[llvm] r192182 - Only modify lto.exports.def when contents have changed.

[Rafael Espindola]

Author: rafael
Date: Tue Oct  8 10:07:00 2013
New Revision: 192182

URL: http://llvm.org/viewvc/llvm-project?rev=192182&view=rev
Log:
Only modify lto.exports.def when contents have changed.

Patch by Greg Bedwell.

Modified:
    llvm/trunk/tools/lto/CMakeLists.txt

Modified: llvm/trunk/tools/lto/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/lto/CMakeLists.txt?rev=192182&r1=192181&r2=192182&view=diff
==============================================================================
--- llvm/trunk/tools/lto/CMakeLists.txt (original)
+++ llvm/trunk/tools/lto/CMakeLists.txt Tue Oct  8 10:07:00 2013
@@ -15,10 +15,16 @@ if( NOT CYGWIN AND LLVM_ENABLE_PIC )
     # 'EXPORTS'.  The file "lto.exports" already contains the list, so we
     # massage it into the correct format here to create "lto.exports.def".
     set(LTO_EXPORTS_DEF ${CMAKE_CURRENT_BINARY_DIR}/lto.exports.def)
+    set(LTO_EXPORTS_DEF_TEMP ${LTO_EXPORTS_DEF}.txt)
     file(READ "lto.exports" exports_list)
-    file(WRITE ${LTO_EXPORTS_DEF} "LIBRARY LTO\n")
-    file(APPEND ${LTO_EXPORTS_DEF} "EXPORTS\n")
-    file(APPEND ${LTO_EXPORTS_DEF} ${exports_list})
+    file(WRITE ${LTO_EXPORTS_DEF_TEMP} "LIBRARY LTO\n")
+    file(APPEND ${LTO_EXPORTS_DEF_TEMP} "EXPORTS\n")
+    file(APPEND ${LTO_EXPORTS_DEF_TEMP} ${exports_list})
+
+    # Copy the file only if it has changed.
+    execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
+      ${LTO_EXPORTS_DEF_TEMP} ${LTO_EXPORTS_DEF})
+
     set(SHARED_LIB_SOURCES ${SOURCES} ${LTO_EXPORTS_DEF})
   else()
     set(SHARED_LIB_SOURCES ${SOURCES})