directory. The appropriate sub-directory should be selected (see the
:doc:`Testing Guide <TestingGuide>` for details).
-* Test cases should be written in `LLVM assembly language <LangRef.html>`_
- unless the feature or regression being tested requires another language
- (e.g. the bug being fixed or feature being implemented is in the llvm-gcc C++
- front-end, in which case it must be written in C++).
+* Test cases should be written in :doc:`LLVM assembly language <LangRef>`.
* Test cases, especially for regressions, should be reduced as much as possible,
- by `bugpoint <Bugpoint.html>`_ or manually. It is unacceptable to place an
+ by :doc:`bugpoint <Bugpoint>` or manually. It is unacceptable to place an
entire failing program into ``llvm/test`` as this creates a *time-to-test*
burden on all developers. Please keep them short.
---------------------
When a developer begins a major new project with the aim of contributing it back
-to LLVM, s/he should inform the community with an email to the `llvmdev
+to LLVM, they should inform the community with an email to the `llvmdev
<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>`_ email list, to the extent
possible. The reason for this is to:
a patch privately, encourage them to submit it to the appropriate list first.
+IR Backwards Compatibility
+--------------------------
+
+When the IR format has to be changed, keep in mind that we try to maintain some
+backwards compatibility. The rules are intended as a balance between convenience
+for llvm users and not imposing a big burden on llvm developers:
+
+* The textual format is not backwards compatible. We don't change it too often,
+ but there are no specific promises.
+
+* The bitcode format produced by a X.Y release will be readable by all following
+ X.Z releases and the (X+1).0 release.
+
+* Newer releases can ignore features from older releases, but they cannot
+ miscompile them. For example, if nsw is ever replaced with something else,
+ dropping it would be a valid way to upgrade the IR.
+
+* Debug metadata is special in that it is currently dropped during upgrades.
+
+* Non-debug metadata is defined to be safe to drop, so a valid way to upgrade
+ it is to drop it. That is not very user friendly and a bit more effort is
+ expected, but no promises are made.
+
.. _copyright-license-patents:
Copyright, License, and Patents
cannot be moved from the LLVM core to libc++ without the copyright owner's
permission.
-Note that the LLVM Project does distribute llvm-gcc and dragonegg, **which are
-GPL.** This means that anything "linked" into llvm-gcc must itself be compatible
+Note that the LLVM Project does distribute dragonegg, **which is
+GPL.** This means that anything "linked" into dragonegg must itself be compatible
with the GPL, and must be releasable under the terms of the GPL. This implies
-that **any code linked into llvm-gcc and distributed to others may be subject to
+that **any code linked into dragonegg and distributed to others may be subject to
the viral aspects of the GPL** (for example, a proprietary code generator linked
-into llvm-gcc must be made available under the GPL). This is not a problem for
+into dragonegg must be made available under the GPL). This is not a problem for
code already distributed under a more liberal license (like the UIUC license),
and GPL-containing subprojects are kept in separate SVN repositories whose
LICENSE.txt files specifically indicate that they contain GPL code.
projects / oota-llvm.git / blobdiff