From: "Andrew Jones" <xluminous AT hotmail DOT com>
Newsgroups: comp.os.msdos.djgpp
References: <fyoofqnexgrpubet DOT fniy770 DOT pminews AT nntp DOT generation DOT net>
Subject: Re: GCC optimization
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Date: Thu, 30 Dec 1999 16:39:28 GMT
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To: djgpp AT delorie DOT com
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> Does GCC optimize "something*1024" into "something << 10"?

Let's see.


TEST.C
~~~~
int glob;

int main(void)
  {
  return(glob * 1024);
  }


gcc -c -S test.c


GLOB.S
~~~~~
[...]
movl _glob,%eax
movl %eax,%edx
movl %edx,%ecx
sall $10,%ecx
movl %ecx,%eax
[...]

In a word: YES.

Andrew Jones.