1. A hierarchical store buffer included in a hierarchical microprocessor including a plurality of execution clusters, the hierarchical store buffer comprising: a first-level store buffer configured to: receive data values to be written to a memory subsystem from the plurality of execution clusters; and store the received data values prior to writing the data values to the memory subsystem; and a plurality of second-level store buffers each operatively coupled with the first-level store buffer, each second-level store buffer being included in a respective execution cluster, the second-level store buffers each being configured to: receive data values to be written to the memory subsystem from one or more execution units of the respective execution cluster; and store the received data values in a respective second-level store buffer prior to copying the data values to the first-level store buffer, wherein the first-level store buffer and the second-level store buffer are collectively configured to copy the stored data values to the first-level store buffer.