September 2009 - Gpc

Inefficiency of `mod'
by Emil Jerabek 26 Oct '10

26 Oct '10

Hi, during some debugging I noticed that GPC generates very hairy code for the `mod' operator with signed arguments. A closer look revealed that the code contains a lot of branching on conditions which can be determined on compile time, and most surprisingly, the value of X mod Y is recomputed _twice_, if X is negative. (I've attached a commented assembler dump.) This may be partially a back-end problem (CSE?), but I feel there's something wrong in the relevant code in gpc-common.c (build_pascal_binary_op) as well. `exp1 mod exp2' gets translated into something like exp2 <= 0 ? error : exp1 >= 0 ? exp1 mod exp2 : ((-exp1) mod exp2) == 0 ? 0 : exp2 - (-exp1) mod exp2 This arranges that both arguments supplied to the "internal mod" are non-negative, but this information is not passed on -- the arguments are still declared as signed types, which apparently makes the back-end to produce the mess it does. I've done a little test: the following replacement for `mod', which differs from the built-in one essentially just by the type-casts to `Cardinal', inline operator xmod (X, Y: Integer) = Z: Integer; begin if Y <= 0 then RuntimeError (714); if X >= 0 then Z := Cardinal (X) mod Y else begin Z := Cardinal (-X) mod Y; if Z <> 0 then Z := Y - Z end end; indeed generates a better code, it measures about 15% faster for positive X and more than twice faster for negative X. YMMV. If this is possible in user code, it should work in the compiler internals as well :) The result type of the whole `mod' expression looks dubious too. IIUIC, `exp1 mod exp2' inherits the type of exp1. Now, the result of `mod' is guaranteed to be nonnegative and to fit in the type of exp2 (or more precisely, it is in 0 .. High (type of (exp2)) - 1), whereas it needn't have anything to do with the type of exp1: consider var X, Z: Integer; Y: LongInt; begin X := -8; Y := High (LongInt); Z := X mod Y { -> overflow } end Or am I missing something? Emil (BTW, where is fjf434c.pas?)

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GPC support for AIX 6?
by Gert Doering 16 Feb '10

16 Feb '10

Hi Gnu Pascal list, we're currently using IBM's xpc pascal compiler on IBM AIX 5.3. New machines are being shipped with AIX 6, and IBM's xpc is no longer supported there - for the time being, it actuall works (the xpc frontend generated intermediate code, and the second stage compiler still groks it). Management is not happy about this, as it might break any day, and I have been asked to "provide GPC" on AIX 6. Googling seems to suggest that the earliest release of GCC to work on AIX 6 is gcc 4.2.4 This mailing list's archive suggests that GPC and GCC 4.2 do not yet work together, due to larger efforts required due to backend changes (Waldek's mail from March 12, 2008). I reported this to management ("there is no GPC on AIX 6"), and they came back with the question "if we pay one of the GPC developers to do a GPC port to a recent GCC, to support AIX 6, how much would that cost?". Here we go - I'm posing this question to you. Is one of you capable and willing to make GPC work on AIX 6? And if yes, what would your conditions be (estimated time to do this, estimated costs)? (I can't promise anything, but will report back to management and they will decide...) thanks, gert -- Gert Doering gd(a)medat.de MEDAT Muenchen Tel: 089/126808-0 Fax: -50

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New (gpc-20060325)
by Waldek Hebisch 08 Dec '09

08 Dec '09

I have put a new gpc snapshot at: http://www.math.uni.wroc.pl/~hebisch/gpc-20060325.tar.bz2 Main change is preliminary gcc-4.0.x support. The other changes are rather small. Note that for "production use" 3.4.x and 3.3.x backend are prefered. Also, using 2.8.1, 2.95.3 and 3.2.3 backend should work, but is depreciated. For more detail see: http://www.math.uni.wroc.pl/~hebisch/gpc/NEWS-20060325 and http://www.math.uni.wroc.pl/~hebisch/gpc/Fixed-20060325 -- Waldek Hebisch hebisch(a)math.uni.wroc.pl

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Re: More issues with EOLN, EOF, and the Pascal standard.
by samiam＠moorecad.com 25 Sep '09

25 Sep '09

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Re: More issues with EOLN, EOF, and the Pascal standard.
by samiam＠moorecad.com 24 Sep '09

24 Sep '09

1 0

Re: More issues with EOLN, EOF, and the Pascal standard.
by samiam＠moorecad.com 24 Sep '09

24 Sep '09

1 0

Re: More issues with EOLN, EOF, and the Pascal standard.
by samiam＠moorecad.com 24 Sep '09

24 Sep '09

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More issues with EOLN, EOF, and the Pascal standard.
by Chad Simmons 24 Sep '09

24 Sep '09

In a continuation of the thread: http://www.gnu-pascal.de/crystal/gpc/en/raw-mail10017.html Regarding conformance to the ISO 7185. It seems that GPC will correctly report EOLN before EOF even when none exists in the file. However, after successfully reading the end of line character, EOLN will still return true while EOF also simultaneously returns true. This has a tendency to give odd results. EOF and EOLN should be mutually exclusive. If the file doesn't properly have it's end of line marker before the end of the file, GPC can, should, and does currently insert the end of line into the buffer. But once it's been read, EOF should return true, and EOLN should not. I'm unfortunately not familiar enough with how gpc source is organized, so I'm not sure where to make the needed correction, in order to submit the patch. I would be willing to work on it however, if someone could point me in the right direction. Thanks, Chad Simmons The following program demonstrates the unusual behavior: PROGRAM GRADES (INPUT,OUTPUT); VAR SUM, COUNT, GRADE : INTEGER; BEGIN SUM := 0; COUNT := 0; WRITELN('ENTER GRADES AND PRESS CTRL-D WHEN FINISHED'); READ(GRADE); WHILE NOT EOF DO BEGIN SUM := SUM + GRADE; COUNT := COUNT + 1; IF EOLN THEN READ(CH); WRITELN('EOLN? ', EOLN); WRITELN('EOF? ', EOF); IF NOT EOF THEN READ(GRADE); END; WRITELN('TOTAL STUDENTS ', COUNT); WRITELN('CLASS AVERAGE ', SUM DIV COUNT); END. The output: $ ./grades ENTER GRADES AND PRESS CTRL-D WHEN FINISHED 20 30 40EOLN? False EOF? False EOLN? False EOF? False EOLN? True EOF? True TOTAL STUDENTS 3 CLASS AVERAGE 30 gpc -v output: $ gpc -v Using built-in specs. Configured with: ../src/configure -v --enable-languages=c,pascal --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.1.3 --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --disable-libmudflap --enable-checking=release x86_64-linux-gnu Thread model: posix gpc version 20070904, based on gcc-4.1.3 20080301 (prerelease) (Ubuntu 2.1-4.1.2-19ubuntu1)

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makefile problems
by Martin Kalbfuß 06 Sep '09

06 Sep '09

Thanks, unit path is the option I was looking for. I have a C background. But I forgot to mention that this is a library. So there's no main file. And the C part is needed to make some C macros and defines visible. It's a wrapper for the brand new allegro library. The keytypes are a long list of key names needed in two places. I decided to separate and include it. .I'm aware of --automake, and It makes the process much easier. But it's far to weak to replace a Makefile. Maybe some of the following things are wrong(hopefully): - no install target - no clean target - no support for building documentation - no dependency checking. (In my case allegro-4.9 for the examples) What's the way to go, when you like to release a library? For C I would use autotools and pkg-config. And I think It would be nice if there are going to be some macros for the use with autotools like an AC_PROG_CC equivalent AC_PROG_GPC which checks for the gpc compiler.

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makefile problems
by Martin Kalbfuß 04 Sep '09

04 Sep '09

Hi, I'm very frustrated. I'm not able to get a working makefile for my project. It has the following directory tree: pallegro |_src | |_pallegro.pas | |_display.pas | |_keyboard.pas | |_altime.pas | |_define.c | |_keytypes.def |_Makefile pallegro.pas depends on everything keyboard.pas depends on display.pas, define.c and keytypes.def display.pas depends on define.c altime.pas depends on define.c define.c depends on nothing keytypes.def depends on nothing I'm not able to create a makefile. Especially the placement in the src directory produces problems. I get dependency problems all the time. Could someone show me a basic makefile? I don't know how to proceed. :-( ________________________________________________________________ Neu: WEB.DE Doppel-FLAT mit Internet-Flatrate + Telefon-Flatrate für nur 19,99 Euro/mtl.!* http://produkte.web.de/go/02/

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