Gpc March 2007

gpc@gnu.de

10 participants
11 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?)

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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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compiling static library + gpc runtime without _statvfs on Mac OS X for Intel
by Glenn Howes 20 Apr '08

20 Apr '08

Hello, After months of being distracted by another portion of my application, I'm back to creating a universal binary version of the Pascal based library we are linking into our C++ based application. The problem is the application will not launch under PPC on Mac OS X 10.3 (Panther). The console registers an undefined symbol: _statvfs expected to be defined in /usr/lib/libSystem.B.dylib After some research, I found this call is being used by the StatFS routine implemented in rts.c (line 1510) /** Get information about a file system. */ GLOBAL (Boolean _p_StatFS (char *Path UNUSED, StatFSBuffer *Buf)) { int Result; #ifdef HAVE_STATVFS struct statvfs b; errno = 0; Result = statvfs (Path, &b); Buf->BlockSize = (long long int) b.f_frsize; Buf->BlocksTotal = (long long int) b.f_blocks; Buf->BlocksFree = (long long int) b.f_bavail; Buf->FilesTotal = (int) b.f_files; Buf->FilesFree = (int) b.f_favail; #elif defined (HAVE_STATFS) struct statfs b; errno = 0; Result = statfs (Path, &b); Buf->BlockSize = (long long int) b.f_bsize; Buf->BlocksTotal = (long long int) b.f_blocks; Buf->BlocksFree = (long long int) b.f_bavail; Buf->FilesTotal = (int) b.f_files; Buf->FilesFree = (int) b.f_ffree; #else Result = -1; errno = ENOSYS; #endif if (Result == 0) return True; Buf->BlockSize = 0; Buf->BlocksTotal = 0; Buf->BlocksFree = 0; Buf->FilesTotal = 0; Buf->FilesFree = 0; return False; } It appears to me that HAVE_STATVFS is defined if my current OS X SDK (10.4) has a statvfs.h header file amongst its include files, which means if I build my Pascal development environment from the build-on- Intel.command that the statvfs version will be hard wired into the runtime and any binary I generate will not work on 10.3 (which does not have statvfs in its libSystem.B.dylib library). Also, if I build my environment/library on a PowerPC using the build-on- powerPC-10.3.command, I end up with a different set of link problems involving the long double version of pow(). Besides which, I'd prefer to do my development on OS X for Intel going forward. I have tried hand editing the above routine and rebuilding my Pascal development environment, and pulling the statvfs.h file from my OS X SDK, and yet when my application links, it still has an unresolved reference to _statvfs. I'm not a build engineer, as my previous missives to this mailing list make clear, and I'm at a loss as to how to proceed. Just to be clear, I link in two static libraries: a universal version of the libgpc.a for the runtime, and a universal version of the library I've created. Neither of them contain the symbol _statvfs (at least I can't find that text in them). I link that with my application. The application now references _statvfs (I can now see the text in it's executable). I can't launch on 10.3. I comment out the calls to the Pascal library and recompile+relink, and the application no longer has the symbol and I can launch under 10.3. So something in either of the gpc associated libraries must be calling something which calls statvfs, making the linker (ld) mark statvfs as an unresolved symbol to be loaded in at runtime. At least that is my impression. So, I'd appreciate some suggestions. --glenn

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Memory layout of array of variable size.
by Bastiaan Veelo 24 Dec '07

24 Dec '07

Hi, In an attempt to hook up to GTK+, I am trying to pass a Pascal array of varible size to C. Static arrays are fine, but these arrays carry some additional information like capacity and size, and I gues they could be received as a struct on the C-side. However, I cannot figure out the structure that the struc should have. I do like this in Pascal: procedure YGTK_init(var argc : CInteger; argv : array of CString); external name 'YGTK_init'; procedure Y_init; var argc : CInteger; argv : array[0..ParamCount] of CString; Counter : integer; begin argc := ParamCount+1; for Counter := 0 to ParamCount do begin argv[Counter] := NewCString(ParamStr(Counter)); end; YGTK_init(argc, argv); end; And like this in C: struct t_argv { int end; void *argv; }; void YGTK_init( int *argc, struct t_argv argv ) { printf("In ygtk.c:YGTK_init.\n"); printf("argv.end: %d\n", argv2.argc); printf("argv.argv address: %p\n", argv2.argv); printf("argv.argv int: %d\n", argv2.argv); printf("argv.argv string: %s\n", argv2.argv); printf("number of arguments: %d\n", *argc); } So I figured out that the first element in the struct is an integer containing the length-1 of the array, but what it should look like for the rest I do not know yet. Do you have an idea? Thanks, Bastiaan.

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indirect jmp redux (Mac OS on Intel)
by Frederick Karl Kepner DuPuy 04 Sep '07

04 Sep '07

Hi. Regarding gpc for Mac OS X on Intel, I found a thread in the archives (see below) from October 2006 concerning an error message a user (Nestor Aguilera) got in compiling even the simplest programs. Unless I'm misreading the thread, no final conclusion was reached. Is anything further known now? Here's the thread: http://www.gnu-pascal.de/crystal/gpc/en/mail13854.html And the gist of the error messages: indirect jmp without `*' I'm having the same issue he had: programs which used to compile and execute happily with the gpc for PPC compiler are less happy with the gpc for Intel compiler--- they're still compiling, but issuing this error message repeatedly as they do so. I believe the output executes OK; but you can see why this is unsettling. So: is this a problem, or just an annoyance to be lived with? And is it happening to everybody trying to use gpc for Mac on Intel? (If so I'm curious as to why it hasn't been discussed since October.) (Please pardon my near-complete ignorance, by the way.) Thanks a lot, Rick DuPuy

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A pascal reference reader
by Russ Whitaker 20 Mar '07

20 Mar '07

Hi Attached are two bz2 files: When unziped, #1 is a plain text file. #2 is a pascal source for a command-line reader of #1. Before compiling, you should change line 10 so it can find where you want to leave #1. Am interested in feedback. a) Do you like it? b) What would you like added the most? If there's enough interest will work on it some more. Russ

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Undefined local symbol error with gpc20060325 on gcc-4.0.3
by Peter Schorn 18 Mar '07

18 Mar '07

I have built gpc20060325 with gcc-4.0.3 on OS X (PowerPC) basically just from the available sources (gcc-core-4.0.3.tar.bz2 and gpc-20060325.tar.bz2). The only patch I applied was related to building a shared library (see the modified gcc-4.0.3/gcc/p/rts/Makefile.in in the attachment). Compiling the attached program "test.pas" yields an assembler error: peter% /Developer/Pascal/gpc403/bin/gpc --version gpc 20060325, based on gcc-4.0.3 ... peter% /Developer/Pascal/gpc403/bin/gpc -mdynamic-no-pic -Os -save-temps --nonlocal-exit -c test.pas test.s:unknown:Undefined local symbol L2 In this particular case this seems to be due to the combination of -Os and --nonlocal-exit but I have seen the same error message also for -O0 (together with --nonlocal-exit) for more complex programs. Can anyone shed light on this problem? Best regards, Peter Schorn

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Compatible versions of gpc and gdb ?
by Ian Thurlbeck 15 Mar '07

15 Mar '07

Dear All A user is trying to get kdevelop+gdb working with gpc. I have installed gpc-20060325 + gcc-3.4.4 on Fedora Core 6 which has gdb-6.5 installed. However, the usual gpc -g -o hello hello.p produces under gdb: (gdb) list 1 <implicit code>: No such file or directory. in <implicit code> I tried -ggdb and -gstabs+ as well... Can anyone recommend a combination of gpc/gdb which works well? Many thanks Ian -- Ian Thurlbeck http://www.stams.strath.ac.uk/ Statistics and Modelling Science, University of Strathclyde Livingstone Tower, 26 Richmond Street, Glasgow, UK, G1 1XH Tel: +44 (0)141 548 3667 Fax: +44 (0)141 552 2079

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GPC unit can't be found
by Silvio a Beccara 12 Mar '07

12 Mar '07

Dear friends, I tried to compile a programme of mine using this version of gpc, I compiled together with gcc: [abeccara@sm1 pi]$ gpc -v Reading specs from /home/abeccara/progs/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/specs Configured with: ./configure --enable-languages=pascal --prefix=/home/abeccara/progs/gcc-3.4.3 Thread model: posix gpc version 20050331, based on gcc-3.4.3 This is the command line: gpc -O3 -w --automake \ --ignore-function-results \ -foptimize-sibling-calls \ --implicit-result \ --unit-path=./units \ --unit-destination-path=unit-obj \ -L$MPICH \ -L. pimb.pas -o pimb but I constantly get this error: error: `gpc.gpi' must be recompiled I never got it before. I tried to set GPC_EXEC_PREFIX as follows: [abeccara@sm1 pi]$ echo $GPC_EXEC_PREFIX /home/abeccara/progs/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/ and also to copy all units from /home/abeccara/progs/gcc-3.4.3/lib/gcc/i686-pc-linux-gnu/3.4.3/units into my units directory but nothing changes. Can you help me? Kind regards Silvio a Beccara -- Email.it, the professional e-mail, gratis per te: http://www.email.it/f Sponsor: Problemi di Liquidità? Con Logos Finanziaria 30.000 in 24 ore a dipendenti e lavoratori autonomi con rimborsi fino a 120 mesi clicca qui * Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=2907&d=12-3

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Re: Warum geht es nicht mit einer
by Frank Heckenbach 11 Mar '07

11 Mar '07

In the German list, Roland Goretzki found a GPC bug (roland2). I've made a fix for older GPC versions (such as 20040516 he's using), which is attached. However, in Waldek's newer GPC versions, the respective code is "#if 0"d, with the comment: "/* save_expr would cause problems */". Unfortunately this comment is not very informative to me. I've built gpc-20060325 with the code back in ("#if 1") on i586-pc-linux-gnu (Debian 3.1) with gcc-3.4.4, and all tests passed (except roland2, of course). So I suppose the problems only affect gcc-4.x or other platforms, is this right? Then I've applied my patch and all test passed, including roland2. Anyway, the point is that in the original code, save_expr is only applied to the string length (which is used twice). However, the whole string expression may contain side-effects (as in roland2.pas), and is accessed for the length (once using save_expr, twice otherwise) and for the chars. So we need to save this. This is what my patch does, removing the (now useless) save_expr for the length. Waldek's code still saves the length, in different way, so the problem still exists. Perhaps save_expr_string works with gcc-4/other platforms, so we don't need the new code. If not, can you change your code to save the whole string, or change save_expr_string if necessary (as you probably know what you'll have to test then; I don't). Frank -- Frank Heckenbach, f.heckenbach(a)fh-soft.de, http://fjf.gnu.de/, 7977168E GPC To-Do list, latest features, fixed bugs: http://www.gnu-pascal.de/todo.html GPC download signing key: ACB3 79B2 7EB2 B7A7 EFDE D101 CD02 4C9D 0FE0 E5E8

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Gpc March 2007