Enable LTO when building corebundle (#26697)

configureoptimization.cmake

@@ -14,6 +14,13 @@ elseif(CLR_CMAKE_PLATFORM_UNIX)
         add_compile_options(-fno-unroll-loops)
         add_compile_options(-fno-asynchronous-unwind-tables)
         add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-fno-rtti>)
+        if (HAVE_LTO)
+            # Set properties instead of using add_compile_options to allow overriding
+            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto")
+            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -flto")
+            set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -flto")
+            set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -flto")
+        endif()
     else()
         add_compile_options($<$<CONFIG:Release>:-O3>)
     endif()

src/coreclr/hosts/unixcorebundle/CMakeLists.txt

@@ -46,11 +46,6 @@ _add_executable(corebundle
 
 set_property(TARGET corebundle APPEND_STRING PROPERTY LINK_FLAGS " -Wl,--export-dynamic") # Necessary to get symbols exported from executable
 
-if (HAVE_LTO)
-   target_compile_options(corebundle PRIVATE -flto)
-   set_property(TARGET corebundle APPEND_STRING PROPERTY LINK_FLAGS " -flto")
-endif()
-
 # The following linked options can be inserted into the linker libraries list to
 # ensure proper resolving of circular references between a subset of the libraries.
 set(START_LIBRARY_GROUP -Wl,--start-group)

src/debug/ee/dactable.cpp

@@ -40,6 +40,9 @@ extern DWORD gAppDomainTLSIndex;
 extern BOOL g_fAppX;
 #endif // FEATURE_APPX
 
+#ifdef PLATFORM_UNIX
+__attribute__((used))
+#endif // PLATFORM_UNIX
 DacGlobals g_dacTable;
 
 // DAC global pointer table initialization

src/pal/src/CMakeLists.txt

@@ -284,6 +284,9 @@ if(NOT CLR_CMAKE_USE_SYSTEM_LIBUNWIND)
   set(LIBUNWIND_OBJECTS $<TARGET_OBJECTS:libunwind>)
 endif(NOT CLR_CMAKE_USE_SYSTEM_LIBUNWIND)
 
+# Disable LTO in this project, as it results in a size increase
+string(REPLACE "-flto" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+
 add_library(coreclrpal
   STATIC
   ${SOURCES}

src/pal/tools/gen-buildsys-clang.sh

@@ -11,7 +11,7 @@ then
   echo "Specify the clang version to use, split into major and minor version"
   echo "Specify the target architecture."
   echo "Specify the script directory."
-  echo "Optionally specify the build configuration (flavor.) Defaults to DEBUG." 
+  echo "Optionally specify the build configuration (flavor.) Defaults to DEBUG."
   echo "Optionally specify 'coverage' to enable code coverage build."
   echo "Optionally specify 'scan-build' to enable build with clang static analyzer."
   echo "Target ninja instead of make. ninja must be on the PATH."
@@ -108,6 +108,8 @@ llvm_link="$(locate_llvm_exec link)"
 [[ $? -eq 0 ]] || { echo "Unable to locate llvm-link"; exit 1; }
 llvm_nm="$(locate_llvm_exec nm)"
 [[ $? -eq 0 ]] || { echo "Unable to locate llvm-nm"; exit 1; }
+llvm_ranlib="$(locate_llvm_exec ranlib)"
+[[ $? -eq 0 ]] || { echo "Unable to locate llvm-ranlib"; exit 1; }
 if [ $OS = "Linux" -o $OS = "FreeBSD" -o $OS = "OpenBSD" -o $OS = "NetBSD" -o $OS = "SunOS" ]; then
   llvm_objdump="$(locate_llvm_exec objdump)"
   [[ $? -eq 0 ]] || { echo "Unable to locate llvm-objdump"; exit 1; }
@@ -164,6 +166,7 @@ $cmake_command \
   "-DCMAKE_AR=$llvm_ar" \
   "-DCMAKE_LINKER=$llvm_link" \
   "-DCMAKE_NM=$llvm_nm" \
+  "-DCMAKE_RANLIB=$llvm_ranlib" \
   "-DCMAKE_OBJDUMP=$llvm_objdump" \
   "-DCMAKE_BUILD_TYPE=$buildtype" \
   "-DCLR_CMAKE_ENABLE_CODE_COVERAGE=$code_coverage" \