From 0fa28bb1721027e0e8abd48f9de90e3cc7546fbf Mon Sep 17 00:00:00 2001
From: Coelacanthus <uwu@coelacanthus.name>
Date: Sun, 15 Dec 2024 10:03:50 +0800
Subject: [PATCH] chore: enable LTO by default and add w/o LTO CI for debug
 (#177)

* chore: enable LTO by default and add w/o LTO CI for debug

* Better performance, small size, in theory.
* Cover more test points.

Signed-off-by: Coelacanthus <uwu@coelacanthus.name>

* fix: github action failed

---------

Signed-off-by: Coelacanthus <uwu@coelacanthus.name>
Co-authored-by: septs <github@septs.pw>
---
 .github/workflows/build.yaml |  3 +++
 CMakeLists.txt               | 12 ++++++++++++
 scripts/build-ci.sh          |  7 +++++++
 3 files changed, 22 insertions(+)

diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 0d0b08c..511cca8 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -18,12 +18,15 @@ jobs:
         os: [ubuntu-latest]
         build:
           - {variant: make, name: Linux, artifact: linux-x64}
+          - {variant: make-without-lto, name: Linux (w/o LTO), artifact: linux-x64-without-lto}
           - {variant: debian, name: Debian, artifact: debian-x64}
           - {variant: mingw, name: Windows with MinGW, artifact: windows-x64}
           - {variant: woa-mingw, name: Windows on ARM with MinGW, artifact: windows-arm64}
         include:
           - os: macos-latest
             build: {variant: make, name: macOS, artifact: macos-universal}
+          - os: macos-latest
+            build: {variant: make-without-lto, name: macOS (w/o LTO), artifact: macos-universal-without-lto}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9853c19..17d43de 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -13,6 +13,18 @@ list(APPEND CMAKE_MODULE_PATH ${LPAC_CMAKE_MODULE_PATH})
 
 # add_compile_options(-Wall -Wextra -Wpedantic)
 
+# Enable LTO when possible.
+cmake_policy(SET CMP0069 NEW)
+include(CheckIPOSupported)
+check_ipo_supported(RESULT result OUTPUT output)
+if(result)
+    if(NOT DEFINED CMAKE_INTERPROCEDURAL_OPTIMIZATION)
+        set(CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)
+    endif()
+else()
+    message(INFO "IPO is not supported: ${output}")
+endif()
+
 if (APPLE)
     set(CMAKE_OSX_ARCHITECTURES "arm64;x86_64")
 endif()
diff --git a/scripts/build-ci.sh b/scripts/build-ci.sh
index 6391e97..f2907c6 100755
--- a/scripts/build-ci.sh
+++ b/scripts/build-ci.sh
@@ -21,6 +21,13 @@ make)
     copy-usage "$BUILD/output"
     create-bundle "$ARTIFACT/lpac-$KERNEL-$MATCHINE.zip" "$BUILD/output"
     ;;
+make-without-lto)
+    cmake -DCMAKE_INTERPROCEDURAL_OPTIMIZATION=OFF "$WORKSPACE"
+    make -j
+    copy-license "$BUILD/output"
+    copy-usage "$BUILD/output"
+    create-bundle "$ARTIFACT/lpac-$KERNEL-$MATCHINE-without-lto.zip" "$BUILD/output"
+    ;;
 debian)
     cmake "$WORKSPACE" -DCPACK_GENERATOR=DEB
     make -j package