Microarchitecture policies and structures partition execution resource clusters. In disclosed microarchitecture embodiments, micro-operations representing a sequential instruction ordering are partitioned into a two sets. To one set of micro-operations execution resources are allocated from a cluster of execution resources that can perform memory access operations but not branching operations. To the other set of micro-operations execution resources are allocated from a cluster of execution resources that can perform branching operations but not memory access operations. The first and second sets of micro-operations may be executed out of sequential order but are retired to represent their sequential instruction ordering.