An optimizing compiler includes a vector optimization mechanism that optimizes vector operations that are reformatting-resistant, such as source instructions that do not have a corresponding reformatting operation, sink instructions that do not have a corresponding reformatting operation, a source instruction that is a scalar value, a sink instruction that may produce a scalar value, and an internal operation that depends on lanes being in a specified order. The ability to optimize vector instructions that are reformatting-resistant reduces the number of operations to improve the run-time performance of the code.