[TUHS] arithmetic IF (was origin of string.h and ctype.h)

arnold at skeeve.com arnold at skeeve.com
Fri Aug 18 20:49:13 AEST 2017


That's it!  Much thanks!

Arnold

Paul McJones <paul at mcjones.org> wrote:

> On Aug 17, 2017, arnold at skeeve.com wrote:
>
> > I remember reading an article somewhere on the history of the first
> > FORTRAN compiler.  The guys doing it wanted it to succeed, and they
> > were fighting the mentality that high level languages could not possibly
> > be as efficient as hand-coded assembly, so they put a lot of work into
> > the optimization of the generated code.
> > 
> > It worked so well that the results that came out of the compiler
> > sometimes suprised the compiler writers!  They then would have to
> > dive into the compiler sources to figure out how it was done.
> > 
> > I don't remember where I read this article. If the story rings a
> > bell with anyone, let me know.
>
> In his paper "The history of FORTRAN I, II and III??? presented at the
> First ACM SIGPLAN conference on History of Programming Languages (1978),
> John Backus said:
> 
> > It was an exciting period; when later on we began to get fragments
> > of compiled programs out of the system, we were often astonished at
> > the surprising transformations in the indexing operations and in the
> > arrangement of the computation which the compiler made, changes which
> > made the object program efficient but which we would not have thought
> > to make as programmers ourselves (even though, of course, Nelson or
> > Ziller could figure out how the indexing worked, Sheridan could explain
> > how an expresssion had been optimized beyond recognition, and Goldberg
> > or Sayre could tell us how section 5 had generated additional indexing
> > operations). Transfers of control appeared which corresponded to no
> > source statement, expressions were radically rearranged, and the same
> > DO statement might produce no instructions in the object program in one
> > context, and in another it would produce many instructions in different
> > places in the program.
>
> The paper is available here, courtesy of ACM:
> http://www.softwarepreservation.org/projects/FORTRAN/index.html .


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