forked from OSchip/llvm-project
Adds loop attribute as a temporary work around to prevent slice fusion of loop nests containing instructions with side effects (the proper solution will be do use memref read/write regions in the future).
PiperOrigin-RevId: 236733739
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@ -435,6 +435,7 @@ static Instruction *getInstAtPosition(ArrayRef<unsigned> positions,
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return nullptr;
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}
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const char *const kSliceFusionBarrierAttrName = "slice_fusion_barrier";
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// Computes memref dependence between 'srcAccess' and 'dstAccess', projects
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// out any dst loop IVs at depth greater than 'dstLoopDepth', and computes slice
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// bounds in 'sliceState' which represent the src IVs in terms of the dst IVs,
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@ -491,16 +492,20 @@ bool mlir::getBackwardComputationSliceState(const MemRefAccess &srcAccess,
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sliceState->lbOperands.resize(numSrcLoopIVs, sliceBoundOperands);
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sliceState->ubOperands.resize(numSrcLoopIVs, sliceBoundOperands);
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// For read-read access pairs, clear any slice bounds on sequential loops.
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if (readReadAccesses) {
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// Get sequential loops in loop nest rooted at 'srcLoopIVs[0]'.
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llvm::SmallDenseSet<Value *, 8> sequentialLoops;
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if (readReadAccesses) {
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// For read-read access pairs, clear any slice bounds on sequential loops.
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// Get sequential loops in loop nest rooted at 'srcLoopIVs[0]'.
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getSequentialLoops(srcLoopIVs[0], &sequentialLoops);
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// Clear all sliced loop bounds beginning at the first sequential loop.
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}
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// Clear all sliced loop bounds beginning at the first sequential loop, or
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// first loop with a slice fusion barrier attribute..
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// TODO(andydavis, bondhugula) Use MemRef read/write regions instead of
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// using 'kSliceFusionBarrierAttrName'.
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for (unsigned i = 0; i < numSrcLoopIVs; ++i) {
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Value *iv = srcLoopIVs[i]->getInductionVar();
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if (sequentialLoops.count(iv) == 0)
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if (sequentialLoops.count(iv) == 0 &&
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srcLoopIVs[i]->getAttr(kSliceFusionBarrierAttrName) == nullptr)
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continue;
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for (unsigned j = i; j < numSrcLoopIVs; ++j) {
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sliceState->lbs[j] = AffineMap();
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@ -508,7 +513,7 @@ bool mlir::getBackwardComputationSliceState(const MemRefAccess &srcAccess,
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}
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break;
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}
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}
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return true;
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}
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@ -2062,3 +2062,40 @@ func @two_matrix_vector_products() {
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// CHECK-NEXT: return
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return
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}
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// -----
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// CHECK-DAG: [[MAP3:#map[0-9]+]] = (d0, d1, d2) -> (-d0 + d1)
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// CHECK-DAG: [[MAP4:#map[0-9]+]] = (d0, d1, d2) -> (d2)
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func @should_not_slice_past_slice_barrier() {
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%0 = alloc() : memref<100x16xf32>
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for %i0 = 0 to 100 {
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for %i1 = 0 to 16 {
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%1 = "op1"() : () -> f32
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store %1, %0[%i0, %i1] : memref<100x16xf32>
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} {slice_fusion_barrier: true}
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}
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for %i2 = 0 to 100 {
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for %i3 = 0 to 16 {
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%2 = load %0[%i2, %i3] : memref<100x16xf32>
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"op2"(%2) : (f32) -> ()
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}
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}
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// The 'slice_fusion_barrier' attribute on '%i1' prevents slicing the
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// iteration space of '%i1' and any enclosing loop nests.
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// CHECK: for %i0 = 0 to 100 {
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// CHECK-NEXT: for %i1 = 0 to 16 {
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// CHECK-NEXT: %1 = "op1"() : () -> f32
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// CHECK-NEXT: %2 = affine.apply [[MAP3]](%i0, %i0, %i1)
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// CHECK-NEXT: %3 = affine.apply [[MAP4]](%i0, %i0, %i1)
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// CHECK-NEXT: store %1, %0[%2, %3] : memref<1x16xf32>
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// CHECK-NEXT: } {slice_fusion_barrier: true}
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// CHECK-NEXT: for %i2 = 0 to 16 {
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// CHECK-NEXT: %4 = affine.apply [[MAP3]](%i0, %i0, %i2)
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// CHECK-NEXT: %5 = affine.apply [[MAP4]](%i0, %i0, %i2)
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// CHECK-NEXT: %6 = load %0[%4, %5] : memref<1x16xf32>
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// CHECK-NEXT: "op2"(%6) : (f32) -> ()
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// CHECK-NEXT: }
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// CHECK-NEXT: }
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return
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}
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