May 2007 - Gpc

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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Port of Knuth's WEB to latest unstable release of GPC
by FL 01 Jun '07

01 Jun '07

Hello, I was unable to locate change files for Knuth's original TANGLE and CWEAVE programs on CTAN, so I've written a port of the system for the gpc version 20060325. I reverted the file I/O in Knuth's code that he ported to C back to GNU Pascal. I might have preserved Knuth's I/O routines in C, except that GNU Pascal changed the way it makes file structures available to the programmer since Knuth wrote his port (around 2000). The GNU PASCAL function GetFile() might have been used to pass a C-style FILE pointer to this code, but GetFile() is no longer availble. In its place, GNU PASCAL provides a BindingType data structure and related functions; these might have been usable if they had provided a valid file descriptor, but on my Debian Linux system, the value of BindingType.Handle is always -1 (if I may abuse the PASCAL language by referring to a variable of BindingType by its type). Am I mistaken about this? Florian P.S. I've made the change files, the mysterious GPCtypes.h file and a modified tangext.c file available at http://research.gc.cuny.edu/wiki/index.php/Port_of_Knuth%27s_TANGLE_and_WEA…

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Parallel GPC?
by Mirsad Todorovac 30 May '07

30 May '07

HI all, Is there a chance that there would be a support for parallel programming constructs in GPC any time soon? This is inspired by OpenMP/GOMP initiative support added to GCC 4.2. I know a couple of projects where this would be useful, and I could smuggle this as a research subject in my main project at my daily 9-5 job. Do you think just a unit/module is required to implement this to GPC; or an actual change of compiler proper? Frank? Thx Mirsad "Be conservative in what you do, be liberal in what you accept from others." -- Jon Postel

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Internal compiler error
by Pascal Viandier 22 May '07

22 May '07

Hi gpc masters, I think I found a bug in gpc. I use gpc 20051116 based on gcc3.4.4 on Sparc Solaris 10. It gives: Internal compiler error: Segmentation Fault when compiling the following code: Module Test1 Interface; Export Test1 = All; Type String200 = String(200); Function TranlateString(S : String200) : String200; End. Module Test1 Implementation; Function TranlateString(S : String) : String200; Begin End; { TranlateString } End. The error is: the type of the function parameter does not match in the interface and implementation sections. Interesting enough, if I reverse the error (that is, put 'String' in the Interface and 'String200' in the Implementation) I get the right error message: 'Routine definition does not match previous declaration'. Kind Regards. Pascal Viandier

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Re: Internal GPC Problem
by Matthew Blaine 20 May '07

20 May '07

Prof. Abimbola A. Olowofoyeku wrote: >What is your Windows version? It seems that the problem might be with a >path that is too long for Windows to handle ... I'm running Windows XP Professional SP2. Do you know what I could change? Thank you, Matt Blaine ____________________________________________________________________________________Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=list&sid=396545469

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Re: Internal GPC Problem
by Matthew Blaine 19 May '07

19 May '07

Prof. A Olowofoyeku (The African Chief) wrote: >On 18 May 2007 at 22:02, Matthew Blaine wrote: > >> Hello, >> I've downloaded and successfully installed Dev+GNU Pascal from: >> http://gnu-pascal.de/contrib/chief/win32/dev_gnu_pascal-1.9.4.8.exe >> >> I've successfully built build_units.pas, however now I'm having trouble >> using the gpc compiler. Trying to compile the GrClock.pas example, for >> instance, works. However, trying to compile a project that includes >> multiple source files, as opposed to just a single source file, does >> not work. I receive the following error: >> gpc: Internal GPC problem: internal option `--amtmpfile' not given > >Is it your own programs, or the test programs supplied with the package? > >Are you compiling from the IDE or from the command line? > >If compiling from the command line, are you supplying the right switches >(e.g., "--automake", etc?). > >If you have built build_units.pas, then the compiler is working correctly. >As you may notice when you look at the sources, build_units uses a whole >load of units. GrClock itself uses two units. > >Best regards, The Chief >-------- >Prof. Abimbola A. Olowofoyeku (The African Chief) >web: http://www.greatchief.plus.com/ Thank you very much for replying. It is one of my own programs that I've compiled on another Pascal compiler (Free Pascal) before. I'm using the IDE, here's what it shows me under the "Compile Log" tab. Compiling files : C:\DEV-PA~1\bin\gpc C:\DOCUME~1\Matthew\Desktop\Pascal\Copy\SOLITA~1.PAS -o.\solita~1.exe -fno-inline -s -fno-io-checking -fno-range-checking -fimplicit-result -O1 -Wno-warnings -fno-assertions -fextended-syntax -fignore-function-results -fcstrings-as-strings -fpointer-arithmetic -march=i686 -mcpu=i686 -funit-path=c:\dev-pa~1\units -fexecutable-path=. -funit-destination-path=c:\dev-pa~1\units -Bc:\DEV-PA~1\units -BC:\DEV-PA~1\bin\ And here's what I see under the "Compiler tab". gpc: Internal GPC problem: internal option `--amtmpfile' not given Again, thank you for your time. Matthew Blaine ____________________________________________________________________________________ Moody friends. Drama queens. Your life? Nope! - their life, your story. Play Sims Stories at Yahoo! Games. http://sims.yahoo.com/

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