[LIT] Make util.executeCommand python3 friendly

Summary: The parameter `input` to `subprocess.Popen.communicate(...)` must be an object of type `bytes` . This is strictly enforced in python3. This patch (1) allows `to_bytes` to be safely called redundantly. (2) Explicitly convert `input` within `executeCommand`. This allows for usages like `executeCommand(['clang++', '-'], input='int main() {}\n')`.

Reviewers: ddunbar, BinaryKhaos, modocache, dim, EricWF

Reviewed By: EricWF

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28736

llvm-svn: 292308

llvm/utils/lit/lit/util.py

@@ -10,6 +10,8 @@ import threading
 
 def to_bytes(str):
     # Encode to UTF-8 to get binary data.
+    if isinstance(str, bytes):
+        return str
     return str.encode('utf-8')
 
 def to_string(bytes):
@@ -200,6 +202,8 @@ def executeCommand(command, cwd=None, env=None, input=None, timeout=0):
         If the timeout is hit an ``ExecuteCommandTimeoutException``
         is raised.
     """
+    if input is not None:
+        input = to_bytes(input)
     p = subprocess.Popen(command, cwd=cwd,
                          stdin=subprocess.PIPE,
                          stdout=subprocess.PIPE,