HIGH PERFORMANCE ZERO BUBBLE CONDITIONAL BRANCH PREDICTION USING MICRO BRANCH TARGET BUFFER

摘要

Embodiments include a micro BTB, which can predict up to two branches per cycle, every cycle, with zero bubble insertion on either a taken or not taken prediction, thereby significantly improving performance and reducing power consumption of a microprocessor. A front end of a microprocessor can include a main front end logic section having a main BTB, a micro BTB to produce prediction information, and a decoupling queue. The micro BTB can include a graph having multiple entries, and a CAM having multiple items. Each of the entries of the graph can include a link pointer to a next branch in a taken direction, and a link pointer to a next branch in a not-taken direction. The micro BTB can insert a hot branch into the graph as a new seed.

主权项

1. A front end of a microprocessor, comprising:
a main front end logic section including a main branch target buffer (BTB); a micro BTB separate from the main BTB of the main front end logic section, and configured to produce prediction information; and a decoupling queue coupled to the micro BTB and to the main front end logic section, and configured to receive and queue the prediction information, and to provide the queued prediction information to the main front end logic section.