158 wr) ==131579== LLd misses: 3,336,167 ( 2,266,653 rd + 1,069,514 wr) ==131579== D1 miss rate: 7.9% ( 9.6% + 0.7% ) ==131579== LLd miss rate: 158 wr) ==131579== LLd misses: 3,336,167 ( 2,266,653 rd + 1,069,514 wr) ==131579== D1 miss rate: 7.9% ( 9.6% + 0.7% ) ==131579== LLd miss rate: ==131579== LLd misses: 3,336,167 ( 2,266,653 rd + 1,069,514 wr) 12 ==131579== D1 miss rate: 7.9% ( 9.6% + 0.7% ) 13 ==131579== LLd miss rate:

write • The phases of translation • Declarations, definitions, and linkage • The one-definition rule (ODR) • Storage duration • ABIs and name-mangling • Linking and loading CppCon 2020 - The Structure use Build Tools Source Code Tools Dependency Packages Dependency Tools ld, ld.bfd, ld.gold, lld, link.exe, …Copyright © 2020 Bob Steagall K E W B C O M P U T I N G C++ Programming Ecosystem – Building and z have no linkageCopyright © 2020 Bob Steagall K E W B C O M P U T I N G The One-Definition Rule (ODR) • A given translation unit can contain at most one definition of any: • variable • function

with – • --no-allow-shlib-undefined (on the exe) • Operates recursively on ld, not on gold/lld. • -z defs (on the shlib) • --no-undefined (on the shlib) 19 bar foo exe lib1 lib2 lib3 lib4 Mach-O and PE/COFF have many problems but this may be a place where they got right.” Fangrui Song, LLD maintainer https://maskray.me/blog/2021-06-13-dependency-related-linker-options 21Position Independent thegreenplace.net/2011/11/03/position-independent-code-pic-in-shared-libraries/ • Fangrui Song, LLVM/LLD contributor: • https://maskray.me/blog/ • SystemV ABI spec and mailing list • https://groups.google

of the systemThe linker [ld] ● Program is typically called ld ○ other implementations: ld.gold, lld, mold ● On Linux, typically invoked by gcc itself via the collect2 tool g++ my_program.cpp -o the collect2 invocation with -v ● GNU Linker is typically the default, there’s others: ○ gold, lld, mold ○ They may have slightly different behaviorsThe linker [ld] - search procedure (cont’d)The dynamic

Clang/LLVMThe Big 3 – Compiler Toolchains Clang/LLVM clang / clang++ Creates object files (.o) lld Creates executables and shared libraries (.so) ar Creates static libraries (.a) llvm Attaches

engine/1.0: Already installed! intro/1.0: Already installed! Note: Best practices As a general rule, avoid modifying or defining values for dependencies options in consumers conanfile.py. The declared global binary compatibility assumptions. The general rule is that every different value of settings and options creates a different package_id. This rule can be relaxed or expanded following different approaches: flag with linkers that supports specifying linker scripts with the -T flag, such as ld, gold, and lld. • tools.build:sysroot defines the --sysroot flag to the compiler. • tools.build:compiler_executables

engine/1.0: Already installed! intro/1.0: Already installed! Note: Best practices As a general rule, avoid modifying or defining values for dependencies options in consumers conanfile.py. The declared ([DEP]/BUILD.bazel, conan_deps_module_extension.bzl and conan_deps_repo_rules.bzl) which define the rule and all the dependencies to create/load them as Bazel repositories. The MODULE.bazel above is ready global binary compatibility assumptions. The general rule is that every different value of settings and options creates a different package_id. This rule can be relaxed or expanded following different approaches:

engine/1.0: Already installed! intro/1.0: Already installed! Note: Best practices As a general rule, avoid modifying or defining values for dependencies options in consumers conanfile.py. The declared ([DEP]/BUILD.bazel, conan_deps_module_extension.bzl and conan_deps_repo_rules.bzl) which define the rule and all the dependencies to create/load them as Bazel repositories. The MODULE.bazel above is ready global binary compatibility assumptions. The general rule is that every different value of settings and options creates a different package_id. This rule can be relaxed or expanded following different approaches:

engine/1.0: Already installed! intro/1.0: Already installed! Note: Best practices As a general rule, avoid modifying or defining values for dependencies options in consumers conanfile.py. The declared global binary compatibility assumptions. The general rule is that every different value of settings and options creates a different package_id. This rule can be relaxed or expanded following different approaches: flag with linkers that supports specifying linker scripts with the -T flag, such as ld, gold, and lld. • tools.build:sysroot defines the --sysroot flag to the compiler. • tools.build:compiler_executables