Apparatus and methods are disclosed for dynamic nullification of memory access instructions, such as memory store instructions. In some examples of the disclosed technology, an apparatus can include memory and one or more block-based processor cores. One of the cores can include an execution unit configured to execute memory access instructions comprising a plurality of memory load and/or memory store instructions contained in an instruction block. The core can also include a hardware structure storing data for at least one predicate instruction in the instruction block, the data identifying whether one or more of the memory store instructions will issue if a condition of the predicate instruction is satisfied. The core may further include a control unit configured to control issuing of the memory access instructions to the execution unit based at least in a part on the hardware structure data.