Update report.
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report.tex
11
report.tex
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@ -44,7 +44,7 @@ As expected, the two stateless predictors, \emph{Taken}
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and \emph{Not Taken}, perform significantly worse than the
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others. These predictors do not keep track of the behavior
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of various branches, and thus have limited ability
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to predict the direction of a branch. Out of the stateful
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to predict the direction or target of a branch. Out of the stateful
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predictors, the \emph{2-level} predictor seems to perform the worst.
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Unsurprisingly, the \emph{Combined} predictor, which is
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a combination of the other two stateful predictors, performs
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@ -102,7 +102,9 @@ since the code in \texttt{sim-outorder.c} converts zero to \texttt{PC+1}),
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or, in the case of unconditional jumps, it returns the expected target
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address (zero), which is \textit{also} \texttt{PC+1}! The fact that
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the two predictors have the same address prediction rate seems
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to be due to the ``FIXME'' in the simulator code.
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to be due to the ``FIXME'' in the simulator code. By the way,
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I write \texttt{PC+1} to mean ``the next program counter'', since
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I do not know the width in bytes of the simulated instructions.
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\section*{Part 2: IPC Benchmarks}
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In this section, we present the IPC results from the previously listed
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@ -212,6 +214,11 @@ tolerate at most one use of the wrong branch predictor before
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switching to the other (if the current predictor is ``strongly''
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predicted).
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Of course, a combined predictor need not specifically consist of
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a bimodal and a 2-level predictor. This approach can be applied
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to combine any two predictors. However, in the code for the simulator,
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it seems like only this specific combination is possible.
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\section*{Part 5 - 3-Bit Branch Predictor}
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For this part, I modified the SimpleScalar codebase to add
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a 3-bit branch predictor. The code will be included with this
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