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Re: [Bug-gnubg] Bitfields
From: |
W.Stroop |
Subject: |
Re: [Bug-gnubg] Bitfields |
Date: |
Mon, 25 Nov 2002 15:22:28 +0100 |
----- Original Message -----
From: "Jim Segrave" <address@hidden>
To: "W.Stroop" <address@hidden>
Cc: <address@hidden>; <address@hidden>
Sent: Monday, November 25, 2002 1:23 PM
Subject: Re: [Bug-gnubg] Bitfields
> On Mon 25 Nov 2002 (12:30 +0100), W.Stroop wrote:
> >
> > ----- Original Message -----
> > From: "Jim Segrave" <address@hidden>
> > To: "W.Stroop" <address@hidden>
> > [snip]
> > You get
> > > sequences like:
> > > if ( ! prc->fCubeful )
> > > ...
> > > compiling to:
> > > testb $0x1,0x78(%ebx)
> > > jne 0x80791ad <RolloutGeneral+809>
> >
> > That's a nice compiler .Unfortunenatly my mingw gcc produces this :
> > mov [ebp-10], 00401216
> > mov eax, dword ptr [ebp-0C]
> > mov dl, byte ptr [eax]
> > and dl, 01
> > test dl, dl
> > jne 00401253
> >
> Hmm - is this a gcc derivative? That's a very poor code
> generator. Leaving out the advantage of doing a testb instruction,
> there's no need to test dl after the 'and dl,01', as the z flag is
You could be right also. I have a pentium 100 (dont laugh :)).
maybe gcc generates better code for a more advanced processor .
Rob
[Bug-gnubg] Bitfields, W.Stroop, 2002/11/25
[Bug-gnubg] bitfields, W.Stroop, 2002/11/25
- Re: [Bug-gnubg] bitfields, Gary Wong, 2002/11/25
- Re: [Bug-gnubg] bitfields, Jim Segrave, 2002/11/25
- Re: [Bug-gnubg] bitfields, Jim Segrave, 2002/11/25
- Re: [Bug-gnubg] bitfields, Gary Wong, 2002/11/25
- Re: [Bug-gnubg] bitfields, Jim Segrave, 2002/11/25
- Re: [Bug-gnubg] bitfields, Joern Thyssen, 2002/11/25
- Re: [Bug-gnubg] bitfields, Jim Segrave, 2002/11/25
- Re: [Bug-gnubg] bitfields, Joseph Heled, 2002/11/25