[GitHub] rahul003 closed pull request #10771: [MXNET-372] Add build flag for USE_F16C in CMake and clarify flag in make

[GitBox <gi...@apache.org>]

rahul003 closed pull request #10771: [MXNET-372] Add build flag for USE_F16C in CMake and clarify flag in make
URL: https://github.com/apache/incubator-mxnet/pull/10771
 
 
   

This is a PR merged from a forked repository.
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the sake of provenance:

As this is a foreign pull request (from a fork), the diff is supplied
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diff --git a/3rdparty/mshadow b/3rdparty/mshadow
index e051c2c91c1..5da1d9084e5 160000
--- a/3rdparty/mshadow
+++ b/3rdparty/mshadow
@@ -1 +1 @@
-Subproject commit e051c2c91c1ac4a3a8fed3e90ef2fb549220d972
+Subproject commit 5da1d9084e56bf1d7af246f632f4d59a995c76cd
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 363237f909e..e08d644348b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,6 +16,7 @@ mxnet_option(USE_OPENCV           "Build with OpenCV support" ON)
 mxnet_option(USE_OPENMP           "Build with Openmp support" ON)
 mxnet_option(USE_CUDNN            "Build with cudnn support"  ON) # one could set CUDNN_ROOT for search path
 mxnet_option(USE_SSE              "Build with x86 SSE instruction support" ON)
+mxnet_option(USE_F16C             "Build with x86 F16C instruction support" ON) # autodetects support if ON
 mxnet_option(USE_LAPACK           "Build with lapack support" ON IF NOT MSVC)
 mxnet_option(USE_MKL_IF_AVAILABLE "Use MKL if found" ON)
 mxnet_option(USE_MKLML_MKL        "Use MKLDNN variant of MKL (if MKL found)" ON IF USE_MKL_IF_AVAILABLE AND UNIX AND (NOT APPLE))
@@ -86,6 +87,10 @@ if(MSVC)
   add_definitions(-DNNVM_EXPORTS)
   add_definitions(-DDMLC_STRICT_CXX11)
   add_definitions(-DNOMINMAX)
+  set(SUPPORT_F16C FALSE)
+  if(USE_F16C)
+    message("F16C instruction set is not yet supported for MSVC")
+  endif()
   set(CMAKE_C_FLAGS "/MP")
   set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS} /bigobj")
 else(MSVC)
@@ -102,6 +107,29 @@ else(MSVC)
   else()
     set(SUPPORT_MSSE2 FALSE)
   endif()
+  # For cross complication, turn off flag if target device does not support it
+  if(USE_F16C)
+    check_cxx_compiler_flag("-mf16c"     COMPILER_SUPPORT_MF16C)
+    if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+      execute_process(COMMAND cat /proc/cpuinfo
+              COMMAND grep flags
+              COMMAND grep f16c
+              OUTPUT_VARIABLE CPU_SUPPORT_F16C)
+    elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+      execute_process(COMMAND sysctl -a
+              COMMAND grep machdep.cpu.features
+              COMMAND grep F16C
+              OUTPUT_VARIABLE CPU_SUPPORT_F16C)
+    endif()
+    if(NOT CPU_SUPPORT_F16C)
+      message("CPU does not support F16C instructions")
+    endif()
+    if(CPU_SUPPORT_F16C AND COMPILER_SUPPORT_MF16C)
+      set(SUPPORT_F16C TRUE)
+    endif()
+  else()
+    set(SUPPORT_F16C FALSE)
+  endif()
   set(CMAKE_C_FLAGS "-Wall -Wno-unknown-pragmas -fPIC -Wno-sign-compare")
   if ("${CMAKE_CXX_COMPILER_ID}" MATCHES ".*Clang$")
     set(CMAKE_C_FLAGS "-Wno-braced-scalar-init")
@@ -132,6 +160,13 @@ else(MSVC)
   endif()
 endif(MSVC)
 
+if(SUPPORT_F16C)
+  add_definitions(-DMSHADOW_USE_F16C=1)
+  set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -mf16c")
+else()
+  add_definitions(-DMSHADOW_USE_F16C=0)
+endif()
+
 if(NOT mxnet_LINKER_LIBS)
   set(mxnet_LINKER_LIBS "")
 endif(NOT mxnet_LINKER_LIBS)
diff --git a/make/config.mk b/make/config.mk
index 9eded6f5080..dd67c33cc9e 100644
--- a/make/config.mk
+++ b/make/config.mk
@@ -132,10 +132,19 @@ endif
 ARCH := $(shell uname -a)
 ifneq (,$(filter $(ARCH), armv6l armv7l powerpc64le ppc64le aarch64))
 	USE_SSE=0
+	USE_F16C=0
 else
 	USE_SSE=1
 endif
 
+#----------------------------
+# F16C instruction support for faster arithmetic of fp16 on CPU
+#----------------------------
+# For distributed training with fp16, this helps even if training on GPUs
+# If left empty, checks CPU support and turns it on.
+# For cross compilation, please check support for F16C on target device and turn off if necessary.
+USE_F16C =
+
 #----------------------------
 # distributed computing
 #----------------------------
diff --git a/make/crosscompile.jetson.mk b/make/crosscompile.jetson.mk
index 31a1398c1b7..acc9c4a5a8a 100644
--- a/make/crosscompile.jetson.mk
+++ b/make/crosscompile.jetson.mk
@@ -132,7 +132,10 @@ endif
 # Settings for power and arm arch
 #----------------------------
 USE_SSE=0
+
+# Turn off F16C instruction set support
 USE_F16C=0
+
 #----------------------------
 # distributed computing
 #----------------------------


 

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