Pattern fusion template

[tancheng]

A pattern fusion template

• With example about fadd-fadd.
• I decide NOT go forward with:
  • user providing any fusion pattern
    • user needs to handle dependency, for large pattern, its complexity is same as writing up the pass/pattern_matcher
  • leverage tablegen
    • Same complexity as writing up pass, and sometimes out of control and less flexibility, and user needs to think more/deep
• I decide to provide specific flag for each type of fusion.

[ShangkunLi]

Everything looks good to me. ^_^

[tancheng]

Everything looks good to me. ^_^

Thanks, plz approve the dependent one :-)