[tools] add fp8 max/min constant in utils (#3959)

python/sglang/srt/utils.py

@@ -14,6 +14,7 @@
 """Common utilities."""
 
 import base64
+import builtins
 import ctypes
 import dataclasses
 import io
@@ -72,12 +73,25 @@ logger = logging.getLogger(__name__)
 show_time_cost = False
 time_infos = {}
 
+HIP_FP8_E4M3_FNUZ_MAX = 224.0
+
 
 # https://pytorch.org/docs/stable/notes/hip.html#checking-for-hip
 def is_hip() -> bool:
     return torch.version.hip is not None
 
 
+if is_hip():
+    FP8_E4M3_MAX = HIP_FP8_E4M3_FNUZ_MAX
+else:
+    FP8_E4M3_MAX = torch.finfo(torch.float8_e4m3fn).max
+
+FP8_E4M3_MIN = -FP8_E4M3_MAX
+
+builtins.FP8_E4M3_MAX = FP8_E4M3_MAX
+builtins.FP8_E4M3_MIN = FP8_E4M3_MIN
+
+
 def is_rocm() -> bool:
     return torch.cuda.is_available() and torch.version.hip