It current sources, you want to define a $target/constraints.md file that has a (define_contraint "I" ...) pattern. See any target for an example.
You can't redefine what 'i' means. That is reserved. See the "Constraints" section of the gcc internals manual.
Jim
