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Restrict bitwise-op non-negativity to i1 results #2652

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Restrict bitwise-op non-negativity to i1 results #2652

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66bf201
Restrict bitwise-op non-negativity to i1 results
kimjune01 Jul 22, 2026
5592faf
Merge remote-tracking branch 'origin/main' into fix/nonneg-signed-bit…
kimjune01 Jul 24, 2026
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11 changes: 9 additions & 2 deletions src/enzyme_ad/jax/Utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -952,8 +952,15 @@ NonNegativeResultAnalysis::State NonNegativeResultAnalysis::localGuaranteed(

// integer ops
if (isa<stablehlo::AbsOp, stablehlo::SqrtOp, stablehlo::ExpOp,
stablehlo::IotaOp, stablehlo::AndOp, stablehlo::OrOp,
stablehlo::XorOp, stablehlo::NotOp>(op)) {
stablehlo::IotaOp>(op)) {
return State::GUARANTEED;
}

// Bitwise ops are non-negative only for boolean (i1) results: on a signed
// integer not(0) == -1, and or/xor/and can set the sign bit.
if (isa<stablehlo::AndOp, stablehlo::OrOp, stablehlo::XorOp,
stablehlo::NotOp>(op) &&
cast<ShapedType>(val.getType()).getElementType().isInteger(1)) {
return State::GUARANTEED;
}

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9 changes: 9 additions & 0 deletions test/lit_tests/abspositive.mlir
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Expand Up @@ -95,3 +95,12 @@ func.func @test8(%arg0: tensor<4xf64>) -> tensor<4xf64> {
// CHECK-NEXT: %0 = stablehlo.logistic %arg0 {enzymexla.non_negative = [#enzymexla<guaranteed GUARANTEED>]} : tensor<4xf64>
// CHECK-NEXT: return %0 : tensor<4xf64>
// CHECK-NEXT: }

// A bitwise op on a signed integer is NOT non-negative: not(0) == -1, so the
// abs must stay.
func.func @test_signed_bitwise(%arg0: tensor<4xi32>) -> tensor<4xi32> {
%0 = stablehlo.not %arg0 : tensor<4xi32>
// CHECK: stablehlo.abs
%1 = stablehlo.abs %0 : tensor<4xi32>
return %1 : tensor<4xi32>
}