[Core] Rework dtype resolution (#18751)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/basic_correctness/test_basic_correctness.py

@@ -60,7 +60,6 @@ def _fix_prompt_embed_outputs(
 
 @pytest.mark.parametrize("model", MODELS)
 @pytest.mark.parametrize("backend", ["FLASH_ATTN"])
-@pytest.mark.parametrize("dtype", ["half"])
 @pytest.mark.parametrize("max_tokens", [5])
 @pytest.mark.parametrize("enforce_eager", [False])
 @pytest.mark.parametrize("enable_prompt_embeds", [True, False])
@@ -69,7 +68,6 @@ def test_models(
     hf_runner,
     model: str,
     backend: str,
-    dtype: str,
     max_tokens: int,
     enforce_eager: bool,
     enable_prompt_embeds: bool,
@@ -97,7 +95,7 @@ def test_models(
             str(i) for i in range(1024)) + " are:"
         example_prompts = [prompt]
 
-        with hf_runner(model, dtype=dtype) as hf_model:
+        with hf_runner(model) as hf_model:
             hf_outputs = hf_model.generate_greedy(example_prompts, max_tokens)
             if enable_prompt_embeds:
                 with torch.no_grad():
@@ -106,7 +104,6 @@ def test_models(
 
         with VllmRunner(model,
                         max_model_len=8192,
-                        dtype=dtype,
                         enforce_eager=enforce_eager,
                         enable_prompt_embeds=enable_prompt_embeds,
                         gpu_memory_utilization=0.7) as vllm_model: