February 2008 - 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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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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Cross Compiler GPC
by david.garcia＠servext.dimetronic.es 25 Feb '08

25 Feb '08

Hi! I want a cross compiler GPC for Power PC, but I don´t know that I make to correctly configure my version of GPC in Linux. I use GCC 3.4.3. and GPC 20060325. Thanks Este mensaje y sus ficheros adjuntos se dirigen exclusivamente a su destinatario y pueden contener información privilegiada o confidencial. Si no es usted el destinatario indicado, queda notificado de que la utilización, divulgación y/o copia sin autorización está prohibida en virtud de la legislación vigente. Si ha recibido este mensaje por error, le rogamos que nos lo comunique inmediatamente por esta misma vía y proceda a su destrucción. Los ficheros adjuntos han sido comprobados con un programa anti virus antes de su transmisión, pero les recomendamos que efectúen sus propias comprobaciones antes de abrir cualquiera de ellos. No aceptamos responsabilidad alguna por daños o pérdidas causados por virus informáticos. English translation Tradução portuguesa

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Building shared objects with GP
by Pascal Viandier 13 Feb '08

13 Feb '08

Hi GPC crew, I am trying to build shared objects with gp on SUN Sparc Solaris 10 using gpc 20070904 based on gcc-4.1.2. I tried many options of gp with no success. It looks like gp does not pass the --shared and -fPIC command line options to gpc so it produces only regular objects. So, is there a way to benefit from gp's great features to generate shared objects? Thanks Pascal Viandier

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Is it possible to use dynamic arrays in gpc?
by Ohonin Yuriy 07 Feb '08

07 Feb '08

Hello. I'm trying to use such a code: type TVar = object param1, param2:string; .... end; TVarList = object Items:array of TVar; count:cardinal; ..... end; In Delphi and FPC it works fine, but in GPC i get an error 45: warning: missing string capacity -- assuming 255 49: error: syntax error before `of' Is it possible to use dynamic arrays in gpc? I had searched gpc manual, but it is not clear for me - may be, it is possible to use dynamic array only as function parametr? It seems to be a little strange - dynamic arrays are a very old feature :( -- Best regards, Yuriy Ohonin.

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"internal compiler error" with gpc-20070904 on CString2String use
by J. David Bryan 05 Feb '08

05 Feb '08

The attached program causes an "internal compiler error" when compiled using gpc version 20070904, based on gcc-3.4.5 (mingw special), running on Windows XP. -- Dave

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-V and -b fail with gpc-20070904
by J. David Bryan 05 Feb '08

05 Feb '08

Attempting to use an alternate installed gpc version or gpc compiled for a different machine does not work: $ gpc -V 4.1.2 a.pas gpc: `-V' must come at the start of the command line $ gpc -b m68k a.pas gpc: `-b' must come at the start of the command line Problem appears to be that "init_gpc_options" inserts "-famtmpfile" and perhaps "-fsyntax-only" in front of all user-specified options, but "process_command" requires that "-V" and "-b" appear first. Workaround is to call the desired compiler driver directly, e.g.: $ i686-pc-mingw32-gpc-4.1.2 a.pas ...although that is somewhat awkward. Also, if the above bug is fixed, it appears that "process_command" will invoke "<machine>-gcc-<version>" instead of "<machine>-gpc-<version>". -- Dave

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Re: Is it possible to use dynamic arrays in gpc?
by Waldek Hebisch 05 Feb '08

05 Feb '08

Ohonin Yuriy wrote: > I'm trying to use such a code: > > type > TVarList = object > Items:array of TVar; > count:cardinal; > ..... > end; > > In Delphi and FPC it works fine, but in GPC i get an error > > 45: warning: missing string capacity -- assuming 255 > 49: error: syntax error before `of' > > Is it possible to use dynamic arrays in gpc? gpc does not implement Delphi style dynamic arrays. As Adriaan wrote you can get very similar functionality using Extended Pascal schema and pointers. Of course Extended Pascal schema have quite different syntax. Also memory management is different: with pointers to schema you must manually deallocate arrays. -- Waldek Hebisch hebisch(a)math.uni.wroc.pl

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[Fwd: GCC 4.2.3 Released]
by Adriaan van Os 04 Feb '08

04 Feb '08

-------- Original Message -------- Subject: GCC 4.2.3 Released Date: Sun, 3 Feb 2008 16:57:35 +0000 (UTC) From: Joseph S. Myers <joseph(a)codesourcery.com> Reply-To: gcc(a)gcc.gnu.org To: gcc-announce(a)gcc.gnu.org, gcc(a)gcc.gnu.org GCC 4.2.3 has been released. GCC 4.2.3 is a bug-fix release, containing fixes for regressions in GCC 4.2.2 relative to previous GCC releases. This release is available from the FTP servers listed at: http://www.gnu.org/order/ftp.html Please do not contact me directly regarding questions or comments about this release. Instead, use the resources available from http://gcc.gnu.org. As always, a vast number of people contributed to this GCC release -- far too many to thank individually!

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