[MacPorts] #50953: gambit-c @4.7.6 Change compiler and add desirable ./configure option

[MacPorts]

#50953: gambit-c @4.7.6 Change compiler and add desirable ./configure option
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 Reporter:  macports@…   |      Owner:  macports-tickets@…
     Type:  enhancement  |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  ports        |    Version:  2.3.4
 Keywords:               |       Port:  gambit-c
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 =Executive Summary:=

 The Gambit-C package should be compiled using recent versions of the
 “macports-gcc” compiler package.  Note that I am deliberately
 distinguishing between the Apple version of GCC (“gcc-4.0”, “apple-
 gcc-4.0”, etc.) and the purer MacPorts version.  Additionally, the
 “--enable-single-host” option should be specified to the “./configure”
 script when gambit is built.


 =Justification:=

 The Gambit-C package is a high-performance interpreter and compiler for
 the Scheme (LISP-family) programming language.  The gambit compiler works
 by first translating Scheme source code into C code, which is then
 compiled using the system’s C compiler.  Because Scheme programs can have
 a very nonlinear flow of control, including advanced features such as
 first class continuations, the C code produced by the gambit compiler is
 complicated and not intended for human consumption - it is an intermediate
 form generated by one compiler for another compiler, principally
 consisting of a single, exceedingly large, C function (a “trampoline”
 function).

 Note that the gambit compiler itself is mostly written in Scheme, so the
 choice of C compiler affects the building of the gambit package by the
 Macports buildbot, not just the usage of the gambit package by the end
 user.

 The complex nature of the intermediate C code generated by gambit tests
 the limits of even modern C compilers.  My recommendation that the purest
 version of GCC (“macports-gcc”) be used to compile gambit is not based on
 compiler favouritism;  past versions of all of the common compilers, GCC,
 LLVM, clang, and the Apple versions of these compilers, have had troubles
 compiling gambit C code in the past.  But the original author of gambit
 “highly recommends” using GCC [see 1].  And currently it seems that recent
 versions [4] of the GCC compiler perform the best, and the difference
 between GCC and the other compilers is significant (30 times faster to
 compiler the gambit scheme compiler than even the Apple GCC compiler!)
 [3].

 Lastly, I would argue that the “--enable-single-host” option should be
 specified to “./configure” when gambit is built because this option
 dramatically improves the efficiency of the compiled code, and because
 this option is highly recommended by the original author of the gambit
 package [2].  Note that adding “--enable-single-host” increases the time
 needed to compile gambit, and this has caused problems for the macports
 buildbot in the past, when the pure macports gcc compiler was not used
 [for example, see https://trac.macports.org/ticket/46013].  The
 improvement in compile-time when using the macports-gcc package should
 more than offset the increased build time incurred by highly desirable
 “--enable-single-host” option.

 - William



 Notes:

 From:  http://gambitscheme.org/wiki/index.php/Configure_script_options

 [1] “It is also highly recommended to use the GCC compiler to build the
 system as the source code can take advantage of some GCC extensions.
 Notably the use of GCC's computed gotos reduces the execution time by
 roughly 35%.”

 [2] “It is highly recommended to use the --enable-single-host option to
 improve the execution speed and compactness of the executables   …   [for
 example] the speed of the Gambit-C interpreter improves by a factor of 2
 as a result.”



 [3]  From:  https://webmail.iro.umontreal.ca/pipermail/gambit-
 list/2015-January/007698.html

 “As can be seen, the Apple C compilers build Gambit in roughly 30 minutes,
 which is about 30x slower than when using GNU gcc 4.9.2 .  The execution
 time is also better for GNU gcc, about 2.3x faster.  So on OS X it is
 clearly advantageous to install GNU gcc when using Gambit.”



 [4]  From:
 https://github.com/Homebrew/homebrew/commit/beb68f8a63243587ea736fd61e7cea2af4fdf9ab#Library/Formula
 /gambit-scheme.rb

 “don't try to build with GCC 4.2 or 4.3 … requires absurd amounts of RAM”

-- 
Ticket URL: <https://trac.macports.org/ticket/50953>
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