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392 lines
12 KiB
C++
392 lines
12 KiB
C++
//===-- ConstantRange.cpp - ConstantRange implementation ------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Represent a range of possible values that may occur when the program is run
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// for an integral value. This keeps track of a lower and upper bound for the
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// constant, which MAY wrap around the end of the numeric range. To do this, it
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// keeps track of a [lower, upper) bound, which specifies an interval just like
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// STL iterators. When used with boolean values, the following are important
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// ranges (other integral ranges use min/max values for special range values):
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//
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// [F, F) = {} = Empty set
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// [T, F) = {T}
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// [F, T) = {F}
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// [T, T) = {F, T} = Full set
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/ConstantRange.h"
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#include "llvm/Support/Streams.h"
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#include <ostream>
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using namespace llvm;
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/// Initialize a full (the default) or empty set for the specified type.
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///
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ConstantRange::ConstantRange(uint32_t BitWidth, bool Full) :
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Lower(BitWidth, 0), Upper(BitWidth, 0) {
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if (Full)
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Lower = Upper = APInt::getMaxValue(BitWidth);
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else
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Lower = Upper = APInt::getMinValue(BitWidth);
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}
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/// Initialize a range to hold the single specified value.
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///
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ConstantRange::ConstantRange(const APInt & V) : Lower(V), Upper(V + 1) { }
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ConstantRange::ConstantRange(const APInt &L, const APInt &U) :
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Lower(L), Upper(U) {
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assert(L.getBitWidth() == U.getBitWidth() &&
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"ConstantRange with unequal bit widths");
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assert((L != U || (L.isMaxValue() || L.isMinValue())) &&
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"Lower == Upper, but they aren't min or max value!");
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}
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/// isFullSet - Return true if this set contains all of the elements possible
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/// for this data-type
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bool ConstantRange::isFullSet() const {
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return Lower == Upper && Lower.isMaxValue();
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}
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/// isEmptySet - Return true if this set contains no members.
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///
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bool ConstantRange::isEmptySet() const {
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return Lower == Upper && Lower.isMinValue();
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}
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/// isWrappedSet - Return true if this set wraps around the top of the range,
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/// for example: [100, 8)
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///
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bool ConstantRange::isWrappedSet() const {
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return Lower.ugt(Upper);
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}
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/// getSetSize - Return the number of elements in this set.
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///
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APInt ConstantRange::getSetSize() const {
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if (isEmptySet())
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return APInt(getBitWidth(), 0);
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if (getBitWidth() == 1) {
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if (Lower != Upper) // One of T or F in the set...
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return APInt(2, 1);
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return APInt(2, 2); // Must be full set...
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}
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// Simply subtract the bounds...
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return Upper - Lower;
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}
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/// getUnsignedMax - Return the largest unsigned value contained in the
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/// ConstantRange.
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///
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APInt ConstantRange::getUnsignedMax() const {
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if (isFullSet() || isWrappedSet())
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return APInt::getMaxValue(getBitWidth());
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else
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return getUpper() - 1;
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}
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/// getUnsignedMin - Return the smallest unsigned value contained in the
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/// ConstantRange.
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///
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APInt ConstantRange::getUnsignedMin() const {
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if (isFullSet() || (isWrappedSet() && getUpper() != 0))
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return APInt::getMinValue(getBitWidth());
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else
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return getLower();
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}
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/// getSignedMax - Return the largest signed value contained in the
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/// ConstantRange.
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///
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APInt ConstantRange::getSignedMax() const {
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APInt SignedMax(APInt::getSignedMaxValue(getBitWidth()));
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if (!isWrappedSet()) {
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if (getLower().slt(getUpper() - 1))
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return getUpper() - 1;
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else
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return SignedMax;
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} else {
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if ((getUpper() - 1).slt(getLower())) {
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if (getLower() != SignedMax)
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return SignedMax;
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else
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return getUpper() - 1;
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} else {
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return getUpper() - 1;
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}
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}
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}
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/// getSignedMin - Return the smallest signed value contained in the
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/// ConstantRange.
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///
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APInt ConstantRange::getSignedMin() const {
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APInt SignedMin(APInt::getSignedMinValue(getBitWidth()));
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if (!isWrappedSet()) {
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if (getLower().slt(getUpper() - 1))
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return getLower();
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else
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return SignedMin;
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} else {
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if ((getUpper() - 1).slt(getLower())) {
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if (getUpper() != SignedMin)
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return SignedMin;
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else
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return getLower();
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} else {
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return getLower();
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}
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}
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}
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/// contains - Return true if the specified value is in the set.
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///
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bool ConstantRange::contains(const APInt &V) const {
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if (Lower == Upper)
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return isFullSet();
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if (!isWrappedSet())
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return Lower.ule(V) && V.ult(Upper);
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else
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return Lower.ule(V) || V.ult(Upper);
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}
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/// subtract - Subtract the specified constant from the endpoints of this
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/// constant range.
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ConstantRange ConstantRange::subtract(const APInt &Val) const {
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assert(Val.getBitWidth() == getBitWidth() && "Wrong bit width");
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// If the set is empty or full, don't modify the endpoints.
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if (Lower == Upper)
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return *this;
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return ConstantRange(Lower - Val, Upper - Val);
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}
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// intersect1Wrapped - This helper function is used to intersect two ranges when
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// it is known that LHS is wrapped and RHS isn't.
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//
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ConstantRange
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ConstantRange::intersect1Wrapped(const ConstantRange &LHS,
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const ConstantRange &RHS) {
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assert(LHS.isWrappedSet() && !RHS.isWrappedSet());
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// Check to see if we overlap on the Left side of RHS...
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//
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if (RHS.Lower.ult(LHS.Upper)) {
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// We do overlap on the left side of RHS, see if we overlap on the right of
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// RHS...
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if (RHS.Upper.ugt(LHS.Lower)) {
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// Ok, the result overlaps on both the left and right sides. See if the
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// resultant interval will be smaller if we wrap or not...
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//
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if (LHS.getSetSize().ult(RHS.getSetSize()))
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return LHS;
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else
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return RHS;
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} else {
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// No overlap on the right, just on the left.
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return ConstantRange(RHS.Lower, LHS.Upper);
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}
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} else {
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// We don't overlap on the left side of RHS, see if we overlap on the right
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// of RHS...
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if (RHS.Upper.ugt(LHS.Lower)) {
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// Simple overlap...
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return ConstantRange(LHS.Lower, RHS.Upper);
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} else {
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// No overlap...
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return ConstantRange(LHS.getBitWidth(), false);
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}
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}
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}
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/// intersectWith - Return the range that results from the intersection of this
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/// range with another range.
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///
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ConstantRange ConstantRange::intersectWith(const ConstantRange &CR) const {
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assert(getBitWidth() == CR.getBitWidth() &&
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"ConstantRange types don't agree!");
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// Handle common special cases
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if (isEmptySet() || CR.isFullSet())
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return *this;
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if (isFullSet() || CR.isEmptySet())
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return CR;
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if (!isWrappedSet()) {
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if (!CR.isWrappedSet()) {
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using namespace APIntOps;
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APInt L = umax(Lower, CR.Lower);
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APInt U = umin(Upper, CR.Upper);
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if (L.ult(U)) // If range isn't empty...
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return ConstantRange(L, U);
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else
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return ConstantRange(getBitWidth(), false);// Otherwise, empty set
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} else
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return intersect1Wrapped(CR, *this);
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} else { // We know "this" is wrapped...
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if (!CR.isWrappedSet())
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return intersect1Wrapped(*this, CR);
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else {
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// Both ranges are wrapped...
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using namespace APIntOps;
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APInt L = umax(Lower, CR.Lower);
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APInt U = umin(Upper, CR.Upper);
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return ConstantRange(L, U);
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}
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}
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return *this;
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}
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/// unionWith - Return the range that results from the union of this range with
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/// another range. The resultant range is guaranteed to include the elements of
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/// both sets, but may contain more. For example, [3, 9) union [12,15) is
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/// [3, 15), which includes 9, 10, and 11, which were not included in either
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/// set before.
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///
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ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
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assert(getBitWidth() == CR.getBitWidth() &&
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"ConstantRange types don't agree!");
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if ( isFullSet() || CR.isEmptySet()) return *this;
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if (CR.isFullSet() || isEmptySet()) return CR;
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if (!isWrappedSet() && CR.isWrappedSet()) return CR.unionWith(*this);
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APInt L = Lower, U = Upper;
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if (!isWrappedSet() && !CR.isWrappedSet()) {
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if (CR.Lower.ult(L))
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L = CR.Lower;
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if (CR.Upper.ugt(U))
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U = CR.Upper;
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}
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if (isWrappedSet() && !CR.isWrappedSet()) {
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if ((CR.Lower.ult(Upper) && CR.Upper.ult(Upper)) ||
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(CR.Lower.ugt(Lower) && CR.Upper.ugt(Lower))) {
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return *this;
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}
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if (CR.Lower.ule(Upper) && Lower.ule(CR.Upper)) {
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return ConstantRange(getBitWidth());
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}
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if (CR.Lower.ule(Upper) && CR.Upper.ule(Lower)) {
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APInt d1 = CR.Upper - Upper, d2 = Lower - CR.Upper;
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if (d1.ult(d2)) {
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U = CR.Upper;
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} else {
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L = CR.Upper;
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}
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}
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if (Upper.ult(CR.Lower) && CR.Upper.ult(Lower)) {
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APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Upper;
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if (d1.ult(d2)) {
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U = CR.Lower + 1;
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} else {
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L = CR.Upper - 1;
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}
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}
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if (Upper.ult(CR.Lower) && Lower.ult(CR.Upper)) {
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APInt d1 = CR.Lower - Upper, d2 = Lower - CR.Lower;
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if (d1.ult(d2)) {
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U = CR.Lower + 1;
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} else {
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L = CR.Lower;
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}
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}
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}
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if (isWrappedSet() && CR.isWrappedSet()) {
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if (Lower.ult(CR.Upper) || CR.Lower.ult(Upper))
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return ConstantRange(getBitWidth());
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if (CR.Upper.ugt(U)) {
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U = CR.Upper;
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}
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if (CR.Lower.ult(L)) {
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L = CR.Lower;
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}
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if (L == U) return ConstantRange(getBitWidth());
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}
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return ConstantRange(L, U);
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}
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/// zeroExtend - Return a new range in the specified integer type, which must
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/// be strictly larger than the current type. The returned range will
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/// correspond to the possible range of values as if the source range had been
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/// zero extended.
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ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
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unsigned SrcTySize = getBitWidth();
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assert(SrcTySize < DstTySize && "Not a value extension");
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if (isFullSet())
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// Change a source full set into [0, 1 << 8*numbytes)
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return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
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APInt L = Lower; L.zext(DstTySize);
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APInt U = Upper; U.zext(DstTySize);
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return ConstantRange(L, U);
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}
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/// signExtend - Return a new range in the specified integer type, which must
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/// be strictly larger than the current type. The returned range will
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/// correspond to the possible range of values as if the source range had been
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/// sign extended.
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ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
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unsigned SrcTySize = getBitWidth();
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assert(SrcTySize < DstTySize && "Not a value extension");
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if (isFullSet()) {
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return ConstantRange(APInt::getHighBitsSet(DstTySize,DstTySize-SrcTySize+1),
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APInt::getLowBitsSet(DstTySize, SrcTySize-1));
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}
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APInt L = Lower; L.sext(DstTySize);
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APInt U = Upper; U.sext(DstTySize);
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return ConstantRange(L, U);
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}
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/// truncate - Return a new range in the specified integer type, which must be
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/// strictly smaller than the current type. The returned range will
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/// correspond to the possible range of values as if the source range had been
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/// truncated to the specified type.
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ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
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unsigned SrcTySize = getBitWidth();
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assert(SrcTySize > DstTySize && "Not a value truncation");
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APInt Size(APInt::getLowBitsSet(SrcTySize, DstTySize));
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if (isFullSet() || getSetSize().ugt(Size))
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return ConstantRange(DstTySize);
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APInt L = Lower; L.trunc(DstTySize);
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APInt U = Upper; U.trunc(DstTySize);
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return ConstantRange(L, U);
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}
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/// print - Print out the bounds to a stream...
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///
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void ConstantRange::print(std::ostream &OS) const {
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OS << "[" << Lower.toStringSigned(10) << ","
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<< Upper.toStringSigned(10) << " )";
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}
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/// dump - Allow printing from a debugger easily...
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///
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void ConstantRange::dump() const {
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print(cerr);
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}
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