[pallas_mgpu] Add a test for emit_pipeline with wgmma.

PiperOrigin-RevId: 723012611

tests/pallas/mosaic_gpu_test.py

@@ -1585,6 +1585,74 @@ class PipelineTest(PallasTest):
     )
     np.testing.assert_array_equal(kernel_fn(x), x + 1.0)
 
+  def test_emit_pipeline_with_wgmma(self):
+    self.skip_unless_sm90a()
+
+    m, n, k = 256, 256, 256
+    dtype = jnp.float16
+    key = jax.random.key(42)
+    x = jax.random.uniform(key, shape=(m, k), dtype=dtype)
+    y = jax.random.uniform(key, shape=(k, n), dtype=dtype)
+
+    swizzle = 128
+    swizzle_elems = swizzle // jnp.dtype(x.dtype).itemsize
+
+    tile_m = 64
+    tile_n = 64
+    tile_k = swizzle_elems
+
+    grid_m = m // tile_m
+    grid_n = n // tile_n
+    grid_k = k // tile_k
+
+    def kernel(a_gmem, b_gmem, c_smem, acc_reg):
+      def pipeline_body(a_smem, b_smem):
+        plgpu.wgmma(acc_reg, a_smem, b_smem)
+
+      plgpu.emit_pipeline(
+          pipeline_body,
+          in_specs=[
+              plgpu.GPUBlockSpec(
+                  (tile_m, tile_k),
+                  lambda i: (0, i),
+                  transforms=(
+                      plgpu.TilingTransform((64, swizzle_elems)),
+                      plgpu.SwizzleTransform(swizzle),
+                  ),
+              ),
+              plgpu.GPUBlockSpec(
+                  (tile_k, tile_n),
+                  lambda i: (i, 0),
+                  transforms=(
+                      plgpu.TilingTransform((swizzle_elems, swizzle_elems)),
+                      plgpu.SwizzleTransform(swizzle),
+                  ),
+              ),
+          ],
+          grid=(grid_k,),
+          max_concurrent_steps=2,
+          delay_release=1,
+      )(a_gmem, b_gmem)
+
+      c_smem[...] = acc_reg[...]
+
+    @jax.jit
+    def matmul(a: jax.Array, b: jax.Array) -> jax.Array:
+      return pl.pallas_call(
+          kernel,
+          in_specs=[
+              pl.BlockSpec(memory_space=plgpu.GMEM),
+              pl.BlockSpec(memory_space=plgpu.GMEM),
+          ],
+          out_specs=pl.BlockSpec((tile_m, tile_n), lambda m, n: (m, n)),
+          grid=(grid_m, grid_n),
+          out_shape=jax.ShapeDtypeStruct((m, n), x.dtype),
+          scratch_shapes=[plgpu.ACC((tile_m, tile_n), dtype)],
+      )(a, b)
+
+    res = matmul(x, y)
+    np.testing.assert_allclose(res, x @ y, rtol=0.4)
+
 
 class WarpSpecializedPipelineTest(PallasTest):