multiple compound blocks in C

ram@aqm.com (M.V.S. Ramanath)
Thu, 9 Dec 1993 17:51:31 GMT

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multiple compound blocks in C ram@aqm.com (1993-12-09)
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Newsgroups: comp.compilers
From: ram@aqm.com (M.V.S. Ramanath)
Summary: do current C compilers like compound blocks ?
Keywords: C, optimize, question
Organization: imagen
Date: Thu, 9 Dec 1993 17:51:31 GMT

For the current batch of C compilers, I'm curious as to whether faster
code is generated if variables local to a code fragment are declared
locally within a compound block. In other words, is it better to structure
a function body thus:


f( ... )
{
        { <local definitions> <code block> }
{ <local definitions> <code block> }
...
}


Or is the live variable analysis and register allocation good enough that
it makes no difference as far as speed of the generated code is concerned
? Stack frame size is not my concern, only speed.


I'm not interested in speculation; I'd like to hear from people who have
specifically looked at currently available compiler output on RISC
processors, especially, the DEC Alpha, HP-PA-RISC, and SPARC.


Ram (ram@aqm.com)
--


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