Update 02-fused-softmax.py (#7473)

docs: Align softmax tutorial benchmark with description

The documentation for the softmax tutorial states that it compares three
implementations: the Triton kernel, torch.softmax, and a naive_softmax
implementation.

However, the accompanying code example only benchmarks the Triton and
Torch versions, omitting the naive implementation. This discrepancy can
cause confusion for users following the tutorial.

This commit updates the benchmark code to include the `native_softmax`
comparison, ensuring the code accurately reflects the tutorial's
description. The changes include:
- Adding 'native_softmax' to the `line_vals` list.
- Adding "Native Softmax" to the `line_names` list.
- Adding the corresponding logic branch to the `benchmark` function.

Here is my code result:
<img width="571" height="432" alt="image"
src="https://github.com/user-attachments/assets/bf6dc821-2ee4-4acc-8002-0cc2188d3497"
/>

Author: princepride

python/tutorials/02-fused-softmax.py

@@ -205,12 +205,9 @@ def softmax(x):
         x_names=['N'],  # argument names to use as an x-axis for the plot
         x_vals=[128 * i for i in range(2, 100)],  # different possible values for `x_name`
         line_arg='provider',  # argument name whose value corresponds to a different line in the plot
-        line_vals=['triton', 'torch'],  # possible values for `line_arg``
-        line_names=[
-            "Triton",
-            "Torch",
-        ],  # label name for the lines
-        styles=[('blue', '-'), ('green', '-')],  # line styles
+        line_vals=['triton', 'torch', 'naive_softmax'],  # possible values for `line_arg``
+        line_names=["Triton", "Torch", "Naive Softmax"],  # label name for the lines
+        styles=[('blue', '-'), ('green', '-'), ('red', '-')],  # line styles
         ylabel="GB/s",  # label name for the y-axis
         plot_name="softmax-performance",  # name for the plot. Used also as a file name for saving the plot.
         args={'M': 4096},  # values for function arguments not in `x_names` and `y_name`
@@ -223,6 +220,8 @@ def benchmark(M, N, provider):
         ms = triton.testing.do_bench(lambda: torch.softmax(x, axis=-1))
     if provider == 'triton':
         ms = triton.testing.do_bench(lambda: softmax(x))
+    if provider == 'naive_softmax':
+        ms = triton.testing.do_bench(lambda: naive_softmax(x))
     gbps = lambda ms: 2 * x.numel() * x.element_size() * 1e-9 / (ms * 1e-3)
     return gbps(ms)