Description: Download the PGO training file earlier in the build sequence, because Launchpad builders have a timeout for how long they are allowed to access the internet (through a proxy) starting from the start of the build.
Author: Olivier Tilloy <olivier.tilloy@canonical.com>
Forwarded: not-needed

--- a/tools/clang/scripts/build.py
+++ b/tools/clang/scripts/build.py
@@ -481,6 +481,15 @@ def compiler_rt_cmake_flags(*, sanitizer
   return args
 
 
+def DownloadPGOTrainingFile():
+  curdir = os.getcwd()
+  os.chdir(THIRD_PARTY_DIR)
+  training_source = 'pgo_training-1.ii'
+  with open(training_source, 'wb') as f:
+    DownloadUrl(CDS_URL + '/' + training_source, f)
+  os.chdir(curdir)
+
+
 def gn_arg(v):
   if v == 'True':
     return True
@@ -617,4 +626,6 @@ def main():
   if not args.use_system_cmake:
     AddCMakeToPath()
+  if args.pgo:
+    DownloadPGOTrainingFile()

   if sys.platform == 'win32':
@@ -908,8 +920,7 @@ def main():
     # from PGO as well. Perhaps the training could be done asynchronously by
     # dedicated buildbots that upload profiles to the cloud.
     training_source = 'pgo_training-1.ii'
-    with open(training_source, 'wb') as f:
-      DownloadUrl(CDS_URL + '/' + training_source, f)
+    shutil.copy(os.path.join(THIRD_PARTY_DIR, training_source), os.getcwd())
     train_cmd = [os.path.join(LLVM_INSTRUMENTED_DIR, 'bin', 'clang++'),
                 '-target', 'x86_64-unknown-unknown', '-O2', '-g', '-std=c++14',
                  '-fno-exceptions', '-fno-rtti', '-w', '-c', training_source]