CMake: gc-sections + no-rtti/exceptions options

Turns out gc-sections helps significantly even with LTO (-84 KiB for the
MinSizeRel rg99 build).

Also adds options for disabling RTTI and exceptions.

CMakeLists.txt

@@ -64,6 +64,9 @@ option(DEVILUTIONX_RESAMPLER_SDL "Build with SDL resampler" ON)
 
 option(DEVILUTIONX_PALETTE_TRANSPARENCY_BLACK_16_LUT "Whether to use a lookup table for transparency blending with black. This improves performance of blending transparent black overlays, such as quest dialog background, at the cost of 128 KiB of RAM." ON)
 
+cmake_dependent_option(DEVILUTIONX_DISABLE_RTTI "Disable RTTI" ON "NONET" OFF)
+cmake_dependent_option(DEVILUTIONX_DISABLE_EXCEPTIONS "Disable exceptions" ON "NONET" OFF)
+
 if(TSAN)
   set(ASAN OFF)
 endif()
@@ -156,6 +159,8 @@ endif()
 if(NONET)
   set(DISABLE_TCP ON)
   set(DISABLE_ZERO_TIER ON)
+  set(DISABLE_RTTI ON)
+  set(DISABLE_EXCEPTIONS ON)
   set(PACKET_ENCRYPTION OFF)
 endif()
 
@@ -177,6 +182,34 @@ if(CCACHE_PROGRAM)
   set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
 endif()
 
+if(DEVILUTIONX_DISABLE_RTTI)
+  if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-rtti")
+  elseif(MSVC)
+    string(REGEX REPLACE "/GR" "/GR-" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+  endif()
+endif()
+
+if(DEVILUTIONX_DISABLE_EXCEPTIONS)
+  if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions")
+  elseif(MSVC)
+    string(REGEX REPLACE "/EHsc" "/EHs-c-" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+  endif()
+endif()
+
+# Remove unused symbols in non-debug mode.
+# This is useful even with LTO (-84 KiB with MinSizeRel).
+if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
+  # For some reason, adding to CMAKE_CXX_FLAGS results in a slightly smaller
+  # binary than using `add_compile/link_options`
+  set(_extra_flags "-ffunction-sections -fdata-sections -Wl,--gc-sections")
+
+  set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} ${_extra_flags}")
+  set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} ${_extra_flags}")
+  set(CMAKE_CXX_FLAGS_MINSIZEREL "${CMAKE_CXX_FLAGS_MINSIZEREL} ${_extra_flags}")
+endif()
+
 # Not a genexp because CMake doesn't support it
 # https://gitlab.kitware.com/cmake/cmake/-/issues/20546
 if(NOT DISABLE_LTO)

test/animationinfo_test.cpp

@@ -5,17 +5,24 @@
 
 using namespace devilution;
 
+enum class TestDataType {
+	SetNewAnimation,
+	GameTick,
+	Rendering
+};
+
 /**
  * @brief Represents a Action in the game_logic or rendering.
  */
 struct TestData {
 	virtual ~TestData() = default;
+	virtual TestDataType type() const = 0;
 };
 
 /**
  * @brief Represents a call to SetNewAnimation
  */
-struct SetNewAnimationData : TestData {
+struct SetNewAnimationData : public TestData {
 	SetNewAnimationData(int numberOfFrames, int delayLen, AnimationDistributionFlags params = AnimationDistributionFlags::None, int numSkippedFrames = 0, int distributeFramesBeforeFrame = 0)
 	{
 		_NumberOfFrames = numberOfFrames;
@@ -24,6 +31,12 @@ struct SetNewAnimationData : TestData {
 		_NumSkippedFrames = numSkippedFrames;
 		_DistributeFramesBeforeFrame = distributeFramesBeforeFrame;
 	}
+
+	TestDataType type() const override
+	{
+		return TestDataType::SetNewAnimation;
+	}
+
 	int _NumberOfFrames;
 	int _DelayLen;
 	AnimationDistributionFlags _Params;
@@ -42,6 +55,11 @@ struct GameTickData : TestData {
 		_ExpectedAnimationFrame = expectedAnimationFrame;
 		_ExpectedAnimationCnt = expectedAnimationCnt;
 	}
+
+	TestDataType type() const override
+	{
+		return TestDataType::GameTick;
+	}
 };
 
 /**
@@ -59,6 +77,11 @@ struct RenderingData : TestData {
 		this->_fProgressToNextGameTick = fProgressToNextGameTick;
 		this->_ExpectedRenderingFrame = expectedRenderingFrame;
 	}
+
+	TestDataType type() const override
+	{
+		return TestDataType::Rendering;
+	}
 };
 
 /**
@@ -73,21 +96,20 @@ void RunAnimationTest(const std::vector<TestData *> &vecTestData)
 
 	int currentGameTick = 0;
 	for (TestData *x : vecTestData) {
-		auto setNewAnimationData = dynamic_cast<SetNewAnimationData *>(x);
-		if (setNewAnimationData != nullptr) {
+		switch (x->type()) {
+		case TestDataType::SetNewAnimation: {
+			auto setNewAnimationData = static_cast<SetNewAnimationData *>(x);
 			animInfo.SetNewAnimation(std::nullopt, setNewAnimationData->_NumberOfFrames, setNewAnimationData->_DelayLen, setNewAnimationData->_Params, setNewAnimationData->_NumSkippedFrames, setNewAnimationData->_DistributeFramesBeforeFrame);
-		}
-
-		auto gameTickData = dynamic_cast<GameTickData *>(x);
-		if (gameTickData != nullptr) {
+		} break;
+		case TestDataType::GameTick: {
+			auto gameTickData = static_cast<GameTickData *>(x);
 			currentGameTick += 1;
 			animInfo.ProcessAnimation();
 			EXPECT_EQ(animInfo.CurrentFrame, gameTickData->_ExpectedAnimationFrame);
 			EXPECT_EQ(animInfo.TickCounterOfCurrentFrame, gameTickData->_ExpectedAnimationCnt);
-		}
-
-		auto renderingData = dynamic_cast<RenderingData *>(x);
-		if (renderingData != nullptr) {
+		} break;
+		case TestDataType::Rendering: {
+			auto renderingData = static_cast<RenderingData *>(x);
 			gfProgressToNextGameTick = renderingData->_fProgressToNextGameTick;
 			EXPECT_EQ(animInfo.GetFrameToUseForRendering(), renderingData->_ExpectedRenderingFrame)
 			    << std::fixed << std::setprecision(2)
@@ -95,6 +117,7 @@ void RunAnimationTest(const std::vector<TestData *> &vecTestData)
 			    << " CurrentFrame: " << animInfo.CurrentFrame
 			    << " DelayCounter: " << animInfo.TickCounterOfCurrentFrame
 			    << " GameTick: " << currentGameTick;
+		} break;
 		}
 	}
 	for (TestData *x : vecTestData) {