Gpc October 2009

gpc@gnu.de

7 participants
6 discussions

Inefficiency of `mod'
by Emil Jerabek 25 Oct '10

25 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

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

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

7 44

Kubuntu AMD-64 Linux: WHAT no graphics?
by twixt＠cstone.net 14 Oct '09

14 Oct '09

I installed gpc and all required or recommended packages using aptitude. The manual apparently contains no mention of graphics output. But that's why I downloaded Pascal in the first place! Looking through the mailing list archives, I find mention of a GRX library. But when I do a search for "grx" within aptitude, I come up empty. All I want to do is create a 432 pixel x 378 pixel image with over 2000 different 24-bit colors, all in a very precise pattern, a fractal shape as a matter of fact. In the time it is taking me to find any programming language that will let me do this, I suppose I could do it manually with a graphics editor, although this would be somewhat tedious. I can create a 432x378 array of strings, where each string is the hexadecimal code for a 24-bit color. How can I turn this array into an image? Does anyone know of a programming language which DOES do graphics? Thanks for your patience. David Bush

5 4

AMD 64 Pascal build error
by twixt＠cstone.net 14 Oct '09

14 Oct '09

3 2

Kubuntu AMD 64: grx build error
by twixt＠cstone.net 11 Oct '09

11 Oct '09

Thanks for your help! Following the installation instructions, I was able to run "make -f makefile.x11" apparently without errors. I used the following choices when editing makedefs.grx: HAVE_LIBTIFF=y HAVE_LIBJPEG=y HAVE_LIBPNG=y NEED_ZLIB=y INCLUDE_PRINTING_CODE=n INCLUDE_BMP_CODE=y INCLUDE_GPC_SUPPORT=y INCLUDE_SHARED_SUPPORT=y INCLUDE_BGI_SUPPORT=y HAVE_UNIX_TOOLS=n BUILD_X86_64=n I left the rest of the makedefs.grx file alone. Then I went into the /test subdirectory and here is the log: david@Achernar:~/software/grx/grx248/grx248/test$ sudo make -f makefile.x11 [sudo] password for david: gcc -c -O2 -fno-strict-aliasing -Wall -m32 -D__XWIN__ -I../include arctest.c -o arctest.o In file included from arctest.c:21: test.h: In function ‘main’: test.h:88: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result gcc -s -m32 -s -o xarctest arctest.o ../lib/unix/libgrx20X.a -ltiff -ljpeg -lpng -lz -L/usr/X11R6/lib -lX11 -lm /usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../libz.so when searching for -lz /usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.3.3/../../../libz.a when searching for -lz /usr/bin/ld: skipping incompatible /usr/lib/libz.so when searching for -lz /usr/bin/ld: skipping incompatible /usr/lib/libz.a when searching for -lz /usr/bin/ld: cannot find -lz collect2: ld returned 1 exit status make: *** [xarctest] Error 1 david@Achernar:~/software/grx/grx248/grx248/test$ What should I do? Thanks again! David

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Gpc October 2009