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[MLIR][Affine] Fix sibling fusion - missing check #126626

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Merged
merged 1 commit into from
Feb 13, 2025
Merged

[MLIR][Affine] Fix sibling fusion - missing check #126626

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41 changes: 29 additions & 12 deletions mlir/lib/Dialect/Affine/Transforms/LoopFusion.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1162,24 +1162,48 @@ struct GreedyFusion {
}

assert(bestDstLoopDepth > 0 && "Unexpected loop fusion depth");
assert(!depthSliceUnions[bestDstLoopDepth - 1].isEmpty() &&

const ComputationSliceState &bestSlice =
depthSliceUnions[bestDstLoopDepth - 1];
assert(!bestSlice.isEmpty() &&
"Fusion depth has no computed slice union");

// Do not perform sibling fusion if it isn't maximal. We always remove the
// sibling node and as such fusion shouldn't be performed if a part of the
// slice is used in the destination.
auto isMaximal = bestSlice.isMaximal();
if (!isMaximal.value_or(false)) {
LLVM_DEBUG(llvm::dbgs()
<< "Slice isn't maximal; not performing sibling fusion.\n");
continue;
}

// Check if source loop is being inserted in the innermost
// destination loop. Based on this, the fused loop may be optimized
// further inside `fuseLoops`.
bool isInnermostInsertion = (bestDstLoopDepth == dstLoopDepthTest);
// Fuse computation slice of 'sibLoopNest' into 'dstLoopNest'.
affine::fuseLoops(sibAffineForOp, dstAffineForOp,
depthSliceUnions[bestDstLoopDepth - 1],
affine::fuseLoops(sibAffineForOp, dstAffineForOp, bestSlice,
isInnermostInsertion);

auto dstForInst = cast<AffineForOp>(dstNode->op);
// Update operation position of fused loop nest (if needed).
if (insertPointInst != dstForInst) {
if (insertPointInst != dstForInst)
dstForInst->moveBefore(insertPointInst);
}

LLVM_DEBUG(llvm::dbgs()
<< "Fused sibling nest " << sibId << " into destination nest "
<< dstNode->id << " at depth " << bestDstLoopDepth << ":\n"
<< dstAffineForOp << "\n");

// Update data dependence graph state post fusion.
updateStateAfterSiblingFusion(sibNode, dstNode);

// Remove old sibling loop nest.
// Get op before we invalidate the MDG node.
Operation *op = sibNode->op;
mdg->removeNode(sibNode->id);
op->erase();
}
}

Expand Down Expand Up @@ -1321,13 +1345,6 @@ struct GreedyFusion {
mdg->addToNode(dstNode->id, dstLoopCollector.loadOpInsts,
dstLoopCollector.storeOpInsts, dstLoopCollector.memrefLoads,
dstLoopCollector.memrefStores, dstLoopCollector.memrefFrees);
// Remove old sibling loop nest if it no longer has outgoing dependence
// edges, and it does not write to a memref which escapes the block.
if (mdg->getOutEdgeCount(sibNode->id) == 0) {
Operation *op = sibNode->op;
mdg->removeNode(sibNode->id);
op->erase();
}
}

// Clean up any allocs with no users.
Expand Down
2 changes: 2 additions & 0 deletions mlir/test/Dialect/Affine/loop-fusion-2.mlir
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Expand Up @@ -389,6 +389,8 @@ func.func @should_fuse_init_loops_siblings_then_shared_producer(%arg0: memref<10

// -----

// Test sibling fusion of two matrix-vector products sharing the input matrix.

func.func @two_matrix_vector_products() {
%in_matrix = memref.alloc() : memref<10x10xf32>
%in_vec0 = memref.alloc() : memref<10xf32>
Expand Down
23 changes: 17 additions & 6 deletions mlir/test/Dialect/Affine/loop-fusion-4.mlir
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@@ -1,5 +1,7 @@
// RUN: mlir-opt -allow-unregistered-dialect %s -pass-pipeline='builtin.module(func.func(affine-loop-fusion{mode=producer}))' -split-input-file | FileCheck %s --check-prefix=PRODUCER-CONSUMER
// RUN: mlir-opt -allow-unregistered-dialect %s -pass-pipeline='builtin.module(func.func(affine-loop-fusion{fusion-maximal mode=sibling}))' -split-input-file | FileCheck %s --check-prefix=SIBLING-MAXIMAL
// All fusion: producer-consumer and sibling.
// RUN: mlir-opt -allow-unregistered-dialect %s -pass-pipeline='builtin.module(func.func(affine-loop-fusion))' -split-input-file | FileCheck %s --check-prefix=ALL
// RUN: mlir-opt -allow-unregistered-dialect %s -pass-pipeline='builtin.module(spirv.func(affine-loop-fusion{mode=producer}))' -split-input-file | FileCheck %s --check-prefix=SPIRV

// Part I of fusion tests in mlir/test/Transforms/loop-fusion.mlir.
Expand Down Expand Up @@ -108,6 +110,7 @@ func.func @check_src_dst_step(%m : memref<100xf32>,
func.func @reduce_add_non_maximal_f32_f32(%arg0: memref<64x64xf32, 1>, %arg1 : memref<1x64xf32, 1>, %arg2 : memref<1x64xf32, 1>) {
%cst_0 = arith.constant 0.000000e+00 : f32
%cst_1 = arith.constant 1.000000e+00 : f32
// This nest writes to %arg1 but can be eliminated post sibling fusion.
affine.for %arg3 = 0 to 1 {
affine.for %arg4 = 0 to 64 {
%accum = affine.for %arg5 = 0 to 64 iter_args (%prevAccum = %cst_0) -> f32 {
Expand Down Expand Up @@ -137,11 +140,11 @@ func.func @reduce_add_non_maximal_f32_f32(%arg0: memref<64x64xf32, 1>, %arg1 : m
// since the destination loop and source loop trip counts do not
// match.
// SIBLING-MAXIMAL: %[[cst_0:.*]] = arith.constant 0.000000e+00 : f32
// SIBLING-MAXIMAL-NEXT: %[[cst_1:.*]] = arith.constant 1.000000e+00 : f32
// SIBLING-MAXIMAL-NEXT: affine.for %[[idx_0:.*]]= 0 to 1 {
// SIBLING-MAXIMAL-NEXT: affine.for %[[idx_1:.*]] = 0 to 64 {
// SIBLING-MAXIMAL-NEXT: %[[result_1:.*]] = affine.for %[[idx_2:.*]] = 0 to 32 iter_args(%[[iter_0:.*]] = %[[cst_1]]) -> (f32) {
// SIBLING-MAXIMAL-NEXT: %[[result_0:.*]] = affine.for %[[idx_3:.*]] = 0 to 64 iter_args(%[[iter_1:.*]] = %[[cst_0]]) -> (f32) {
// SIBLING-MAXIMAL-NEXT: %[[cst_1:.*]] = arith.constant 1.000000e+00 : f32
// SIBLING-MAXIMAL-NEXT: affine.for %{{.*}} = 0 to 1 {
// SIBLING-MAXIMAL-NEXT: affine.for %{{.*}} = 0 to 64 {
// SIBLING-MAXIMAL-NEXT: affine.for %{{.*}} = 0 to 32 iter_args(%{{.*}} = %[[cst_1]]) -> (f32) {
// SIBLING-MAXIMAL-NEXT: affine.for %{{.*}} = 0 to 64 iter_args(%{{.*}} = %[[cst_0]]) -> (f32) {

// -----

Expand Down Expand Up @@ -315,11 +318,16 @@ func.func @same_memref_load_store(%producer : memref<32xf32>, %consumer: memref<
return
}

// -----

// PRODUCER-CONSUMER-LABEL: func @same_memref_load_multiple_stores
// ALL-LABEL: func @same_memref_load_multiple_stores
func.func @same_memref_load_multiple_stores(%producer : memref<32xf32>, %producer_2 : memref<32xf32>, %consumer: memref<16xf32>){
%cst = arith.constant 2.000000e+00 : f32
// Source isn't removed.
// Ensure that source isn't removed during both producer-consumer fusion and
// sibling fusion.
// PRODUCER-CONSUMER: affine.for %{{.*}} = 0 to 32
// ALL: affine.for %{{.*}} = 0 to 32
affine.for %arg3 = 0 to 32 {
%0 = affine.load %producer[%arg3] : memref<32xf32>
%2 = arith.mulf %0, %cst : f32
Expand All @@ -343,5 +351,8 @@ func.func @same_memref_load_multiple_stores(%producer : memref<32xf32>, %produce
// PRODUCER-CONSUMER-NEXT: arith.addf
// PRODUCER-CONSUMER-NEXT: affine.store
// PRODUCER-CONSUMER-NEXT: }
// ALL: affine.for %{{.*}} = 0 to 16
// ALL: mulf
// ALL: addf
return
}
3 changes: 3 additions & 0 deletions mlir/test/Dialect/Affine/loop-fusion.mlir
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Expand Up @@ -1206,6 +1206,9 @@ func.func @should_fuse_with_private_memref() {
// CHECK: affine.for %{{.*}} = 0 to 17 {
// CHECK-NEXT: affine.store %{{.*}}, %{{.*}}[0] : memref<1xf32>
// CHECK-NEXT: affine.load %{{.*}}[0] : memref<1xf32>
// CHECK-NEXT: }
// CHECK: affine.for %{{.*}} = 0 to 82 {
// CHECK-NEXT: affine.store %{{.*}}, %{{.*}}[0] : memref<1xf32>
// CHECK-NEXT: affine.load %{{.*}}[0] : memref<1xf32>
// CHECK-NEXT: }
// CHECK-NEXT: return
Expand Down