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From:	CBFalconer <cbfalconer AT yahoo DOT com>
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Newsgroups:	comp.os.msdos.djgpp,comp.lang.c
Subject:	gcc 2.953 output - is this a bug?
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Date:	Thu, 07 Feb 2002 02:31:00 GMT
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Please look at the following disassembly:

00000578 <_hshstrehash>:

/* 1------------------1 */

/* ReHash a string quantity */
unsigned long hshstrehash(const char * string)
{
 578:   55                      push   %ebp
 579:   89 e5                   mov    %esp,%ebp
 57b:   8b 4d 08                mov    0x8(%ebp),%ecx
   unsigned long h;

   h = 0;
 57e:   31 d2                   xor    %edx,%edx
   while (*string) {
 580:   80 39 00                cmpb   $0x0,(%ecx)
 583:   74 12                   je     597 <_hshstrehash+0x1f>
      h = h * 37UL + (unsigned char) *string++;
 585:   8d 04 d2                lea    (%edx,%edx,8),%eax <<***
 588:   8d 04 82                lea    (%edx,%eax,4),%eax <<***
 58b:   31 d2                   xor    %edx,%edx
 58d:   8a 11                   mov    (%ecx),%dl
 58f:   41                      inc    %ecx
 590:   01 c2                   add    %eax,%edx
   }
 592:   80 39 00                cmpb   $0x0,(%ecx)
 595:   75 ee                   jne    585 <_hshstrehash+0xd>
   return h;
 597:   89 d0                   mov    %edx,%eax
 599:   89 ec                   mov    %ebp,%esp
 59b:   5d                      pop    %ebp
 59c:   c3                      ret
} /* hshstrehash */

look at the lines marked "<<***".  I fail to see how this
implements h * 37UL.  This is compiled with -O2 and disassembled
by objdump -dS.

c.l.c justification - purely standard source code :-)  I AM
impressed by gcc's code generation.

-- 
Chuck F (cbfalconer AT yahoo DOT com) (cbfalconer AT XXXXworldnet DOT att DOT net)
   Available for consulting/temporary embedded and systems.
   (Remove "XXXX" from reply address. yahoo works unmodified)
   mailto:uce AT ftc DOT gov  (for spambots to harvest)

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