Fusible instructions and logic provide OR-test and AND-test functionality on multiple test sources. Some embodiments include a processor decode stage to decode a test instruction for execution, the instruction specifying first, second and third source data operands, and an operation type. Execution units, responsive to the decoded test instruction, perform one logical operation, according to the specified operation type, between data from the first and second source data operands, and perform a second logical operation between the data from the third source data operand and the result of the first logical operation to set a condition flag. Some embodiments generate the test instruction dynamically by fusing one logical instruction with a prior-art test instruction. Other embodiments generate the test instruction through a just-in-time compiler. Some embodiments also fuse the test instruction with a subsequent conditional branch instruction, and perform a branch according to how the condition flag is set.