[build-script] Bring in modernizations from downstream:

- Don't do any checks of the current SCM repository if the
  llvm repositories are already there.  Useful for bots.
- When symlinking, remove old symlinks.
- Support loading build-script as a library, not necessarily
  under Xcode.
- Stringify args before passing them to subprocess.

llvm-svn: 309631

1 files changed, 25 insertions, 6 deletions

diff --git a/lldb/scripts/Xcode/build-llvm.py b/lldb/scripts/Xcode/build-llvm.py
index e2a46de1a16..4a18abefc85 100755
--- a/lldb/scripts/Xcode/build-llvm.py
+++ b/lldb/scripts/Xcode/build-llvm.py
@@ -14,7 +14,6 @@ from lldbbuild import *
 
 #### SETTINGS ####
 
-
 def LLVM_HASH_INCLUDES_DIFFS():
     return False
 
@@ -42,7 +41,25 @@ def process_repo(r):
         'ref': r["ref"]
     }
 
+def fallback_repo(name):
+    return {
+        'name': name,
+        'vcs': None,
+        'root': process_root(name),
+        'url': None,
+        'ref': None
+    }
+
+def dirs_exist(names):
+    for name in names:
+        if not os.path.isdir(process_root(name)):
+            return False
+    return True
+
 def XCODE_REPOSITORIES():
+    names = ["llvm", "clang", "ninja"]
+    if dirs_exist(names):
+        return [fallback_repo(n) for n in names]
     override = repo.get_override()
     if override:
         return [process_repo(r) for r in override]
@@ -233,6 +250,8 @@ def should_build_llvm():
 
 def do_symlink(source_path, link_path):
     print "Symlinking " + source_path + " to " + link_path
+    if os.path.islink(link_path):
+        os.remove(link_path)
     if not os.path.exists(link_path):
         os.symlink(source_path, link_path)
 
@@ -433,8 +452,8 @@ def build_llvm_if_needed():
 
 #### MAIN LOGIC ####
 
-all_check_out_if_needed()
-build_llvm_if_needed()
-write_archives_txt()
-
-sys.exit(0)
+if __name__ == "__main__":
+    all_check_out_if_needed()
+    build_llvm_if_needed()
+    write_archives_txt()
+    sys.exit(0)