merge tagless reshapes (#12474)

* merge tagless reshapes

* cleanup

extra/thunder/gemm.py

@@ -1,4 +1,5 @@
 # include directory copied from https://github.com/HazyResearch/ThunderMittens
+# https://hazyresearch.stanford.edu/blog/2024-11-28-tk-mlx
 
 gemm = """
 #include <metal_stdlib>
@@ -41,10 +42,9 @@ kernel void matmul_naive(GEMM_PARAMS_DEF(T)) {
 instantiate_matmul_custom(float32, float);
 """
 
-from tinygrad import Device, Tensor
+from tinygrad import Device, Tensor, Context
 
 if __name__ == "__main__":
-  # TODO: why isn't this type inferred?
   device = Device["METAL"]
   lib = device.compiler.compile(gemm)
   prg = device.runtime("matmul_custom_float32", lib)
@@ -65,7 +65,10 @@ if __name__ == "__main__":
             global_size=gsz, local_size=(32,1,1), vals=(N, N, N), wait=True)
     print(f"{N*N*N*2/(et*1e9):2f} GFLOPS")
 
-  val = ((a@b).contiguous()-c).mean()
-  print(val.item())
+  for _ in range(5):
+    with Context(DEBUG=2):
+      ref = (a@b).realize()
+
+  print((ref-c).mean().item())