view dmd/artistic.txt @ 1117:4c20fcc4252b

Fun with parameter attributes: For several of the "synthetic" parameters added to D functions, we can apply noalias and nocapture. They are sret parameters, 'nest' pointers passed to nested functions, and _argptr: Nocapture: - Sret and nest are nocapture because they don't represent D-level variables, and thus the callee can't (validly) obtain a pointer to them, let alone keep it around after it returns. - _argptr is nocapture because although the callee has access to it as a pointer, that pointer is invalidated when it returns. All three are noalias because they're function-local variables - Sret and _argptr are noalias because they're freshly alloca'd memory only used for a single function call that's not allowed to keep an aliasing pointer to it around (since the parameter is nocapture). - 'Nest' is noalias because the callee only ever has access to one such pointer per parent function, and every parent function has a different one. This commit also ensures attributes set on sret, _arguments and _argptr are propagated to calls to such functions. It also adds one exception to the general rule that attributes on function types should propagate to calls: the type of a delegate's function pointer has a 'nest' parameter, but this can either be a true 'nest' (for delegates to nested functions) or a 'this' (for delegates to member functions). Since 'this' is neither noalias nor nocapture, and there's generally no way to tell which one it is, we remove these attributes at the call site if the callee is a delegate.
author Frits van Bommel <fvbommel wxs.nl>
date Sat, 14 Mar 2009 22:15:31 +0100
parents c53b6e3fe49a
children
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			 The "Artistic License"

				Preamble

The intent of this document is to state the conditions under which a
Package may be copied, such that the Copyright Holder maintains some
semblance of artistic control over the development of the package,
while giving the users of the package the right to use and distribute
the Package in a more-or-less customary fashion, plus the right to make
reasonable modifications.

Definitions:

	"Package" refers to the collection of files distributed by the
	Copyright Holder, and derivatives of that collection of files
	created through textual modification.

	"Standard Version" refers to such a Package if it has not been
	modified, or has been modified in accordance with the wishes
	of the Copyright Holder as specified below.

	"Copyright Holder" is whoever is named in the copyright or
	copyrights for the package.

	"You" is you, if you're thinking about copying or distributing
	this Package.

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	basis of media cost, duplication charges, time of people involved,
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	Copyright Holder, but only to the computing community at large
	as a market that must bear the fee.)

	"Freely Available" means that no fee is charged for the item
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	It also means that recipients of the item may redistribute it
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1. You may make and give away verbatim copies of the source form of the
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    d) make other distribution arrangements with the Copyright Holder.

5. You may charge a reasonable copying fee for any distribution of this
Package.  You may charge any fee you choose for support of this
Package.  You may not charge a fee for this Package itself.  However,
you may distribute this Package in aggregate with other (possibly
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an executable of yours (by linking); this shall be construed as a mere
form of aggregation, provided that the complete Standard Version of the
interpreter is so embedded.

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Package.

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to the end user of the commercial distribution.  Such use shall not be
construed as a distribution of this Package.

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products derived from this software without specific prior written permission.

9. THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

				The End