add "Fast" option to LinkTimeOptimization API which enables LTCG:incremental for vs2010, and behaves as "On" for other toolsets

withmorten · withmorten · commit 417dcac75f9f · 2025-12-14T15:25:14.000+01:00
add missing clang toolset tests for LinkTimeOptimization
diff --git a/modules/gmakelegacy/tests/cpp/test_clang.lua b/modules/gmakelegacy/tests/cpp/test_clang.lua
@@ -78,3 +78,20 @@ ifeq ($(config),debug)
 		]]
 	end
 
+	function suite.usesCorrectCompilersAndFastLinkTimeOptimizationViaAPI()
+		linktimeoptimization "Fast"
+		make.cppConfigs(prj)
+		test.capture [[
+ifeq ($(config),debug)
+  ifeq ($(origin CC), default)
+    CC = clang
+  endif
+  ifeq ($(origin CXX), default)
+    CXX = clang++
+  endif
+  ifeq ($(origin AR), default)
+    AR = llvm-ar
+  endif
+		]]
+	end
+
diff --git a/modules/vstudio/tests/linux/test_linux_files.lua b/modules/vstudio/tests/linux/test_linux_files.lua
@@ -42,6 +42,22 @@ local vc2010 = p.vstudio.vc2010
 		]]
 	end
 
+--
+-- Test fast link time optimization being equivalent to on. 
+--
+
+	function suite.linkTimeOptimization_Fast()
+		linktimeoptimization('fast')
+		prepareConfigProperties()
+		test.capture [[
+<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x86'" Label="Configuration">
+	<ConfigurationType>Application</ConfigurationType>
+	<PlatformToolset>v142</PlatformToolset>
+	<LinkTimeOptimization>true</LinkTimeOptimization>
+</PropertyGroup>
+		]]
+	end
+
 --
 -- Test multiprocessor compilation.
 --
diff --git a/modules/vstudio/tests/vc200x/test_compiler_block.lua b/modules/vstudio/tests/vc200x/test_compiler_block.lua
@@ -632,6 +632,18 @@
 
 	end
 
+	function suite.flags_onLinkTimeOptimizationFast()
+		linktimeoptimization "Fast"
+		prepare()
+		test.capture [[
+<Tool
+	Name="VCCLCompilerTool"
+	Optimization="0"
+	WholeProgramOptimization="true"
+		]]
+
+	end
+
 
 --
 -- Check the optimization flags.
diff --git a/modules/vstudio/tests/vc2010/test_config_props.lua b/modules/vstudio/tests/vc2010/test_config_props.lua
@@ -364,6 +364,19 @@
 		]]
 	end
 
+	function suite.useOfLinkTimeOptimizationViaAPI_Fast()
+		linktimeoptimization "Fast"
+		prepare()
+		test.capture [[
+<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">
+	<ConfigurationType>Application</ConfigurationType>
+	<UseDebugLibraries>false</UseDebugLibraries>
+	<CharacterSet>Unicode</CharacterSet>
+	<PlatformToolset>v100</PlatformToolset>
+	<WholeProgramOptimization>true</WholeProgramOptimization>
+		]]
+	end
+
 
 --
 -- Check the WindowsSDKDesktopARMSupport element
diff --git a/modules/vstudio/vs200x_vcproj.lua b/modules/vstudio/vs200x_vcproj.lua
@@ -1614,7 +1614,7 @@
 
 
 	function m.wholeProgramOptimization(cfg)
-		if cfg.linktimeoptimization == "On" then
+		if cfg.linktimeoptimization == "On" or cfg.linktimeoptimization == "Fast" then
 			p.x('WholeProgramOptimization="true"')
 		elseif cfg.linktimeoptimization == "Off" then
 			p.x('WholeProgramOptimization="false"')
diff --git a/modules/vstudio/vs2010_vcxproj.lua b/modules/vstudio/vs2010_vcxproj.lua
@@ -2298,7 +2298,7 @@
 
 
 	function m.wholeProgramOptimization(cfg)
-		if cfg.linktimeoptimization == "On" then
+		if cfg.linktimeoptimization == "On" or cfg.linktimeoptimization == "Fast" then
 			m.element("WholeProgramOptimization", nil, "true")
 		elseif cfg.linktimeoptimization == "Off" then
 			m.element("WholeProgramOptimization", nil, "false")
@@ -3080,6 +3080,8 @@
 	function m.linkTimeCodeGeneration(cfg)
 		if cfg.linktimeoptimization == "On" then
 			m.element("LinkTimeCodeGeneration", nil, "UseLinkTimeCodeGeneration")
+		elseif cfg.linktimeoptimization == "Fast" then
+			m.element("LinkTimeCodeGeneration", nil, "UseFastLinkTimeCodeGeneration")
 		end
 	end
 
@@ -4016,7 +4018,7 @@
 	end
 
 	function m.linuxWholeProgramOptimization(cfg)
-		if cfg.linktimeoptimization == "On" then
+		if cfg.linktimeoptimization == "On" or cfg.linktimeoptimization == "Fast" then
 			m.element("LinkTimeOptimization", nil, "true")
 		elseif cfg.linktimeoptimization == "Off" then
 			m.element("LinkTimeOptimization", nil, "false")
@@ -4032,7 +4034,7 @@
 	end
 
 	function m.linuxLinkTimeCodeGeneration(cfg)
-		if cfg.linktimeoptimization == "On" then
+		if cfg.linktimeoptimization == "On" or cfg.linktimeoptimization == "Fast" then
 			m.element("LinkTimeOptimization", nil, "true")
 		end
 	end
diff --git a/src/_premake_init.lua b/src/_premake_init.lua
@@ -1129,6 +1129,7 @@
 		allowed = {
 			"Default",
 			"On",
+			"Fast",
 			"Off"
 		}
 	}
diff --git a/src/base/config.lua b/src/base/config.lua
@@ -155,7 +155,8 @@
 		if cfg.kind == "StaticLib"
 				or config.isOptimizedBuild(cfg)
 				or cfg.flags.NoIncrementalLink
-				or cfg.linktimeoptimization == "On" then
+				or cfg.linktimeoptimization == "On"
+				or cfg.linktimeoptimization == "Fast" then
 			return false
 		end
 		return true
diff --git a/src/tools/clang.lua b/src/tools/clang.lua
@@ -349,7 +349,7 @@
 	clang.tools = {
 		cc = "clang",
 		cxx = "clang++",
-		ar = function(cfg) return iif(cfg.linktimeoptimization == "On", "llvm-ar", "ar") end,
+		ar = function(cfg) return iif(cfg.linktimeoptimization == "On" or cfg.linktimeoptimization == "Fast", "llvm-ar", "ar") end,
 		rc = "windres"
 	}
 
diff --git a/src/tools/gcc.lua b/src/tools/gcc.lua
@@ -71,6 +71,7 @@
 		},
 		linktimeoptimization = {
 			On = "-flto",
+			Fast = "-flto",
 		},
 		strictaliasing = {
 			Off = "-fno-strict-aliasing",
diff --git a/src/tools/msc.lua b/src/tools/msc.lua
@@ -92,6 +92,7 @@
 		},
 		linktimeoptimization = {
 			On = "/GL",
+			Fast = "/GL",
 		},
 		optimize = {
 			Off = "/Od",
@@ -351,7 +352,8 @@
 			WindowedApp = "/SUBSYSTEM:WINDOWS"
 		},
 		linktimeoptimization = {
-			On = "/LTCG"
+			On = "/LTCG",
+			Fast = "/LTCG:incremental",
 		},
 		symbols = {
 			On = "/DEBUG"
diff --git a/tests/tools/test_clang.lua b/tests/tools/test_clang.lua
@@ -39,6 +39,33 @@
 		test.isequal("windres", clang.gettoolname(cfg, "rc"))
 	end
 
+	function suite.tools_onLinkTimeOptimizationViaFlag()
+		flags { "LinkTimeOptimization" }
+		prepare()
+		test.isequal("clang", clang.gettoolname(cfg, "cc"))
+		test.isequal("clang++", clang.gettoolname(cfg, "cxx"))
+		test.isequal("llvm-ar", clang.gettoolname(cfg, "ar"))
+		test.isequal("windres", clang.gettoolname(cfg, "rc"))
+	end
+
+	function suite.tools_onLinkTimeOptimizationViaAPI()
+		linktimeoptimization "On"
+		prepare()
+		test.isequal("clang", clang.gettoolname(cfg, "cc"))
+		test.isequal("clang++", clang.gettoolname(cfg, "cxx"))
+		test.isequal("llvm-ar", clang.gettoolname(cfg, "ar"))
+		test.isequal("windres", clang.gettoolname(cfg, "rc"))
+	end
+
+	function suite.tools_onFastLinkTimeOptimizationViaAPI()
+		linktimeoptimization "Fast"
+		prepare()
+		test.isequal("clang", clang.gettoolname(cfg, "cc"))
+		test.isequal("clang++", clang.gettoolname(cfg, "cxx"))
+		test.isequal("llvm-ar", clang.gettoolname(cfg, "ar"))
+		test.isequal("windres", clang.gettoolname(cfg, "rc"))
+	end
+
 	function suite.tools_forVersion()
 		toolset "clang-16"
 		prepare()
@@ -48,6 +75,36 @@
 		test.isequal("windres-16", clang.gettoolname(cfg, "rc"))
 	end
 
+	function suite.tools_forVersion_onLinkTimeOptimizationViaFlag()
+		toolset "clang-16"
+		flags { "LinkTimeOptimization" }
+		prepare()
+		test.isequal("clang-16", clang.gettoolname(cfg, "cc"))
+		test.isequal("clang++-16", clang.gettoolname(cfg, "cxx"))
+		test.isequal("llvm-ar-16", clang.gettoolname(cfg, "ar"))
+		test.isequal("windres-16", clang.gettoolname(cfg, "rc"))
+	end
+
+	function suite.tools_forVersion_onLinkTimeOptimizationViaAPI()
+		toolset "clang-16"
+		linktimeoptimization "On"
+		prepare()
+		test.isequal("clang-16", clang.gettoolname(cfg, "cc"))
+		test.isequal("clang++-16", clang.gettoolname(cfg, "cxx"))
+		test.isequal("llvm-ar-16", clang.gettoolname(cfg, "ar"))
+		test.isequal("windres-16", clang.gettoolname(cfg, "rc"))
+	end
+
+	function suite.tools_forVersion_onFastLinkTimeOptimizationViaAPI()
+		toolset "clang-16"
+		linktimeoptimization "Fast"
+		prepare()
+		test.isequal("clang-16", clang.gettoolname(cfg, "cc"))
+		test.isequal("clang++-16", clang.gettoolname(cfg, "cxx"))
+		test.isequal("llvm-ar-16", clang.gettoolname(cfg, "ar"))
+		test.isequal("windres-16", clang.gettoolname(cfg, "rc"))
+	end
+
 --
 -- Check Mac OS X deployment target flags
 --
diff --git a/tests/tools/test_gcc.lua b/tests/tools/test_gcc.lua
@@ -969,6 +969,12 @@ end
 		test.contains("-flto", gcc.getcflags(cfg))
 	end
 
+	function suite.cflags_onFastLinkTimeOptimizationViaAPI()
+		linktimeoptimization "Fast"
+		prepare()
+		test.contains("-flto", gcc.getcflags(cfg))
+	end
+
 	function suite.ldflags_onLinkTimeOptimizationViaFlag()
 		flags "LinkTimeOptimization"
 		prepare()
@@ -981,6 +987,12 @@ end
 		test.contains("-flto", gcc.getldflags(cfg))
 	end
 
+	function suite.ldflags_onFastLinkTimeOptimizationViaAPI()
+		linktimeoptimization "Fast"
+		prepare()
+		test.contains("-flto", gcc.getldflags(cfg))
+	end
+
 
 --
 -- Check link mode preference for system libraries.
diff --git a/tests/tools/test_msc.lua b/tests/tools/test_msc.lua
@@ -113,6 +113,12 @@
 		test.contains("/GL", msc.getcflags(cfg))
 	end
 
+	function suite.cflags_onFastLinkTimeOptimizationsViaAPI()
+		linktimeoptimization "Fast"
+		prepare()
+		test.contains("/GL", msc.getcflags(cfg))
+	end
+
 	function suite.ldflags_onLinkTimeOptimizationsViaFlag()
 		flags "LinkTimeOptimization"
 		prepare()
@@ -125,6 +131,12 @@
 		test.contains("/LTCG", msc.getldflags(cfg))
 	end
 
+	function suite.ldflags_onFastLinkTimeOptimizationsViaAPI()
+		linktimeoptimization "Fast"
+		prepare()
+		test.contains("/LTCG:incremental", msc.getldflags(cfg))
+	end
+
 	function suite.cflags_onStringPoolingOn()
 		stringpooling "On"
 		prepare()
diff --git a/website/docs/linktimeoptimization.md b/website/docs/linktimeoptimization.md
@@ -12,6 +12,7 @@ linktimeoptimization "value"
 |---------|--------------------------------------------------------|
 | Off     | No LTO to be performed.                                |
 | On      | LTO optimization enabled.                              |
+| Fast    | Incremental/Fast LTO optimization enabled.             |
 | Default | Default LTO optimizations for the toolset or exporter. |
 
 ### Applies To ###
@@ -20,4 +21,6 @@ Project configurations
 
 ### Availability ###
 
-Premake 5.0-beta4 and later
+Premake 5.0-beta4 and later
+
+Fast only applies to Visual Studio 2010, will behave as On for other toolsets and is available from Premake 5.0-beta8 or later.

Original file line number	Diff line number	Diff line change
`@@ -1129,6 +1129,7 @@`
`1129`	`1129`	`allowed = {`
`1130`	`1130`	`"Default",`
`1131`	`1131`	`"On",`
	`1132`	`+ "Fast",`
`1132`	`1133`	`"Off"`
`1133`	`1134`	`}`
`1134`	`1135`	`}`
Original file line number	Diff line number	Diff line change
`@@ -349,7 +349,7 @@`
`349`	`349`	`clang.tools = {`
`350`	`350`	`cc = "clang",`
`351`	`351`	`cxx = "clang++",`
`352`		`- ar = function(cfg) return iif(cfg.linktimeoptimization == "On", "llvm-ar", "ar") end,`
	`352`	`+ ar = function(cfg) return iif(cfg.linktimeoptimization == "On" or cfg.linktimeoptimization == "Fast", "llvm-ar", "ar") end,`
`353`	`353`	`rc = "windres"`
`354`	`354`	`}`
`355`	`355`