[GitHub] [tvm] tkonolige commented on a change in pull request #7917: allow libbacktrace to be used when cross compiling the runtime

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

tkonolige commented on a change in pull request #7917:
URL: https://github.com/apache/tvm/pull/7917#discussion_r625176936



##########
File path: cmake/libs/Libbacktrace.cmake
##########
@@ -16,12 +16,28 @@
 # under the License.
 include(ExternalProject)
 
+
+if(CMAKE_SYSTEM_NAME MATCHES "Darwin" AND (CMAKE_C_COMPILER MATCHES "^/Library"
+  OR CMAKE_C_COMPILER MATCHES "^/Applications"))
+    set(c_compiler "/usr/bin/cc")
+  else()
+    set(c_compiler "${CMAKE_C_COMPILER}")
+endif()
+
 ExternalProject_Add(project_libbacktrace
   PREFIX libbacktrace
   SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/../../3rdparty/libbacktrace
   BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/libbacktrace
   CONFIGURE_COMMAND "${CMAKE_CURRENT_LIST_DIR}/../../3rdparty/libbacktrace/configure"
-                    "--prefix=${CMAKE_CURRENT_BINARY_DIR}/libbacktrace" --with-pic
+                    "--prefix=${CMAKE_CURRENT_BINARY_DIR}/libbacktrace"
+                    --with-pic
+                    "CC=${CMAKE_C_COMPILER}"

Review comment:
       ```suggestion
                       "CC=${c_compiler}"
   ```
   You need this change to match the lines above.

##########
File path: cmake/libs/Libbacktrace.cmake
##########
@@ -16,12 +16,28 @@
 # under the License.
 include(ExternalProject)
 
+
+if(CMAKE_SYSTEM_NAME MATCHES "Darwin" AND (CMAKE_C_COMPILER MATCHES "^/Library"
+  OR CMAKE_C_COMPILER MATCHES "^/Applications"))
+    set(c_compiler "/usr/bin/cc")
+  else()
+    set(c_compiler "${CMAKE_C_COMPILER}")
+endif()
+
 ExternalProject_Add(project_libbacktrace
   PREFIX libbacktrace
   SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/../../3rdparty/libbacktrace
   BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/libbacktrace
   CONFIGURE_COMMAND "${CMAKE_CURRENT_LIST_DIR}/../../3rdparty/libbacktrace/configure"
-                    "--prefix=${CMAKE_CURRENT_BINARY_DIR}/libbacktrace" --with-pic
+                    "--prefix=${CMAKE_CURRENT_BINARY_DIR}/libbacktrace"
+                    --with-pic
+                    "CC=${CMAKE_C_COMPILER}"
+                    "CFLAGS=${CMAKE_C_FLAGS}"
+                    "LDFLAGS=${CMAKE_EXE_LINKER_FLAGS}"
+                    "CPP=${CMAKE_C_COMPILER} -E"

Review comment:
       ```suggestion
                       "CPP=${c_compiler} -E"
   ```

##########
File path: cmake/libs/Libbacktrace.cmake
##########
@@ -16,12 +16,28 @@
 # under the License.
 include(ExternalProject)
 
+

Review comment:
       Could you add this comment:
   
   ```
   # On MacOS, the default C compiler (/usr/bin/cc) is actually a small script that dispatches to a
   # compiler the default SDK (usually /Library/Developer/CommandLineTools/usr/bin/ or
   # /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/). CMake
   # automatically detects what is being dispatched and uses it instead along with all the flags it
   # needs. CMake makes this second compiler avaliable through the CMAKE_C_COMPILER variable, but it
   # does not make the necessary flags available. This leads to configuration errors in libbacktrace
   # because it can't find system libraries. Our solution is to detect if CMAKE_C_COMPILER lives in
   # /Library or /Applications and switch to the default compiler instead.
   ```




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