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| author | goldsteinn <35538541+goldsteinn@users.noreply.github.com> | 2024-10-29 07:41:59 -0700 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-10-29 09:41:59 -0500 |
| commit | 2e612f8d868b3fb88a44964a3d4efd61ee63e06a (patch) | |
| tree | d21945696fa80ad6697847bf5382d993741b50a1 | |
| parent | a388df712700f38ad9a51d49a657a28e739f5eb4 (diff) | |
| download | llvm-2e612f8d868b3fb88a44964a3d4efd61ee63e06a.zip llvm-2e612f8d868b3fb88a44964a3d4efd61ee63e06a.tar.gz llvm-2e612f8d868b3fb88a44964a3d4efd61ee63e06a.tar.bz2 | |
[MLIR][Arith] Improve accuracy of `inferDivU` (#113789)
1) We can always bound the maximum with the numerator.
- https://alive2.llvm.org/ce/z/PqHvuT
2) Even if denominator min can be zero, we can still bound the minimum
result with `lhs.umin u/ rhs.umax`.
This is similar to https://github.com/llvm/llvm-project/pull/110169
| -rw-r--r-- | mlir/lib/Interfaces/Utils/InferIntRangeCommon.cpp | 10 | ||||
| -rw-r--r-- | mlir/test/Dialect/Arith/int-range-interface.mlir | 21 |
2 files changed, 25 insertions, 6 deletions
diff --git a/mlir/lib/Interfaces/Utils/InferIntRangeCommon.cpp b/mlir/lib/Interfaces/Utils/InferIntRangeCommon.cpp index ec9ed87..a2acf3e 100644 --- a/mlir/lib/Interfaces/Utils/InferIntRangeCommon.cpp +++ b/mlir/lib/Interfaces/Utils/InferIntRangeCommon.cpp @@ -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 diff --git a/mlir/test/Dialect/Arith/int-range-interface.mlir b/mlir/test/Dialect/Arith/int-range-interface.mlir index 4b04229..6d66da2 100644 --- a/mlir/test/Dialect/Arith/int-range-interface.mlir +++ b/mlir/test/Dialect/Arith/int-range-interface.mlir @@ -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 @@ -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]] @@ -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 |