Make WinCOFFObjectWriter.cpp's timestamp writing not use ENABLE_TIMESTAMPS

[oota-llvm.git] / cmake / modules / HandleLLVMOptions.cmake

diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index 4c5ffe2f7b28e78094fa3da23ba55314be8eab16..6db258ff66a156f6c611380dcdf693e14a42dd91 100644 (file)
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -363,6 +363,36 @@ if( MSVC )
 
   append("/Zc:inline" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 
+  if (NOT LLVM_ENABLE_TIMESTAMPS AND CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    # clang-cl and cl by default produce non-deterministic binaries because
+    # link.exe /incremental requires a timestamp in the .obj file.  clang-cl
+    # has the flag /Brepro to force deterministic binaries, so pass that when
+    # LLVM_ENABLE_TIMESTAMPS is turned off.
+    # This checks CMAKE_CXX_COMPILER_ID in addition to check_cxx_compiler_flag()
+    # because cl.exe does not emit an error on flags it doesn't understand,
+    # letting check_cxx_compiler_flag() claim it understands all flags.
+    check_cxx_compiler_flag("/Brepro" SUPPORTS_BREPRO)
+    append_if(SUPPORTS_BREPRO "/Brepro" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+
+    if (SUPPORTS_BREPRO)
+      # Check if /INCREMENTAL is passed to the linker and complain that it
+      # won't work with /Brepro.
+      string(TOUPPER "${CMAKE_EXE_LINKER_FLAGS}" upper_exe_flags)
+      string(TOUPPER "${CMAKE_MODULE_LINKER_FLAGS}" upper_module_flags)
+      string(TOUPPER "${CMAKE_SHARED_LINKER_FLAGS}" upper_shared_flags)
+
+      string(FIND "${upper_exe_flags}" "/INCREMENTAL" exe_index)
+      string(FIND "${upper_module_flags}" "/INCREMENTAL" module_index)
+      string(FIND "${upper_shared_flags}" "/INCREMENTAL" shared_index)
+      
+      if (${exe_index} GREATER -1 OR
+          ${module_index} GREATER -1 OR
+          ${shared_index} GREATER -1)
+        message(FATAL_ERROR "LLVM_ENABLE_TIMESTAMPS not compatible with /INCREMENTAL linking")
+      endif()
+    endif()
+  endif()
+
   # Disable sized deallocation if the flag is supported. MSVC fails to compile
   # the operator new overload in User otherwise.
   check_c_compiler_flag("/WX /Zc:sizedDealloc-" SUPPORTS_SIZED_DEALLOC)