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[FXML-1991] Reciprocal Constant Folding For a Splat Tensor #32

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Merged
merged 5 commits into from
May 16, 2023
Merged

[FXML-1991] Reciprocal Constant Folding For a Splat Tensor #32

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987f02e
feat(TosaCanonicalizations): add reciprocal folding for constants
May 9, 2023
3f33917
test(constant-op-fold.mlir): add reciprocal folding case
May 9, 2023
c366cad
fix(TosaCanonicalizations.cpp): remove accidental condition statement
May 11, 2023
8914fd1
style(TosaCanonicalizations.cpp): use free-function version of dyn_cast
May 11, 2023
17885ab
refactor(TosaCanonicalizations.cpp): use TOSA semantics for fp
May 11, 2023
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2 changes: 2 additions & 0 deletions mlir/include/mlir/Dialect/Tosa/IR/TosaOps.td
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Original file line number Diff line number Diff line change
Expand Up @@ -1057,6 +1057,8 @@ def Tosa_ReciprocalOp : Tosa_Op<"reciprocal", [
let results = (outs
Tosa_Tensor:$output
);

let hasFolder = 1;
}

//===----------------------------------------------------------------------===//
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20 changes: 20 additions & 0 deletions mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
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Expand Up @@ -629,6 +629,26 @@ OpFoldResult MulOp::fold(ArrayRef<Attribute> operands) {
return mulBinaryFolder(lhsAttr, rhsAttr, lhsTy, getShift());
}

OpFoldResult ReciprocalOp::fold(ArrayRef<Attribute> operands) {
auto constantAttr = dyn_cast_or_null<DenseElementsAttr>(operands[0]);
auto lhsTy = dyn_cast<RankedTensorType>(getInput1().getType());

if (!lhsTy || !constantAttr) {
return {};
}

if (!constantAttr.isSplat()) {
return {};
}

auto floatVal = constantAttr.getSplatValue<llvm::APFloat>();

auto recipAttr = FloatAttr::get(lhsTy.getElementType(), 1.0);
APFloat recip = recipAttr.getValue();
recip.divide(floatVal, APFloat::rmNearestTiesToEven);
return DenseElementsAttr::get(lhsTy, recip);
}

OpFoldResult SubOp::fold(ArrayRef<Attribute> operands) {
auto lhsTy = getInput1().getType().dyn_cast<RankedTensorType>();
auto rhsTy = getInput2().getType().dyn_cast<RankedTensorType>();
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23 changes: 23 additions & 0 deletions mlir/test/Dialect/Tosa/constant-op-fold.mlir
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Expand Up @@ -306,6 +306,29 @@ func.func @fold_mul_splat_f32() -> tensor<10xf32> {

// -----

// CHECK-LABEL: @fold_reciprocal_splat_f32
func.func @fold_reciprocal_splat_f32() -> tensor<f32> {
%half = "tosa.const"() {value = dense<0.5> : tensor<f32>} : () -> tensor<f32>
%recp = "tosa.reciprocal"(%half) : (tensor<f32>) -> tensor<f32>
// CHECK: %[[CST:.*]] = "tosa.const"() {value = dense<2.000000e+00> : tensor<f32>}
// CHECK: return %[[CST]]
return %recp : tensor<f32>
}

// -----

// CHECK-LABEL: @fold_reciprocal_splat_zero_f32
func.func @fold_reciprocal_splat_zero_f32() -> tensor<f32> {
%zero = "tosa.const"() {value = dense<0.0> : tensor<f32>} : () -> tensor<f32>
%recp = "tosa.reciprocal"(%zero) : (tensor<f32>) -> tensor<f32>
// 0x7F800000 represents +inf as we have computed 1/0
// CHECK: %[[CST:.*]] = "tosa.const"() {value = dense<0x7F800000> : tensor<f32>}
// CHECK: return %[[CST]]
return %recp : tensor<f32>
}

// -----

// CHECK-LABEL: @fold_sub_zero_rhs_f32
func.func @fold_sub_zero_rhs_f32(%arg0: tensor<f32>) -> tensor<f32> {
%zero = "tosa.const"() {value = dense<0.0> : tensor<f32>} : () -> tensor<f32>
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