February 2010 - 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?)

10 16

Re: gpc installation support
by Maurice Lombardi 23 Feb '10

23 Feb '10

kriti panday a écrit : > HELLO > Please tell me how can i get support for gpc installation.To which mail > ID ,i will send my question. > Please support me.Tell me the procedure for GPC installation on Unix. send mail to the gpc list, not to gpc-doc which is specialized and pretty dead download the latest gpc snapshot http://www.math.uni.wroc.pl/~hebisch/gpc/gpc-20070904.tar.bz2 and gcc sources for backend (3.4.x and 4.1.x are fine) The instructions are in p/INSTALL in the gpc snapshot: in Unix better compile the compiler than install binaries. There has been posted in this list a script to automate the building, but I never used it. Maybe the author will give the reference. Maurice -- Maurice Lombardi Laboratoire de Spectrometrie Physique, Universite Joseph Fourier de Grenoble, BP87 38402 Saint Martin d'Heres Cedex FRANCE Tel: 33 (0)4 76 51 47 51 Fax: 33 (0)4 76 63 54 95 mailto:Maurice.Lombardi@ujf-grenoble.fr

2 1

Re: gpc installation support
by Adriaan van Os 23 Feb '10

23 Feb '10

kriti panday wrote: > HELLO > Please tell me how can i get support for gpc installation.To which mail > ID ,i will send my question. > Please support me.Tell me the procedure for GPC installation on Unix. More info here <http://alignment.hep.brandeis.edu/Software/Pascal/Index.html> Regards, Adriaan van Os

1 0

Hi everyone - got a question about GPC
by Hodges, Robert CTR USAF AFMC 520 SMXS/MXDEC 18 Feb '10

18 Feb '10

I downloaded GPC from this web site: http://www.gnu-pascal.de/binary/ I downloaded the binary version of GPC and GCC bundled together in RMP format for Linux. I specifically need GPC 2.1 with GCC 2.95, the file called gpc-2.1-with-gcc.i686-pc-linux-gnu.tar.gz <http://www.gnu-pascal.de/binary/gpc-2.1-with-gcc.i686-pc-linux-gnu.tar.gz> . I was greatly relieved to find this web site, and that binaries were available in the versions I needed. Problem is, when I install the RPM, it looks like the "binary" GCC compiler is incomplete - no actual binaries, compiler not ready to run. I could be wrong, so if I am, I need someone to help point me in the right direction. I'm a sysadmin who's installing this software for a developer, which I am not. Since I personally think the most ridiculous thing in the world is a compiler that won't work until it's compiled by another compiler, can anybody point me in the right direction to either an installable package of GPC 2.1, GCC 2.95 for Linux or tell me how to get this particular backage to work? Oh, I am attempting to install and run this package on SuSE Linux Enterprise Server 11. Major thanks in advance to anyone that can help out. Not sure what to think, the most recent update I can identify on the above web site was 5 years ago. Anybody out there? Bob

6 16

Re: Zeichensalat
by Adriaan van Os 17 Feb '10

17 Feb '10

egbert(a)seibertz.de wrote: > Moin Pascaller, > > im Rahmen von systemweiten Zeichensatzumstellungen (von > latin1 auf utf8) funktionieren nun erwartungsgemäß einige > Pascalprogramme nicht mehr. Teilweise weil Dateinamen > nicht mehr verstanden werden und teilweise weil Eingaben > nicht mehr verstanden werden. Oder die Nutzer die Ausgaben > nur noch erraten können ... > > Sehr ärgerlich an utf8 ist, daß durch die variable > Zeichenlänge der Programmieraufwand für die Erkennung > überproportional ansteigt. Möglicher Weise wäre utf16 > (USC2) deutlich einfacher im Aufwand ... Nach meiner Meinung ist UTF-16 wohl die slechteste Wahl, weil auch UTF-16 eine Kodierung ist mit variabeler Länge (<http://en.wikipedia.org/wiki/Utf-16>), obwohl Sie oft nicht als Solches behandelt wird, was dann wiederum zu Fehlern führt ! Ich bevorzuge UTF-8. Adriaan van Os

1 0

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

7 13

Long String Generation
by Kevan Hashemi 16 Feb '10

16 Feb '10

Dear GPC Users, I use long strings to pass numerical data into and out of a shared library I compile from Pascal. Right now, I generate a long string of numbers like this. program string_demo; var long_string:string(100000); i:integer; begin long_string:=''; for i:=1 to 10000 do writestr(long_string,long_string,i:1,' '); end. Clearly, this is inefficient. It takes 200 ms on my machine. If I use an array of characters instead of a string, and append each new entry to the array, execution time drops to 10 ms. I can't see a way of using GPC's writestr, concat, or trim functions to accelerate my string generation. I can't alter the long_string.length field directly. If I could fill up the string with spaces first, I could use the string as an array, then trim the spaces off the end. But filling up the string with spaces requires multiple calls to writestr, so I'm back where I started. It seems to me that I'm missing an obvious solution to my problem, and I thought you might point it out to me. Yours, Kevan -- Kevan Hashemi, Electrical Engineer Physics Department, Brandeis University http://alignment.hep.brandeis.edu/

4 6

compiler directives should be shut off when using --standard-pascal
by Rugxulo 03 Feb '10

03 Feb '10

Hi, I agree. This basically means that cmdline dialect options should take precedence over any listed in the file itself. This should not cause anybody much trouble, if any, except in some rare makefiles, and even that should be an easy fix. ---------- Forwarded message ---------- From: Scott Moore Date: Tue, Feb 2, 2010 at 1:38 PM Subject: Re: New P5 available To: Rugxulo In retrospect, it's probably not a good idea that GPC tries to take compiler directives from the programs. There should be a way to turn off GPC's parse of the compiler directives, since that would make GPC defacto non-standard. It should have been shut off with the --standard-pascal switch.

1 0