[TKW] Fix indexing of permute to enable attention (#244)

Most of the time in GPU programming, we would only materialize
"transposes"/"permutes" of data during reads and writes. When doing
transposes/permutations of data in GPU registers, it is most of the time
free/no-op, since threads will still own the same data but just
symbolically different.

Signed-off-by: Stanley Winata <stanley.winata@amd.com>

iree/turbine/kernel/ops/wave_ops.py

@@ -1400,18 +1400,3 @@ def type(self) -> Register:
             self.target_shape
         ), f"Target shape {self.target_shape} must be a permutation of source shape {src_type.symbolic_shape}"
         return Register[*self.target_shape, src_type.dtype]
-
-    @property
-    def index(self) -> Optional[dict[IndexSymbol, IndexSequence]]:
-        """
-        Computes the permuted index based on the target shape.
-        """
-        src_type = get_custom(self.arg).type
-        dim_map = {
-            tgt: src for src, tgt in zip(src_type.symbolic_shape, self.target_shape)
-        }
-        return {tgt: get_custom(self.arg).index[src] for tgt, src in dim_map.items()}
-
-    @index.setter
-    def index(self, value: Any):
-        CustomOp.index.fset(self, value)

tests/kernel/wave/wave_attention_test.py

@@ -7,6 +7,7 @@
 import logging
 import pytest
 import torch
+import math
 import unittest
 import iree.turbine.kernel as tk
 import iree.turbine.kernel.lang as tkl
@@ -20,7 +21,7 @@
 from iree.turbine.kernel.wave.constraints import MMAType
 import os
 import json
-from torch.testing import assert_close
+from torch.testing import assert_close, assert_allclose
 
 _run_e2e = int(os.environ.get("WAVE_RUN_E2E_TESTS", 0))
 require_e2e = pytest.mark.skipif(not _run_e2e, reason="e2e tests are disabled")
@@ -194,3 +195,167 @@ def repeat(
             "chain_mmt", [q, k, v], [iree_ref], config, run_bench=run_bench
         )
         assert_close(output, iree_ref)
+
+
+@require_e2e
+@pytest.mark.parametrize("shape", get_test_shapes("test_attention"))
+@pytest.mark.parametrize("enable_scheduling", [False])
+@pytest.mark.parametrize(
+    "mfma_variant",
+    [
+        MMAType.F32_16x16x16_F16,
+    ],
+)
+def testAttention(
+    shape: tuple[int], enable_scheduling: bool, mfma_variant: MMAType, request
+):
+    run_bench = request.config.getoption("--runperf")
+    dump_perf = request.config.getoption("--dump-perf-files-path")
+    # Input sizes
+    B = tkl.sym.B
+    M = tkl.sym.M
+    N = tkl.sym.N
+    K1 = tkl.sym.K1
+    K2 = tkl.sym.K2
+    # Workgroup tile sizes
+    BLOCK_B = tkl.sym.BLOCK_B
+    BLOCK_M = tkl.sym.BLOCK_M
+    BLOCK_N = tkl.sym.BLOCK_N
+    BLOCK_K2 = tkl.sym.BLOCK_K2
+    # Address space (for GPU, shared(1) or global(0))
+    ADDRESS_SPACE = tkl.sym.ADDRESS_SPACE
+    # Other hyperparameters
+    LOAD_ELEMS_PER_THREAD = tkl.sym.LOAD_ELEMS_PER_THREAD
+    STORE_ELEMS_PER_THREAD = tkl.sym.STORE_ELEMS_PER_THREAD
+
+    # Expose user-constraints
+    constraints: list[tkw.Constraint] = [tkw.WorkgroupConstraint(M, BLOCK_M, 0)]
+    constraints += [tkw.WorkgroupConstraint(N, BLOCK_N, 1)]
+    constraints += [tkw.WorkgroupConstraint(B, BLOCK_B, 2)]
+    constraints += [tkw.TilingConstraint(K2, BLOCK_K2)]
+    constraints += [tkw.WaveConstraint(M, BLOCK_M / 2)]
+    constraints += [tkw.WaveConstraint(N, BLOCK_N / 2)]
+
+    constraints += [
+        tkw.HardwareConstraint(
+            threads_per_wave=64,
+            waves_per_block=(2, 2, 1),
+            mma_type=mfma_variant,
+            vector_shapes={B: 0, M: 16, N: 16},
+        )
+    ]
+
+    i = tkw.IndexMapping.iterator(0)
+    j = tkw.IndexMapping.iterator(1)
+    k = tkw.IndexMapping.iterator(2)
+    mapping = tkw.IndexMapping(
+        num_iterators=3, inputs={B: i, M: j, N: k}, outputs={B: i, N: k, M: j}
+    )
+
+    @tkw.wave(constraints)
+    def base_attention(
+        q: tkl.Memory[B, M, K1, ADDRESS_SPACE, tkl.f16],
+        k: tkl.Memory[B, K2, K1, ADDRESS_SPACE, tkl.f16],
+        v: tkl.Memory[B, N, K2, ADDRESS_SPACE, tkl.f16],
+        c: tkl.Memory[B, M, N, GLOBAL_ADDRESS_SPACE, tkl.f32],
+    ):
+        c_reg = tkl.Register[B, N, M, tkl.f32](0.0)
+        init_sum = tkl.Register[B, M, tkl.f32](0.0)
+        init_max = tkl.Register[B, M, tkl.f32](-1e6)
+        # This microkernel encodes the fact that if the reduction
+        # dimension were tiled, then we would need to materialize a loop.
+        @tkw.reduction(K2, init_args=[init_max, init_sum, c_reg])
+        def repeat(
+            partial_max: tkl.Register[B, M, tkl.f32],
+            partial_sum: tkl.Register[B, M, tkl.f32],
+            acc: tkl.Register[B, N, M, tkl.f32],
+        ) -> (
+            tkl.Register[B, M, tkl.f32],
+            tkl.Register[B, M, tkl.f32],
+            tkl.Register[B, N, M, tkl.f32],
+        ):
+            imm_reg = tkl.Register[B, K2, M, tkl.f32](0.0)
+            q_reg = tkw.read(q, elements_per_thread=LOAD_ELEMS_PER_THREAD)
+            # b_reg: tkw.Register[B, N, K, tkl.f16]
+            k_reg = tkw.read(k, elements_per_thread=LOAD_ELEMS_PER_THREAD)
+            # acc: tkw.Register[B, N, M, tkl.f32]
+            inner_acc = tkw.mma(k_reg, q_reg, imm_reg)
+            x_j = tkw.permute(inner_acc, target_shape=[B, M, K2])
+            m_j = tkw.max(x_j, partial_max, dim=K2)
+            e_delta_max = tkw.exp2(partial_max - m_j)
+            e_delta = tkw.exp2(x_j - m_j)
+            e_init = partial_sum * e_delta_max
+            d_j = tkw.sum(e_delta, e_init, dim=K2)
+            imm_f16 = tkw.cast(e_delta, tkl.f16)
+            v_reg = tkw.read(v, elements_per_thread=LOAD_ELEMS_PER_THREAD)
+            new_acc = acc * e_delta_max
+            acc = tkw.mma(v_reg, imm_f16, new_acc)
+            return m_j, d_j, acc
+
+        # repeat represents the results of the loop
+        res_max, res_sum, res_mm = repeat
+        res = res_mm / res_sum
+        tkw.write(res, c, elements_per_thread=STORE_ELEMS_PER_THREAD)
+
+    hyperparams = {
+        ADDRESS_SPACE: SHARED_ADDRESS_SPACE,
+        LOAD_ELEMS_PER_THREAD: get_mfma_load_elems_per_thread(mfma_variant),
+        STORE_ELEMS_PER_THREAD: get_mfma_store_elems_per_thread(mfma_variant),
+        BLOCK_B: 1,
+        BLOCK_M: 64,
+        BLOCK_N: 64,
+        BLOCK_K2: 32,
+        B: shape[0],
+        M: shape[1],
+        N: shape[2],
+        K1: shape[3],
+        K2: shape[4],
+        READ_SHARED_DELAY: 1,
+        WRITE_SHARED_DELAY: 1,
+        READ_GLOBAL_DELAY: 2,
+        WRITE_GLOBAL_DELAY: 2,
+        MMA_DELAY: 1,
+        SHARED_MEMORY_UNITS: 4,
+        GLOBAL_MEMORY_UNITS: 4,
+        MMA_UNITS: 4,
+    }
+    config = {"backend": "rocm", "device": "hip", "target": "gfx942"}
+    if run_bench:
+        config["benchmark_batch_size"] = 10
+        config["benchmark_repetitions"] = 3
+    if dump_perf is not None:
+        perf_filename = request.node.name + ".json"
+        config["benchmark_results_file"] = os.path.join(
+            dump_perf, "tk_" + perf_filename
+        )
+
+    with tk.gen.TestLaunchContext(
+        hyperparams,
+        canonicalize=True,
+        run=True,
+        run_bench=run_bench,
+        run_config=config,
+        schedule=enable_scheduling,
+        use_scheduling_barriers=enable_scheduling_barriers,
+    ):
+        torch.manual_seed(0)
+        q = torch.randn(shape[0], shape[1], shape[3], dtype=torch.float16)
+        k = torch.randn(shape[0], shape[4], shape[3], dtype=torch.float16)
+        v = torch.randn(shape[0], shape[4], shape[2], dtype=torch.float16)
+        output = torch.zeros(shape[0], shape[1], shape[2], dtype=torch.float32)
+        log2e = 1.44269504089
+        dk_sqrt = math.sqrt(1.0 / shape[3])
+        # TODO: Add scaling of QK as part of kernel.
+        # TODO: Add variant of non-transposed V attention kernel.
+        mb = base_attention(q * dk_sqrt * log2e, k, v.permute([0, 2, 1]), output)
+        torch_ref = torch.nn.functional.scaled_dot_product_attention(
+            q, k, v, attn_mask=None
+        )
+
+        if test_dump_generated_mlir:
+            filename = f"wave_attention_{'x'.join(map(str, shape))}.mlir"
+            with open(filename, "w") as f:
+                f.write(mb.module_op.get_asm())
+
+        # TODO: Fix transposed writes to output.
+        assert_allclose(output.permute([0, 2, 1]), torch_ref)