[Simh] The new Makefile

[Larry Baker]

I have not compared the SIMH V3.8 Makefile with the replacement  
proposed by Philipp.  I have converted the SIMH V3.4 descrip.mms file  
(the OpenVMS equivalent of a Makefile) to a DCL command procedure (the  
OpenVMS equivalent of a shell script or batch file), make.com, for  
compiling with DEC C on OpenVMS/Alpha and OpenVMS/VAX.  I compiled  
everything using our 333 MHz AlphaServer 1000A 5/333 (OpenVMS V7.2-1)  
and MicroVAX 4000-100 (OpenVMS V6.2) cluster.  As you know, these are  
VERY slow computers compared to any modern PC or Mac.  I did not find  
the time it took to compile objectionable.  I liked that I could see  
everything that went into each simulator in one command line.

My experience is that I recompile the simulator I use (MicroVAX) maybe  
once or twice when a new release looks interesting.  I don't usually  
have to do that more than once a year or two.  I am not concerned with  
the time that takes.  I am concerned about the performance of the  
simulator.  My preference is to provide the compiler with every  
opportunity at compile time to optimize the generated code,  
specifically, by aggressively inlining procedures and, when that is  
not possible, by making full use of inter-procedural optimizations  
(IPOs).  My impression is that the practice of separately compiling  
every module makes this more difficult, if not impossible, which makes  
me favor the current Makefile method.  Of course this assumes SIMH  
benefits from inlining and IPOs.  My bias, when choices have to be  
made, is to prefer alternatives that make the SIMH executable run  
faster, even if that increases the compilation time.

Larry Baker
US Geological Survey
650-329-5608
baker at usgs.gov

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