[BUILD] Re-enable ccache by default

CMakeLists.txt

@@ -72,6 +72,7 @@ tvm_option(USE_PAPI "Use Performance Application Programming Interface (PAPI) to
 tvm_option(USE_GTEST "Use GoogleTest for C++ sanity tests" AUTO)
 tvm_option(USE_CUSTOM_LOGGING "Use user-defined custom logging, tvm::runtime::detail::LogFatalImpl and tvm::runtime::detail::LogMessageImpl must be implemented" OFF)
 tvm_option(USE_ALTERNATIVE_LINKER "Use 'mold' or 'lld' if found when invoking compiler to link artifact" AUTO)
+tvm_option(USE_CCACHE "Use ccache if found when invoking compiler" AUTO)
 
 # 3rdparty libraries
 tvm_option(DLPACK_PATH "Path to DLPACK" "3rdparty/dlpack/include")
@@ -460,6 +461,11 @@ if(USE_PIPELINE_EXECUTOR)
   list(APPEND RUNTIME_SRCS ${RUNTIME_PIPELINE_SRCS})
 endif(USE_PIPELINE_EXECUTOR)
 
+# Caches the build.
+# Note that ccache-3.x doesn't support nvcc well, so CUDA kernels may never hit the cache and still
+# need to be re-compiled every time. Using ccache 4.0+ can resolve this issue.
+include(cmake/utils/CCache.cmake)
+
 # Module rules
 include(cmake/modules/VTA.cmake)
 include(cmake/modules/StandaloneCrt.cmake)

cmake/config.cmake

@@ -352,6 +352,17 @@ set(USE_LIBBACKTRACE AUTO)
 # runtime functions to be unavailable to the program.
 set(BUILD_STATIC_RUNTIME OFF)
 
+# Caches the build so that building is faster when switching between branches.
+# If you switch branches, build and then encounter a linking error, you may
+# need to regenerate the build tree through "make .." (the cache will
+# still provide significant speedups).
+# Possible values:
+# - AUTO: search for path to ccache, disable if not found.
+# - ON: enable ccache by searching for the path to ccache, report an error if not found
+# - OFF: disable ccache
+# - /path/to/ccache: use specific path to ccache
+set(USE_CCACHE AUTO)
+
 # Whether to enable PAPI support in profiling. PAPI provides access to hardware
 # counters while profiling.
 # Possible values:

cmake/modules/LibInfo.cmake

@@ -117,6 +117,7 @@ function(add_lib_info src_file)
     TVM_INFO_USE_CLML="${USE_CLML}"
     TVM_INFO_USE_CLML_GRAPH_EXECUTOR="${USE_CLML_GRAPH_EXECUTOR}"
     TVM_INFO_USE_UMA="${USE_UMA}"
+    TVM_INFO_USE_CCACHE="${USE_CCACHE}"
   )
 
 endfunction()

cmake/utils/CCache.cmake

@@ -0,0 +1,52 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+if(USE_CCACHE) # True for AUTO, ON, /path/to/ccache
+  if(DEFINED CXX_COMPILER_LAUNCHER OR DEFINED C_COMPILER_LAUNCHER)
+    if("${USE_CCACHE}" STREQUAL "AUTO")
+      message(STATUS "CXX_COMPILER_LAUNCHER or C_COMPILER_LAUNCHER already defined, not using ccache")
+    elseif("${USE_CCACHE}" MATCHES ${IS_TRUE_PATTERN})
+      message(FATAL_ERROR "CXX_COMPILER_LAUNCHER or C_COMPILER_LAUNCHER is already defined, refusing to override with ccache. Either unset or disable ccache.")
+    endif()
+  else()
+    if("${USE_CCACHE}" STREQUAL "AUTO") # Auto mode
+      find_program(CCACHE_FOUND "ccache")
+      if(CCACHE_FOUND)
+        message(STATUS "Found the path to ccache, enabling ccache")
+        set(PATH_TO_CCACHE "ccache")
+      else()
+        message(STATUS "Didn't find the path to CCACHE, disabling ccache")
+      endif(CCACHE_FOUND)
+    elseif("${USE_CCACHE}" MATCHES ${IS_TRUE_PATTERN})
+      find_program(CCACHE_FOUND "ccache")
+      if(CCACHE_FOUND)
+        message(STATUS "Found the path to ccache, enabling ccache")
+        set(PATH_TO_CCACHE "ccache")
+      else()
+        message(FATAL_ERROR "Cannot find ccache. Set USE_CCACHE mode to AUTO or OFF to build without ccache. USE_CCACHE=" "${USE_CCACHE}")
+      endif(CCACHE_FOUND)
+    else() # /path/to/ccache
+      set(PATH_TO_CCACHE "${USE_CCACHE}")
+      message(STATUS "Setting ccache path to " "${PATH_TO_CCACHE}")
+    endif()
+    # Set the flag for ccache
+    if(DEFINED PATH_TO_CCACHE)
+      set(CXX_COMPILER_LAUNCHER "${PATH_TO_CCACHE}")
+      set(C_COMPILER_LAUNCHER "${PATH_TO_CCACHE}")
+    endif()
+  endif()
+endif(USE_CCACHE)

cmake/utils/Summary.cmake

@@ -42,6 +42,7 @@ macro(print_summary)
     message(STATUS "  C++ compiler ID       : ${CMAKE_CXX_COMPILER_ID}")
     message(STATUS "  C++ compiler version  : ${CMAKE_CXX_COMPILER_VERSION}")
     message(STATUS "  CXX flags             : ${CMAKE_CXX_FLAGS}")
+    message(STATUS "  CXX launcher          : ${CMAKE_CXX_LAUNCHER}")
     message(STATUS "  Linker flags          : ${CMAKE_SHARED_LINKER_FLAGS}")
     message(STATUS "  Build type            : ${CMAKE_BUILD_TYPE}")
     get_directory_property(READABLE_COMPILE_DEFS DIRECTORY ${PROJECT_SOURCE_DIR} COMPILE_DEFINITIONS)

docs/install/from_source.rst

@@ -141,6 +141,8 @@ The configuration of TVM can be modified by editing `config.cmake` and/or by pas
   - On supported platforms, the `Ccache compiler wrapper <https://ccache.dev/>`_ may be helpful for
     reducing TVM's build time.  There are several ways to enable CCache in TVM builds:
 
+    - Leave `USE_CCACHE=AUTO` in `build/config.cmake`. CCache will be used if it is found.
+
     - Ccache's Masquerade mode. This is typically enabled during the Ccache installation process.
       To have TVM use Ccache in masquerade, simply specify the appropriate C/C++ compiler
       paths when configuring TVM's build system.  For example:

src/support/libinfo.cc

@@ -318,6 +318,7 @@ TVM_DLL Map<String, String> GetLibInfo() {
       {"USE_CLML", TVM_INFO_USE_CLML},
       {"USE_CLML_GRAPH_EXECUTOR", TVM_INFO_USE_CLML_GRAPH_EXECUTOR},
       {"USE_UMA", TVM_INFO_USE_UMA},
+      {"USE_CCACHE", TVM_INFO_USE_CCACHE},
   };
   return result;
 }