Apparatus and methods are disclosed for controlling execution of memory access instructions in a block-based processor architecture using a hardware structure that generates a relative ordering of memory access instruction in an instruction block. In one example of the disclosed technology, a method of executing an instruction block having a plurality of memory load and/or memory store instructions includes decoding an instruction block encoding a plurality of memory access instructions and generating data indicating a relative order for executing the memory access instructions in the instruction block and scheduling operation of a portion of the instruction block based at least in part on the relative order data. In some examples, a store vector data register can store the generated relative ordering data for use in subsequent instances of the instruction block.