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From: RayeR <glaux AT centrum DOT cz>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: CC1.EXE/GCC.EXE crashes with SIGILL, hard.
Date: Mon, 9 Apr 2012 15:21:59 -0700 (PDT)
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

I met the problem with GCC 4.6.2 and CMOV with my project too. I
compiled DOS port of FFMPEG optimized for pentium (-march=pentium) and
my friend tested it on AMD K6-II and program crashed during
compression due to invalid opcode. Grrr I objdumped the binary and
see:
1ec15d:	0f 4e 06             	cmovle (%esi),%eax
1edf71:	0f 42 05 48 f2 c3 08 	cmovb  0x8c3f248,%eax
1f334e:	0f 40 23             	cmovo  (%ebx),%esp
1f4b35:	0f 4a 05 b4 fe 61 ef 	cmovp  0xef61feb4,%eax
1f7969:	0f 43 2a             	cmovae (%edx),%ebp
1fd563:	0f 44 28             	cmove  (%eax),%ebp
4024e3:	0f 42 0f             	cmovb  (%edi),%ecx
4024e7:	0f 44 0f             	cmove  (%edi),%ecx
4024ef:	0f 48 0f             	cmovs  (%edi),%ecx
4024f7:	0f 4c 0f             	cmovl  (%edi),%ecx
410f31:	0f 41 00             	cmovno (%eax),%eax
49af38:	0f 4f 2f             	cmovg  (%edi),%ebp
5c275d:	0f 47 3f             	cmova  (%edi),%edi
...
tens of occurences of CMOV. It seems there's no way to produce valid
code with gcc 4.6.2. I wonder it is still not fixed. There are some
small embedded PC in industry based on 386 and 486 core that doesn't
support CMOV. Shame on GCC....
In my case I will try some older gcc versions and check when CMOV
disapper...