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Mail Archives: djgpp-workers/2003/12/21/12:46:20

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From: Kbwms AT aol DOT com
Message-ID: <39.421eff94.2d173662@aol.com>
Date: Sun, 21 Dec 2003 12:46:10 EST
Subject: Re: isnanf et al
To: djgpp-workers AT delorie DOT com
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Reply-To: djgpp-workers AT delorie DOT com

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In a message dated 12/21/2003 12:30:14 PM Eastern Standard Time, 
rich AT phekda DOT gotadsl DOT co DOT uk writes:

> They were errors about type-punning breaking strict aliasing (search the 
> gcc info docs for -fstrict-aliasing and you should find a section about 
> it). Using a union is the only valid way of doing type-punning, but it 
> seems that using it was the wrong solution. By using the union I guess 
> you're telling the compiler "I know what I'm doing", like with typecasts.
> 

As was pointed out in a previous email, the macros should have never been 
used.  The names of the macros conflict with function names in libm.  The punning 
continues because it is executed in the macros no matter what is done by 
using unions.

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<HTML><FONT FACE=3Darial,helvetica><HTML><FONT  SIZE=3D3 PTSIZE=3D12 FAMILY=
=3D"SERIF" FACE=3D"Georgia" LANG=3D"0">In a message dated 12/21/2003 12:30:1=
4 PM Eastern Standard Time, rich AT phekda DOT gotadsl DOT co DOT uk writes:<BR>
<BR>
<BLOCKQUOTE TYPE=3DCITE style=3D"BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT=
: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"></FONT><FONT  COLOR=3D"#000000"=
 BACK=3D"#ffffff" style=3D"BACKGROUND-COLOR: #ffffff" SIZE=3D2 PTSIZE=3D10 F=
AMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0">They were errors about type-pu=
nning breaking strict aliasing (search the <BR>
gcc info docs for -fstrict-aliasing and you should find a section about <BR>
it). Using a union is the only valid way of doing type-punning, but it <BR>
seems that using it was the wrong solution. By using the union I guess <BR>
you're telling the compiler "I know what I'm doing", like with typecasts.<BR=
>
</BLOCKQUOTE><BR>
</FONT><FONT  COLOR=3D"#000000" BACK=3D"#ffffff" style=3D"BACKGROUND-COLOR:=20=
#ffffff" SIZE=3D3 PTSIZE=3D12 FAMILY=3D"SERIF" FACE=3D"Georgia" LANG=3D"0"><=
BR>
As was pointed out in a previous email, the macros should have never been us=
ed.&nbsp; The names of the macros conflict with function names in libm.&nbsp=
; The punning continues because it is executed in the macros no matter what=20=
is done by using unions.<BR>
</FONT></HTML>
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