[ATFE] Improve error handling and header optimisation in common header generation logic. (#456)

This patch introduces additional error checking and handle edge cases in
common header generation script.

1. Adds a check to handle cases where the multilib folder is either
empty or does not exist, avoiding unhandled exceptions.
2. Improves logic by allowing header optimisation to proceed for targets
that have more than two variants, even if another target lacks
sufficient variants for a comparison. These changes ensure the script
can still performing valid optimisations where possible.
3. Copying multilib.yaml can be moved outside the loop, as it only needs
to be done once after all target folders are generated.

(cherry picked from commit 256be48)

Author: simpal01

arm-software/embedded/arm-multilib/common-headers-generate.py

@@ -55,6 +55,24 @@ def extract_common_headers_for_targets(args):
     if os.path.exists(args.multilib_optimised_dir):
         shutil.rmtree(args.multilib_optimised_dir)
 
+    if os.path.isdir(args.multilib_non_optimised_dir):
+        existing_target_dirs = [
+            dir_name
+            for dir_name in MULTILIB_TARGET_DIRS
+            if os.path.isdir(os.path.join(args.multilib_non_optimised_dir, dir_name))
+        ]
+        if not existing_target_dirs:
+            raise Exception(
+                f"Error: Expected to find either arm-none-eabi or aarch64-none-elf in '{args.multilib_non_optimised_dir}', but folder is empty."
+            )
+        src_yaml = os.path.join(args.multilib_non_optimised_dir, "multilib.yaml")
+        if not os.path.exists(src_yaml):
+            raise FileNotFoundError(f"Source yaml '{src_yaml}' does not exist.")
+    else:
+        raise FileNotFoundError(
+            f"Error: Expected folder '{args.multilib_non_optimised_dir}' does not exist"
+        )
+
     for target in MULTILIB_TARGET_DIRS:
         input_target_dir = os.path.join(
             os.path.abspath(args.multilib_non_optimised_dir), target
@@ -73,17 +91,18 @@ def extract_common_headers_for_targets(args):
         variant_includes = collect_variant_include_paths(input_target_dir)
         if len(variant_includes) < 2:
             print(
-                f"Skipping extracting the common headers for {target}: not enough variants to compare.At least two variants must be enabled for the multilib header optimisation phase to proceed."
+                f"Skipping extracting the common headers for {target}: not enough variants to compare. "
+                "At least two variants must be enabled for the multilib header optimisation phase to proceed."
             )
             # The script always creates the multilib-optimised folder, even when there's only one variant and no
             # optimization is applied. In that case, multilib-optimised will just contain a copy of the
             # single variant from the non-optimised multilib directory.
-            if os.path.exists(args.multilib_non_optimised_dir):
-                shutil.copytree(args.multilib_non_optimised_dir, args.multilib_optimised_dir)
-            return
+            if os.path.exists(input_target_dir):
+                shutil.copytree(input_target_dir, output_target_dir, dirs_exist_ok=False)
+            continue
 
         # Creating the common include headers for each target
-        os.makedirs(output_include_dir, exist_ok=True)
+        os.makedirs(output_include_dir, exist_ok=False)
 
         # Step 1: compare first two variants and extract the common headers into the targets common include directory
         base_dir = list(variant_includes.values())[0]
@@ -137,13 +156,10 @@ def extract_common_headers_for_targets(args):
                 else:
                     print(f"Warning: {src_dir} does not exist and will be skipped.")
 
-        # Step4: Copy multilib.yaml file as it is from the non-optimised multilib directoy.
-        src_yaml = os.path.join(args.multilib_non_optimised_dir, "multilib.yaml")
-        dst_yaml = os.path.join(args.multilib_optimised_dir, "multilib.yaml")
-        if os.path.exists(src_yaml):
-            shutil.copy2(src_yaml, dst_yaml)
-        else:
-            raise FileNotFoundError(f"Source yaml '{src_yaml}' does not exist.")
+    # Step4: Copy multilib.yaml file as it is from the non-optimised multilib directoy.
+    src_yaml = os.path.join(args.multilib_non_optimised_dir, "multilib.yaml")
+    dst_yaml = os.path.join(args.multilib_optimised_dir, "multilib.yaml")
+    shutil.copy2(src_yaml, dst_yaml)
 
 
 def main():