Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

As an extra point, removing the 'skip' check (i.e. cmp ax, $3FE0, jbe @@skip) removes 6 bytes from the code size and shaves about 2 to 3 nanoseconds off the execution time in most cases, and it could be argued that it's worth going for the 'no skip' version because using Frac on a value of x

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

I've done some speed and accuracy comparisons between our respective Frac functions.  Initially, my "SafeFrac" was marginally faster than "FracDoSkip", but I managed to optimise Thorsten's routine a little bit into the following: function FracSkip2(const X: ValReal): ValReal; assembler;

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

If I may add a possible solution, would code akin to the following fix the problems? (Pray that the mail list formatting doesn't mess it all up!) {$WARN 7121 off : Check size of memory operand "$1: memory-operand-size is $2 bits, but expected [$3 bits]"} {$ASMMODE Intel} const  

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

On 04/28/2018 07:01 AM, Thorsten Engler wrote: The effects of code alignment beyond a granularity of 16 on such short code is interesting: Code address: Frac1: 00536430 (48) Frac2: 00536480 (0) Frac3: 005364D0 (80) Frac4: 00536520 (32) Frac5: 00536570

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

> -Original Message- > From: fpc-devel On Behalf > Of Sven Barth via fpc-devel > Thorsten, do you have tests that could go with the new > Frac() implementation? Something simply that checks the results and > does a Halt() if something is wrong

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

Am 28.04.2018 um 11:28 schrieb Thorsten Engler: Basically that. For doubles that don't fit into an Int64, any fraction is beyond the significant number of digits that the double can store anyway, so 0 is the valid and correct result for Frac in that case. Since a float only stores the

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

ascal.org> On Behalf > Of Mattias Gaertner > Sent: Saturday, 28 April 2018 19:18 > To: fpc-devel@lists.freepascal.org > Subject: Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows > x86_64 > > On Sat, 28 Apr 2018 10:55:10 +0200 > Sven Barth via fpc-devel &l

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

On Sat, 28 Apr 2018 10:55:10 +0200 Sven Barth via fpc-devel wrote: >[...] > The question is whether we should really return 0 for numbers that would > cause an integer overflow as from the user's perspective of this > function integers aren't involved at all

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

Am 28.04.2018 um 10:11 schrieb Thorsten Engler: Oops, small mistake caused by last minute change (I replaced rol with shl): it needs to be shr (or ror or rol, they all perform about the same on my cpu). And in case anyone wonders, the first cmp and branch returns 0 for numbers that would

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

freepascal.org <mailto:fpc-devel@lists.freepascal.org> > Cc: Sven Barth <pascaldra...@googlemail.com <mailto:pascaldra...@googlemail.com> > Subject: *** GMX Spamverdacht *** Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64 Bart <bartjun...@gmail.com

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

On Sat, 28 Apr 2018 02:48:14 +1000 "Thorsten Engler" wrote: > For what it’s worth, Delphi simply decided to give up on doing it correctly > and silently fail if the double is too large to fit in an Int64. >[...] > WriteLn(Frac(1e15+0.5)); > > WriteLn(Frac(1e16+0.5)); >

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

Thorsten Engler schrieb am Fr., 27. Apr. 2018, 18:48: > For what it’s worth, Delphi simply decided to give up on doing it > correctly and silently fail if the double is too large to fit in an Int64. > > > > WriteLn(Frac(1e15+0.5)); > > WriteLn(Frac(1e16+0.5)); > > > >

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

For what it’s worth, Delphi simply decided to give up on doing it correctly and silently fail if the double is too large to fit in an Int64. WriteLn(Frac(1e15+0.5)); WriteLn(Frac(1e16+0.5)); When executed in 32bit code, returns: 5.00E-0001 5.00E-0001 And

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

Bart schrieb am Fr., 27. Apr. 2018, 13:42: > On Wed, Apr 25, 2018 at 11:04 AM, wrote: > > > If you compile and run this 64-bit program on Win 64 you get a crash > > And AFAICS your analysis of the cause (see bugtracker) is correct as well. > >

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

On Wed, Apr 25, 2018 at 11:04 AM, wrote: > If you compile and run this 64-bit program on Win 64 you get a crash And AFAICS your analysis of the cause (see bugtracker) is correct as well. function fpc_frac_real(d: ValReal) : ValReal;compilerproc; assembler;

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

On Wed, Apr 25, 2018 at 11:04 AM, wrote: > If you compile and run this 64-bit program on Win 64 you get a crash Confirmed on Win64 with r37885 . Bart ___ fpc-devel maillist - fpc-devel@lists.freepascal.org

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

> Note that "reporter" means that somebody's not a manager of the bug > tracker. The designation covers a lot of people who are regular > contributors to- and testers of- the core FPC code, and it's > probably unfair for somebody to accuse one of them of trolling > without considering that.

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

On 27/04/18 06:45, Thorsten Engler wrote: But the only responses are by a reporter named Thaddy de Koning,> which are for me totally useless and IMO he did miss the point.It's not the first time the person has been less than helpful... After looking through other issues he has commented on, I

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

On 25.04.2018 11:04, i...@wolfgang-ehrhardt.de wrote: But the only responses are by a reporter named Thaddy de Koning, which are for me totally useless and IMO he did miss the point. Welcome to the FPC bug tracker! ;) Ondrej ___ fpc-devel maillist

Re: [fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

> But the only responses are by a reporter named Thaddy de Koning, > which are for me totally useless and IMO he did miss the point. It's not the first time the person has been less than helpful... After looking through other issues he has commented on, I don't think he has contributed anything

[fpc-devel] Broken frac function in FPC3.1.1 / Windows x86_64

If you compile and run this 64-bit program on Win 64 you get a crash program tfrac; var x,y: double; begin x := 1e20; writeln('x=',x); y := frac(x); writeln('frac(x)=',y); end. D:\Work\DAMath>D:\FPC311\bin\i386-win32\ppcrossx64.exe tfrac.pas Free Pascal Compiler version