Adding git hash info to version output line (#572)

[ROCm/rccl commit: a89a9966aa]

projects/rccl/cmake/git_version.cmake

@@ -0,0 +1,37 @@
+# Attempt to collect the latest git hash
+execute_process(COMMAND git log --pretty=format:'%h' -n 1
+                OUTPUT_VARIABLE GIT_REV
+                ERROR_QUIET)
+
+# Check if git information was found
+if ("${GIT_REV}" STREQUAL "")
+  set(GIT_VERSION "const char *rcclGitHash =\"Unknown \";")
+else()
+  # Check for changes (denote with a '+') after hash
+  execute_process(
+    COMMAND bash -c "git diff --quiet --exit-code || echo +"
+    OUTPUT_VARIABLE GIT_DIFF)
+  # Collect branch information
+  execute_process(
+    COMMAND git rev-parse --abbrev-ref HEAD
+    OUTPUT_VARIABLE GIT_BRANCH)
+
+  string(STRIP "${GIT_REV}" GIT_REV)
+  string(SUBSTRING "${GIT_REV}" 1 7 GIT_REV)
+  string(STRIP "${GIT_DIFF}" GIT_DIFF)
+  string(STRIP "${GIT_BRANCH}" GIT_BRANCH)
+
+  set(GIT_VERSION "const char *rcclGitHash =\"${GIT_BRANCH}:${GIT_REV}${GIT_DIFF}\";")
+endif()
+
+# Compare file with existing file (if any)
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/git_version.cpp)
+  file(READ ${CMAKE_CURRENT_SOURCE_DIR}/git_version.cpp GIT_VERSION_)
+else()
+  set(GIT_VERSION_ "")
+endif()
+
+# Write updated file
+if (NOT "${GIT_VERSION}" STREQUAL "${GIT_VERSION_}")
+  file(WRITE ${CMAKE_CURRENT_SOURCE_DIR}/git_version.cpp "${GIT_VERSION}")
+endif()