Add option to control patch apply.

Author: haonanya1

CMakeLists.txt

@@ -152,14 +152,20 @@ if(NOT USE_PREBUILT_LLVM)
     get_filename_component(LLVM_MONOREPO_DIR ${LLVM_SOURCE_DIR} DIRECTORY)
     set(LLVM_PATCHES_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/patches/llvm
                           ${CMAKE_CURRENT_SOURCE_DIR}/patches/clang)
-    apply_patches(${LLVM_MONOREPO_DIR}
-                  "${LLVM_PATCHES_DIRS}"
-                  ${LLVM_BASE_REVISION}
-                  ${TARGET_BRANCH})
-    apply_patches(${SPIRV_SOURCE_DIR}
-                  ${CMAKE_CURRENT_SOURCE_DIR}/patches/spirv
-                  ${SPIRV_BASE_REVISION}
-                  ${TARGET_BRANCH})
+    option(APPLY_PATCHES "option to apply patches" ON)
+    if(APPLY_PATCHES)
+      message(STATUS "APPLY_PATCHES is enabled.")
+      apply_patches(${LLVM_MONOREPO_DIR}
+                    "${LLVM_PATCHES_DIRS}"
+                    ${LLVM_BASE_REVISION}
+                    ${TARGET_BRANCH})
+      apply_patches(${SPIRV_SOURCE_DIR}
+                    ${CMAKE_CURRENT_SOURCE_DIR}/patches/spirv
+                    ${SPIRV_BASE_REVISION}
+                    ${TARGET_BRANCH})
+    else()
+      message(STATUS "APPLY_PATCHES is disabled, skip patch apply process.")
+    endif()
 endif(NOT USE_PREBUILT_LLVM)
 
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