Xcode: Support IPO (LTO)

Modules/CheckIPOSupported.cmake

@@ -217,7 +217,7 @@ function(check_ipo_supported)
     return()
   endif()
 
-  if(CMAKE_GENERATOR MATCHES "^(Visual Studio |Xcode$)")
+  if(CMAKE_GENERATOR MATCHES "^Visual Studio ")
     _ipo_not_supported("CMake doesn't support IPO for current generator")
     return()
   endif()

Source/cmGlobalXCodeGenerator.cxx

@@ -1683,8 +1683,11 @@ void cmGlobalXCodeGenerator::CreateBuildSettings(cmGeneratorTarget* gtgt,
     return;
   }
 
-  // Check IPO related warning/error.
-  gtgt->IsIPOEnabled(configName);
+  if (gtgt->IsIPOEnabled(configName)) {
+    const char* ltoValue =
+      this->CurrentMakefile->IsOn("_CMAKE_LTO_THIN") ? "YES_THIN" : "YES";
+    buildSettings->AddAttribute("LLVM_LTO", this->CreateString(ltoValue));
+  }
 
   // Add define flags
   this->CurrentLocalGenerator->AppendFlags(

Source/cmGlobalXCodeGenerator.h

@@ -90,6 +90,8 @@ public:
 
   bool HasKnownObjectFileLocation(std::string* reason) const CM_OVERRIDE;
 
+  bool IsIPOSupported() const CM_OVERRIDE { return true; }
+
   bool UseEffectivePlatformName(cmMakefile* mf) const CM_OVERRIDE;
 
   bool ShouldStripResourcePath(cmMakefile*) const CM_OVERRIDE;

Tests/RunCMake/CMP0069/RunCMakeTest.cmake

@@ -5,7 +5,6 @@ run_cmake(CMP0069-NEW-cmake)
 run_cmake(CMP0069-NEW-compiler)
 run_cmake(CMP0069-WARN)
 
-string(COMPARE EQUAL "${RunCMake_GENERATOR}" "Xcode" is_xcode)
-if(is_xcode OR RunCMake_GENERATOR MATCHES "^Visual Studio ")
+if(RunCMake_GENERATOR MATCHES "^Visual Studio ")
   run_cmake(CMP0069-NEW-generator)
 endif()

Tests/RunCMake/CheckIPOSupported/RunCMakeTest.cmake

@@ -8,6 +8,6 @@ run_cmake(not-supported-by-compiler)
 run_cmake(save-to-result)
 run_cmake(cmp0069-is-old)
 
-if(RunCMake_GENERATOR MATCHES "^(Visual Studio |Xcode$)")
+if(RunCMake_GENERATOR MATCHES "^Visual Studio ")
   run_cmake(not-supported-by-generator)
 endif()