From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp17.mail.ru (smtp17.mail.ru [94.100.176.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 8DD6A469710 for ; Mon, 25 May 2020 15:59:18 +0300 (MSK) Date: Mon, 25 May 2020 15:58:27 +0300 From: Sergey Bronnikov Message-ID: <20200525125827.GA20107@pony.bronevichok.ru> References: <20200312100549.31608-1-arkholga@tarantool.org> <20200414091803.GJ5713@tarantool.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Subject: Re: [Tarantool-patches] [PATCH] cmake: add LTO support for building luajit List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Olga Arkhangelskaia Cc: tarantool-patches@dev.tarantool.org Olya, I have reviewed patch in a branch and below my comments. formatting issues still exist: + if (CMAKE_COMPILER_IS_CLANG) + if (${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS 3.9) + set (luajit_cflags ${luajit_cflags} -flto=full) + else() + # ThinLTO that is both scalable and incremental + # due to parallel IPO, available since 3.9 and above. + # See http://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html + set (luajit_cflags ${luajit_cflags} -flto=thin) + endif() + # XCode linker dynamically load libLTO.dylib to perform + # link-time optimization. + # http://lists.llvm.org/pipermail/llvm-dev/2009-November/027103.html ^^^^^^^^^^^^^^^^^^^^^^^^ + if (NOT TARGET_OS_DARWIN) + # llvm-ar is just a wrapper over ar to pass --plugin= option, + # so that ar can understand LTO objects. + # See https://lists.llvm.org/pipermail/llvm-dev/2018-March/122018.html + set (CMAKE_AR llvm-ar) + endif() + else() + # GNU opts to support lto ^^^^^^^^^^^^^^^^^^^^^^ + # Due to some problems (bugs, slow work, etc) we support LTO + # only for 5.0+. The same is for binutils prior to 2.27 + # See comments in scripts/Makefile.lto in scope of + # the patch: https://patchwork.kernel.org/patch/10078207/ + if (NOT ${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS 5.0 + AND NOT ${linker_version} VERSION_LESS 2.27) + set (luajit_cflags ${luajit_cflags} -flto -fuse-linker-plugin -fno-fat-lto-objects) + endif() ^^^^^^^^^^^^^^^^^^^^^^ + # gcc-ar is just a wrapper over ar to pass --plugin option Unfortunatlely I have no minimal required version of binutils on my system and I tested patch with ld gold (cmake -DCMAKE_LINKER=/usr/bin/ld.gold ..), as Timur Safin advised. How I tested: $ mkdir build; cd build $ make build_bundled_libs VERBOSE=1 2>&1 | tee log.txt with commands above output in log.txt doesn't contain LTO related options in compilation lines for luajit. gcc 8.3.1, clang 8.0.1, CentOS 8.1.1911 Sergey On 17:33 Tue 14 Apr , Olga Arkhangelskaia wrote: > Fixed tabs: > >  +            # Depending of compiler we need to set appropriate llvm/gcc-ar > lib >  +            # llvm/gcc -ar is just a wrapper over ar to pass --plugin= > option, >  +            # so that ar can understand LTO objects. > > 14.04.2020 12:18, Igor Munkin пишет: > > Olya, > > > > Thanks for the patch! I left several comments below, please consider > > them. > > > > On 12.03.20, Olga Arkhangelskaia wrote: > > > Tarantool has LTO support, however while building luajit this opt. was > > > omitted. Patch adds necessary flag to turn it on. > > > > > > Minimum compiler/linker versions: clang 3.4, gcc 5.0+, ld 2.27+. > > > > > > Closes #3743 > > > --- > > > Branch: OKriw/gh-3743-LuaJIT-does-not-use-LTO-with-DENABLE_LTO=ON-full-ci > > > cmake/lto.cmake | 3 ++- > > > cmake/luajit.cmake | 26 ++++++++++++++++++++++++++ > > > 2 files changed, 28 insertions(+), 1 deletion(-) > > > > > > diff --git a/cmake/lto.cmake b/cmake/lto.cmake > > > index 95ade75f4..9f29f3324 100644 > > > --- a/cmake/lto.cmake > > > +++ b/cmake/lto.cmake > > > @@ -78,7 +78,8 @@ if (NOT TARGET_OS_DARWIN) > > > if (linker_version VERSION_LESS "2.31") > > > message(FATAL_ERROR "ld.bfd >= 2.31 is needed for LTO") > > > endif() > > > - elseif(matched_gold) > > > + > > > + elseif(matched_gold) > > Typo: there is a mess with whitespace above. > > > > However this chunk provides no changes except whitespace and newline. > > Please drop it. > > > > > set(linker_version ${CMAKE_MATCH_1}) > > > message(STATUS "Found ld.gold version: ${linker_version}") > > > diff --git a/cmake/luajit.cmake b/cmake/luajit.cmake > > > index 072db8269..da1b4926d 100644 > > > --- a/cmake/luajit.cmake > > > +++ b/cmake/luajit.cmake > > > @@ -225,6 +225,32 @@ macro(luajit_build) > > > set(luajit_xcflags ${luajit_xcflags} -D${def}) > > > endforeach() > > > + # Add LTO option to luajit > > > + if (CMAKE_INTERPROCEDURAL_OPTIMIZATION) > > > + message("Setting LTO flags for building luajit") > > > + # Clang opt to support LTO > > > + if (CMAKE_COMPILER_IS_CLANG AND > > > + NOT ${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS 3.4) > > So, if clang toolchain is used but version is less than 3.4, then gcc > > toolchain settings are used. It's either totally wrong or definitely > > need to be clarified with a corresponding comment. > > > > Also, AFAICS LTO support for toolchain is checked via CheckIPOSupported > > CMake module. So additional check here looks to be excess or also need > > to be clarified. > > > > > + if (${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS 3.9) > > > + set(luajit_cflags ${luajit_cflags} -flto=full) > > > + else() > > > + set(luajit_cflags ${luajit_cflags} -flto=full) > > > + endif() > > I see no difference in the branches above. > > > > > + if (NOT TARGET_OS_DARWIN) > > > + # Depending of compiler we need to set appropriate llvm/gcc-ar lib > > > + set (CMAKE_AR llvm-ar) > > What ar is used on systems different from Darwin based ones when clang > > toolchain is used? > > > > > + endif() > > > + # GNU opts to support lto > > > + else() > > > + #Due to some problems (bugs, slow work, etc) we support LTO only for 5.0+ > > > + #The same is for binutils prior 2.27 > > > + if (NOT ${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS 5.0 > > > + AND NOT ${linker_version} VERSION_LESS 2.27) > > > + set(luajit_cflags ${luajit_cflags} -flto -fuse-linker-plugin -fno-fat-lto-objects) > > > + endif() > > > + set (CMAKE_AR gcc-ar) > > Could you please clarify why ar is set explicitly here? > > > > > + endif() > > > + endif() > > Typo: there is a mess with indent above. Unfortunately I failed to find > > our CMake style guide, so please adjust your changes considering the > > code nearby. > > > > > # Pass the same toolchain that is used for building of > > > # tarantool itself, because tools from different toolchains > > > # can be incompatible. A compiler and a linker are already set > > > -- > > > 2.20.1 (Apple Git-117) > > >