[LoopVectorize] Remove redundant assignment.

[oota-llvm.git] / docs / ReleaseNotes.rst

diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 4b7e87be4c5a25a462be984d3f3c4e62cddf85a2..b56664d1d9d25e01ef9822520f5522fa8ee6ea81 100644 (file)
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -7,7 +7,7 @@ LLVM 3.5 Release Notes
 
 .. warning::
    These are in-progress notes for the upcoming LLVM 3.6 release.  You may
-   prefer the `LLVM 3.5 Release Notes <http://llvm.org/releases/3.5/docs
+   prefer the `LLVM 3.5 Release Notes <http://llvm.org/releases/3.5.0/docs
    /ReleaseNotes.html>`_.
 
 
@@ -41,6 +41,11 @@ Non-comprehensive list of changes in this release
    functionality, or simply have a lot to talk about), see the `NOTE` below
    for adding a new subsection.
 
+* Support for AuroraUX has been removed.
+
+* Added support for a `native object file-based bitcode wrapper format
+  <BitCodeFormat.html#native-object-file>`_.
+
 * ... next change ...
 
 .. NOTE
@@ -53,6 +58,50 @@ Non-comprehensive list of changes in this release
 
    Makes programs 10x faster by doing Special New Thing.
 
+Prefix data rework
+------------------
+
+The semantics of the ``prefix`` attribute have been changed. Users
+that want the previous ``prefix`` semantics should instead use
+``prologue``.  To motivate this change, let's examine the primary
+usecases that these attributes aim to serve,
+
+  1. Code sanitization metadata (e.g. Clang's undefined behavior
+     sanitizer)
+
+  2. Function hot-patching: Enable the user to insert ``nop`` operations
+     at the beginning of the function which can later be safely replaced
+     with a call to some instrumentation facility.
+
+  3. Language runtime metadata: Allow a compiler to insert data for
+     use by the runtime during execution. GHC is one example of a
+     compiler that needs this functionality for its
+     tables-next-to-code functionality.
+
+Previously ``prefix`` served cases (1) and (2) quite well by allowing the user
+to introduce arbitrary data at the entrypoint but before the function
+body. Case (3), however, was poorly handled by this approach as it
+required that prefix data was valid executable code.
+
+In this release the concept of prefix data has been redefined to be
+data which occurs immediately before the function entrypoint (i.e. the
+symbol address). Since prefix data now occurs before the function
+entrypoint, there is no need for the data to be valid code.
+
+The previous notion of prefix data now goes under the name "prologue
+data" to emphasize its duality with the function epilogue.
+
+The intention here is to handle cases (1) and (2) with prologue data and
+case (3) with prefix data. See the language reference for further details
+on the semantics of these attributes.
+
+This refactoring arose out of discussions_ with Reid Kleckner in
+response to a proposal to introduce the notion of symbol offsets to
+enable handling of case (3).
+
+.. _discussions: http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-May/073235.html
+
+
 Changes to the ARM Backend
 --------------------------