Final answer:
The direct answer is (d) write result stage. In the Tomasulo approach, the output dependency is resolved during the Write Result stage, where instructions' execution results are safely written to their intended destinations, avoiding write-after-write hazards.
Step-by-step explanation:
In the Tomasulo approach, an algorithm for dynamic scheduling of instructions that allows out-of-order execution and enables more efficient use of multiple execution units, the output dependency, also known as write-after-write (WAW) hazard, is resolved in the Write Result stage (d). This stage is crucial as it ensures that once an instruction's execution is complete, the result is written into the intended destination without being affected by other instructions that might be executing concurrently.
The Tomasulo algorithm utilizes reservation stations, which hold instruction specific information, and a common data bus (CDB) to broadcast results. The robust handling of dependencies through reservation stations, where each station monitors the CDB to capture the results of pending instructions, significantly diminishes output dependency issues. It is particularly effective as multiple functional units can write results independently and simultaneously without causing conflicts.
In the Tomasulo approach, the output dependency is resolved in the (d) write result stage. This stage is part of the out-of-order execution process where the computed result is written back to the register file. Prior stages, such as issue stage (a), read operand stage (b), and execution stage (c), contribute to the computation and tracking of dependencies.
It is in the write result stage that the instruction's result is written to the register file, making it available for subsequent instructions, thereby resolving the output dependency and progressing the pipeline in the dynamic instruction scheduling approach.