1 ========================
2 LLVM 7.0.0 Release Notes
3 ========================
9 These are in-progress notes for the upcoming LLVM 7 release.
10 Release notes for previous releases can be found on
11 `the Download Page <http://releases.llvm.org/download.html>`_.
17 This document contains the release notes for the LLVM Compiler Infrastructure,
18 release 7.0.0. Here we describe the status of LLVM, including major improvements
19 from the previous release, improvements in various subprojects of LLVM, and
20 some of the current users of the code. All LLVM releases may be downloaded
21 from the `LLVM releases web site <http://llvm.org/releases/>`_.
23 For more information about LLVM, including information about the latest
24 release, please check out the `main LLVM web site <http://llvm.org/>`_. If you
25 have questions or comments, the `LLVM Developer's Mailing List
26 <http://lists.llvm.org/mailman/listinfo/llvm-dev>`_ is a good place to send
29 Note that if you are reading this file from a Subversion checkout or the main
30 LLVM web page, this document applies to the *next* release, not the current
31 one. To see the release notes for a specific release, please see the `releases
32 page <http://llvm.org/releases/>`_.
34 Non-comprehensive list of changes in this release
35 =================================================
37 For small 1-3 sentence descriptions, just add an entry at the end of
38 this list. If your description won't fit comfortably in one bullet
39 point (e.g. maybe you would like to give an example of the
40 functionality, or simply have a lot to talk about), see the `NOTE` below
41 for adding a new subsection.
43 * Libraries have been renamed from 7.0 to 7. This change also impacts
44 downstream libraries like lldb.
46 * The LoopInstSimplify pass (-loop-instsimplify) has been removed.
48 * Symbols starting with ``?`` are no longer mangled by LLVM when using the
49 Windows ``x`` or ``w`` IR mangling schemes.
51 * A new tool named :doc:`llvm-exegesis <CommandGuide/llvm-exegesis>` has been
52 added. :program:`llvm-exegesis` automatically measures instruction scheduling
53 properties (latency/uops) and provides a principled way to edit scheduling
56 * A new tool named :doc:`llvm-mca <CommandGuide/llvm-mca>` has been added.
57 :program:`llvm-mca` is a static performance analysis tool that uses
58 information available in LLVM to statically predict the performance of
59 machine code for a specific CPU.
61 * The optimization flag to merge constants (-fmerge-all-constants) is no longer
64 * Optimization of floating-point casts is improved. This may cause surprising
65 results for code that is relying on the undefined behavior of overflowing
66 casts. The optimization can be disabled by specifying a function attribute:
67 "fp-cast-overflow-workaround"="true". This attribute may be created by the
68 clang option :option:`-ffp-cast-overflow-workaround`.
69 Code sanitizers can be used to detect affected patterns. The option for
70 detecting this problem alone is "-fsanitize=float-cast-overflow":
75 float x = 4294967296.0f;
77 printf("junk in the ftrunc: %f\n", x);
83 clang -O1 ftrunc.c -fsanitize=float-cast-overflow ; ./a.out
84 ftrunc.c:5:15: runtime error: 4.29497e+09 is outside the range of representable values of type 'int'
85 junk in the ftrunc: 0.000000
91 If you would like to document a larger change, then you can add a
92 subsection about it right here. You can copy the following boilerplate
93 and un-indent it (the indentation causes it to be inside this comment).
98 Makes programs 10x faster by doing Special New Thing.
100 Changes to the LLVM IR
101 ----------------------
103 * The signatures for the builtins @llvm.memcpy, @llvm.memmove, and @llvm.memset
104 have changed. Alignment is no longer an argument, and are instead conveyed as
105 parameter attributes.
107 Changes to the ARM Backend
108 --------------------------
110 During this release ...
113 Changes to the MIPS Target
114 --------------------------
116 During this release ...
119 Changes to the PowerPC Target
120 -----------------------------
122 During this release ...
124 Changes to the X86 Target
125 -------------------------
127 During this release ...
129 Changes to the AMDGPU Target
130 -----------------------------
132 During this release ...
134 Changes to the AVR Target
135 -----------------------------
137 During this release ...
139 Changes to the OCaml bindings
140 -----------------------------
142 During this release ...
148 During this release ...
151 External Open Source Projects Using LLVM 7
152 ==========================================
157 Additional Information
158 ======================
160 A wide variety of additional information is available on the `LLVM web page
161 <http://llvm.org/>`_, in particular in the `documentation
162 <http://llvm.org/docs/>`_ section. The web page also contains versions of the
163 API documentation which is up-to-date with the Subversion version of the source
164 code. You can access versions of these documents specific to this release by
165 going into the ``llvm/docs/`` directory in the LLVM tree.
167 If you have any questions or comments about LLVM, please feel free to contact
168 us via the `mailing lists <http://llvm.org/docs/#maillist>`_.