This program is a simulator for a 2-level branch predictor. The configuration of the predictor will be defined at the beginning of the simulation run using parameters.
| Parameter | Available Parameters |
|---|---|
| Branch Target Buffer (BTB) size | 1, 2, 4, 8, 16, 32 |
| History register size (in Bits) | 1 to 8 |
| Size of the Tag field in the BTB (in Bits) | 0 to (30 - log2[BTB Size]) |
| Starting state of the Bimodal State machines | 0 to 3 (0 = SNT, 1 = WNT, 2 = WT, 3 = ST) |
| History mode | local_history, global_history |
| State machines Tables | local_tables, global_tables |
| Usage of Lshare/Gshare (only relevant with global_tables) | not_using_share, using_share_mid, using_share_lsb |
An example for the input file first line that sets the parameters for the simulator:
16 5 20 1global_history global_tables not_using_share
To compile the program run:
make
To run the program run:
./bp_main <trace filename>
The trace file contains branch instructions events by command address, branch decision and target address Calculated. you can see the format of the trace files in the given examples.
The program output would contain a line for each branch instruction with: its address, its decision, and its actual target address.
Also, the program writes the number of flushes (from any cause), the number of branches and the needed size for all the BTB to work.