Gpc August 2005

gpc@gnu.de

17 participants
30 discussions

Code generation error?
by Peter N Lewis 16 Aug '05

16 Aug '05

The code which generates a dynamic array on the stack in the middle of a procedure (which I never would have suspected you could do in Pascal) appears to corrupt the stack in a way which makes ReturnAddress(0) either return bogus numbers or crash with a bus error. Or more accurately, assigning to sections of the created array corrupts the stack. I don't know if this is a PowerPC only issue, or applies to other platforms as well. This code: program peter103; uses GPC; procedure Test( ParameterCount: Integer ); var i: Integer; begin WriteLn( StdErr, 'T1 ', ParameterCount, ' ', ReturnAddr2Hex(ReturnAddress (0)) ); var CProcessParameters: array [0 .. ParameterCount + 1] of CString; WriteLn( StdErr, 'T2 ', ParameterCount, ' ', Low(CProcessParameters), ' ', High(CProcessParameters), ' ', ReturnAddr2Hex(ReturnAddress (0)) ); CProcessParameters[0] := nil; for i := 1 to ParameterCount do CProcessParameters[i] := nil; WriteLn( StdErr, 'T3 ', ParameterCount, ' ', Low(CProcessParameters), ' ', High(CProcessParameters), ' ', ReturnAddr2Hex(ReturnAddress (0)) ); end; var i: Integer; begin for i := 0 to 10 do Test( i ); end. will either crash in the last ReturnAddress with a bus error, fail with a range check if ReturnAddress decides to return nil (because ReturnAddr2Hex range checks if passed 0 as a parameter) or return a different bogus number (different to the two previous addresses). I discovered this as it affects Pipe in pipes.pas which is used by gp. The code for the creation of CProcessParameters is: lwz r2,12520(r30) addi r2,r2,1 stw r2,12448(r30) lwz r0,12448(r30) cmpwi cr7,r0,0 bge cr7,L5 bl L__p_SubrangeError$stub L5: lwz r0,12448(r30) slwi r2,r0,2 addi r2,r2,4 stw r1,12452(r30) addi r2,r2,15 addi r0,r2,15 srwi r0,r0,4 slwi r0,r0,4 lwz r2,0(r1) neg r0,r0 stwux r2,r1,r0 addi r2,r1,56 addi r0,r2,15 srwi r0,r0,4 slwi r2,r0,4 stw r2,12456(r30) I'm afraid this taxes my PPC decoding and ABI abilities past the limits, so I can't actually tell where the problem in the code is. Moving the definition of CProcessParameters into the variable section does not change the behaviour. Could someone try duplicating this Linux or Windows perhaps to see if it is PPC only, or can anyone read enough PPC to figure out if the code is correct or not? I'll keep trying to pin down exactly what is wrong... Thanks, Peter. -- <http://www.stairways.com/> <http://download.stairways.com/>

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Re: can't get dbx to find lines
by Tom Schneider 15 Aug '05

15 Aug '05

Adriaan: > Did you try the addr2line utility (mentioned in a previous email) ? Or > run the program under control of gdb and then use the 'bt' command to > list a backtrace when it crashes. Thanks! That did the trick! Tom Dr. Thomas D. Schneider National Institutes of Health National Cancer Institute Center for Cancer Research Nanobiology Program Molecular Information Theory Group Frederick, Maryland 21702-1201 toms(a)ncifcrf.gov permanent email: toms(a)alum.mit.edu (use only if first address fails) http://www.ccrnp.ncifcrf.gov/~toms/

1 0

Error message bug
by Prof. Harley Flanders 15 Aug '05

15 Aug '05

Code lines 246 Writeln(OutFile, Copy(TempStr, 1, K - 1); 247 Writeln(OutFile, S1); Error message: pubtotex\pubtotex.pas:247: missing comma pubtotex\pubtotex.pas: In procedure `Pass1': The actual error is a missing ) on line 246 -- =========================================== Prof. Harley Flanders 3533 Windemere Court Ann Arbor, MI 48105-2867 Home: 734 668 1546 harley(a)umich.edu ===========================================

1 0

delay in daily digest postings?
by Tom Schneider 15 Aug '05

15 Aug '05

Hi - I put a message to GPC a while ago and some kind people responded, as I could find them in the archive. But my message and the response has not appeared on the daily digests. It seems that the daily digests are still for July! Regards, Tom Dr. Thomas D. Schneider National Institutes of Health National Cancer Institute Center for Cancer Research Nanobiology Program Molecular Information Theory Group Frederick, Maryland 21702-1201 toms(a)ncifcrf.gov permanent email: toms(a)alum.mit.edu (use only if first address fails) http://www.ccrnp.ncifcrf.gov/~toms/

2 1

Dynamic arrays
by Prof. Harley Flanders 15 Aug '05

15 Aug '05

{ This program compiles and runs with Free Pascal. See GPC compile error below. Apparently GPC doesn't line "array of string" although it doesn't choke on the declaration } program Test; var A: array of string; begin SetLength(A, 10); // Compilation fails on previous line: // pubtotex\test.pas:6: undeclared identifier `A' (first use in this routine) A[3] := 'Hello World'; Writeln(A[3]); Readln; end. -- =========================================== Prof. Harley Flanders 3533 Windemere Court Ann Arbor, MI 48105-2867 Home: 734 668 1546 harley(a)umich.edu ===========================================

3 2

list downtime due to server upgrade
by Anja Gerwinski 12 Aug '05

12 Aug '05

Hello all, we are going to upgrade our server to faster hardware today. This means that the gpc mailing list and the GNU Pascal server (gnu-pascal.de) will be down for about an hour this afternoon. Best wishes, Anja

1 0

GPC integration Kit for Apple's Xcode IDE
by Adriaan van Os 12 Aug '05

12 Aug '05

Available for download from <http://www.microbizz.nl/gpc.html> is the GNU Pascal Xcode integration Kit for Apple's Xcode IDE. Screendumps can be found at <http://www.microbizz.nl/gpcxcode.html>. The Xcode Kit includes demo programs, Pascal source file icons, a compiler update and project templates for Mac OS X for: * applications * application packages * application packages with nib files * command line tools * portable command line tools * dynamic libraries * frameworks * bundle files * loadable bundle packages * relocatable object files * static archive libraries Release notes are included in the package. Regards, Adriaan van Os P.S. A remaining (known (but annoying)) problem while debugging is the wrong-line (one-line-offset) problem.

2 1

Integration Kit for Apple's Xcode IDE
by Adriaan van Os 12 Aug '05

12 Aug '05

(reposting) Available for download from <http://www.microbizz.nl/gpc.html> is the GNU Pascal Xcode integration Kit for Apple's Xcode IDE. Screendumps can be found at <http://www.microbizz.nl/gpcxcode.html>. The Xcode Kit includes demo programs, Pascal source file icons, a compiler update and project templates for Mac OS X for: * applications * application packages * application packages with nib files * command line tools * portable command line tools * dynamic libraries * frameworks * bundle files * loadable bundle packages * relocatable object files * static archive libraries Release notes are included in the package. Regards, Adriaan van Os P.S. A remaining (known (but annoying)) problem while debugging is the wrong-line (one-line-offset) problem.

1 0

FillChar Suggestion
by Pascal Viandier 11 Aug '05

11 Aug '05

Hello, Do you think it is possible to modify the prcedure "FillChar()" to make it work correctly with the type String(xx)? For example the code: VAR S10 : String(10); .... FillChar(S10, 10, 'A'); WriteLn(S10); Would display: AAAAAAAAAA I ask this because I am working on (converting to GPC) a lot of existing code, with FillChar() spread everywhere (more than 1200 SUN Pascal sources), and it works as expected on strings on SUN Pascal. However, since there is no 'Capacity' field in SUN Pascal strings, it cannot be overridden. I understand this can be a big job since calling FillChar() on a record containing Strings should work as well. I think this would be a nice feature anyway, don't you? Also, if this cannot be done or desirable from your point of view, is there a way to override the build-in FillChar() for one of mine that would be called for the type String(xx) only? I know this is not an elegant workaround, but this problem causes a lot of nasty bugs in the converted programs. If I was to write the code from scratch this would not be an issue, but rewriting more than 600 000 lines of Pascal code is an even bigger challenge :-( Regards Pascal Viandier pascal(a)accovia.com

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TR : Comparing Records
by Pascal Viandier 11 Aug '05

11 Aug '05

Hi, <snip> > Out of curiosity, what kind of application is this where you have to > compare more than 600 different record types for equality? It is a complete integrated solution for the travel industry. The oldest code parts are from 1985, and it is still in development for new functionalities. > In my > whole code base, I probably have just a handful of such cases (which > I do field by field then). In fact, I don't have to compare all the record types (I hope so!). I just encountered the first case yesterday during the conversion process, and I realized I missed this one in my gap analysis between SUN and GNU Pascal. <snip> > How carefully have you tested it? Did you try global, local and > heap-allocated variables? Did you intentionally garbage-fill the > memory used before allocating the records (not applicable to global > ones, but to local and dynamic ones, with some tricks)? No, I did not check extensively. Since the SUN Pascal Manual says the records can be compared, I just dumped some to see how they were laid out. Perhaps SUN does field by field comparison, I don't know. Anyway, I will create = and <> operators only for the records implied in comparisons. Regards Pascal Viandier pascal(a)accovia.com

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Gpc August 2005