Simple LaTeX macro to draw a t(ombstone) diagram for compiler chains.

examples.tex

%Creates an image displaying the compilation of a compiler and the result
\begin{picture}(300,75)
  \put(0,25) {\tdiagram(from Q to M_2 in Q)}
  \put(65,0) {\tdiagram(from Q to M_1 in M_1)}
  \put(130,25) {\tdiagram(from Q to M_2 in M_1)}
\end{picture}

%Creates an image of a compiler chain
\begin{picture}(200,50)
  \put(0,0) {\tdiagram(from Q to Z in Q)}
  \put(100,0) {\tdiagram(from Z to M_2 in Q)}
\end{picture}

tdiagram.tex

%Usage:
% \tdiagram{from Q to Z in M_1}
\def\tdiagram(from #1 to #2 in #3){%
  \begin{picture}(100,50)

   \put (0,50)  {\line(1,0)   {100}}
   \put (0,25)  {\line(0,1)   {25}}
   \put (100,50) {\line(0,-1) {25}}

   % __   __ T bottom elements
   \put (100,25) {\line(-1,0) {35}}
   \put (0, 25)  {\line(1,0)  {35}}
   
   % |  | left and right
   \put (35,25)  {\line(0,-1) {25}}
   \put (65,25)  {\line(0,-1) {25}}

   % |__| bottom
   \put (35,0)   {\line(1,0)  {30}}

   %From -> To
   \put(10,35){$#1$}
   \put(45,35){$\rightarrow$}
   \put(80,35){$#2$}

   %In
   \put(45,10) {$#3$}
  \end{picture}
}