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Re: [PATCH] df: new option: --total (-c) to produce grand total (in the

From: Bruno Haible
Subject: Re: [PATCH] df: new option: --total (-c) to produce grand total (in the same way as du)
Date: Thu, 4 Sep 2008 00:28:11 +0200
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Jim Meyering wrote:
> Other opinions welcome.

I mostly agree with Eric here: gnulib's substitute does not guarantee
that values stored in a 'bool' are either 0 or 1, therefore the code that
creates 'bool' values must guarantee it.

> The question is how best to *maintain* the precondition in
> the face of future development.

By code inspection. We have no compiler warning for this kind of thing.

>> Some of the changes (& => &&) are unconditional improvements, imho.

I disagree. The & => && change inserts a conditional branch into the control
flow, with the potential to save a single memory access. I count ca. 2 CPU
cycles for a memory access and ca. 8 CPU cycles for a conditional jump,
therefore I would say that the change slows down the program a bit.


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