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Re: Null pointer check elimination
- From: Per Bothner <per at bothner dot com>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: Gabriel Dos Reis <gdr at integrable-solutions dot net>, Anthony Green <green at redhat dot com>, java at gcc dot gnu dot org, GCC Mailing List <gcc at gcc dot gnu dot org>
- Date: Sat, 12 Nov 2005 10:47:33 -0800
- Subject: Re: Null pointer check elimination
- References: <200511121838.jACIcBge006902@earth.phy.uc.edu>
Per Bothner wrote:
A "function-never-returns-null" attribute doesn't seem like
the right mechanism. Instead, there should be a "never-null"
attribute on pointer types. A "function-never-returns-null" is
just a function whose return-type has the "never-null" attribute.
Gabriel Does Reis wrote:
We already have such mechanism: a reference type -- which morally is
implemented as a pointer type.
Andrew Pinski wrote:
That was mentioned a way ago as being wrong. A reference type can be NULL.
There are other differences, at least in C++: If you assign to a
pointer, you change the pointer, while if you assign to a reference
you modify the referenced object. I.e. if a variable has reference
type, then the reference itself is constant.
--
--Per Bothner
per@bothner.com http://per.bothner.com/