August 2006 - 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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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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gpc20060325 says "new style GCC `-H' output detected" and doesn't want to build
by Igor Marnat 03 Oct '06

03 Oct '06

Hello List! I've built two toolchains (native for i386-linux and cross for ppc-linux target) based on gpc 20060325 and gcc 4.0.3. I have the units that use {$L file.c} directive. Native compiler build them just fine but cross compiler of the same version gives an error "new style GCC `-H' output detected" and stops build. I couldn't find any information in Google and GPC mailing lists. Please, any ideas? Native compiler version: [igor@marnat2 main_program]$ gpc -v Using built-in specs. Configured with: ../gcc-4.0.3/configure --enable-languages=c,pascal --enable-threads=posix --prefix=/home/igor/src-big/tools Thread model: posix gpc version 20060325, based on gcc-4.0.3 Cross compiler version: [igor@marnat2 main_program]$ ppc-linux-gpc -v Using built-in specs. Configured with: ../configure --prefix=/home/igor/src-big/ELDK4.0/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --disable-checking --with-system-zlib --enable-__cxa_atexit --disable-libgcj --target=ppc-linux --with-newlib --enable-languages=c,pascal --enable-multilib=no --disable-multilib Thread model: posix gpc version 20060325, based on gcc-4.0.3 (DENX ELDK custom version 4.0.3-1) Best regards, Igor Marnat mailto:marny@rambler.ru

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internal compiler error when trying to use record variable declared using "absolute" keyword
by Igor Marnat 04 Sep '06

04 Sep '06

Hello, List! Trying to build the program below using gpc 20060325 based on gcc 4.0.3 I've got "Internal compiler error". Sorry for a bit complicated test program but it's the simplest one I could produce to reproduce the bug. Error message: [igor@marnat2 internal_compiler_error]$ make gpc --automake test.pas <var_decl 0x401910d8 Eepromstor.155419 type <pointer_type 0x4018ec3c type <pointer_type 0x4018ea8c Eepromptr type <record_type 0x4018e510 Eepromtype> unsigned SI size <integer_cst 0x40139888 constant invariant 32> unit size <integer_cst 0x401398a0 constant invariant 4> align 32 symtab 0 alias set -1 main_variant <pointer_type 0x4018ea8c Eepromptr> pointer_to_this <pointer_type 0x4018ec3c>> unsigned SI size <integer_cst 0x40139888 32> unit size <integer_cst 0x401398a0 4> align 32 symtab 0 alias set -1 main_variant <pointer_type 0x4018ec3c>> used unsigned ignored SI file test.pas line 26 size <integer_cst 0x40139888 32> unit size <integer_cst 0x401398a0 4> align 32 context <function_decl 0x4018ee58 Eep> (reg/f:SI 0 ax [orig:63 Eepromstor.155419 ] [63]) chain <var_decl 0x40191144 D.606>> test.pas: In function `EAdvLineInfo': test.pas:31: internal compiler error: in expand_expr_real_1, at expr.c:6800 Please submit a full bug report, with preprocessed source if appropriate. See <URL:http://www.gnu-pascal.de/todo.html> for instructions. make: *** [all] Error 1 Offending program: program test; type LinesInfoPtr = ^LinesInfoType; LinesInfoType = array [0..99] of word; type EEPROMType = record LinesInfo: word; end; type StoragePtr = ^StorageType; StorageType = array [0..99] of byte; type EEPROMPtr = ^EEPROMType; var EEPROMStor: StoragePtr; EEPROMData: EEPROMPtr absolute EEPromStor; function EEP ( W: word): pointer; begin EEP := pointer (word (EEPromData) + W) end; function EAdvLineInfo (Line: ShortWord): word; begin EAdvLineInfo := LinesInfoPtr (EEP (EEPROMData^.LinesInfo))^ [Line]; end; begin writeln (integer (EAdvLineInfo (1))); end. ~ -- Best regards, Igor mailto:marny@rambler.ru

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GPC, CGI units, and program size
by Prof. A Olowofoyeku (The African Chief) 30 Aug '06

30 Aug '06

Hi I have downloaded Frank's cgiprogs package, for the purpose of building a cgi program for an adsl router (running MontaVista Linux on a mipsfple processor). First, hats off to Frank. The program compiled and runs fine on the router. The problem is the size of the compiled program (320kb when statically linked with libgpc.a, and 250kb when linked to libgpc.so, which itself is 320kb). This is a significant amount of space for a single program to take on a router. My question (and probably only Frank can answer this) is, how can one reduce the size of this program? The program uses the gpc and cgi units only. From the GPC unit it calls "Execute" and "GetTempDirectory", and from the cgi unit it calls: GetVar IsCGI CGIInitVars If it is not possible to reduce the program size, then I guess that would have to be it - I just thought I'd ask anyway :) Perhaps there is a C cgi library? Thanks. Best regards, The Chief --------- Prof. Abimbola Olowofoyeku (The African Chief) Web: http://www.greatchief.plus.com/

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results of cross compilation gpc20060325 for ppc-linux target on i386-linux platform
by Igor Marnat 29 Aug '06

29 Aug '06

Hello List. I've cross built gpc20060325 for ppc-linux target. In order to do that I've made the changes attached. The second and the third changes were needed because otherwise compilation process called xgpc (cross-compiler just built) with native CFLAGS (-O2 -g -march=i386 -mcpu=i686) which it didn't want to accept. The first change allowed me to install the result compiler as ppc-linux-gpc instead of ppc-linuxppc-linux-gpc as it wanted to do first. Perhaps some changes are to be made in sources. diff -urN gpc-20060325/p/Make-lang.in gpc-20060325-ppc/p/Make-lang.in --- gpc-20060325/p/Make-lang.in 2006-03-25 06:33:50.000000000 +0300 +++ gpc-20060325-ppc/p/Make-lang.in 2006-08-29 19:04:08.057019832 +0400 @@ -179,7 +179,8 @@ # Actual names to use when installing a cross-compiler. GPC_CROSS_NAME_=`t='$(program_transform_cross_name)'; echo gpc | sed $$t` -GPC_CROSS_NAME_34=$(target_noncanonical)`t='$(program_transform_name)'; echo gpc | sed $$t` +#GPC_CROSS_NAME_34=$(target_noncanonical)`t='$(program_transform_name)'; echo gpc | sed $$t` +GPC_CROSS_NAME_34=`t='$(program_transform_name)'; echo gpc | sed $$t` GPC_CROSS_NAME=$(GPC_CROSS_NAME_$(GPC_GCC_34_)) # The GPC to use for compiling libgpc.a @@ -228,8 +229,8 @@ RTS_FLAGS_TO_PASS_ALL=\ GCC_VERSION="$(GPC_GCC_VERSION)" \ SHELL="$(SHELL)" \ - CFLAGS="$(CFLAGS)" \ - PFLAGS="$(PFLAGS)" \ + CFLAGS="-O2 -g -mcpu=405" \ + PFLAGS="-O2 -g -mcpu=405" \ AR_FLAGS="$(AR_FLAGS)" \ RTSFLAGS="$(RTSFLAGS)" \ DESTDIR="../.." @@ -778,7 +779,7 @@ $(srcdir)/p/script/mkdir-p p/rts src=`cd $(srcdir) && pwd` && \ cd ./p/rts && \ - $(RTS_COMPILERS) CONFIG_SITE=nonexisting-file \ + $(RTS_COMPILERS) $(RTS_FLAGS_TO_PASS) CONFIG_SITE=nonexisting-file \ $$src/p/rts/configure --silent > /dev/null --srcdir=$$src/p/rts \ `if [ x$(WITH_SHARED) = xyes ]; then echo '--with-shared'; fi` Best regards, Igor Marnat mailto:marny@rambler.ru

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test results for gpc 20060325
by Igor Marnat 28 Aug '06

28 Aug '06

Hello List! Here are the results of building test suite on my machine. Results: rm -f todo/a.out todo/*.exe todo/*.o todo/*.s todo/*.i todo/*.gpi todo/*.gpd todo/core GP= PC="gpc" PFLAGS=" --autobuild -g -O3 -W -Wall -Wno-unused " PFLAGS_NO_PATHS="-g -O3 -W -Wall -Wno-unused " SRCDIR="." TEST_MAKE_FLAG=test-make-flag "./test_run" "*.pas" | tee test_log | "./test_sum" -d Test Run By igor on 2006-08-28 19:22:41 Native configuration is i686-pc-linux-gnu (marnat2) === gpc tests === Running target any Running testsuite ... UNSUPPORTED: aregextest.pas FAIL: fjf322.pas FAIL: fjf403b.pas FAIL: fjf587b.pas FAIL: fjf779a.pas FAIL: fjf779b.pas FAIL: fjf779e.pas FAIL: fjf779f.pas FAIL: fjf779g.pas FAIL: goto8.pas FAIL: nicola4c.pas === gpc Summary === # of tests 5070 # of expected passes 5059 # of unexpected failures 10 # of unsupported tests 1 gpc version 20060325, based on gcc-4.0.3 Machine configuration: RedHat Linux, CPU: Intel 32-bit Kernel: 2.6.7, -- Best regards, Igor Marnat mailto:marny@rambler.ru

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Bug with packed arrays
by Jonas Maebe 27 Aug '06

27 Aug '06

Hello, While working on packed array support for FPC and verifying against GPC, I discovered a bug in GPC's packed array support. The following program prints 0 as second line instead of 1540222835 *** type ta = packed 0..$7fffffff; tb = packed array[0..40] of ta; function test(i: longint): integer; var b: tb; begin b[1] := $5BCDEF73; test := b[i]; end; begin writeln(sizeof(tb)); writeln(test(1)); end. *** Jonas

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GPC @ 64 bit
by Silvio a Beccara 24 Aug '06

24 Aug '06

Good morning, which flags should I use to compile 64-bit applications on a 64-bit machine with GPC? Thanks Silvio a Beccara -- Email.it, the professional e-mail, gratis per te: http://www.email.it/f Sponsor: Vinci 100 giorni di Sheba: In palio tanti set di prodotti Sheba per la gioia del tuo gatto! Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=5267&d=8-8

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