Instructions and logic provide SIMD address conflict detection functionality. Some embodiments include processors with a register with a variable plurality of data fields, each of the data fields to store an offset for a data element in a memory. A destination register has corresponding data fields, each of these data fields to store a variable second plurality of bits to store a conflict mask having a mask bit for each offset. Responsive to decoding a vector conflict instruction, execution units compare the offset in each data field with every less significant data field to determine if they hold a matching offset, and in corresponding conflict masks in the destination register, set any mask bits corresponding to a less significant data field with a matching offset. Vector address conflict detection can be used with variable sized elements and to generate conflict masks to resolve dependencies in gather-modify-scatter SIMD operations.