Optimizing empty functions in C

"Andrzej Wasowski" <wasowski@data.pl>
13 Jun 2002 21:01:12 -0400

          From comp.compilers

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[10 later articles]
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From: "Andrzej Wasowski" <wasowski@data.pl>
Newsgroups: comp.compilers
Date: 13 Jun 2002 21:01:12 -0400
Organization: UNI-C
Keywords: C, optimize, question
Posted-Date: 13 Jun 2002 21:01:12 EDT

hello all C-compiler gurus,


I just wondered what is the tradition of C-compilers about redundeant
code. Will two identical functions generate the same code twice? A
special case of this problem is most interesting for me: if I put many
empty functions of the same time (let's say void f(void)) in my code -
will I get many empty functions generated, just one of them, or
perhaps none (because the compiler can eliminate the call alread)?


what if the function is potentially called via function pointer? (I
belive it is non-trivial to eliminate the call then).


Last but not the list: what would be normally faster to execute:


a call to an empty function or a check of integer flag (check if there
is any function to call), sthg like"


if non_empty_f then f(); /* if f is empty */


andrzej




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