pre-commit check for torch.cuda in code (#2981)

Co-authored-by: Olatunji Ruwase <olruwase@microsoft.com>

scripts/check-torchcuda.py

@@ -0,0 +1,66 @@
+#!/usr/bin/env python3
+from __future__ import annotations
+'''Copyright The Microsoft DeepSpeed Team'''
+"""
+Checks each file in sys.argv for the string "torch.cuda".
+Modified from https://github.com/jlebar/pre-commit-hooks/blob/master/check_do_not_submit.py
+"""
+
+import subprocess
+import sys
+
+
+def err(s: str) -> None:
+    print(s, file=sys.stderr)
+
+
+# There are many ways we could search for the string "torch.cuda", but `git
+# grep --no-index` is nice because
+#  - it's very fast (as compared to iterating over the file in Python)
+#  - we can reasonably assume it's available on all machines
+#  - unlike plain grep, which is slower and has different flags on MacOS versus
+#    Linux, git grep is always the same.
+res = subprocess.run(
+    [
+        "git",
+        "grep",
+        "-Hn",
+        "--no-index",
+        "-e",
+        r"torch\.cuda",
+        "--and",
+        "--not",
+        "-e",
+        "#ignore-cuda",
+        *sys.argv[1:]
+    ],
+    capture_output=True,
+)
+if res.returncode == 0:
+    err('Error: The string "torch.cuda" was found.\nPlease replace all calls to torch.cuda with "get_accelerator()" and add the following import line:\n\n    from deepspeed.accelerator import get_accelerator\n\nIf your code is mean to be cuda specific, please add the following comment in the line with torch.cuda:\n\n    #ignore-cuda\n'
+        )
+    err(res.stdout.decode("utf-8"))
+    sys.exit(1)
+elif res.returncode == 2:
+    err(f"Error invoking grep on {', '.join(sys.argv[1:])}:")
+    err(res.stderr.decode("utf-8"))
+    sys.exit(2)
+
+res = subprocess.run(
+    ["git",
+     "grep",
+     "-Hn",
+     "--no-index",
+     r"\.cuda()",
+     *sys.argv[1:]],
+    capture_output=True,
+)
+if res.returncode == 0:
+    err('Error: The string ".cuda()" was found. This implies convert a tensor to cuda tensor.  Please replace all calls to tensor.cuda() with "tensor.to(get_accelerator().device_name())" and add the following import line:\nfrom deepspeed.accelerator import get_accelerator'
+        )
+    err(res.stdout.decode("utf-8"))
+    sys.exit(1)
+elif res.returncode == 2:
+    err(f"Error invoking grep on {', '.join(sys.argv[1:])}:")
+    err(res.stderr.decode("utf-8"))
+    sys.exit(2)