PPT-The AMD Branch (Mis)predictor

New Types and Methods of StraightLine Speculation SLS Vulnerabilities April 2022 hardweario webinar Pawel Wieczorkiewicz Open Source Security Inc Pawel Wieczorkiewicz Email wipawelgrsecuritynet. Static Branch Prediction. Code around delayed branch. To reorder code around branches, need to predict branch statically when compile . Simplest scheme is to predict a branch as taken. Average misprediction = untaken branch frequency = 34% SPEC. Gaurav Chadha, Scott . Mahlke. , . Satish. . Narayanasamy. 17 June 2015. University of Michigan. Electrical Engineering and Computer Science. Internet-of-Things. Mobile. Web. Servers (. node.js. ). Debajit. B. h. attacharya. Ali . JavadiAbhari. ELE 475 Final Project. 9. th. May, 2012. Motivation. Branch Prediction. Simulation Setup & Testing Methodology. Dynamic Branch Prediction. Single Bit Saturating Counter. The Alternative Way to Improve . TAGE Branch Predictor. Yasuo Ishii. Executive Summary. We. submitted the perceptron inspired branch predictor in previous championships. Fused Two Level (FTL) Branch Predictor. . . Advanced Branch Prediction. Lihu Rappoport and Adi Yoaz. Introduction. Need to predict:. Conditional branch direction (taken or no taken). Actual direction is known only after execution. Wrong direction prediction causes a full flush. 5. Branch Prediction . (2.3) and . Scoreboarding. (A.7). 2. Why do we want to predict branches?. MIPS based pipeline – 1 instruction issued per cycle, branch hazard of 1 cycle.. Delayed branch. Modern processor and next generation – multiple instructions issued per cycle, more branch hazard cycles will incur.. Predictor . Virtualization. Andreas . Moshovos. Univ. of Toronto. Ioana . Burcea’s. . Thesis work. Some parts joint with Stephen . Somogyi. (CMU) and . Babak. . Falsafi. (EPFL). 2. Prediction . Computer Architecture and Implementation. Montek Singh. Oct 10, 2016. Topic: . Instruction-Level . Parallelism - . I. (Dynamic Branch Prediction). Instruction-Level Parallelism. Exploit . parallelism . Branch Prediction. Static Branch Prediction. To reorder code around branches, we need to predict branch statically when compiling. Always taken / not taken. Can be compiler directed. Delayed Branch . As we saw last week, dynamic instruction issue allows us to exploit as much parallelism as exists in instruction code. Our stalling situations are limited to finite resources, cache misses and branches. As we saw last week, dynamic instruction issue allows us to exploit as much parallelism as exists in instruction code. Our stalling situations are limited to finite resources, cache misses and branches. Address prediction and recovery. (And interrupt recovery too.). Announcements:. Programming assignment #2 . Due today. Extending to midnight.. HW . #2 due . Monday 2/3. P3 posted . tonight. Reading. Today’s topics: . Hazards and instruction scheduling. Branch prediction. Out-of-order execution. 2. Problem 0. add $1, $2, $3. add $5, $1, $4. Without bypassing:. add $1, $2, $3: IF DR AL DM RW. Topics: branch predictors, out-of-order intro, register renaming. 2. 2-Bit Bimodal Prediction. For each branch, maintain a 2-bit saturating counter:. if the branch is taken: counter = min(3,counter+1).