Separate the repos from the environments

Before this patch, we had an LLVM_ROOT directory which contained the
repos and a series of environments (worktrees + build dicretories).
However, there is no good reason to have such a rigid layout, and in
fact it prevents us from sharing the repos in any meaningful way.

This patch removes LLVM_ROOT and instead introduces two command line
parameters, repos and env, which represent the path to the directory
containing the LLVM repositories and respectively the path to the
environment that we intend to modify. The two paths may be completely
independent. A side effect of this is that we can now also have
different environments in different, unrelated locations (whereas
previously they had to be siblings in LLVM_ROOT).

For the time being, both parameters are compulsory (not only for
llvm-projects, but for all subcommands). There may be situations where
we can get away with only one of them (e.g. `llvm-projs <env>`, which
just lists the projects enabled in the given <env> - it does not need to
know where the repos are in order to do this). There may also be
situations where one of them doesn't make any sense at all (e.g.
`llvm-prepare`, which is not implemented yet in python, only needs the
path to the repos and it would not know what to do with an environment).
Making them optional would require some additional validation logic as
well as more tests, and it feels a bit early on to introduce all that.
It would be nice to have at least one or 2 more subcommands implemented
before we invest time in it.

Change-Id: Ibc1321d18476c2c4a65b5b05ca3fce3467d72fc3

1 files changed, 10 insertions, 18 deletions

diff --git a/scripts/llvm.py b/scripts/llvm.py
index 13e5de6..829c720 100644
--- a/scripts/llvm.py
+++ b/scripts/llvm.py
@@ -20,24 +20,9 @@ def die(message, config_to_dump=None):
     exit(1)
 
 
-def get_llvm_root():
-    """Get the path to the LLVM root, which contains the repos as well as all
-    the work environments."""
-    return os.environ["LLVM_ROOT"]
-
-
 def get_worktree_root(env):
-    """
-    Get the path to the LLVM worktree corresponding to env. The value will be
-    based on the LLVM root.
-    """
-    return os.path.join(get_llvm_root(), env, "llvm")
-
-# Figure out the path to the LLVM repos
-if "LLVM_ROOT" not in os.environ:
-    die("Please, define $LLVM_ROOT to point to the root\n"
-        "path where the worktree setup should be performed")
-llvm_repos_root = os.path.join(get_llvm_root(), "repos")
+    """Get the path to the LLVM worktree corresponding to env."""
+    return os.path.join(env, "llvm")
 
 
 def dump_config(config):
@@ -58,6 +43,7 @@ def projects(args):
     proj = Proj()
 
     llvm_worktree_root = get_worktree_root(args.env)
+    llvm_repos_root = args.repos
     config = LLVMSourceConfig(proj, llvm_worktree_root)
 
     if not args.add and not args.remove:
@@ -87,7 +73,13 @@ def projects(args):
 valid_subprojects = list(LLVMSubproject.get_all_subprojects().keys())
 
 options = ArgumentParser(formatter_class=RawTextHelpFormatter)
-options.add_argument('env', help="The environment to update.")
+options.add_argument(
+    '--env',
+    required=True,
+    help="Path to the environment to update.")
+options.add_argument(
+    '--repos', required=True,
+    help="Path to the directory containing the repositories for all LLVM subprojects.")
 
 subcommands = options.add_subparsers()