Tomasulo's algorithm: Difference between revisions

Revision as of 12:05, 11 May 2015

Revision as of 18:09, 15 May 2015

Line 36:

===Register renaming===

Tomasulo's Algorithm uses [[register renaming]] to correctly perform ordecutionout-of-order execution. All general-purpose and reservation station registers hold either a real values or a placeholder value. If a real value is unavailable to a destination register during the issue stage, a placeholder value is initially used. The placeholder value is a tag indicating which reservation station will produce the real value. When the unit finishes and broadcasts the result on the CDB, the placeholder will be replaced with the real value.

Each functional unit has a single reservation station. Reservation stations hold information needed to execute a single instruction, including the operation and the operands. The functional unit begins processing when it is free and when all source operands needed for an instruction are real.