Vendor import of lld release_39 branch r279477:vendor/lld/lldb-release_39-r279477vendor/lld/lld-release_390-r280324vendor/lld/lld-release_39-r279689

https://llvm.org/svn/llvm-project/lld/branches/release_39@279477

1 files changed, 77 insertions, 16 deletions

diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index a257676cded5..5344fc4d2dad 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -5,9 +5,6 @@ LLD 3.9 Release Notes
 .. contents::
     :local:
 
-.. warning::
-   These are in-progress notes for the upcoming LLVM 3.9 release.
-
 Introduction
 ============
 
@@ -16,26 +13,90 @@ Here we describe the status of LLD, including major improvements
 from the previous release. All LLD releases may be downloaded
 from the `LLVM releases web site <http://llvm.org/releases/>`_.
 
-Non-comprehensive list of changes in this release
-=================================================
+What's new in ELF Support?
+==========================
+
+LLD 3.9 is a major milestone for us. It is the first release that can
+link real-world large userland programs, including LLVM/Clang/LLD
+themselves. In fact, for example, it can now be used to produce most
+userland programs distributed as part of FreeBSD.
+
+Many contributors have joined to the project to develop new features,
+port it to new architectures and fix issues since the last release.
+
+Link-Time Optimization
+----------------------
+
+Initial support for LTO has been added. It is compatible with
+`the LLVM gold plugin <http://llvm.org/docs/GoldPlugin.html>`_ in terms of
+command line flags and input file format so that LLD is usable as a
+drop-in replacement for GNU gold. LTO is implemented as a native
+feature unlike the GNU gold's plugin mechanism.
+
+Identical Code Folding
+----------------------
+
+LLD 3.9 can now merge identical code sections to produce smaller
+output files. It is expected to be used with ``-ffunction-sections``.
+
+Symbol Versioning
+-----------------
+
+LLD 3.9 is able to link against versioned symbols as well as produce
+versioned symbols. Both the original Sun's symbol versioning scheme
+and the GNU extension are supported.
+
+New Targets
+-----------
+
+LLD has expanded support for new targets, including ARM/Thumb, the x32
+ABI and MIPS N64 ABI, in addition to the existing support for x86,
+x86-64, MIPS, PowerPC and PPC64.
 
-ELF Improvements
+TLS Relocation Optimizations
+----------------------------
+
+The ELF ABI specification of the thread-local variable define a few
+peephole optimizations linkers can do by rewriting instructions at the
+link-time to reduce run-time overhead to access TLS variables. That
+feature has been implemented.
+
+New Linker Flags
 ----------------
 
-* Initial support for LTO.
+Many command line options have been added in this release, including:
+
+- Symbol resolution and output options: ``-Bsymbolic-functions``,
+  ``-export-dynamic-symbol``, ``-image-base``, ``-pie``, ``-end-lib``,
+  ``-start-lib``, ``-build-id={md5,sha1,none,0x<hexstring>}``.
+
+- Symbol versioning option: ``-dynamic-list``.
+
+- LTO options: ``-lto-O``, ``-lto-aa-pipeline``, ``-lto-jobs``,
+  ``-lto-newpm-passes``, ``-plugin``, ``-plugin-eq``, ``-plugin-opt``,
+  ``-plugin-opt-eq``, ``-disable-verify``, ``-mllvm``.
+
+- Driver optionss: ``-help``, ``-version``, ``-unresolved-symbols``.
+
+- Debug options: ``-demangle``, ``-reproduce``, ``-save-temps``,
+  ``-strip-debug``, ``-trace``, ``-trace-symbol``,
+  ``-warn-execstack``.
+
+- Exception handling option: ``-eh-frame-hdr``.
+
+- Identical Code Folding option: ``-icf``.
 
 Changes to the MIPS Target
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+--------------------------
 
 * Added support for MIPS N64 ABI.
 * Added support for TLS relocations for both O32 and N64 MIPS ABIs.
 
-COFF Improvements
------------------
-
-* Item 1.
-
-MachO Improvements
-------------------
+Building LLVM Toolchain with LLD
+--------------------------------
 
-* Item 1.
+A new CMake variable, ``LLVM_ENABLE_LLD``, has been added to use LLD
+to build the LLVM toolchain. If the varaible is true, ``-fuse-ld=lld``
+option will be added to linker flags so that ``ld.lld`` is used
+instead of default ``ld``.  Because ``-fuse-ld=lld`` is a new compiler
+driver option, you need Clang 3.8 or newer to use the feature.