add lto flags for gcc/clang

2 files changed, 43 insertions, 0 deletions

diff --git a/xmake/core/project/policy.lua b/xmake/core/project/policy.lua
index e6a20aef9..e73f67a83 100644
--- a/xmake/core/project/policy.lua
+++ b/xmake/core/project/policy.lua
@@ -49,6 +49,8 @@ function policy.policies()
             ["build.ccache"]                     = {description = "Enable C/C++ build cache.", type = "boolean"},
             -- Enable build warning output, it's disabled by default and we need `xmake -w/-vD` to look at it.
             ["build.warning"]                    = {description = "Enable build warning output.", type = "boolean"},
+            -- Enable LTO linker-time optimization for c/c++ building.
+            ["build.optimization.lto"]           = {description = "Enable LTO linker-time optimization for c/c++ building.", type = "boolean"},
             -- preprocessor configuration for ccache/distcc, we can disable linemarkers to speed up preprocess
             ["preprocessor.linemarkers"]         = {description = "Enable linemarkers for preprocessor.", default = true, type = "boolean"},
             -- preprocessor configuration for ccache/distcc, we can disable it to avoid cache object file with __DATE__, __TIME__
diff --git a/xmake/rules/c++/build_optimization/load.lua b/xmake/rules/c++/build_optimization/load.lua
index eb9fe3863..faf91add8 100644
--- a/xmake/rules/c++/build_optimization/load.lua
+++ b/xmake/rules/c++/build_optimization/load.lua
@@ -18,5 +18,46 @@
 -- @file        load.lua
 --
 
+-- imports
+import("core.tool.compiler")
+
+-- add lto optimization
+function _add_lto_optimization(target, sourcekind)
+
+    -- add cflags
+    local _, cc = target:tool(sourcekind)
+    local cflag = sourcekind == "cxx" and "cxxflags" or "cflags"
+    if cc == "cl" then
+        -- TODO
+    elseif cc == "clang" or cc == "clangxx" then
+        target:add(cflag, "-flto=thin")
+    elseif cc == "gcc" or cc == "gxx" then
+        target:add(cflag, "-flto")
+    end
+
+    -- add ldflags and shflags
+    local _, ld = target:tool("ld")
+    if ld == "cl" then
+        -- TODO
+    elseif ld == "clang" or ld == "clangxx" then
+        target:add("ldflags", "-flto=thin")
+        target:add("shflags", "-flto=thin")
+    elseif ld == "gcc" or ld == "gxx" then
+        target:add("ldflags", "-flto")
+        target:add("shflags", "-flto")
+        -- to use the link-time optimizer, -flto and optimization options should be specified at compile time and during the final link.
+        -- @see https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
+        local optimize = target:get("optimize")
+        if optimize then
+            local optimize_flags = compiler.map_flags(sourcekind == "cc" and "c" or "cxx", "optimize", optimize)
+            target:add("ldflags", optimize_flags)
+            target:add("shflags", optimize_flags)
+        end
+    end
+end
+
 function main(target, sourcekind)
+    if target:policy("build.optimization.lto") then
+        _add_lto_optimization(target, sourcekind)
+    end
 end