[LLVMdev] LLVM Weekly - #50, Dec 15th 2014
asb at asbradbury.org
Mon Dec 15 03:26:40 PST 2014
LLVM Weekly - #50, Dec 15th 2014
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Welcome to the fiftieth issue of LLVM Weekly, a weekly newsletter (published
every Monday) covering developments in LLVM, Clang, and related projects.
LLVM Weekly is brought to you by [Alex Bradbury](http://asbradbury.org).
Subscribe to future issues at <http://llvmweekly.org> and pass it on to anyone
else you think may be interested. Please send any tips or feedback to
<asb at asbradbury.org>, or @llvmweekly or @asbradbury on Twitter.
I'll be at [MICRO-47](http://www.microarch.org/micro47/) this week. If you're
there do say hi, especially if you want to chat about LLVM or lowRISC/RISC-V.
## News and articles from around the web
The videos and slides from the 2014 LLVM dev meeting went online last week. I
already linked to them then, but there's enough interesting stuff there I
think I can justify [linking again](http://llvm.org/devmtg/2014-10/).
LLVM/Clang 3.5.1-rc1 [has been
Volunteer testers are very welcome.
Clang UPC 3.4.1 [has been
This is a Unified Parallel C compiler that can target SMP systems or
## On the mailing lists
* Discussion has continued on [future plans for GC in
input from [Russel Hadley at
[Ben Karel](article.gmane.org/gmane.comp.compilers.llvm.devel/79581), who
seems to be the most extensive user of the existing GC infrastructure with his
* Chris Bieneman started a discussion about [supporting stripping out unused
with the aim of reducing the size of libLLVM. The proposed patches reduce
binary size by
he later points out is more significant in the context of their already
* Marshall Clow has shared a [proposal on how to manage ABI changes in
proposal involves introducing macros to enable ABI-breaking changes.
## LLVM commits
* The LLVM Kaleidoscope tutorial has been extended with an 8th chapter,
describing how to add debug information using DWARF And DIBuilder.
[r223671](http://reviews.llvm.org/rL223671). A rendered version can be found
* Extensive documentation has been added for the MergeFunctions pass.
* A monster commit to split Metadata from the Value class hierarchy has
* InstrProf has been born. This involves the `llvm.instrprof_increment`
instrinsic and the `-instrprof` pass. This moves logic from Clang's CodeGenPGO
into LLVM. [r223672](http://reviews.llvm.org/rL223672).
* With the addition of support for SELECT nodes, the MIPS backend now supports
codegen of MIPS-II targets on the LLVM test-suite. Code generation has also
been enabled for MIPS-III. [r224124](http://reviews.llvm.org/rL224124),
* Work has started on an LLVM-based dsymutil tool, with the aim to replace
Darwin's dsymutil (a DWARF linker).
* LiveInterval has gained support to track the liveness of subregisters.
* Work has started on converting moves to pushes on X86 when appropriate.
* Print and verify passes are now added after each MachineFunctionPass by
default, rather than on some arbitrarily chosen subset.
* LLVM now requires Python 2.7. Previously 2.5 was required.
## Clang commits
* The `__builtin_call_with_static_chain` GNU extension has been implemented.
* Clang's CodeGenPGO has moved to using the new LLVM `-instrprof` pass.
* Clang now accepts Intel microarchitecture names as the `-march` argument.
## Other project commits
* libcxx gained relational operators in std::experimental::optional.
* libcxx can now be built as a 32-bit library.
* The lldb unwinder has learned to use unwind information from the
compact-unwind section for x86-64 and i386 on Darwin.
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