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From: | "sl" <junk AT bbs DOT darktech DOT org> |
Newsgroups: | comp.os.msdos.djgpp |
Subject: | Re: GCC optimization |
Date: | Thu, 30 Dec 1999 20:09:46 -0500 (EST) |
Organization: | Posted via Supernews, http://www.supernews.com |
Lines: | 37 |
Message-ID: | <fyoofqnexgrpubet.fnkz8a2.pminews@nntp.generation.net> |
References: | <fyoofqnexgrpubet DOT fniy770 DOT pminews AT nntp DOT generation DOT net> <4VLa4.70142$X47 DOT 388252 AT quark DOT idirect DOT com> |
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To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
Reply-To: | djgpp AT delorie DOT com |
On Thu, 30 Dec 1999 16:39:28 GMT, Andrew Jones wrote: >> 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. Hehehe.. Thanks! Gili
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