https://sourceware.org/bugzilla/show_bug.cgi?id=32238
--- Comment #7 from Naveen Kumar <kumar.naveen099 at gmail dot com> --- Host & Target: x86_64 I've been able to repro a ~10x slowdown between 2.29 and 2.36 using open-source LLVM. 1) Download LLVM 19.1.0 sources from https://github.com/llvm/llvm-project/releases/download/llvmorg-19.1.0/llvm-project-19.1.0.src.tar.xz 2) Unarchive and configure with: cmake -DCMAKE_BUILD_TYPE=Debug -G Ninja -DLLVM_TARGETS_TO_BUILD=X86 -DCMAKE_INSTALL_PREFIX=/path/to/install/dir -DCMAKE_C_FLAGS="-ffunction-sections -fdata-sections" -DCMAKE_CXX_FLAGS="-ffunction-sections -fdata-sections" <local_path>/llvm-project-19.1.0.src/llvm <local_path> => This is the folder path where we do unarchive of 'llvm-project-19.1.0.src.tar.xz' file. 3) Build with command: ninja install 4) copy attached main.cpp & Makefile at <local_path>/llvm-project-19.1.0.src folder 5) Modify the Makefile: => 'LLVM_CONFIG' variable to point to your installed 'llvm-config' utility. => 'LD' variable to point to 2.34 ld version. 6) run the command 'make' and record the build time => if you notice any compiler issues, Please add '-std=c++17' to 'CFLAGS' and rerun 'make' command. 7) Rerun with another ld version (anything b/w 2.36 to 2.42) to observe build time difference (delete main.o first). At 6th step, You can find the linker command in the log where you can see all the flags we are using. Note:- The main.cpp source is taken from an LLVM example, modifying to include some extra stuff, meaning extra required LLVM symbols. Build time metrics: ld 2.34.1-64: real 1m25.619s user 1m20.950s sys 0m4.287s ld 2.36.1-64: real 13m23.851s user 13m19.463s sys 0m4.268s perf metrics while running culprit linker (2.36) process:- Samples: 3M of event 'cycles', Event count (approx.): 4629795486714 Children Self Command Shared Object Symbol + 89.25% 89.17% ld ld [.] lang_output_section_statement_lookup I hope above repro testcase is sufficient for your use case. BTW, In our original build system we deal with huge set of obj files and linker/ld (> 2.36 version) takes around 65mins to complete. Where as same linker command with ld (< 2.36) will take less than 2mins. -- You are receiving this mail because: You are on the CC list for the bug.
