From: Joel Rosdahl <joel@rosdahl.net>
Date: Fri, 30 Jul 2021 18:10:50 +0000 (+0200)
Subject: build: Only probe for faster linker in dev build mode and on x86_64
X-Git-Tag: v4.4~67
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9d68f0542d70477f9eaf6292367da53643af0d6d;p=thirdparty%2Fccache.git

build: Only probe for faster linker in dev build mode and on x86_64

Using Gold or LLD on less common platforms such as MIPS may not be a
good idea (see e.g.
<https://www.sourceware.org/bugzilla/show_bug.cgi?id=22838>), so be
conservative and only probe for a faster linker on platforms that likely
don’t have toolchain bugs. Also, using a faster linker is in practice
only relevant for dev builds.

Fixes #907.
---

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2c6c4511a..4cf2e5f3e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -66,9 +66,7 @@ endif()
 message(STATUS "Ccache dev mode: ${CCACHE_DEV_MODE}")
 
 include(UseCcache)
-if(NOT MSVC)
-  include(UseFastestLinker)
-endif()
+include(UseFastestLinker)
 include(StandardSettings)
 include(StandardWarnings)
 include(CIBuildType)
diff --git a/cmake/UseFastestLinker.cmake b/cmake/UseFastestLinker.cmake
index ffc26ea29..9b4fdd6ab 100644
--- a/cmake/UseFastestLinker.cmake
+++ b/cmake/UseFastestLinker.cmake
@@ -1,3 +1,23 @@
+if(NOT CCACHE_DEV_MODE)
+  # For ccache, using a faster linker is in practice only relevant to reduce the
+  # compile-link-test cycle for developers, so use the standard linker for
+  # non-developer builds.
+  return()
+endif()
+
+if(MSVC)
+  message(STATUS "Using standard linker for MSVC")
+  return()
+endif()
+
+if(NOT CMAKE_SYSTEM_PROCESSOR STREQUAL x86_64)
+  # Be conservative and only probe for a faster linker on platforms that likely
+  # don't have toolchain bugs. See for example
+  # <https://www.sourceware.org/bugzilla/show_bug.cgi?id=22838>.
+  message(STATUS "Not probing for faster linker on ${CMAKE_SYSTEM_PROCESSOR}")
+  return()
+endif()
+
 function(check_linker linker)
   string(TOUPPER ${linker} upper_linker)
   file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/CMakefiles/CMakeTmp/main.c" "int main() { return 0; }")