# machine with no git.
#
# NOTE: when releasing the "-dev" suffix needs to be stripped off!
-set(PROJECT_VERSION "4.6.3-dev")
+set(PROJECT_VERSION "4.6.8-dev")
# The version number of the regressiontest tarball against which this
# git branch can be tested. Normally, this will be the version of the
# last patch release. Comment the next line out for branches leading
# to a major/minor release.
-set(REGRESSIONTEST_VERSION "4.6.2")
+set(REGRESSIONTEST_VERSION "4.6.7")
set(CUSTOM_VERSION_STRING ""
CACHE STRING "Custom version string (if empty, use hard-coded default)")
mark_as_advanced(CUSTOM_VERSION_STRING)
option(GMX_FAHCORE "Build a library with mdrun functionality" OFF)
mark_as_advanced(GMX_FAHCORE)
-include(gmxDetectAcceleration)
-if(NOT DEFINED GMX_CPU_ACCELERATION)
- if(CMAKE_CROSSCOMPILING)
- if("${CMAKE_SYSTEM_NAME}" MATCHES "BlueGeneQ")
- set(GMX_SUGGESTED_CPU_ACCELERATION "IBM_QPX")
- else()
- set(GMX_SUGGESTED_CPU_ACCELERATION "None")
- endif()
- else(CMAKE_CROSSCOMPILING)
- gmx_detect_acceleration(GMX_SUGGESTED_CPU_ACCELERATION)
- endif(CMAKE_CROSSCOMPILING)
-endif(NOT DEFINED GMX_CPU_ACCELERATION)
+if(NOT DEFINED GMX_CPU_ACCELERATION AND NOT CMAKE_CROSSCOMPILING)
+ include(gmxDetectAcceleration)
+ gmx_detect_acceleration(GMX_SUGGESTED_CPU_ACCELERATION)
+endif()
+# Detect the architecture the compiler is targetting, detect
+# acceleration possibilities on that hardware, suggest an acceleration
+# to use if none is specified, and populate the cache option for CPU
+# accleration.
+include(gmxDetectTargetArchitecture)
+gmx_detect_target_architecture()
+include(gmxDetectAcceleration)
+gmx_detect_acceleration(GMX_SUGGESTED_CPU_ACCELERATION)
set(GMX_CPU_ACCELERATION "@GMX_SUGGESTED_CPU_ACCELERATION@"
CACHE STRING "Accelerated CPU kernels. Pick one of: None, SSE2, SSE4.1, AVX_128_FMA, AVX_256, IBM_QPX, Sparc64_HPC_ACE")
set(GMX_USE_CLANG_FMA_BUG_WORKAROUND TRUE)
endif()
+# GMX_CPU_ACCELERATION will not be set automatically until the second
+# pass (which is not strictly guaranteed to occur), so putting this
+# check here among logically-related tests is inefficient, but the
+# potential loss is likely zero.
+if(GMX_CPU_ACCELERATION STREQUAL "AVX_256"
+ AND CMAKE_COMPILER_IS_GNUCC
+ AND (C_COMPILER_VERSION VERSION_EQUAL "4.6.1"
+ OR CXX_COMPILER_VERSION VERSION_EQUAL "4.6.1"))
+ message(FATAL_ERROR "gcc 4.6.1 has buggy support for AVX, and GROMACS mdrun will not work. If you want simulation performance, use a more recent compiler. Otherwise, use GMX_CPU_ACCELERATION=SSE4.1")
+ # See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49002
+endif()
+
if (CMAKE_C_COMPILER_ID STREQUAL "PGI")
message(WARNING "All tested PGI compiler versions (up to 12.9.0) generate binaries which produce incorrect results, or even fail to compile Gromacs. Highly recommended to use a different compiler. If you choose to use PGI, make sure to run the regressiontests.")
endif()
message(WARNING "Intel compilers before 12.0.0 are not routinely tested, so there may be problems. Version 11.1 with SSE4.1 is known to produce incorrect results. It is highly recommended to use a more up-to-date compiler. If you choose to use this version, make sure you run the regressiontests.")
endif()
-########################################################################
-# Set up binary and library suffixing
-########################################################################
-set(GMX_BINARY_SUFFIX "" CACHE STRING "Suffix for GROMACS binaries (default: _d for double, _mpi for MPI, _mpi_d for MPI and double).")
-set(GMX_LIBS_SUFFIX ""
- CACHE STRING "Suffix for GROMACS libs (default: _d for double, _mpi for MPI, _mpi_d for MPI and double).")
-if (GMX_DEFAULT_SUFFIX)
- set(GMX_BINARY_SUFFIX "")
- set(GMX_LIBS_SUFFIX "")
- if (GMX_MPI)
- set(GMX_BINARY_SUFFIX "_mpi")
- set(GMX_LIBS_SUFFIX "_mpi")
- endif(GMX_MPI)
- if (GMX_DOUBLE)
- set (GMX_BINARY_SUFFIX "${GMX_BINARY_SUFFIX}_d")
- set (GMX_LIBS_SUFFIX "${GMX_LIBS_SUFFIX}_d")
- endif(GMX_DOUBLE)
- mark_as_advanced(FORCE GMX_BINARY_SUFFIX GMX_LIBS_SUFFIX)
- if (NOT SUFFIX_QUIETLY)
- message(STATUS "Using default binary suffix: \"${GMX_BINARY_SUFFIX}\"")
- message(STATUS "Using default library suffix: \"${GMX_LIBS_SUFFIX}\"")
- endif (NOT SUFFIX_QUIETLY)
-else(GMX_DEFAULT_SUFFIX)
- mark_as_advanced(CLEAR GMX_BINARY_SUFFIX GMX_LIBS_SUFFIX)
- if (NOT SUFFIX_QUIETLY)
- message(STATUS "Using manually set binary suffix: \"${GMX_BINARY_SUFFIX}\"")
- message(STATUS "Using manually set library suffix: \"${GMX_LIBS_SUFFIX}\"")
- endif (NOT SUFFIX_QUIETLY)
-endif(GMX_DEFAULT_SUFFIX)
-set(SUFFIX_QUIETLY TRUE CACHE INTERNAL "")
-
set(PKG_CFLAGS "")
if(GMX_DOUBLE)
set(PKG_CFLAGS "${PKG_CFLAGS} -DGMX_DOUBLE")
test_big_endian(GMX_INTEGER_BIG_ENDIAN)
-if(APPLE OR CYGWIN OR ${CMAKE_SYSTEM_NAME} MATCHES "Linux|.*BSD")
+if(APPLE OR CYGWIN OR ${CMAKE_SYSTEM_NAME} MATCHES "Linux|.*BSD|GNU")
# Maybe Solaris should be here? Patch this if you know!
SET(SHARED_LIBS_DEFAULT ON)
elseif(WIN32 OR ${CMAKE_SYSTEM_NAME} MATCHES "BlueGene")
gmx_gpu_setup()
endif(GMX_GPU)
-if(APPLE)
- find_library(ACCELERATE_FRAMEWORK Accelerate)
- list(APPEND GMX_EXTRA_LIBRARIES ${ACCELERATE_FRAMEWORK})
-endif(APPLE)
-
if(CYGWIN)
set(GMX_CYGWIN 1)
endif(CYGWIN)
include(gmxSetBuildInformation)
gmx_set_build_information()
-if(BUILD_CPU_FEATURES MATCHES "rdtscp" AND NOT GMX_DISTRIBUTABLE_BUILD)
+# Turn on RDTSCP if:
+# - the build system's CPU supports it
+# - the acceleration is set to AVX as all AVX-capable CPUs support AVX (which
+# at this point means that the user set it).
+# Note: it's better to not use the later set value of GMX_CPU_ACCELERATION because
+# it reflects the system's capability of both compiling and running AVX code.
+# TODO: After merge with 5.0 one could implement a cache variable dependency
+# such that GMX_USE_RDTSCP can change if GMX_CPU_ACCELERATION is changed to AVX
+# after the first cmake pass.
+if (BUILD_CPU_FEATURES MATCHES "rdtscp" OR GMX_CPU_ACCELERATION MATCHES "AVX")
+ set(GMX_USE_RDTSCP_DEFAULT_VALUE ON)
+else()
+ set(GMX_USE_RDTSCP_DEFAULT_VALUE OFF)
+endif()
+option(GMX_USE_RDTSCP "Use RDTSCP for better CPU-based timers (available on recent x86 CPUs; might need to be off when compiling for heterogeneous environments)" ${GMX_USE_RDTSCP_DEFAULT_VALUE})
+mark_as_advanced(GMX_USE_RDTSCP)
+if(GMX_USE_RDTSCP)
# The timestep counter headers do not include config.h
add_definitions(-DHAVE_RDTSCP)
-endif(BUILD_CPU_FEATURES MATCHES "rdtscp" AND NOT GMX_DISTRIBUTABLE_BUILD)
+endif()
include(gmxTestFloatFormat)
gmx_test_float_format(GMX_FLOAT_FORMAT_IEEE754
# The user should not be able to set this orthogonally to the acceleration
set(GMX_X86_SSE2 1)
if (NOT ACCELERATION_QUIETLY)
- message(STATUS "Enabling SSE2 Gromacs acceleration, and it will help compiler optimization.")
+ message(STATUS "Enabling SSE2 Gromacs acceleration")
endif()
elseif(${GMX_CPU_ACCELERATION} STREQUAL "SSE4.1")
set(GMX_X86_SSE4_1 1)
set(GMX_X86_SSE2 1)
if (NOT ACCELERATION_QUIETLY)
- message(STATUS "Enabling SSE4.1 Gromacs acceleration, and it will help compiler optimization.")
+ message(STATUS "Enabling SSE4.1 Gromacs acceleration")
endif()
if(CMAKE_C_COMPILER_ID MATCHES "Intel" AND C_COMPILER_VERSION VERSION_EQUAL "11.1")
GMX_TEST_CFLAG(MSVC_AVX_CFLAG "/arch:AVX" ACCELERATION_C_FLAGS)
endif (NOT GNU_AVX_CFLAG AND GMX_NATIVE_WINDOWS)
if (NOT GNU_AVX_CFLAG AND NOT MSVC_AVX_CFLAG)
- message(WARNING "No C AVX flag found. Consider a newer compiler, or try SSE4.1 (lower performance).")
+ message(WARNING "No C AVX flag found. Consider a newer compiler, or try SSE4.1 (lower performance) giving the -DGMX_CPU_ACCELERATION=SSE4.1 to cmake.")
endif (NOT GNU_AVX_CFLAG AND NOT MSVC_AVX_CFLAG)
if (CMAKE_CXX_COMPILER_LOADED)
GMX_TEST_CXXFLAG(MSVC_AVX_CXXFLAG "/arch:AVX" ACCELERATION_CXX_FLAGS)
endif (NOT GNU_AVX_CXXFLAG AND GMX_NATIVE_WINDOWS)
if (NOT GNU_AVX_CXXFLAG AND NOT MSVC_AVX_CXXFLAG)
- message(WARNING "No C++ AVX flag found. Consider a newer compiler, or try SSE4.1 (lower performance).")
+ message(WARNING "No C++ AVX flag found. Consider a newer compiler, or try SSE4.1 (lower performance) giving the -DGMX_CPU_ACCELERATION=SSE4.1 to cmake.")
endif (NOT GNU_AVX_CXXFLAG AND NOT MSVC_AVX_CXXFLAG)
endif()
set(GMX_CPU_ACCELERATION_X86_AVX_128_FMA 1)
set(GMX_X86_AVX_128_FMA 1)
if (NOT ACCELERATION_QUIETLY)
- message(STATUS "Enabling 128-bit AVX Gromacs acceleration (with fused-multiply add), and it will help compiler optimization.")
+ message(STATUS "Enabling 128-bit AVX Gromacs acceleration (with fused-multiply add)")
endif()
# We don't have the full compiler version string yet (BUILD_C_COMPILER),
set(GMX_CPU_ACCELERATION_X86_AVX_256 1)
set(GMX_X86_AVX_256 1)
if (NOT ACCELERATION_QUIETLY)
- message(STATUS "Enabling 256-bit AVX Gromacs acceleration, and it will help compiler optimization.")
+ message(STATUS "Enabling 256-bit AVX Gromacs acceleration")
endif()
endif()
gmx_test_avx_gcc_maskload_bug(${ACCELERATION_C_FLAGS} GMX_X86_AVX_GCC_MASKLOAD_BUG)
elseif(${GMX_CPU_ACCELERATION} STREQUAL "IBM_QPX")
- # Used on BlueGene/Q
- if (CMAKE_C_COMPILER_ID MATCHES "XL")
- GMX_TEST_CFLAG(XLC_BLUEGENEQ_CFLAG "-qarch=qp -qtune=qp" ACCELERATION_C_FLAGS)
- try_compile(TEST_QPX ${CMAKE_BINARY_DIR}
- "${CMAKE_SOURCE_DIR}/cmake/TestQPX.c"
- COMPILE_DEFINITIONS "${ACCELERATION_C_FLAGS}")
- if(NOT TEST_QPX)
- message(FATAL_ERROR "Cannot compile the requested IBM QPX intrinsics.")
- endif()
- endif()
- if (CMAKE_CXX_COMPILER_ID MATCHES "XL" AND CMAKE_CXX_COMPILER_LOADED)
- GMX_TEST_CXXFLAG(XLC_BLUEGENEQ_CXXFLAG "-qarch=qp -qtune=qp" ACCELERATION_CXX_FLAGS)
- try_compile(TEST_QPX ${CMAKE_BINARY_DIR}
- "${CMAKE_SOURCE_DIR}/cmake/TestQPX.c"
- COMPILE_DEFINITIONS "${ACCELERATION_CXX_FLAGS}")
- if(NOT TEST_QPX)
- message(FATAL_ERROR "Cannot compile the requested IBM QPX intrinsics.")
- endif()
- endif()
+ try_compile(TEST_QPX ${CMAKE_BINARY_DIR}
+ "${CMAKE_SOURCE_DIR}/cmake/TestQPX.c")
if (TEST_QPX)
- message(WARNING "IBM QPX acceleration was selected and could be compiled, but the accelerated kernels are not yet available.")
+ message(WARNING "IBM QPX acceleration was selected. This will work, but SIMD-accelerated kernels are only available for the Verlet cut-off scheme. The plain C kernels that are used for the group cut-off scheme kernels will be slow, so please consider using the Verlet cut-off scheme.")
set(GMX_CPU_ACCELERATION_IBM_QPX 1)
else()
- message(FATAL_ERROR "Cannot compile IBM QPX intrinsics without the XL compiler. If you are compiling for BlueGene/Q, use 'cmake .. -DCMAKE_TOOLCHAIN_FILE=BlueGeneQ-static-XL-C' to set up the tool chain.")
+ message(FATAL_ERROR "Cannot compile the requested IBM QPX intrinsics. If you are compiling for BlueGene/Q with the XL compilers, use 'cmake .. -DCMAKE_TOOLCHAIN_FILE=Platform/BlueGeneQ-static-XL-C' to set up the tool chain.")
endif()
elseif(${GMX_CPU_ACCELERATION} STREQUAL "SPARC64_HPC_ACE")
set(GMX_CPU_ACCELERATION_SPARC64_HPC_ACE 1)
endif()
string(TOUPPER "${FFTW}" FFTW)
- set(PKG_FFT "${${FFTW}_PKG}")
- include_directories(${${FFTW}_INCLUDE_DIRS})
- set(FFT_LIBRARIES ${${FFTW}_LIBRARIES})
if(NOT ${FFTW}_FOUND)
- MESSAGE(FATAL_ERROR "Cannot find FFTW 3 (with correct precision - libfftw3f for single-precision GROMACS or libfftw3 for double-precision GROMACS). Either choose the right precision, choose another FFT(W) library, enable the advanced option to let GROMACS build FFTW 3 for you, or use the really slow GROMACS built-in fftpack library.")
+ MESSAGE(FATAL_ERROR "Cannot find FFTW 3 (with correct precision - libfftw3f for single-precision GROMACS or libfftw3 for double-precision GROMACS). Either choose the right precision, choose another FFT(W) library (-DGMX_FFT_LIBRARY), enable the advanced option to let GROMACS build FFTW 3 for you (-DGMX_BUILD_OWN_FFTW=ON) , or use the really slow GROMACS built-in fftpack library (-DGMX_FFT_LIBRARY=fftpack).")
endif()
+ set(PKG_FFT "${${FFTW}_PKG}")
+ include_directories(${${FFTW}_INCLUDE_DIRS})
+ set(FFT_LIBRARIES ${${FFTW}_LIBRARIES})
set(GMX_FFT_FFTW3 1)
if ((${GMX_CPU_ACCELERATION} MATCHES "SSE" OR ${GMX_CPU_ACCELERATION} MATCHES "AVX") AND NOT ${FFTW}_HAVE_SIMD)
else()
set(FFT_LINKER_FLAGS "-mkl=sequential")
endif()
+ # Some versions of icc require this in order that mkl.h can be
+ # found at compile time.
+ set(EXTRA_C_FLAGS "${EXTRA_C_FLAGS} ${FFT_LINKER_FLAGS}")
+
set(MKL_ERROR_MESSAGE "Make sure you have configured your compiler so that ${FFT_LINKER_FLAGS} will work.")
else()
# The user will have to provide the set of magic libraries in
add_definitions(-DFFT5D_FFTW_THREADS)
endif()
-set(GMX_EXTERNAL_BLAS TRUE CACHE BOOL "Use external BLAS instead of built-in")
-set(GMX_EXTERNAL_LAPACK TRUE CACHE BOOL "Use external LAPACK instead of built-in")
-# MKL has BLAS/LAPACK routines
-if(NOT HAVE_LIBMKL AND NOT ACCELERATE_FRAMEWORK)
- if(GMX_EXTERNAL_BLAS)
- if (GMX_BLAS_USER)
- list(APPEND GMX_EXTRA_LIBRARIES ${GMX_BLAS_USER})
- else(GMX_BLAS_USER)
- set(BLAS_FIND_QUIETLY ON)
- find_package(BLAS)
- if (BLAS_FOUND)
- list(APPEND GMX_EXTRA_LIBRARIES ${BLAS_LIBRARIES})
- else()
- MESSAGE(STATUS "Using internal BLAS library")
- set(GMX_EXTERNAL_BLAS FALSE CACHE BOOL "Use external BLAS instead of built-in" FORCE)
- endif()
- endif(GMX_BLAS_USER)
- endif(GMX_EXTERNAL_BLAS)
- if(GMX_EXTERNAL_LAPACK)
- if (GMX_LAPACK_USER)
- list(APPEND GMX_EXTRA_LIBRARIES ${GMX_LAPACK_USER})
- else(GMX_LAPACK_USER)
- set(LAPACK_FIND_QUIETLY ON)
- find_package(LAPACK)
- if (LAPACK_FOUND)
- list(APPEND GMX_EXTRA_LIBRARIES ${LAPACK_LIBRARIES})
- else()
- MESSAGE(STATUS "Using internal LAPACK library")
- set(GMX_EXTERNAL_LAPACK FALSE CACHE BOOL "Use external LAPACK instead of built-in" FORCE)
- endif()
- endif(GMX_LAPACK_USER)
- endif(GMX_EXTERNAL_LAPACK)
-endif()
-mark_as_advanced(GMX_EXTERNAL_LAPACK)
-mark_as_advanced(GMX_EXTERNAL_BLAS)
+include(gmxManageLinearAlgebraLibraries)
set(GMX_USE_PLUGINS OFF CACHE INTERNAL "Whether GROMACS will really try to compile support for VMD plugins")
if(HAVE_LIBM)
list(APPEND GMX_EXTRA_LIBRARIES m)
endif(HAVE_LIBM)
+if (${CMAKE_SYSTEM_NAME} MATCHES "BlueGene")
+ check_library_exists(mass_simd atan2f4 "" HAVE_MASS_SIMD)
+ if(HAVE_MASS_SIMD)
+ list(APPEND GMX_EXTRA_LIBRARIES mass_simd)
+ else()
+ message(FATAL_ERROR "Could not link to the SIMD version of the IBM MASS library. Please adjust your CMAKE_PREFIX_PATH to contain it")
+ endif()
+endif()
+
+
+option(GMX_NACL "Configure for Native Client builds" OFF)
+if (GMX_NACL)
+ list(APPEND GMX_EXTRA_LIBRARIES nosys)
+ set(GMX_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -lnosys")
+ set(GMX_NO_NICE 1)
+ set(GMX_NO_RENAME 1)
+endif()
+mark_as_advanced(GMX_NACL)
if(GMX_FAHCORE)
set(COREWRAP_INCLUDE_DIR "${CMAKE_SOURCE_DIR}/../corewrap" CACHE STRING
if (CMAKE_CXX_COMPILER_LOADED)
get_compiler_info(CXX BUILD_CXX_COMPILER BUILD_CXXFLAGS)
endif ()
+if(GMX_GPU)
+ get_cuda_compiler_info(CUDA_NVCC_COMPILER_INFO CUDA_NVCC_COMPILER_FLAGS)
+endif(GMX_GPU)
+
########################################################################
# Specify install locations and which subdirectories to process #
set(GMXLIBDIR ${DATA_INSTALL_DIR}/top)
-##################################################################
-# Shared library settings - Darwin uses INSTALL_NAME_DIR instead!
-##################################################################
-if(NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+########################################################################
+# Set up binary and library suffixing
+########################################################################
+set(GMX_BINARY_SUFFIX "" CACHE STRING "Suffix for GROMACS binaries (default: _d for double, _mpi for MPI, _mpi_d for MPI and double).")
+set(GMX_LIBS_SUFFIX ""
+ CACHE STRING "Suffix for GROMACS libs (default: _d for double, _mpi for MPI, _mpi_d for MPI and double).")
+if (GMX_DEFAULT_SUFFIX)
+ set(GMX_BINARY_SUFFIX "")
+ set(GMX_LIBS_SUFFIX "")
+ if (GMX_LIB_MPI)
+ set(GMX_BINARY_SUFFIX "_mpi")
+ set(GMX_LIBS_SUFFIX "_mpi")
+ endif()
+ if (GMX_DOUBLE)
+ set (GMX_BINARY_SUFFIX "${GMX_BINARY_SUFFIX}_d")
+ set (GMX_LIBS_SUFFIX "${GMX_LIBS_SUFFIX}_d")
+ endif(GMX_DOUBLE)
+ mark_as_advanced(FORCE GMX_BINARY_SUFFIX GMX_LIBS_SUFFIX)
+ if (NOT SUFFIX_QUIETLY)
+ message(STATUS "Using default binary suffix: \"${GMX_BINARY_SUFFIX}\"")
+ message(STATUS "Using default library suffix: \"${GMX_LIBS_SUFFIX}\"")
+ endif (NOT SUFFIX_QUIETLY)
+else(GMX_DEFAULT_SUFFIX)
+ mark_as_advanced(CLEAR GMX_BINARY_SUFFIX GMX_LIBS_SUFFIX)
+ if (NOT SUFFIX_QUIETLY)
+ message(STATUS "Using manually set binary suffix: \"${GMX_BINARY_SUFFIX}\"")
+ message(STATUS "Using manually set library suffix: \"${GMX_LIBS_SUFFIX}\"")
+ endif (NOT SUFFIX_QUIETLY)
+endif(GMX_DEFAULT_SUFFIX)
+set(SUFFIX_QUIETLY TRUE CACHE INTERNAL "")
+
+################################################################
+# Shared library settings
+################################################################
+if((NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin") OR ((CMAKE_SYSTEM_VERSION VERSION_GREATER 8.0) AND (NOT CMAKE_VERSION VERSION_LESS 2.8.12)))
set(CMAKE_SKIP_BUILD_RPATH FALSE)
set(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE)
- set(CMAKE_INSTALL_RPATH "\\\$ORIGIN/../${GMXLIB}")
+ if(NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+ set(CMAKE_INSTALL_RPATH "\\\$ORIGIN/../${GMXLIB}")
+ else()
+ set(CMAKE_INSTALL_RPATH "@executable_path/../${GMXLIB}")
+ endif()
set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
+ set(CMAKE_MACOSX_RPATH 1)
+else()
+ # We are on Darwin/OSX, and cmake cannot handle proper RPATHs
+ set(CMAKE_INSTALL_NAME_DIR "${LIB_INSTALL_DIR}")
endif()
#COPYING file: Only necessary for binary distributions.
biod.pnpi.spb.ru / alexxy / gromacs.git / blobdiff