\frame{\frametitle{Predication key-value CSR store}
\begin{itemize}
- \item key is int regfile number or FP regfile number (1 bit)\vspace{10pt}
- \item register to be predicated if referred to (5 bits, key)\vspace{10pt}
- \item register to store actual predication in (5 bits, value)\vspace{10pt}
- \item predication is inverted (1 bit)\vspace{10pt}
+ \item key is int regfile number or FP regfile number (1 bit)\vspace{6pt}
+ \item register to be predicated if referred to (5 bits, key)\vspace{6pt}
+ \item register to store actual predication in (5 bits, value)\vspace{6pt}
+ \item predication is inverted (1 bit)\vspace{6pt}
+ \item non-predicated elements are to be zero'd (1 bit)\vspace{6pt}
\end{itemize}
Notes:\vspace{10pt}
\begin{itemize}
\frame{\frametitle{Register key-value CSR store}
\begin{itemize}
- \item key is int regfile number or FP regfile number (1 bit)\vspace{10pt}
- \item register to be predicated if referred to (5 bits, key)\vspace{10pt}
- \item register to store actual predication in (5 bits, value)\vspace{10pt}
- \item TODO\vspace{10pt}
+ \item key is int regfile number or FP regfile number (1 bit)\vspace{6pt}
+ \item treated as vector if referred to in op (5 bits, key)\vspace{6pt}
+ \item starting register to actually be used (5 bits, value)\vspace{6pt}
+ \item element bitwidth: default/8/16/32/64/rsvd (3 bits)\vspace{6pt}
+ \item element type: still under consideration\vspace{6pt}
\end{itemize}
Notes:\vspace{10pt}
\begin{itemize}
- \item Table should be expanded out for high-speed implementations
- \item Multiple "keys" (and values) theoretically permitted
- \item RVV rules about deleting higher-indexed CSRs followed
+ \item Same notes apply (previous slide) as for predication CSR table
+ \item Level of indirection has implications for pipeline latency
\end{itemize}
}
\begin{itemize}
\item Is C.FNE actually needed? Should it be added if it is?
+ \item Element type implies polymorphism. Should it be in SV?
\item Should use of registers be allowed to "wrap" (x30 x31 x1 x2)?
\item Is detection of all-scalar ops ok (without slowing pipeline)?
\item Can VSELECT be removed? (it's really complex)