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Mar 22, 2024
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[mlir][arith] fix wrong floordivsi fold (#83079) #83248

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ec294c9
[mlir][arith] fix wrong floordivsi fold (#83079)
lipracer Mar 11, 2024
1217ab5
add more corner test
lipracer Mar 21, 2024
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36 changes: 5 additions & 31 deletions mlir/lib/Dialect/Arith/IR/ArithOps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -689,43 +689,17 @@ OpFoldResult arith::FloorDivSIOp::fold(FoldAdaptor adaptor) {
return getLhs();

// Don't fold if it would overflow or if it requires a division by zero.
bool overflowOrDiv0 = false;
bool overflowOrDiv = false;
auto result = constFoldBinaryOp<IntegerAttr>(
adaptor.getOperands(), [&](APInt a, const APInt &b) {
if (overflowOrDiv0 || !b) {
overflowOrDiv0 = true;
if (b.isZero()) {
overflowOrDiv = true;
return a;
}
if (!a)
return a;
// After this point we know that neither a or b are zero.
unsigned bits = a.getBitWidth();
APInt zero = APInt::getZero(bits);
bool aGtZero = a.sgt(zero);
bool bGtZero = b.sgt(zero);
if (aGtZero && bGtZero) {
// Both positive, return a / b.
return a.sdiv_ov(b, overflowOrDiv0);
}
if (!aGtZero && !bGtZero) {
// Both negative, return -a / -b.
APInt posA = zero.ssub_ov(a, overflowOrDiv0);
APInt posB = zero.ssub_ov(b, overflowOrDiv0);
return posA.sdiv_ov(posB, overflowOrDiv0);
}
if (!aGtZero && bGtZero) {
// A is negative, b is positive, return - ceil(-a, b).
APInt posA = zero.ssub_ov(a, overflowOrDiv0);
APInt ceil = signedCeilNonnegInputs(posA, b, overflowOrDiv0);
return zero.ssub_ov(ceil, overflowOrDiv0);
}
// A is positive, b is negative, return - ceil(a, -b).
APInt posB = zero.ssub_ov(b, overflowOrDiv0);
APInt ceil = signedCeilNonnegInputs(a, posB, overflowOrDiv0);
return zero.ssub_ov(ceil, overflowOrDiv0);
return a.sfloordiv_ov(b, overflowOrDiv);
});

return overflowOrDiv0 ? Attribute() : result;
return overflowOrDiv ? Attribute() : result;
}

//===----------------------------------------------------------------------===//
Expand Down
58 changes: 25 additions & 33 deletions mlir/lib/Dialect/Arith/Transforms/ExpandOps.cpp
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Expand Up @@ -110,9 +110,13 @@ struct CeilDivSIOpConverter : public OpRewritePattern<arith::CeilDivSIOp> {
}
};

/// Expands FloorDivSIOp (n, m) into
/// 1) x = (m<0) ? 1 : -1
/// 2) return (n*m<0) ? - ((-n+x) / m) -1 : n / m
/// Expands FloorDivSIOp (x, y) into
/// z = x / y
/// if (z * y != x && (x < 0) != (y < 0)) {
/// return z - 1;
/// } else {
/// return z;
/// }
struct FloorDivSIOpConverter : public OpRewritePattern<arith::FloorDivSIOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(arith::FloorDivSIOp op,
Expand All @@ -121,41 +125,29 @@ struct FloorDivSIOpConverter : public OpRewritePattern<arith::FloorDivSIOp> {
Type type = op.getType();
Value a = op.getLhs();
Value b = op.getRhs();
Value plusOne = createConst(loc, type, 1, rewriter);

Value quotient = rewriter.create<arith::DivSIOp>(loc, a, b);
Value product = rewriter.create<arith::MulIOp>(loc, quotient, b);
Value notEqualDivisor = rewriter.create<arith::CmpIOp>(
loc, arith::CmpIPredicate::ne, a, product);
Value zero = createConst(loc, type, 0, rewriter);
Value minusOne = createConst(loc, type, -1, rewriter);
// Compute x = (b<0) ? 1 : -1.
Value compare =
rewriter.create<arith::CmpIOp>(loc, arith::CmpIPredicate::slt, b, zero);
Value x = rewriter.create<arith::SelectOp>(loc, compare, plusOne, minusOne);
// Compute negative res: -1 - ((x-a)/b).
Value xMinusA = rewriter.create<arith::SubIOp>(loc, x, a);
Value xMinusADivB = rewriter.create<arith::DivSIOp>(loc, xMinusA, b);
Value negRes = rewriter.create<arith::SubIOp>(loc, minusOne, xMinusADivB);
// Compute positive res: a/b.
Value posRes = rewriter.create<arith::DivSIOp>(loc, a, b);
// Result is (a*b<0) ? negative result : positive result.
// Note, we want to avoid using a*b because of possible overflow.
// The case that matters are a>0, a==0, a<0, b>0 and b<0. We do
// not particuliarly care if a*b<0 is true or false when b is zero
// as this will result in an illegal divide. So `a*b<0` can be reformulated
// as `(a>0 && b<0) || (a>0 && b<0)' or `(a>0 && b<0) || (a>0 && b<=0)'.
// We pick the first expression here.

Value aNeg =
rewriter.create<arith::CmpIOp>(loc, arith::CmpIPredicate::slt, a, zero);
Value aPos =
rewriter.create<arith::CmpIOp>(loc, arith::CmpIPredicate::sgt, a, zero);
Value bNeg =
rewriter.create<arith::CmpIOp>(loc, arith::CmpIPredicate::slt, b, zero);
Value bPos =
rewriter.create<arith::CmpIOp>(loc, arith::CmpIPredicate::sgt, b, zero);
Value firstTerm = rewriter.create<arith::AndIOp>(loc, aNeg, bPos);
Value secondTerm = rewriter.create<arith::AndIOp>(loc, aPos, bNeg);
Value compareRes =
rewriter.create<arith::OrIOp>(loc, firstTerm, secondTerm);
// Perform substitution and return success.
rewriter.replaceOpWithNewOp<arith::SelectOp>(op, compareRes, negRes,
posRes);

Value signOpposite = rewriter.create<arith::CmpIOp>(
loc, arith::CmpIPredicate::ne, aNeg, bNeg);
Value cond =
rewriter.create<arith::AndIOp>(loc, notEqualDivisor, signOpposite);

Value minusOne = createConst(loc, type, -1, rewriter);
Value quotientMinusOne =
rewriter.create<arith::AddIOp>(loc, quotient, minusOne);

rewriter.replaceOpWithNewOp<arith::SelectOp>(op, cond, quotientMinusOne,
quotient);
return success();
}
};
Expand Down
84 changes: 33 additions & 51 deletions mlir/test/Dialect/Arith/expand-ops.mlir
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Expand Up @@ -66,23 +66,17 @@ func.func @ceildivi_index(%arg0: index, %arg1: index) -> (index) {
func.func @floordivi(%arg0: i32, %arg1: i32) -> (i32) {
%res = arith.floordivsi %arg0, %arg1 : i32
return %res : i32
// CHECK: [[ONE:%.+]] = arith.constant 1 : i32
// CHECK: [[ZERO:%.+]] = arith.constant 0 : i32
// CHECK: [[MIN1:%.+]] = arith.constant -1 : i32
// CHECK: [[CMP1:%.+]] = arith.cmpi slt, [[ARG1]], [[ZERO]] : i32
// CHECK: [[X:%.+]] = arith.select [[CMP1]], [[ONE]], [[MIN1]] : i32
// CHECK: [[TRUE1:%.+]] = arith.subi [[X]], [[ARG0]] : i32
// CHECK: [[TRUE2:%.+]] = arith.divsi [[TRUE1]], [[ARG1]] : i32
// CHECK: [[TRUE3:%.+]] = arith.subi [[MIN1]], [[TRUE2]] : i32
// CHECK: [[FALSE:%.+]] = arith.divsi [[ARG0]], [[ARG1]] : i32
// CHECK: [[NNEG:%.+]] = arith.cmpi slt, [[ARG0]], [[ZERO]] : i32
// CHECK: [[NPOS:%.+]] = arith.cmpi sgt, [[ARG0]], [[ZERO]] : i32
// CHECK: [[MNEG:%.+]] = arith.cmpi slt, [[ARG1]], [[ZERO]] : i32
// CHECK: [[MPOS:%.+]] = arith.cmpi sgt, [[ARG1]], [[ZERO]] : i32
// CHECK: [[TERM1:%.+]] = arith.andi [[NNEG]], [[MPOS]] : i1
// CHECK: [[TERM2:%.+]] = arith.andi [[NPOS]], [[MNEG]] : i1
// CHECK: [[CMP2:%.+]] = arith.ori [[TERM1]], [[TERM2]] : i1
// CHECK: [[RES:%.+]] = arith.select [[CMP2]], [[TRUE3]], [[FALSE]] : i32
// CHECK: %[[QUOTIENT:.*]] = arith.divsi %arg0, %arg1 : i32
// CHECK: %[[PRODUCT:.*]] = arith.muli %[[QUOTIENT]], %arg1 : i32
// CHECK: %[[NOT_EQ_PRODUCT:.*]] = arith.cmpi ne, %arg0, %[[PRODUCT]] : i32
// CHECK-DAG: %[[ZERO:.*]] = arith.constant 0 : i32
// CHECK: %[[NEG_DIVISOR:.*]] = arith.cmpi slt, %arg0, %[[ZERO]] : i32
// CHECK: %[[NEG_DIVIDEND:.*]] = arith.cmpi slt, %arg1, %[[ZERO]] : i32
// CHECK: %[[OPPOSITE_SIGN:.*]] = arith.cmpi ne, %[[NEG_DIVISOR]], %[[NEG_DIVIDEND]] : i1
// CHECK: %[[CONDITION:.*]] = arith.andi %[[NOT_EQ_PRODUCT]], %[[OPPOSITE_SIGN]] : i1
// CHECK-DAG: %[[NEG_ONE:.*]] = arith.constant -1 : i32
// CHECK: %[[MINUS_ONE:.*]] = arith.addi %[[QUOTIENT]], %[[NEG_ONE]] : i32
// CHECK: %[[RES:.*]] = arith.select %[[CONDITION]], %[[MINUS_ONE]], %[[QUOTIENT]] : i32
}

// -----
Expand All @@ -93,23 +87,17 @@ func.func @floordivi(%arg0: i32, %arg1: i32) -> (i32) {
func.func @floordivi_index(%arg0: index, %arg1: index) -> (index) {
%res = arith.floordivsi %arg0, %arg1 : index
return %res : index
// CHECK: [[ONE:%.+]] = arith.constant 1 : index
// CHECK: [[ZERO:%.+]] = arith.constant 0 : index
// CHECK: [[MIN1:%.+]] = arith.constant -1 : index
// CHECK: [[CMP1:%.+]] = arith.cmpi slt, [[ARG1]], [[ZERO]] : index
// CHECK: [[X:%.+]] = arith.select [[CMP1]], [[ONE]], [[MIN1]] : index
// CHECK: [[TRUE1:%.+]] = arith.subi [[X]], [[ARG0]] : index
// CHECK: [[TRUE2:%.+]] = arith.divsi [[TRUE1]], [[ARG1]] : index
// CHECK: [[TRUE3:%.+]] = arith.subi [[MIN1]], [[TRUE2]] : index
// CHECK: [[FALSE:%.+]] = arith.divsi [[ARG0]], [[ARG1]] : index
// CHECK: [[NNEG:%.+]] = arith.cmpi slt, [[ARG0]], [[ZERO]] : index
// CHECK: [[NPOS:%.+]] = arith.cmpi sgt, [[ARG0]], [[ZERO]] : index
// CHECK: [[MNEG:%.+]] = arith.cmpi slt, [[ARG1]], [[ZERO]] : index
// CHECK: [[MPOS:%.+]] = arith.cmpi sgt, [[ARG1]], [[ZERO]] : index
// CHECK: [[TERM1:%.+]] = arith.andi [[NNEG]], [[MPOS]] : i1
// CHECK: [[TERM2:%.+]] = arith.andi [[NPOS]], [[MNEG]] : i1
// CHECK: [[CMP2:%.+]] = arith.ori [[TERM1]], [[TERM2]] : i1
// CHECK: [[RES:%.+]] = arith.select [[CMP2]], [[TRUE3]], [[FALSE]] : index
// CHECK: %[[QUOTIENT:.*]] = arith.divsi %arg0, %arg1 : index
// CHECK: %[[PRODUCT:.*]] = arith.muli %[[QUOTIENT]], %arg1 : index
// CHECK: %[[NOT_EQ_PRODUCT:.*]] = arith.cmpi ne, %arg0, %[[PRODUCT]] : index
// CHECK-DAG: %[[ZERO:.*]] = arith.constant 0 : index
// CHECK: %[[NEG_DIVISOR:.*]] = arith.cmpi slt, %arg0, %[[ZERO]] : index
// CHECK: %[[NEG_DIVIDEND:.*]] = arith.cmpi slt, %arg1, %[[ZERO]] : index
// CHECK: %[[OPPOSITE_SIGN:.*]] = arith.cmpi ne, %[[NEG_DIVISOR]], %[[NEG_DIVIDEND]] : i1
// CHECK: %[[CONDITION:.*]] = arith.andi %[[NOT_EQ_PRODUCT]], %[[OPPOSITE_SIGN]] : i1
// CHECK: %[[NEG_ONE:.*]] = arith.constant -1 : index
// CHECK-DAG: %[[MINUS_ONE:.*]] = arith.addi %[[QUOTIENT]], %[[NEG_ONE]] : index
// CHECK: %[[RES:.*]] = arith.select %[[CONDITION]], %[[MINUS_ONE]], %[[QUOTIENT]] : index
}

// -----
Expand All @@ -121,23 +109,17 @@ func.func @floordivi_index(%arg0: index, %arg1: index) -> (index) {
func.func @floordivi_vec(%arg0: vector<4xi32>, %arg1: vector<4xi32>) -> (vector<4xi32>) {
%res = arith.floordivsi %arg0, %arg1 : vector<4xi32>
return %res : vector<4xi32>
// CHECK: %[[VAL_2:.*]] = arith.constant dense<1> : vector<4xi32>
// CHECK: %[[VAL_3:.*]] = arith.constant dense<0> : vector<4xi32>
// CHECK: %[[VAL_4:.*]] = arith.constant dense<-1> : vector<4xi32>
// CHECK: %[[VAL_5:.*]] = arith.cmpi slt, %[[VAL_1]], %[[VAL_3]] : vector<4xi32>
// CHECK: %[[VAL_6:.*]] = arith.select %[[VAL_5]], %[[VAL_2]], %[[VAL_4]] : vector<4xi1>, vector<4xi32>
// CHECK: %[[VAL_7:.*]] = arith.subi %[[VAL_6]], %[[VAL_0]] : vector<4xi32>
// CHECK: %[[VAL_8:.*]] = arith.divsi %[[VAL_7]], %[[VAL_1]] : vector<4xi32>
// CHECK: %[[VAL_9:.*]] = arith.subi %[[VAL_4]], %[[VAL_8]] : vector<4xi32>
// CHECK: %[[VAL_10:.*]] = arith.divsi %[[VAL_0]], %[[VAL_1]] : vector<4xi32>
// CHECK: %[[VAL_11:.*]] = arith.cmpi slt, %[[VAL_0]], %[[VAL_3]] : vector<4xi32>
// CHECK: %[[VAL_12:.*]] = arith.cmpi sgt, %[[VAL_0]], %[[VAL_3]] : vector<4xi32>
// CHECK: %[[VAL_13:.*]] = arith.cmpi slt, %[[VAL_1]], %[[VAL_3]] : vector<4xi32>
// CHECK: %[[VAL_14:.*]] = arith.cmpi sgt, %[[VAL_1]], %[[VAL_3]] : vector<4xi32>
// CHECK: %[[VAL_15:.*]] = arith.andi %[[VAL_11]], %[[VAL_14]] : vector<4xi1>
// CHECK: %[[VAL_16:.*]] = arith.andi %[[VAL_12]], %[[VAL_13]] : vector<4xi1>
// CHECK: %[[VAL_17:.*]] = arith.ori %[[VAL_15]], %[[VAL_16]] : vector<4xi1>
// CHECK: %[[VAL_18:.*]] = arith.select %[[VAL_17]], %[[VAL_9]], %[[VAL_10]] : vector<4xi1>, vector<4xi32>
// CHECK: %[[QUOTIENT:.*]] = arith.divsi %arg0, %arg1 : vector<4xi32>
// CHECK: %[[PRODUCT:.*]] = arith.muli %[[QUOTIENT]], %arg1 : vector<4xi32>
// CHECK: %[[NOT_EQ_PRODUCT:.*]] = arith.cmpi ne, %arg0, %[[PRODUCT]] : vector<4xi32>
// CHECK-DAG: %[[ZERO:.*]] = arith.constant dense<0> : vector<4xi32>
// CHECK: %[[NEG_DIVISOR:.*]] = arith.cmpi slt, %arg0, %[[ZERO]] : vector<4xi32>
// CHECK: %[[NEG_DIVIDEND:.*]] = arith.cmpi slt, %arg1, %[[ZERO]] : vector<4xi32>
// CHECK: %[[OPPOSITE_SIGN:.*]] = arith.cmpi ne, %[[NEG_DIVISOR]], %[[NEG_DIVIDEND]] : vector<4xi1>
// CHECK: %[[CONDITION:.*]] = arith.andi %[[NOT_EQ_PRODUCT]], %[[OPPOSITE_SIGN]] : vector<4xi1>
// CHECK-DAG: %[[NEG_ONE:.*]] = arith.constant dense<-1> : vector<4xi32>
// CHECK: %[[MINUS_ONE:.*]] = arith.addi %[[QUOTIENT]], %[[NEG_ONE]] : vector<4xi32>
// CHECK: %[[RES:.*]] = arith.select %[[CONDITION]], %[[MINUS_ONE]], %[[QUOTIENT]] : vector<4xi1>, vector<4xi32>
}

// -----
Expand Down
30 changes: 30 additions & 0 deletions mlir/test/Integration/Dialect/Standard/CPU/test-ceil-floor-pos-neg.mlir
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,10 @@
// RUN: mlir-cpu-runner -e entry -entry-point-result=void \
// RUN: -shared-libs=%mlir_c_runner_utils | \
// RUN: FileCheck %s
// RUN: mlir-opt %s -pass-pipeline="builtin.module(func.func(convert-vector-to-scf,lower-affine,convert-scf-to-cf,memref-expand,arith-expand),convert-vector-to-llvm,finalize-memref-to-llvm,convert-func-to-llvm,reconcile-unrealized-casts)" | \
// RUN: mlir-cpu-runner -e main -entry-point-result=void \
// RUN: -shared-libs=%mlir_c_runner_utils | \
// RUN: FileCheck %s --check-prefix=SCHECK

func.func @transfer_read_2d(%A : memref<40xi32>, %base1: index) {
%i42 = arith.constant -42: i32
Expand Down Expand Up @@ -101,3 +105,29 @@ func.func @entry() {
// CHECK:( 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -2, -2, -2, -2, -2, -2, -2 )
// CHECK:( 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4 )
// CHECK:( 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 )

// -----

func.func @non_inline_function() -> (i64, i64, i64, i64, i64, i64) {
%MIN_INT_MINUS_ONE = arith.constant -9223372036854775807 : i64
%NEG_ONE = arith.constant -1 : i64
%MIN_INT = arith.constant -9223372036854775808 : i64
%ONE = arith.constant 1 : i64
%MAX_INT = arith.constant 9223372036854775807 : i64
return %MIN_INT_MINUS_ONE, %NEG_ONE, %MIN_INT, %ONE, %MAX_INT, %NEG_ONE : i64, i64, i64, i64, i64, i64
}

func.func @main() {
%0:6 = call @non_inline_function() : () -> (i64, i64, i64, i64, i64, i64)
%1 = arith.floordivsi %0#0, %0#1 : i64
%2 = arith.floordivsi %0#2, %0#3 : i64
%3 = arith.floordivsi %0#4, %0#5 : i64
vector.print %1 : i64
vector.print %2 : i64
vector.print %3 : i64
return
}

// SCHECK: 9223372036854775807
// SCHECK: -9223372036854775808
// SCHECK: -9223372036854775807
9 changes: 9 additions & 0 deletions mlir/test/Transforms/canonicalize.mlir
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Expand Up @@ -989,6 +989,15 @@ func.func @tensor_arith.floordivsi_by_one(%arg0: tensor<4x5xi32>) -> tensor<4x5x
return %res : tensor<4x5xi32>
}

// CHECK-LABEL: func @arith.floordivsi_by_one_overflow
func.func @arith.floordivsi_by_one_overflow() -> i64 {
%neg_one = arith.constant -1 : i64
%min_int = arith.constant -9223372036854775808 : i64
// CHECK: arith.floordivsi
%poision = arith.floordivsi %min_int, %neg_one : i64
return %poision : i64
}

// -----

// CHECK-LABEL: func @arith.ceildivsi_by_one
Expand Down