pipeline
\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{tikzmark}
\usepackage{longtable}
\iffalse
The following table illustrates the state of a 4-stage processor pipeline with data forwarding paths during the execution of the following program:
LOAD R1, R8, numX % Carreguem x a R1
LOAD R2, R8, num1 % Carreguem 2 a R2
LOAD R3, R8, num2 % Carreguem 3 a R3
BLE R1, R7, final % Comprovem que x > -1
SQR R4, R1 % Calculem x^2
DIV R5, R1, R3 % Calculem x/3
DIV R3, R4, R2 % Calculem x^2/2
MUL R5, R4, R5 % x/3 * x^2 = x^3/3
SQR R6, R3 % (x^2/2)^2 = x^4/4
SUB R1, R1, R3 % Calculem x - x^2/2
SUB R5, R5, R6 % Calculem x^3/3 - x^4/4
ADD R1, R1, R5 % Calculem x- x^2/2 + x^3/3 - x^4/4
STORE R1, R8, numY % Guardem el resultat a memoria
final:
\fi
\begin{document}
\begin{tabular}{|l|l|l|l|l|l|l|l|l|l|l|}
\hline
\textbf{Cycle} & \textbf{0} & \textbf{1} & \textbf{2} & \textbf{3} & \textbf{4} & \textbf{5} & \textbf{6} & \textbf{7} & \textbf{8} & \textbf{9} \\
\hline
\textbf{Read PC} & 100 & 101 & 102 & 103 & 104 & 105 & 106 & 107 & 108 & 109 \\
\textbf{Write IR} & LOAD & LOAD & LOAD & BLE & SQR & DIV & NO-OP & DIV & MUL & NO-OP \\
\hline
\textbf{Write RA} & & & & & R1 & R1 & R1 & & R4 & R4 \\
\textbf{Write RB} & & R8 & R8 & R8 & R7 & & R3 & & R2 & R5 \\
\hline
\textbf{Write AR} & & & {[}R8]+numX & {[}R8]+num1 & {[}R8]+num2 & & & & & \\
\textbf{Write DR} & & & & & & & R1*R1 & R1/R3 & & R4/R2 \\
\hline
\textbf{Write CR} & & & & {[}R1]=x & {[}R2]=2 & {[}R3]=3 & & {[}R4]=$x^2$ & {[}R5]=$\frac{x}{3}$ & \\
\textbf{Write MEM} & & & & & & & & & & \\
\textbf{Write PC} & 101 & 102 & 103 & 104 & 105 & 106 & 107 & 108 & 109 & 110 \\
\hline
\multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} & \multicolumn{1}{l}{} \\
\hline
\textbf{Cycle} & \textbf{10} & \textbf{11} & \textbf{12} & \textbf{13} & \textbf{14} & \textbf{15} & \textbf{16} & \textbf{17} & \textbf{18} & \textbf{19} \\
\hline
\textbf{Read PC} & 110 & 111 & 112 & 113 & 114 & 115 & 116 & 117 & 118 & 119 \\
\textbf{Write IR} & SQR & SUB & SUB & ADD & STORE & & & & & \\
\hline
\textbf{Write RA} & & R3 & R1 & R5 & R5-R6 \tikzmark{b4} & \tikzmark{c2}R1+R5 & & & & \\
\textbf{Write RB} & & & R3 & \tikzmark{a2}(R6) & \tikzmark{b2}(R1) & & & & & \\
\hline
\textbf{Write AR} & & & & & & & {[}R8]+numY & & & \\
\textbf{Write DR} & R4*R5 & & R3*R3 & R1-R3 & R5-R6 \tikzmark{b3} & \tikzmark{c1} R1+R5 & & & & \\
\hline
\textbf{Write CR} & {[}R3]=$\frac{x^2}{2}$ & {[}R5]=$\frac{x^3}{3}$ & & \tikzmark{a1}{[}R6]=$\frac{x^4}{4}$ & \tikzmark{b1}{[}R1]=$x-\frac{x^2}{2}$ & {[}R5]=$\frac{x^3}{3}-\frac{x^4}{4}$ & {[}R1]=$x-\frac{x^2}{2}+\frac{x^3}{3}-\frac{x^4}{4}$ & & & \\
\textbf{Write MEM} & & & & & & & & {[}R8+numY]=[R1] & & \\
\textbf{Write PC} & 111 & 112 & 113 & 114 & 115 & & & & & \\
\hline
\end{tabular}
\begin{tikzpicture}[overlay, remember picture, yshift=.25\baselineskip, shorten >=.5pt, shorten <=.5pt]
\draw [->] ({pic cs:a1}) [bend left] to ({pic cs:a2});
\draw [->] ({pic cs:b1}) [bend left] to ({pic cs:b2});
\draw [->] ({pic cs:b3}) [bend right] to ({pic cs:b4});
\draw [->] ({pic cs:c1}) [bend left] to ({pic cs:c2});
\end{tikzpicture}
\end{document}