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InferIntRangeCommon.cpp
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InferIntRangeCommon.cpp
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//===- InferIntRangeCommon.cpp - Inference for common ops ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains implementations of range inference for operations that are
// common to both the `arith` and `index` dialects to facilitate reuse.
//
//===----------------------------------------------------------------------===//
#include "mlir/Interfaces/Utils/InferIntRangeCommon.h"
#include "mlir/Interfaces/InferIntRangeInterface.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
#include <iterator>
#include <optional>
using namespace mlir;
#define DEBUG_TYPE "int-range-analysis"
//===----------------------------------------------------------------------===//
// General utilities
//===----------------------------------------------------------------------===//
/// Function that evaluates the result of doing something on arithmetic
/// constants and returns std::nullopt on overflow.
using ConstArithFn =
function_ref<std::optional<APInt>(const APInt &, const APInt &)>;
/// Compute op(minLeft, minRight) and op(maxLeft, maxRight) if possible,
/// If either computation overflows, make the result unbounded.
static ConstantIntRanges computeBoundsBy(ConstArithFn op, const APInt &minLeft,
const APInt &minRight,
const APInt &maxLeft,
const APInt &maxRight, bool isSigned) {
std::optional<APInt> maybeMin = op(minLeft, minRight);
std::optional<APInt> maybeMax = op(maxLeft, maxRight);
if (maybeMin && maybeMax)
return ConstantIntRanges::range(*maybeMin, *maybeMax, isSigned);
return ConstantIntRanges::maxRange(minLeft.getBitWidth());
}
/// Compute the minimum and maximum of `(op(l, r) for l in lhs for r in rhs)`,
/// ignoring unbounded values. Returns the maximal range if `op` overflows.
static ConstantIntRanges minMaxBy(ConstArithFn op, ArrayRef<APInt> lhs,
ArrayRef<APInt> rhs, bool isSigned) {
unsigned width = lhs[0].getBitWidth();
APInt min =
isSigned ? APInt::getSignedMaxValue(width) : APInt::getMaxValue(width);
APInt max =
isSigned ? APInt::getSignedMinValue(width) : APInt::getZero(width);
for (const APInt &left : lhs) {
for (const APInt &right : rhs) {
std::optional<APInt> maybeThisResult = op(left, right);
if (!maybeThisResult)
return ConstantIntRanges::maxRange(width);
APInt result = std::move(*maybeThisResult);
min = (isSigned ? result.slt(min) : result.ult(min)) ? result : min;
max = (isSigned ? result.sgt(max) : result.ugt(max)) ? result : max;
}
}
return ConstantIntRanges::range(min, max, isSigned);
}
//===----------------------------------------------------------------------===//
// Ext, trunc, index op handling
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferIndexOp(InferRangeFn inferFn,
ArrayRef<ConstantIntRanges> argRanges,
intrange::CmpMode mode) {
ConstantIntRanges sixtyFour = inferFn(argRanges);
SmallVector<ConstantIntRanges, 2> truncated;
llvm::transform(argRanges, std::back_inserter(truncated),
[](const ConstantIntRanges &range) {
return truncRange(range, /*destWidth=*/indexMinWidth);
});
ConstantIntRanges thirtyTwo = inferFn(truncated);
ConstantIntRanges thirtyTwoAsSixtyFour =
extRange(thirtyTwo, /*destWidth=*/indexMaxWidth);
ConstantIntRanges sixtyFourAsThirtyTwo =
truncRange(sixtyFour, /*destWidth=*/indexMinWidth);
LLVM_DEBUG(llvm::dbgs() << "Index handling: 64-bit result = " << sixtyFour
<< " 32-bit = " << thirtyTwo << "\n");
bool truncEqual = false;
switch (mode) {
case intrange::CmpMode::Both:
truncEqual = (thirtyTwo == sixtyFourAsThirtyTwo);
break;
case intrange::CmpMode::Signed:
truncEqual = (thirtyTwo.smin() == sixtyFourAsThirtyTwo.smin() &&
thirtyTwo.smax() == sixtyFourAsThirtyTwo.smax());
break;
case intrange::CmpMode::Unsigned:
truncEqual = (thirtyTwo.umin() == sixtyFourAsThirtyTwo.umin() &&
thirtyTwo.umax() == sixtyFourAsThirtyTwo.umax());
break;
}
if (truncEqual)
// Returing the 64-bit result preserves more information.
return sixtyFour;
ConstantIntRanges merged = sixtyFour.rangeUnion(thirtyTwoAsSixtyFour);
return merged;
}
ConstantIntRanges mlir::intrange::extRange(const ConstantIntRanges &range,
unsigned int destWidth) {
APInt umin = range.umin().zext(destWidth);
APInt umax = range.umax().zext(destWidth);
APInt smin = range.smin().sext(destWidth);
APInt smax = range.smax().sext(destWidth);
return {umin, umax, smin, smax};
}
ConstantIntRanges mlir::intrange::extUIRange(const ConstantIntRanges &range,
unsigned destWidth) {
APInt umin = range.umin().zext(destWidth);
APInt umax = range.umax().zext(destWidth);
return ConstantIntRanges::fromUnsigned(umin, umax);
}
ConstantIntRanges mlir::intrange::extSIRange(const ConstantIntRanges &range,
unsigned destWidth) {
APInt smin = range.smin().sext(destWidth);
APInt smax = range.smax().sext(destWidth);
return ConstantIntRanges::fromSigned(smin, smax);
}
ConstantIntRanges mlir::intrange::truncRange(const ConstantIntRanges &range,
unsigned int destWidth) {
// If you truncate the first four bytes in [0xaaaabbbb, 0xccccbbbb],
// the range of the resulting value is not contiguous ind includes 0.
// Ex. If you truncate [256, 258] from i16 to i8, you validly get [0, 2],
// but you can't truncate [255, 257] similarly.
bool hasUnsignedRollover =
range.umin().lshr(destWidth) != range.umax().lshr(destWidth);
APInt umin = hasUnsignedRollover ? APInt::getZero(destWidth)
: range.umin().trunc(destWidth);
APInt umax = hasUnsignedRollover ? APInt::getMaxValue(destWidth)
: range.umax().trunc(destWidth);
// Signed post-truncation rollover will not occur when either:
// - The high parts of the min and max, plus the sign bit, are the same
// - The high halves + sign bit of the min and max are either all 1s or all 0s
// and you won't create a [positive, negative] range by truncating.
// For example, you can truncate the ranges [256, 258]_i16 to [0, 2]_i8
// but not [255, 257]_i16 to a range of i8s. You can also truncate
// [-256, -256]_i16 to [-2, 0]_i8, but not [-257, -255]_i16.
// You can also truncate [-130, 0]_i16 to i8 because -130_i16 (0xff7e)
// will truncate to 0x7e, which is greater than 0
APInt sminHighPart = range.smin().ashr(destWidth - 1);
APInt smaxHighPart = range.smax().ashr(destWidth - 1);
bool hasSignedOverflow =
(sminHighPart != smaxHighPart) &&
!(sminHighPart.isAllOnes() &&
(smaxHighPart.isAllOnes() || smaxHighPart.isZero())) &&
!(sminHighPart.isZero() && smaxHighPart.isZero());
APInt smin = hasSignedOverflow ? APInt::getSignedMinValue(destWidth)
: range.smin().trunc(destWidth);
APInt smax = hasSignedOverflow ? APInt::getSignedMaxValue(destWidth)
: range.smax().trunc(destWidth);
return {umin, umax, smin, smax};
}
//===----------------------------------------------------------------------===//
// Addition
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferAdd(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
ConstArithFn uadd = [](const APInt &a,
const APInt &b) -> std::optional<APInt> {
bool overflowed = false;
APInt result = a.uadd_ov(b, overflowed);
return overflowed ? std::optional<APInt>() : result;
};
ConstArithFn sadd = [](const APInt &a,
const APInt &b) -> std::optional<APInt> {
bool overflowed = false;
APInt result = a.sadd_ov(b, overflowed);
return overflowed ? std::optional<APInt>() : result;
};
ConstantIntRanges urange = computeBoundsBy(
uadd, lhs.umin(), rhs.umin(), lhs.umax(), rhs.umax(), /*isSigned=*/false);
ConstantIntRanges srange = computeBoundsBy(
sadd, lhs.smin(), rhs.smin(), lhs.smax(), rhs.smax(), /*isSigned=*/true);
return urange.intersection(srange);
}
//===----------------------------------------------------------------------===//
// Subtraction
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferSub(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
ConstArithFn usub = [](const APInt &a,
const APInt &b) -> std::optional<APInt> {
bool overflowed = false;
APInt result = a.usub_ov(b, overflowed);
return overflowed ? std::optional<APInt>() : result;
};
ConstArithFn ssub = [](const APInt &a,
const APInt &b) -> std::optional<APInt> {
bool overflowed = false;
APInt result = a.ssub_ov(b, overflowed);
return overflowed ? std::optional<APInt>() : result;
};
ConstantIntRanges urange = computeBoundsBy(
usub, lhs.umin(), rhs.umax(), lhs.umax(), rhs.umin(), /*isSigned=*/false);
ConstantIntRanges srange = computeBoundsBy(
ssub, lhs.smin(), rhs.smax(), lhs.smax(), rhs.smin(), /*isSigned=*/true);
return urange.intersection(srange);
}
//===----------------------------------------------------------------------===//
// Multiplication
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferMul(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
ConstArithFn umul = [](const APInt &a,
const APInt &b) -> std::optional<APInt> {
bool overflowed = false;
APInt result = a.umul_ov(b, overflowed);
return overflowed ? std::optional<APInt>() : result;
};
ConstArithFn smul = [](const APInt &a,
const APInt &b) -> std::optional<APInt> {
bool overflowed = false;
APInt result = a.smul_ov(b, overflowed);
return overflowed ? std::optional<APInt>() : result;
};
ConstantIntRanges urange =
minMaxBy(umul, {lhs.umin(), lhs.umax()}, {rhs.umin(), rhs.umax()},
/*isSigned=*/false);
ConstantIntRanges srange =
minMaxBy(smul, {lhs.smin(), lhs.smax()}, {rhs.smin(), rhs.smax()},
/*isSigned=*/true);
return urange.intersection(srange);
}
//===----------------------------------------------------------------------===//
// DivU, CeilDivU (Unsigned division)
//===----------------------------------------------------------------------===//
/// Fix up division results (ex. for ceiling and floor), returning an APInt
/// if there has been no overflow
using DivisionFixupFn = function_ref<std::optional<APInt>(
const APInt &lhs, const APInt &rhs, const APInt &result)>;
static ConstantIntRanges inferDivURange(const ConstantIntRanges &lhs,
const ConstantIntRanges &rhs,
DivisionFixupFn fixup) {
const APInt &lhsMin = lhs.umin(), &lhsMax = lhs.umax(), &rhsMin = rhs.umin(),
&rhsMax = rhs.umax();
if (!rhsMin.isZero()) {
auto udiv = [&fixup](const APInt &a,
const APInt &b) -> std::optional<APInt> {
return fixup(a, b, a.udiv(b));
};
return minMaxBy(udiv, {lhsMin, lhsMax}, {rhsMin, rhsMax},
/*isSigned=*/false);
}
// Otherwise, it's possible we might divide by 0.
return ConstantIntRanges::maxRange(rhsMin.getBitWidth());
}
ConstantIntRanges
mlir::intrange::inferDivU(ArrayRef<ConstantIntRanges> argRanges) {
return inferDivURange(argRanges[0], argRanges[1],
[](const APInt &lhs, const APInt &rhs,
const APInt &result) { return result; });
}
ConstantIntRanges
mlir::intrange::inferCeilDivU(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
DivisionFixupFn ceilDivUIFix =
[](const APInt &lhs, const APInt &rhs,
const APInt &result) -> std::optional<APInt> {
if (!lhs.urem(rhs).isZero()) {
bool overflowed = false;
APInt corrected =
result.uadd_ov(APInt(result.getBitWidth(), 1), overflowed);
return overflowed ? std::optional<APInt>() : corrected;
}
return result;
};
return inferDivURange(lhs, rhs, ceilDivUIFix);
}
//===----------------------------------------------------------------------===//
// DivS, CeilDivS, FloorDivS (Signed division)
//===----------------------------------------------------------------------===//
static ConstantIntRanges inferDivSRange(const ConstantIntRanges &lhs,
const ConstantIntRanges &rhs,
DivisionFixupFn fixup) {
const APInt &lhsMin = lhs.smin(), &lhsMax = lhs.smax(), &rhsMin = rhs.smin(),
&rhsMax = rhs.smax();
bool canDivide = rhsMin.isStrictlyPositive() || rhsMax.isNegative();
if (canDivide) {
auto sdiv = [&fixup](const APInt &a,
const APInt &b) -> std::optional<APInt> {
bool overflowed = false;
APInt result = a.sdiv_ov(b, overflowed);
return overflowed ? std::optional<APInt>() : fixup(a, b, result);
};
return minMaxBy(sdiv, {lhsMin, lhsMax}, {rhsMin, rhsMax},
/*isSigned=*/true);
}
return ConstantIntRanges::maxRange(rhsMin.getBitWidth());
}
ConstantIntRanges
mlir::intrange::inferDivS(ArrayRef<ConstantIntRanges> argRanges) {
return inferDivSRange(argRanges[0], argRanges[1],
[](const APInt &lhs, const APInt &rhs,
const APInt &result) { return result; });
}
ConstantIntRanges
mlir::intrange::inferCeilDivS(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
DivisionFixupFn ceilDivSIFix =
[](const APInt &lhs, const APInt &rhs,
const APInt &result) -> std::optional<APInt> {
if (!lhs.srem(rhs).isZero() && lhs.isNonNegative() == rhs.isNonNegative()) {
bool overflowed = false;
APInt corrected =
result.sadd_ov(APInt(result.getBitWidth(), 1), overflowed);
return overflowed ? std::optional<APInt>() : corrected;
}
return result;
};
return inferDivSRange(lhs, rhs, ceilDivSIFix);
}
ConstantIntRanges
mlir::intrange::inferFloorDivS(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
DivisionFixupFn floorDivSIFix =
[](const APInt &lhs, const APInt &rhs,
const APInt &result) -> std::optional<APInt> {
if (!lhs.srem(rhs).isZero() && lhs.isNonNegative() != rhs.isNonNegative()) {
bool overflowed = false;
APInt corrected =
result.ssub_ov(APInt(result.getBitWidth(), 1), overflowed);
return overflowed ? std::optional<APInt>() : corrected;
}
return result;
};
return inferDivSRange(lhs, rhs, floorDivSIFix);
}
//===----------------------------------------------------------------------===//
// Signed remainder (RemS)
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferRemS(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
const APInt &lhsMin = lhs.smin(), &lhsMax = lhs.smax(), &rhsMin = rhs.smin(),
&rhsMax = rhs.smax();
unsigned width = rhsMax.getBitWidth();
APInt smin = APInt::getSignedMinValue(width);
APInt smax = APInt::getSignedMaxValue(width);
// No bounds if zero could be a divisor.
bool canBound = (rhsMin.isStrictlyPositive() || rhsMax.isNegative());
if (canBound) {
APInt maxDivisor = rhsMin.isStrictlyPositive() ? rhsMax : rhsMin.abs();
bool canNegativeDividend = lhsMin.isNegative();
bool canPositiveDividend = lhsMax.isStrictlyPositive();
APInt zero = APInt::getZero(maxDivisor.getBitWidth());
APInt maxPositiveResult = maxDivisor - 1;
APInt minNegativeResult = -maxPositiveResult;
smin = canNegativeDividend ? minNegativeResult : zero;
smax = canPositiveDividend ? maxPositiveResult : zero;
// Special case: sweeping out a contiguous range in N/[modulus].
if (rhsMin == rhsMax) {
if ((lhsMax - lhsMin).ult(maxDivisor)) {
APInt minRem = lhsMin.srem(maxDivisor);
APInt maxRem = lhsMax.srem(maxDivisor);
if (minRem.sle(maxRem)) {
smin = minRem;
smax = maxRem;
}
}
}
}
return ConstantIntRanges::fromSigned(smin, smax);
}
//===----------------------------------------------------------------------===//
// Unsigned remainder (RemU)
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferRemU(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
const APInt &rhsMin = rhs.umin(), &rhsMax = rhs.umax();
unsigned width = rhsMin.getBitWidth();
APInt umin = APInt::getZero(width);
APInt umax = APInt::getMaxValue(width);
if (!rhsMin.isZero()) {
umax = rhsMax - 1;
// Special case: sweeping out a contiguous range in N/[modulus]
if (rhsMin == rhsMax) {
const APInt &lhsMin = lhs.umin(), &lhsMax = lhs.umax();
if ((lhsMax - lhsMin).ult(rhsMax)) {
APInt minRem = lhsMin.urem(rhsMax);
APInt maxRem = lhsMax.urem(rhsMax);
if (minRem.ule(maxRem)) {
umin = minRem;
umax = maxRem;
}
}
}
}
return ConstantIntRanges::fromUnsigned(umin, umax);
}
//===----------------------------------------------------------------------===//
// Max and min (MaxS, MaxU, MinS, MinU)
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferMaxS(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
const APInt &smin = lhs.smin().sgt(rhs.smin()) ? lhs.smin() : rhs.smin();
const APInt &smax = lhs.smax().sgt(rhs.smax()) ? lhs.smax() : rhs.smax();
return ConstantIntRanges::fromSigned(smin, smax);
}
ConstantIntRanges
mlir::intrange::inferMaxU(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
const APInt &umin = lhs.umin().ugt(rhs.umin()) ? lhs.umin() : rhs.umin();
const APInt &umax = lhs.umax().ugt(rhs.umax()) ? lhs.umax() : rhs.umax();
return ConstantIntRanges::fromUnsigned(umin, umax);
}
ConstantIntRanges
mlir::intrange::inferMinS(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
const APInt &smin = lhs.smin().slt(rhs.smin()) ? lhs.smin() : rhs.smin();
const APInt &smax = lhs.smax().slt(rhs.smax()) ? lhs.smax() : rhs.smax();
return ConstantIntRanges::fromSigned(smin, smax);
}
ConstantIntRanges
mlir::intrange::inferMinU(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
const APInt &umin = lhs.umin().ult(rhs.umin()) ? lhs.umin() : rhs.umin();
const APInt &umax = lhs.umax().ult(rhs.umax()) ? lhs.umax() : rhs.umax();
return ConstantIntRanges::fromUnsigned(umin, umax);
}
//===----------------------------------------------------------------------===//
// Bitwise operators (And, Or, Xor)
//===----------------------------------------------------------------------===//
/// "Widen" bounds - if 0bvvvvv??? <= a <= 0bvvvvv???,
/// relax the bounds to 0bvvvvv000 <= a <= 0bvvvvv111, where vvvvv are the bits
/// that both bonuds have in common. This gives us a consertive approximation
/// for what values can be passed to bitwise operations.
static std::tuple<APInt, APInt>
widenBitwiseBounds(const ConstantIntRanges &bound) {
APInt leftVal = bound.umin(), rightVal = bound.umax();
unsigned bitwidth = leftVal.getBitWidth();
unsigned differingBits = bitwidth - (leftVal ^ rightVal).countl_zero();
leftVal.clearLowBits(differingBits);
rightVal.setLowBits(differingBits);
return std::make_tuple(std::move(leftVal), std::move(rightVal));
}
ConstantIntRanges
mlir::intrange::inferAnd(ArrayRef<ConstantIntRanges> argRanges) {
auto [lhsZeros, lhsOnes] = widenBitwiseBounds(argRanges[0]);
auto [rhsZeros, rhsOnes] = widenBitwiseBounds(argRanges[1]);
auto andi = [](const APInt &a, const APInt &b) -> std::optional<APInt> {
return a & b;
};
return minMaxBy(andi, {lhsZeros, lhsOnes}, {rhsZeros, rhsOnes},
/*isSigned=*/false);
}
ConstantIntRanges
mlir::intrange::inferOr(ArrayRef<ConstantIntRanges> argRanges) {
auto [lhsZeros, lhsOnes] = widenBitwiseBounds(argRanges[0]);
auto [rhsZeros, rhsOnes] = widenBitwiseBounds(argRanges[1]);
auto ori = [](const APInt &a, const APInt &b) -> std::optional<APInt> {
return a | b;
};
return minMaxBy(ori, {lhsZeros, lhsOnes}, {rhsZeros, rhsOnes},
/*isSigned=*/false);
}
ConstantIntRanges
mlir::intrange::inferXor(ArrayRef<ConstantIntRanges> argRanges) {
auto [lhsZeros, lhsOnes] = widenBitwiseBounds(argRanges[0]);
auto [rhsZeros, rhsOnes] = widenBitwiseBounds(argRanges[1]);
auto xori = [](const APInt &a, const APInt &b) -> std::optional<APInt> {
return a ^ b;
};
return minMaxBy(xori, {lhsZeros, lhsOnes}, {rhsZeros, rhsOnes},
/*isSigned=*/false);
}
//===----------------------------------------------------------------------===//
// Shifts (Shl, ShrS, ShrU)
//===----------------------------------------------------------------------===//
ConstantIntRanges
mlir::intrange::inferShl(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
ConstArithFn shl = [](const APInt &l,
const APInt &r) -> std::optional<APInt> {
return r.uge(r.getBitWidth()) ? std::optional<APInt>() : l.shl(r);
};
ConstantIntRanges urange =
minMaxBy(shl, {lhs.umin(), lhs.umax()}, {rhs.umin(), rhs.umax()},
/*isSigned=*/false);
ConstantIntRanges srange =
minMaxBy(shl, {lhs.smin(), lhs.smax()}, {rhs.umin(), rhs.umax()},
/*isSigned=*/true);
return urange.intersection(srange);
}
ConstantIntRanges
mlir::intrange::inferShrS(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
ConstArithFn ashr = [](const APInt &l,
const APInt &r) -> std::optional<APInt> {
return r.uge(r.getBitWidth()) ? std::optional<APInt>() : l.ashr(r);
};
return minMaxBy(ashr, {lhs.smin(), lhs.smax()}, {rhs.umin(), rhs.umax()},
/*isSigned=*/true);
}
ConstantIntRanges
mlir::intrange::inferShrU(ArrayRef<ConstantIntRanges> argRanges) {
const ConstantIntRanges &lhs = argRanges[0], &rhs = argRanges[1];
ConstArithFn lshr = [](const APInt &l,
const APInt &r) -> std::optional<APInt> {
return r.uge(r.getBitWidth()) ? std::optional<APInt>() : l.lshr(r);
};
return minMaxBy(lshr, {lhs.umin(), lhs.umax()}, {rhs.umin(), rhs.umax()},
/*isSigned=*/false);
}
//===----------------------------------------------------------------------===//
// Comparisons (Cmp)
//===----------------------------------------------------------------------===//
static intrange::CmpPredicate invertPredicate(intrange::CmpPredicate pred) {
switch (pred) {
case intrange::CmpPredicate::eq:
return intrange::CmpPredicate::ne;
case intrange::CmpPredicate::ne:
return intrange::CmpPredicate::eq;
case intrange::CmpPredicate::slt:
return intrange::CmpPredicate::sge;
case intrange::CmpPredicate::sle:
return intrange::CmpPredicate::sgt;
case intrange::CmpPredicate::sgt:
return intrange::CmpPredicate::sle;
case intrange::CmpPredicate::sge:
return intrange::CmpPredicate::slt;
case intrange::CmpPredicate::ult:
return intrange::CmpPredicate::uge;
case intrange::CmpPredicate::ule:
return intrange::CmpPredicate::ugt;
case intrange::CmpPredicate::ugt:
return intrange::CmpPredicate::ule;
case intrange::CmpPredicate::uge:
return intrange::CmpPredicate::ult;
}
llvm_unreachable("unknown cmp predicate value");
}
static bool isStaticallyTrue(intrange::CmpPredicate pred,
const ConstantIntRanges &lhs,
const ConstantIntRanges &rhs) {
switch (pred) {
case intrange::CmpPredicate::sle:
return lhs.smax().sle(rhs.smin());
case intrange::CmpPredicate::slt:
return lhs.smax().slt(rhs.smin());
case intrange::CmpPredicate::ule:
return lhs.umax().ule(rhs.umin());
case intrange::CmpPredicate::ult:
return lhs.umax().ult(rhs.umin());
case intrange::CmpPredicate::sge:
return lhs.smin().sge(rhs.smax());
case intrange::CmpPredicate::sgt:
return lhs.smin().sgt(rhs.smax());
case intrange::CmpPredicate::uge:
return lhs.umin().uge(rhs.umax());
case intrange::CmpPredicate::ugt:
return lhs.umin().ugt(rhs.umax());
case intrange::CmpPredicate::eq: {
std::optional<APInt> lhsConst = lhs.getConstantValue();
std::optional<APInt> rhsConst = rhs.getConstantValue();
return lhsConst && rhsConst && lhsConst == rhsConst;
}
case intrange::CmpPredicate::ne: {
// While equality requires that there is an interpration of the preceeding
// computations that produces equal constants, whether that be signed or
// unsigned, statically determining inequality requires that neither
// interpretation produce potentially overlapping ranges.
bool sne = isStaticallyTrue(intrange::CmpPredicate::slt, lhs, rhs) ||
isStaticallyTrue(intrange::CmpPredicate::sgt, lhs, rhs);
bool une = isStaticallyTrue(intrange::CmpPredicate::ult, lhs, rhs) ||
isStaticallyTrue(intrange::CmpPredicate::ugt, lhs, rhs);
return sne && une;
}
}
return false;
}
std::optional<bool> mlir::intrange::evaluatePred(CmpPredicate pred,
const ConstantIntRanges &lhs,
const ConstantIntRanges &rhs) {
if (isStaticallyTrue(pred, lhs, rhs))
return true;
if (isStaticallyTrue(invertPredicate(pred), lhs, rhs))
return false;
return std::nullopt;
}