[MTP] Force greedy sampling on AMD (#9127)

python/sglang/srt/speculative/eagle_utils.py

@@ -49,6 +49,8 @@ SIMULATE_ACC_METHOD = os.environ.get("SIMULATE_ACC_METHOD", "multinomial")
 
 TREE_TRAVERSE_TIME_THRESHOLD = 1  # TODO: set this properly
 
+TREE_SPEC_KERNEL_AVAILABLE = "tree_speculative_sampling_target_only" in globals()
+
 
 @dataclass
 class EagleDraftInput:
@@ -423,8 +425,15 @@ class EagleVerifyInput:
                 logits=logits_output.next_token_logits, vocab_mask=vocab_mask
             )
 
-        # Sample tokens
-        if batch.sampling_info.is_all_greedy:
+        # Sample tokens. Force greedy sampling on AMD
+        is_all_greedy = sampling_info.is_all_greedy
+        if (not is_all_greedy) and (not TREE_SPEC_KERNEL_AVAILABLE):
+            logger.warning(
+                "Tree speculative sampling kernel unavailable (likely AMD/HIP build). "
+                "Falling back to greedy verification."
+            )
+
+        if is_all_greedy or not TREE_SPEC_KERNEL_AVAILABLE:
             target_predict = torch.argmax(logits_output.next_token_logits, dim=-1)
             target_predict = target_predict.reshape(bs, self.draft_token_num)