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[MLIR][Arith] Improve accuracy of inferDivU #113789

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Merged
merged 2 commits into from
Oct 29, 2024
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[MLIR][Arith] Improve accuracy of inferDivU #113789

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ba4ba42
[MLIR][Arith] Add tests for improving accurate of `inferDivU`; NFC
goldsteinn Oct 25, 2024
c11ca14
[MLIR][Arith] Improve accuracy of `inferDivU`
goldsteinn Oct 25, 2024
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10 changes: 8 additions & 2 deletions mlir/lib/Interfaces/Utils/InferIntRangeCommon.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -298,8 +298,14 @@ static ConstantIntRanges inferDivURange(const ConstantIntRanges &lhs,
return minMaxBy(udiv, {lhsMin, lhsMax}, {rhsMin, rhsMax},
/*isSigned=*/false);
}
// Otherwise, it's possible we might divide by 0.
return ConstantIntRanges::maxRange(rhsMin.getBitWidth());

APInt umin = APInt::getZero(rhsMin.getBitWidth());
if (lhsMin.uge(rhsMax) && !rhsMax.isZero())
umin = lhsMin.udiv(rhsMax);

// X u/ Y u<= X.
APInt umax = lhsMax;
return ConstantIntRanges::fromUnsigned(umin, umax);
}

ConstantIntRanges
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21 changes: 17 additions & 4 deletions mlir/test/Dialect/Arith/int-range-interface.mlir
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Expand Up @@ -178,8 +178,8 @@ func.func @div_bounds_negative(%arg0 : index) -> i1 {
}

// CHECK-LABEL: func @div_zero_undefined
// CHECK: %[[ret:.*]] = arith.cmpi ule
// CHECK: return %[[ret]]
// CHECK: %[[true:.*]] = arith.constant true
// CHECK: return %[[true]]
func.func @div_zero_undefined(%arg0 : index) -> i1 {
%c0 = arith.constant 0 : index
%c1 = arith.constant 1 : index
Expand All @@ -190,6 +190,19 @@ func.func @div_zero_undefined(%arg0 : index) -> i1 {
func.return %2 : i1
}

// CHECK-LABEL: func @div_refine_min
// CHECK: %[[true:.*]] = arith.constant true
// CHECK: return %[[true]]
func.func @div_refine_min(%arg0 : index) -> i1 {
%c0 = arith.constant 1 : index
%c1 = arith.constant 2 : index
%c4 = arith.constant 4 : index
%0 = arith.andi %arg0, %c1 : index
%1 = arith.divui %c4, %0 : index
%2 = arith.cmpi uge, %1, %c0 : index
func.return %2 : i1
}

// CHECK-LABEL: func @ceil_divui
// CHECK: %[[ret:.*]] = arith.cmpi eq
// CHECK: return %[[ret]]
Expand Down Expand Up @@ -271,13 +284,13 @@ func.func @remui_base(%arg0 : index, %arg1 : index ) -> i1 {
// CHECK: return %[[true]]
func.func @remui_base_maybe_zero(%arg0 : index, %arg1 : index ) -> i1 {
%c4 = arith.constant 4 : index
%c5 = arith.constant 5 : index
%c5 = arith.constant 5 : index

%0 = arith.minui %arg1, %c4 : index
%1 = arith.remui %arg0, %0 : index
%2 = arith.cmpi ult, %1, %c5 : index
func.return %2 : i1
}
}

// CHECK-LABEL: func @remsi_base
// CHECK: %[[ret:.*]] = arith.cmpi sge
Expand Down
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