[AMD] Refine handling kpack parameter for gfx950 (#7518)

Current implementation reports an assert error if `kpack != 1` is used
for MI350. One problem is many legacy code on MI300 has the value `kpack
= 2`. When running them on MI350, an assert error is reported, and users
need to change all places where `kpack = 2` is used. To avoid the
problem, if `kpack = 2` is used on MI350, we will issue a warning
message and overwrite it to 1 internally. So users are aware of the
problem, but do not have to change their source code.

Author: scxiao

third_party/amd/backend/compiler.py

@@ -9,6 +9,7 @@
 import re
 import subprocess
 import functools
+import warnings
 from pathlib import Path
 
 
@@ -73,8 +74,11 @@ def __post_init__(self):
         assert self.num_warps > 0 and (self.num_warps & (self.num_warps - 1)) == 0, \
                "num_warps must be a power of 2"
 
-        if self.arch == 'gfx950':
-            assert self.kpack == 1, "gfx950 only accepts kpack == 1"
+        if (self.arch == 'gfx950') and (self.kpack != 1):
+            warnings.warn(
+                f"kpack is deprecated starting from gfx950 and will be removed in later releases. So for now kpack = {self.kpack} will be overwritten to 1 to make transitioning easier."
+            )
+            object.__setattr__(self, 'kpack', 1)
 
         default_libdir = Path(__file__).parent / 'lib'
         extern_libs = {} if self.extern_libs is None else dict(self.extern_libs)