LLVM Weekly - #218, Mar 5th 2018

Welcome to the two hundred and eighteenth 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. Subscribe to future issues at https://llvmweekly.org and pass it on to anyone else you think may be interested. Please send any tips or feedback to asb@asbradbury.org, or @llvmweekly or @asbradbury on Twitter.

News and articles from around the web

LLVM 6.0.0 final has been tagged and will be released shortly.

The program for the EuroLLVM'18 Developers' Meeting has been announced.

On the mailing lists

• Sanjay Patel triggered a long discussion on simplifying floating point operations with an undef operand. Chris Lattner posted a summary of concerns around signalling NaNs in LLVM IR. The discussion proceeded productively after that, pointing out that sNaNs raise an invalid flag, but don't have to trap.

• Andrea Di Biagio shared an RFC on llvm-mca, a static performance analysis tool capable of estimating performance for a given sequence of machine code. It's received lots of positive feedback, and the thread is well worth a read.

• In response to a question, Peter Smith has summarised the status of Arm LLD support.

• Marc-André Laperle started a discussion about cquery vs clangd.

LLVM commits

• The update_cc_test_checks.py utility has been added, which can be used to update LLVM IR in C/C++ FileCheck test files. r326591.

• COPY source forwarding in MachineCopyPropagation has been re-enabled. r326208.

• A new -disable-gisel-legality-check command line option has been added, intended to be used in early stages of porting. r326396.

• The SystemZ backend gained support for the stackmap and patchpoint intrinsics. r326611.

Clang commits

• Initial ('naive') support for cross translation unit analysis with the Clang Static Analyzer has been added. r326323.

• The flags -fforce-enable-int128 and -fno-force-enable-int128 were added to 'force' support for __int128_t and __uint128_t for a target. r326045.

• A heuristic was added so the static analyzer skips yacc/bison-generated files. r326135.

Other project commits

• Initial PPC64 instruction emulation landed in LLDB. r326224.

• Support was added for building compiler-rt for RISC-V RV32 and RV64. r326420.

• lld now accepts both --foo bar and --foo=bar command line option styles. r326506.