diff options
| author | Dimitry Andric <dim@FreeBSD.org> | 2019-12-20 19:53:05 +0000 |
|---|---|---|
| committer | Dimitry Andric <dim@FreeBSD.org> | 2019-12-20 19:53:05 +0000 |
| commit | 0b57cec536236d46e3dba9bd041533462f33dbb7 (patch) | |
| tree | 56229dbdbbf76d18580f72f789003db17246c8d9 /contrib/llvm/lib/Support/APInt.cpp | |
| parent | 718ef55ec7785aae63f98f8ca05dc07ed399c16d (diff) | |
Notes
Diffstat (limited to 'contrib/llvm/lib/Support/APInt.cpp')
| -rw-r--r-- | contrib/llvm/lib/Support/APInt.cpp | 2989 |
1 files changed, 0 insertions, 2989 deletions
diff --git a/contrib/llvm/lib/Support/APInt.cpp b/contrib/llvm/lib/Support/APInt.cpp deleted file mode 100644 index 43173311cd80..000000000000 --- a/contrib/llvm/lib/Support/APInt.cpp +++ /dev/null @@ -1,2989 +0,0 @@ -//===-- APInt.cpp - Implement APInt class ---------------------------------===// -// -// 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 implements a class to represent arbitrary precision integer -// constant values and provide a variety of arithmetic operations on them. -// -//===----------------------------------------------------------------------===// - -#include "llvm/ADT/APInt.h" -#include "llvm/ADT/ArrayRef.h" -#include "llvm/ADT/FoldingSet.h" -#include "llvm/ADT/Hashing.h" -#include "llvm/ADT/Optional.h" -#include "llvm/ADT/SmallString.h" -#include "llvm/ADT/StringRef.h" -#include "llvm/ADT/bit.h" -#include "llvm/Config/llvm-config.h" -#include "llvm/Support/Debug.h" -#include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/MathExtras.h" -#include "llvm/Support/raw_ostream.h" -#include <climits> -#include <cmath> -#include <cstdlib> -#include <cstring> -using namespace llvm; - -#define DEBUG_TYPE "apint" - -/// A utility function for allocating memory, checking for allocation failures, -/// and ensuring the contents are zeroed. -inline static uint64_t* getClearedMemory(unsigned numWords) { - uint64_t *result = new uint64_t[numWords]; - memset(result, 0, numWords * sizeof(uint64_t)); - return result; -} - -/// A utility function for allocating memory and checking for allocation -/// failure. The content is not zeroed. -inline static uint64_t* getMemory(unsigned numWords) { - return new uint64_t[numWords]; -} - -/// A utility function that converts a character to a digit. -inline static unsigned getDigit(char cdigit, uint8_t radix) { - unsigned r; - - if (radix == 16 || radix == 36) { - r = cdigit - '0'; - if (r <= 9) - return r; - - r = cdigit - 'A'; - if (r <= radix - 11U) - return r + 10; - - r = cdigit - 'a'; - if (r <= radix - 11U) - return r + 10; - - radix = 10; - } - - r = cdigit - '0'; - if (r < radix) - return r; - - return -1U; -} - - -void APInt::initSlowCase(uint64_t val, bool isSigned) { - U.pVal = getClearedMemory(getNumWords()); - U.pVal[0] = val; - if (isSigned && int64_t(val) < 0) - for (unsigned i = 1; i < getNumWords(); ++i) - U.pVal[i] = WORDTYPE_MAX; - clearUnusedBits(); -} - -void APInt::initSlowCase(const APInt& that) { - U.pVal = getMemory(getNumWords()); - memcpy(U.pVal, that.U.pVal, getNumWords() * APINT_WORD_SIZE); -} - -void APInt::initFromArray(ArrayRef<uint64_t> bigVal) { - assert(BitWidth && "Bitwidth too small"); - assert(bigVal.data() && "Null pointer detected!"); - if (isSingleWord()) - U.VAL = bigVal[0]; - else { - // Get memory, cleared to 0 - U.pVal = getClearedMemory(getNumWords()); - // Calculate the number of words to copy - unsigned words = std::min<unsigned>(bigVal.size(), getNumWords()); - // Copy the words from bigVal to pVal - memcpy(U.pVal, bigVal.data(), words * APINT_WORD_SIZE); - } - // Make sure unused high bits are cleared - clearUnusedBits(); -} - -APInt::APInt(unsigned numBits, ArrayRef<uint64_t> bigVal) - : BitWidth(numBits) { - initFromArray(bigVal); -} - -APInt::APInt(unsigned numBits, unsigned numWords, const uint64_t bigVal[]) - : BitWidth(numBits) { - initFromArray(makeArrayRef(bigVal, numWords)); -} - -APInt::APInt(unsigned numbits, StringRef Str, uint8_t radix) - : BitWidth(numbits) { - assert(BitWidth && "Bitwidth too small"); - fromString(numbits, Str, radix); -} - -void APInt::reallocate(unsigned NewBitWidth) { - // If the number of words is the same we can just change the width and stop. - if (getNumWords() == getNumWords(NewBitWidth)) { - BitWidth = NewBitWidth; - return; - } - - // If we have an allocation, delete it. - if (!isSingleWord()) - delete [] U.pVal; - - // Update BitWidth. - BitWidth = NewBitWidth; - - // If we are supposed to have an allocation, create it. - if (!isSingleWord()) - U.pVal = getMemory(getNumWords()); -} - -void APInt::AssignSlowCase(const APInt& RHS) { - // Don't do anything for X = X - if (this == &RHS) - return; - - // Adjust the bit width and handle allocations as necessary. - reallocate(RHS.getBitWidth()); - - // Copy the data. - if (isSingleWord()) - U.VAL = RHS.U.VAL; - else - memcpy(U.pVal, RHS.U.pVal, getNumWords() * APINT_WORD_SIZE); -} - -/// This method 'profiles' an APInt for use with FoldingSet. -void APInt::Profile(FoldingSetNodeID& ID) const { - ID.AddInteger(BitWidth); - - if (isSingleWord()) { - ID.AddInteger(U.VAL); - return; - } - - unsigned NumWords = getNumWords(); - for (unsigned i = 0; i < NumWords; ++i) - ID.AddInteger(U.pVal[i]); -} - -/// Prefix increment operator. Increments the APInt by one. -APInt& APInt::operator++() { - if (isSingleWord()) - ++U.VAL; - else - tcIncrement(U.pVal, getNumWords()); - return clearUnusedBits(); -} - -/// Prefix decrement operator. Decrements the APInt by one. -APInt& APInt::operator--() { - if (isSingleWord()) - --U.VAL; - else - tcDecrement(U.pVal, getNumWords()); - return clearUnusedBits(); -} - -/// Adds the RHS APint to this APInt. -/// @returns this, after addition of RHS. -/// Addition assignment operator. -APInt& APInt::operator+=(const APInt& RHS) { - assert(BitWidth == RHS.BitWidth && "Bit widths must be the same"); - if (isSingleWord()) - U.VAL += RHS.U.VAL; - else - tcAdd(U.pVal, RHS.U.pVal, 0, getNumWords()); - return clearUnusedBits(); -} - -APInt& APInt::operator+=(uint64_t RHS) { - if (isSingleWord()) - U.VAL += RHS; - else - tcAddPart(U.pVal, RHS, getNumWords()); - return clearUnusedBits(); -} - -/// Subtracts the RHS APInt from this APInt -/// @returns this, after subtraction -/// Subtraction assignment operator. -APInt& APInt::operator-=(const APInt& RHS) { - assert(BitWidth == RHS.BitWidth && "Bit widths must be the same"); - if (isSingleWord()) - U.VAL -= RHS.U.VAL; - else - tcSubtract(U.pVal, RHS.U.pVal, 0, getNumWords()); - return clearUnusedBits(); -} - -APInt& APInt::operator-=(uint64_t RHS) { - if (isSingleWord()) - U.VAL -= RHS; - else - tcSubtractPart(U.pVal, RHS, getNumWords()); - return clearUnusedBits(); -} - -APInt APInt::operator*(const APInt& RHS) const { - assert(BitWidth == RHS.BitWidth && "Bit widths must be the same"); - if (isSingleWord()) - return APInt(BitWidth, U.VAL * RHS.U.VAL); - - APInt Result(getMemory(getNumWords()), getBitWidth()); - - tcMultiply(Result.U.pVal, U.pVal, RHS.U.pVal, getNumWords()); - - Result.clearUnusedBits(); - return Result; -} - -void APInt::AndAssignSlowCase(const APInt& RHS) { - tcAnd(U.pVal, RHS.U.pVal, getNumWords()); -} - -void APInt::OrAssignSlowCase(const APInt& RHS) { - tcOr(U.pVal, RHS.U.pVal, getNumWords()); -} - -void APInt::XorAssignSlowCase(const APInt& RHS) { - tcXor(U.pVal, RHS.U.pVal, getNumWords()); -} - -APInt& APInt::operator*=(const APInt& RHS) { - assert(BitWidth == RHS.BitWidth && "Bit widths must be the same"); - *this = *this * RHS; - return *this; -} - -APInt& APInt::operator*=(uint64_t RHS) { - if (isSingleWord()) { - U.VAL *= RHS; - } else { - unsigned NumWords = getNumWords(); - tcMultiplyPart(U.pVal, U.pVal, RHS, 0, NumWords, NumWords, false); - } - return clearUnusedBits(); -} - -bool APInt::EqualSlowCase(const APInt& RHS) const { - return std::equal(U.pVal, U.pVal + getNumWords(), RHS.U.pVal); -} - -int APInt::compare(const APInt& RHS) const { - assert(BitWidth == RHS.BitWidth && "Bit widths must be same for comparison"); - if (isSingleWord()) - return U.VAL < RHS.U.VAL ? -1 : U.VAL > RHS.U.VAL; - - return tcCompare(U.pVal, RHS.U.pVal, getNumWords()); -} - -int APInt::compareSigned(const APInt& RHS) const { - assert(BitWidth == RHS.BitWidth && "Bit widths must be same for comparison"); - if (isSingleWord()) { - int64_t lhsSext = SignExtend64(U.VAL, BitWidth); - int64_t rhsSext = SignExtend64(RHS.U.VAL, BitWidth); - return lhsSext < rhsSext ? -1 : lhsSext > rhsSext; - } - - bool lhsNeg = isNegative(); - bool rhsNeg = RHS.isNegative(); - - // If the sign bits don't match, then (LHS < RHS) if LHS is negative - if (lhsNeg != rhsNeg) - return lhsNeg ? -1 : 1; - - // Otherwise we can just use an unsigned comparison, because even negative - // numbers compare correctly this way if both have the same signed-ness. - return tcCompare(U.pVal, RHS.U.pVal, getNumWords()); -} - -void APInt::setBitsSlowCase(unsigned loBit, unsigned hiBit) { - unsigned loWord = whichWord(loBit); - unsigned hiWord = whichWord(hiBit); - - // Create an initial mask for the low word with zeros below loBit. - uint64_t loMask = WORDTYPE_MAX << whichBit(loBit); - - // If hiBit is not aligned, we need a high mask. - unsigned hiShiftAmt = whichBit(hiBit); - if (hiShiftAmt != 0) { - // Create a high mask with zeros above hiBit. - uint64_t hiMask = WORDTYPE_MAX >> (APINT_BITS_PER_WORD - hiShiftAmt); - // If loWord and hiWord are equal, then we combine the masks. Otherwise, - // set the bits in hiWord. - if (hiWord == loWord) - loMask &= hiMask; - else - U.pVal[hiWord] |= hiMask; - } - // Apply the mask to the low word. - U.pVal[loWord] |= loMask; - - // Fill any words between loWord and hiWord with all ones. - for (unsigned word = loWord + 1; word < hiWord; ++word) - U.pVal[word] = WORDTYPE_MAX; -} - -/// Toggle every bit to its opposite value. -void APInt::flipAllBitsSlowCase() { - tcComplement(U.pVal, getNumWords()); - clearUnusedBits(); -} - -/// Toggle a given bit to its opposite value whose position is given -/// as "bitPosition". -/// Toggles a given bit to its opposite value. -void APInt::flipBit(unsigned bitPosition) { - assert(bitPosition < BitWidth && "Out of the bit-width range!"); - if ((*this)[bitPosition]) clearBit(bitPosition); - else setBit(bitPosition); -} - -void APInt::insertBits(const APInt &subBits, unsigned bitPosition) { - unsigned subBitWidth = subBits.getBitWidth(); - assert(0 < subBitWidth && (subBitWidth + bitPosition) <= BitWidth && - "Illegal bit insertion"); - - // Insertion is a direct copy. - if (subBitWidth == BitWidth) { - *this = subBits; - return; - } - - // Single word result can be done as a direct bitmask. - if (isSingleWord()) { - uint64_t mask = WORDTYPE_MAX >> (APINT_BITS_PER_WORD - subBitWidth); - U.VAL &= ~(mask << bitPosition); - U.VAL |= (subBits.U.VAL << bitPosition); - return; - } - - unsigned loBit = whichBit(bitPosition); - unsigned loWord = whichWord(bitPosition); - unsigned hi1Word = whichWord(bitPosition + subBitWidth - 1); - - // Insertion within a single word can be done as a direct bitmask. - if (loWord == hi1Word) { - uint64_t mask = WORDTYPE_MAX >> (APINT_BITS_PER_WORD - subBitWidth); - U.pVal[loWord] &= ~(mask << loBit); - U.pVal[loWord] |= (subBits.U.VAL << loBit); - return; - } - - // Insert on word boundaries. - if (loBit == 0) { - // Direct copy whole words. - unsigned numWholeSubWords = subBitWidth / APINT_BITS_PER_WORD; - memcpy(U.pVal + loWord, subBits.getRawData(), - numWholeSubWords * APINT_WORD_SIZE); - - // Mask+insert remaining bits. - unsigned remainingBits = subBitWidth % APINT_BITS_PER_WORD; - if (remainingBits != 0) { - uint64_t mask = WORDTYPE_MAX >> (APINT_BITS_PER_WORD - remainingBits); - U.pVal[hi1Word] &= ~mask; - U.pVal[hi1Word] |= subBits.getWord(subBitWidth - 1); - } - return; - } - - // General case - set/clear individual bits in dst based on src. - // TODO - there is scope for optimization here, but at the moment this code - // path is barely used so prefer readability over performance. - for (unsigned i = 0; i != subBitWidth; ++i) { - if (subBits[i]) - setBit(bitPosition + i); - else - clearBit(bitPosition + i); - } -} - -APInt APInt::extractBits(unsigned numBits, unsigned bitPosition) const { - assert(numBits > 0 && "Can't extract zero bits"); - assert(bitPosition < BitWidth && (numBits + bitPosition) <= BitWidth && - "Illegal bit extraction"); - - if (isSingleWord()) - return APInt(numBits, U.VAL >> bitPosition); - - unsigned loBit = whichBit(bitPosition); - unsigned loWord = whichWord(bitPosition); - unsigned hiWord = whichWord(bitPosition + numBits - 1); - - // Single word result extracting bits from a single word source. - if (loWord == hiWord) - return APInt(numBits, U.pVal[loWord] >> loBit); - - // Extracting bits that start on a source word boundary can be done - // as a fast memory copy. - if (loBit == 0) - return APInt(numBits, makeArrayRef(U.pVal + loWord, 1 + hiWord - loWord)); - - // General case - shift + copy source words directly into place. - APInt Result(numBits, 0); - unsigned NumSrcWords = getNumWords(); - unsigned NumDstWords = Result.getNumWords(); - - uint64_t *DestPtr = Result.isSingleWord() ? &Result.U.VAL : Result.U.pVal; - for (unsigned word = 0; word < NumDstWords; ++word) { - uint64_t w0 = U.pVal[loWord + word]; - uint64_t w1 = - (loWord + word + 1) < NumSrcWords ? U.pVal[loWord + word + 1] : 0; - DestPtr[word] = (w0 >> loBit) | (w1 << (APINT_BITS_PER_WORD - loBit)); - } - - return Result.clearUnusedBits(); -} - -unsigned APInt::getBitsNeeded(StringRef str, uint8_t radix) { - assert(!str.empty() && "Invalid string length"); - assert((radix == 10 || radix == 8 || radix == 16 || radix == 2 || - radix == 36) && - "Radix should be 2, 8, 10, 16, or 36!"); - - size_t slen = str.size(); - - // Each computation below needs to know if it's negative. - StringRef::iterator p = str.begin(); - unsigned isNegative = *p == '-'; - if (*p == '-' || *p == '+') { - p++; - slen--; - assert(slen && "String is only a sign, needs a value."); - } - - // For radixes of power-of-two values, the bits required is accurately and - // easily computed - if (radix == 2) - return slen + isNegative; - if (radix == 8) - return slen * 3 + isNegative; - if (radix == 16) - return slen * 4 + isNegative; - - // FIXME: base 36 - - // This is grossly inefficient but accurate. We could probably do something - // with a computation of roughly slen*64/20 and then adjust by the value of - // the first few digits. But, I'm not sure how accurate that could be. - - // Compute a sufficient number of bits that is always large enough but might - // be too large. This avoids the assertion in the constructor. This - // calculation doesn't work appropriately for the numbers 0-9, so just use 4 - // bits in that case. - unsigned sufficient - = radix == 10? (slen == 1 ? 4 : slen * 64/18) - : (slen == 1 ? 7 : slen * 16/3); - - // Convert to the actual binary value. - APInt tmp(sufficient, StringRef(p, slen), radix); - - // Compute how many bits are required. If the log is infinite, assume we need - // just bit. If the log is exact and value is negative, then the value is - // MinSignedValue with (log + 1) bits. - unsigned log = tmp.logBase2(); - if (log == (unsigned)-1) { - return isNegative + 1; - } else if (isNegative && tmp.isPowerOf2()) { - return isNegative + log; - } else { - return isNegative + log + 1; - } -} - -hash_code llvm::hash_value(const APInt &Arg) { - if (Arg.isSingleWord()) - return hash_combine(Arg.U.VAL); - - return hash_combine_range(Arg.U.pVal, Arg.U.pVal + Arg.getNumWords()); -} - -bool APInt::isSplat(unsigned SplatSizeInBits) const { - assert(getBitWidth() % SplatSizeInBits == 0 && - "SplatSizeInBits must divide width!"); - // We can check that all parts of an integer are equal by making use of a - // little trick: rotate and check if it's still the same value. - return *this == rotl(SplatSizeInBits); -} - -/// This function returns the high "numBits" bits of this APInt. -APInt APInt::getHiBits(unsigned numBits) const { - return this->lshr(BitWidth - numBits); -} - -/// This function returns the low "numBits" bits of this APInt. -APInt APInt::getLoBits(unsigned numBits) const { - APInt Result(getLowBitsSet(BitWidth, numBits)); - Result &= *this; - return Result; -} - -/// Return a value containing V broadcasted over NewLen bits. -APInt APInt::getSplat(unsigned NewLen, const APInt &V) { - assert(NewLen >= V.getBitWidth() && "Can't splat to smaller bit width!"); - - APInt Val = V.zextOrSelf(NewLen); - for (unsigned I = V.getBitWidth(); I < NewLen; I <<= 1) - Val |= Val << I; - - return Val; -} - -unsigned APInt::countLeadingZerosSlowCase() const { - unsigned Count = 0; - for (int i = getNumWords()-1; i >= 0; --i) { - uint64_t V = U.pVal[i]; - if (V == 0) - Count += APINT_BITS_PER_WORD; - else { - Count += llvm::countLeadingZeros(V); - break; - } - } - // Adjust for unused bits in the most significant word (they are zero). - unsigned Mod = BitWidth % APINT_BITS_PER_WORD; - Count -= Mod > 0 ? APINT_BITS_PER_WORD - Mod : 0; - return Count; -} - -unsigned APInt::countLeadingOnesSlowCase() const { - unsigned highWordBits = BitWidth % APINT_BITS_PER_WORD; - unsigned shift; - if (!highWordBits) { - highWordBits = APINT_BITS_PER_WORD; - shift = 0; - } else { - shift = APINT_BITS_PER_WORD - highWordBits; - } - int i = getNumWords() - 1; - unsigned Count = llvm::countLeadingOnes(U.pVal[i] << shift); - if (Count == highWordBits) { - for (i--; i >= 0; --i) { - if (U.pVal[i] == WORDTYPE_MAX) - Count += APINT_BITS_PER_WORD; - else { - Count += llvm::countLeadingOnes(U.pVal[i]); - break; - } - } - } - return Count; -} - -unsigned APInt::countTrailingZerosSlowCase() const { - unsigned Count = 0; - unsigned i = 0; - for (; i < getNumWords() && U.pVal[i] == 0; ++i) - Count += APINT_BITS_PER_WORD; - if (i < getNumWords()) - Count += llvm::countTrailingZeros(U.pVal[i]); - return std::min(Count, BitWidth); -} - -unsigned APInt::countTrailingOnesSlowCase() const { - unsigned Count = 0; - unsigned i = 0; - for (; i < getNumWords() && U.pVal[i] == WORDTYPE_MAX; ++i) - Count += APINT_BITS_PER_WORD; - if (i < getNumWords()) - Count += llvm::countTrailingOnes(U.pVal[i]); - assert(Count <= BitWidth); - return Count; -} - -unsigned APInt::countPopulationSlowCase() const { - unsigned Count = 0; - for (unsigned i = 0; i < getNumWords(); ++i) - Count += llvm::countPopulation(U.pVal[i]); - return Count; -} - -bool APInt::intersectsSlowCase(const APInt &RHS) const { - for (unsigned i = 0, e = getNumWords(); i != e; ++i) - if ((U.pVal[i] & RHS.U.pVal[i]) != 0) - return true; - - return false; -} - -bool APInt::isSubsetOfSlowCase(const APInt &RHS) const { - for (unsigned i = 0, e = getNumWords(); i != e; ++i) - if ((U.pVal[i] & ~RHS.U.pVal[i]) != 0) - return false; - - return true; -} - -APInt APInt::byteSwap() const { - assert(BitWidth >= 16 && BitWidth % 16 == 0 && "Cannot byteswap!"); - if (BitWidth == 16) - return APInt(BitWidth, ByteSwap_16(uint16_t(U.VAL))); - if (BitWidth == 32) - return APInt(BitWidth, ByteSwap_32(unsigned(U.VAL))); - if (BitWidth == 48) { - unsigned Tmp1 = unsigned(U.VAL >> 16); - Tmp1 = ByteSwap_32(Tmp1); - uint16_t Tmp2 = uint16_t(U.VAL); - Tmp2 = ByteSwap_16(Tmp2); - return APInt(BitWidth, (uint64_t(Tmp2) << 32) | Tmp1); - } - if (BitWidth == 64) - return APInt(BitWidth, ByteSwap_64(U.VAL)); - - APInt Result(getNumWords() * APINT_BITS_PER_WORD, 0); - for (unsigned I = 0, N = getNumWords(); I != N; ++I) - Result.U.pVal[I] = ByteSwap_64(U.pVal[N - I - 1]); - if (Result.BitWidth != BitWidth) { - Result.lshrInPlace(Result.BitWidth - BitWidth); - Result.BitWidth = BitWidth; - } - return Result; -} - -APInt APInt::reverseBits() const { - switch (BitWidth) { - case 64: - return APInt(BitWidth, llvm::reverseBits<uint64_t>(U.VAL)); - case 32: - return APInt(BitWidth, llvm::reverseBits<uint32_t>(U.VAL)); - case 16: - return APInt(BitWidth, llvm::reverseBits<uint16_t>(U.VAL)); - case 8: - return APInt(BitWidth, llvm::reverseBits<uint8_t>(U.VAL)); - default: - break; - } - - APInt Val(*this); - APInt Reversed(BitWidth, 0); - unsigned S = BitWidth; - - for (; Val != 0; Val.lshrInPlace(1)) { - Reversed <<= 1; - Reversed |= Val[0]; - --S; - } - - Reversed <<= S; - return Reversed; -} - -APInt llvm::APIntOps::GreatestCommonDivisor(APInt A, APInt B) { - // Fast-path a common case. - if (A == B) return A; - - // Corner cases: if either operand is zero, the other is the gcd. - if (!A) return B; - if (!B) return A; - - // Count common powers of 2 and remove all other powers of 2. - unsigned Pow2; - { - unsigned Pow2_A = A.countTrailingZeros(); - unsigned Pow2_B = B.countTrailingZeros(); - if (Pow2_A > Pow2_B) { - A.lshrInPlace(Pow2_A - Pow2_B); - Pow2 = Pow2_B; - } else if (Pow2_B > Pow2_A) { - B.lshrInPlace(Pow2_B - Pow2_A); - Pow2 = Pow2_A; - } else { - Pow2 = Pow2_A; - } - } - - // Both operands are odd multiples of 2^Pow_2: - // - // gcd(a, b) = gcd(|a - b| / 2^i, min(a, b)) - // - // This is a modified version of Stein's algorithm, taking advantage of - // efficient countTrailingZeros(). - while (A != B) { - if (A.ugt(B)) { - A -= B; - A.lshrInPlace(A.countTrailingZeros() - Pow2); - } else { - B -= A; - B.lshrInPlace(B.countTrailingZeros() - Pow2); - } - } - - return A; -} - -APInt llvm::APIntOps::RoundDoubleToAPInt(double Double, unsigned width) { - uint64_t I = bit_cast<uint64_t>(Double); - - // Get the sign bit from the highest order bit - bool isNeg = I >> 63; - - // Get the 11-bit exponent and adjust for the 1023 bit bias - int64_t exp = ((I >> 52) & 0x7ff) - 1023; - - // If the exponent is negative, the value is < 0 so just return 0. - if (exp < 0) - return APInt(width, 0u); - - // Extract the mantissa by clearing the top 12 bits (sign + exponent). - uint64_t mantissa = (I & (~0ULL >> 12)) | 1ULL << 52; - - // If the exponent doesn't shift all bits out of the mantissa - if (exp < 52) - return isNeg ? -APInt(width, mantissa >> (52 - exp)) : - APInt(width, mantissa >> (52 - exp)); - - // If the client didn't provide enough bits for us to shift the mantissa into - // then the result is undefined, just return 0 - if (width <= exp - 52) - return APInt(width, 0); - - // Otherwise, we have to shift the mantissa bits up to the right location - APInt Tmp(width, mantissa); - Tmp <<= (unsigned)exp - 52; - return isNeg ? -Tmp : Tmp; -} - -/// This function converts this APInt to a double. -/// The layout for double is as following (IEEE Standard 754): -/// -------------------------------------- -/// | Sign Exponent Fraction Bias | -/// |-------------------------------------- | -/// | 1[63] 11[62-52] 52[51-00] 1023 | -/// -------------------------------------- -double APInt::roundToDouble(bool isSigned) const { - - // Handle the simple case where the value is contained in one uint64_t. - // It is wrong to optimize getWord(0) to VAL; there might be more than one word. - if (isSingleWord() || getActiveBits() <= APINT_BITS_PER_WORD) { - if (isSigned) { - int64_t sext = SignExtend64(getWord(0), BitWidth); - return double(sext); - } else - return double(getWord(0)); - } - - // Determine if the value is negative. - bool isNeg = isSigned ? (*this)[BitWidth-1] : false; - - // Construct the absolute value if we're negative. - APInt Tmp(isNeg ? -(*this) : (*this)); - - // Figure out how many bits we're using. - unsigned n = Tmp.getActiveBits(); - - // The exponent (without bias normalization) is just the number of bits - // we are using. Note that the sign bit is gone since we constructed the - // absolute value. - uint64_t exp = n; - - // Return infinity for exponent overflow - if (exp > 1023) { - if (!isSigned || !isNeg) - return std::numeric_limits<double>::infinity(); - else - return -std::numeric_limits<double>::infinity(); - } - exp += 1023; // Increment for 1023 bias - - // Number of bits in mantissa is 52. To obtain the mantissa value, we must - // extract the high 52 bits from the correct words in pVal. - uint64_t mantissa; - unsigned hiWord = whichWord(n-1); - if (hiWord == 0) { - mantissa = Tmp.U.pVal[0]; - if (n > 52) - mantissa >>= n - 52; // shift down, we want the top 52 bits. - } else { - assert(hiWord > 0 && "huh?"); - uint64_t hibits = Tmp.U.pVal[hiWord] << (52 - n % APINT_BITS_PER_WORD); - uint64_t lobits = Tmp.U.pVal[hiWord-1] >> (11 + n % APINT_BITS_PER_WORD); - mantissa = hibits | lobits; - } - - // The leading bit of mantissa is implicit, so get rid of it. - uint64_t sign = isNeg ? (1ULL << (APINT_BITS_PER_WORD - 1)) : 0; - uint64_t I = sign | (exp << 52) | mantissa; - return bit_cast<double>(I); -} - -// Truncate to new width. -APInt APInt::trunc(unsigned width) const { - assert(width < BitWidth && "Invalid APInt Truncate request"); - assert(width && "Can't truncate to 0 bits"); - - if (width <= APINT_BITS_PER_WORD) - return APInt(width, getRawData()[0]); - - APInt Result(getMemory(getNumWords(width)), width); - - // Copy full words. - unsigned i; - for (i = 0; i != width / APINT_BITS_PER_WORD; i++) - Result.U.pVal[i] = U.pVal[i]; - - // Truncate and copy any partial word. - unsigned bits = (0 - width) % APINT_BITS_PER_WORD; - if (bits != 0) - Result.U.pVal[i] = U.pVal[i] << bits >> bits; - - return Result; -} - -// Sign extend to a new width. -APInt APInt::sext(unsigned Width) const { - assert(Width > BitWidth && "Invalid APInt SignExtend request"); - - if (Width <= APINT_BITS_PER_WORD) - return APInt(Width, SignExtend64(U.VAL, BitWidth)); - - APInt Result(getMemory(getNumWords(Width)), Width); - - // Copy words. - std::memcpy(Result.U.pVal, getRawData(), getNumWords() * APINT_WORD_SIZE); - - // Sign extend the last word since there may be unused bits in the input. - Result.U.pVal[getNumWords() - 1] = - SignExtend64(Result.U.pVal[getNumWords() - 1], - ((BitWidth - 1) % APINT_BITS_PER_WORD) + 1); - - // Fill with sign bits. - std::memset(Result.U.pVal + getNumWords(), isNegative() ? -1 : 0, - (Result.getNumWords() - getNumWords()) * APINT_WORD_SIZE); - Result.clearUnusedBits(); - return Result; -} - -// Zero extend to a new width. -APInt APInt::zext(unsigned width) const { - assert(width > BitWidth && "Invalid APInt ZeroExtend request"); - - if (width <= APINT_BITS_PER_WORD) - return APInt(width, U.VAL); - - APInt Result(getMemory(getNumWords(width)), width); - - // Copy words. - std::memcpy(Result.U.pVal, getRawData(), getNumWords() * APINT_WORD_SIZE); - - // Zero remaining words. - std::memset(Result.U.pVal + getNumWords(), 0, - (Result.getNumWords() - getNumWords()) * APINT_WORD_SIZE); - - return Result; -} - -APInt APInt::zextOrTrunc(unsigned width) const { - if (BitWidth < width) - return zext(width); - if (BitWidth > width) - return trunc(width); - return *this; -} - -APInt APInt::sextOrTrunc(unsigned width) const { - if (BitWidth < width) - return sext(width); - if (BitWidth > width) - return trunc(width); - return *this; -} - -APInt APInt::zextOrSelf(unsigned width) const { - if (BitWidth < width) - return zext(width); - return *this; -} - -APInt APInt::sextOrSelf(unsigned width) const { - if (BitWidth < width) - return sext(width); - return *this; -} - -/// Arithmetic right-shift this APInt by shiftAmt. -/// Arithmetic right-shift function. -void APInt::ashrInPlace(const APInt &shiftAmt) { - ashrInPlace((unsigned)shiftAmt.getLimitedValue(BitWidth)); -} - -/// Arithmetic right-shift this APInt by shiftAmt. -/// Arithmetic right-shift function. -void APInt::ashrSlowCase(unsigned ShiftAmt) { - // Don't bother performing a no-op shift. - if (!ShiftAmt) - return; - - // Save the original sign bit for later. - bool Negative = isNegative(); - - // WordShift is the inter-part shift; BitShift is intra-part shift. - unsigned WordShift = ShiftAmt / APINT_BITS_PER_WORD; - unsigned BitShift = ShiftAmt % APINT_BITS_PER_WORD; - - unsigned WordsToMove = getNumWords() - WordShift; - if (WordsToMove != 0) { - // Sign extend the last word to fill in the unused bits. - U.pVal[getNumWords() - 1] = SignExtend64( - U.pVal[getNumWords() - 1], ((BitWidth - 1) % APINT_BITS_PER_WORD) + 1); - - // Fastpath for moving by whole words. - if (BitShift == 0) { - std::memmove(U.pVal, U.pVal + WordShift, WordsToMove * APINT_WORD_SIZE); - } else { - // Move the words containing significant bits. - for (unsigned i = 0; i != WordsToMove - 1; ++i) - U.pVal[i] = (U.pVal[i + WordShift] >> BitShift) | - (U.pVal[i + WordShift + 1] << (APINT_BITS_PER_WORD - BitShift)); - - // Handle the last word which has no high bits to copy. - U.pVal[WordsToMove - 1] = U.pVal[WordShift + WordsToMove - 1] >> BitShift; - // Sign extend one more time. - U.pVal[WordsToMove - 1] = - SignExtend64(U.pVal[WordsToMove - 1], APINT_BITS_PER_WORD - BitShift); - } - } - - // Fill in the remainder based on the original sign. - std::memset(U.pVal + WordsToMove, Negative ? -1 : 0, - WordShift * APINT_WORD_SIZE); - clearUnusedBits(); -} - -/// Logical right-shift this APInt by shiftAmt. -/// Logical right-shift function. -void APInt::lshrInPlace(const APInt &shiftAmt) { - lshrInPlace((unsigned)shiftAmt.getLimitedValue(BitWidth)); -} - -/// Logical right-shift this APInt by shiftAmt. -/// Logical right-shift function. -void APInt::lshrSlowCase(unsigned ShiftAmt) { - tcShiftRight(U.pVal, getNumWords(), ShiftAmt); -} - -/// Left-shift this APInt by shiftAmt. -/// Left-shift function. -APInt &APInt::operator<<=(const APInt &shiftAmt) { - // It's undefined behavior in C to shift by BitWidth or greater. - *this <<= (unsigned)shiftAmt.getLimitedValue(BitWidth); - return *this; -} - -void APInt::shlSlowCase(unsigned ShiftAmt) { - tcShiftLeft(U.pVal, getNumWords(), ShiftAmt); - clearUnusedBits(); -} - -// Calculate the rotate amount modulo the bit width. -static unsigned rotateModulo(unsigned BitWidth, const APInt &rotateAmt) { - unsigned rotBitWidth = rotateAmt.getBitWidth(); - APInt rot = rotateAmt; - if (rotBitWidth < BitWidth) { - // Extend the rotate APInt, so that the urem doesn't divide by 0. - // e.g. APInt(1, 32) would give APInt(1, 0). - rot = rotateAmt.zext(BitWidth); - } - rot = rot.urem(APInt(rot.getBitWidth(), BitWidth)); - return rot.getLimitedValue(BitWidth); -} - -APInt APInt::rotl(const APInt &rotateAmt) const { - return rotl(rotateModulo(BitWidth, rotateAmt)); -} - -APInt APInt::rotl(unsigned rotateAmt) const { - rotateAmt %= BitWidth; - if (rotateAmt == 0) - return *this; - return shl(rotateAmt) | lshr(BitWidth - rotateAmt); -} - -APInt APInt::rotr(const APInt &rotateAmt) const { - return rotr(rotateModulo(BitWidth, rotateAmt)); -} - -APInt APInt::rotr(unsigned rotateAmt) const { - rotateAmt %= BitWidth; - if (rotateAmt == 0) - return *this; - return lshr(rotateAmt) | shl(BitWidth - rotateAmt); -} - -// Square Root - this method computes and returns the square root of "this". -// Three mechanisms are used for computation. For small values (<= 5 bits), -// a table lookup is done. This gets some performance for common cases. For -// values using less than 52 bits, the value is converted to double and then -// the libc sqrt function is called. The result is rounded and then converted -// back to a uint64_t which is then used to construct the result. Finally, -// the Babylonian method for computing square roots is used. -APInt APInt::sqrt() const { - - // Determine the magnitude of the value. - unsigned magnitude = getActiveBits(); - - // Use a fast table for some small values. This also gets rid of some - // rounding errors in libc sqrt for small values. - if (magnitude <= 5) { - static const uint8_t results[32] = { - /* 0 */ 0, - /* 1- 2 */ 1, 1, - /* 3- 6 */ 2, 2, 2, 2, - /* 7-12 */ 3, 3, 3, 3, 3, 3, - /* 13-20 */ 4, 4, 4, 4, 4, 4, 4, 4, - /* 21-30 */ 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, - /* 31 */ 6 - }; - return APInt(BitWidth, results[ (isSingleWord() ? U.VAL : U.pVal[0]) ]); - } - - // If the magnitude of the value fits in less than 52 bits (the precision of - // an IEEE double precision floating point value), then we can use the - // libc sqrt function which will probably use a hardware sqrt computation. - // This should be faster than the algorithm below. - if (magnitude < 52) { - return APInt(BitWidth, - uint64_t(::round(::sqrt(double(isSingleWord() ? U.VAL - : U.pVal[0]))))); - } - - // Okay, all the short cuts are exhausted. We must compute it. The following - // is a classical Babylonian method for computing the square root. This code - // was adapted to APInt from a wikipedia article on such computations. - // See http://www.wikipedia.org/ and go to the page named - // Calculate_an_integer_square_root. - unsigned nbits = BitWidth, i = 4; - APInt testy(BitWidth, 16); - APInt x_old(BitWidth, 1); - APInt x_new(BitWidth, 0); - APInt two(BitWidth, 2); - - // Select a good starting value using binary logarithms. - for (;; i += 2, testy = testy.shl(2)) - if (i >= nbits || this->ule(testy)) { - x_old = x_old.shl(i / 2); - break; - } - - // Use the Babylonian method to arrive at the integer square root: - for (;;) { - x_new = (this->udiv(x_old) + x_old).udiv(two); - if (x_old.ule(x_new)) - break; - x_old = x_new; - } - - // Make sure we return the closest approximation - // NOTE: The rounding calculation below is correct. It will produce an - // off-by-one discrepancy with results from pari/gp. That discrepancy has been - // determined to be a rounding issue with pari/gp as it begins to use a - // floating point representation after 192 bits. There are no discrepancies - // between this algorithm and pari/gp for bit widths < 192 bits. - APInt square(x_old * x_old); - APInt nextSquare((x_old + 1) * (x_old +1)); - if (this->ult(square)) - return x_old; - assert(this->ule(nextSquare) && "Error in APInt::sqrt computation"); - APInt midpoint((nextSquare - square).udiv(two)); - APInt offset(*this - square); - if (offset.ult(midpoint)) - return x_old; - return x_old + 1; -} - -/// Computes the multiplicative inverse of this APInt for a given modulo. The -/// iterative extended Euclidean algorithm is used to solve for this value, -/// however we simplify it to speed up calculating only the inverse, and take -/// advantage of div+rem calculations. We also use some tricks to avoid copying -/// (potentially large) APInts around. -/// WARNING: a value of '0' may be returned, -/// signifying that no multiplicative inverse exists! -APInt APInt::multiplicativeInverse(const APInt& modulo) const { - assert(ult(modulo) && "This APInt must be smaller than the modulo"); - - // Using the properties listed at the following web page (accessed 06/21/08): - // http://www.numbertheory.org/php/euclid.html - // (especially the properties numbered 3, 4 and 9) it can be proved that - // BitWidth bits suffice for all the computations in the algorithm implemented - // below. More precisely, this number of bits suffice if the multiplicative - // inverse exists, but may not suffice for the general extended Euclidean - // algorithm. - - APInt r[2] = { modulo, *this }; - APInt t[2] = { APInt(BitWidth, 0), APInt(BitWidth, 1) }; - APInt q(BitWidth, 0); - - unsigned i; - for (i = 0; r[i^1] != 0; i ^= 1) { - // An overview of the math without the confusing bit-flipping: - // q = r[i-2] / r[i-1] - // r[i] = r[i-2] % r[i-1] - // t[i] = t[i-2] - t[i-1] * q - udivrem(r[i], r[i^1], q, r[i]); - t[i] -= t[i^1] * q; - } - - // If this APInt and the modulo are not coprime, there is no multiplicative - // inverse, so return 0. We check this by looking at the next-to-last - // remainder, which is the gcd(*this,modulo) as calculated by the Euclidean - // algorithm. - if (r[i] != 1) - return APInt(BitWidth, 0); - - // The next-to-last t is the multiplicative inverse. However, we are - // interested in a positive inverse. Calculate a positive one from a negative - // one if necessary. A simple addition of the modulo suffices because - // abs(t[i]) is known to be less than *this/2 (see the link above). - if (t[i].isNegative()) - t[i] += modulo; - - return std::move(t[i]); -} - -/// Calculate the magic numbers required to implement a signed integer division -/// by a constant as a sequence of multiplies, adds and shifts. Requires that -/// the divisor not be 0, 1, or -1. Taken from "Hacker's Delight", Henry S. -/// Warren, Jr., chapter 10. -APInt::ms APInt::magic() const { - const APInt& d = *this; - unsigned p; - APInt ad, anc, delta, q1, r1, q2, r2, t; - APInt signedMin = APInt::getSignedMinValue(d.getBitWidth()); - struct ms mag; - - ad = d.abs(); - t = signedMin + (d.lshr(d.getBitWidth() - 1)); - anc = t - 1 - t.urem(ad); // absolute value of nc - p = d.getBitWidth() - 1; // initialize p - q1 = signedMin.udiv(anc); // initialize q1 = 2p/abs(nc) - r1 = signedMin - q1*anc; // initialize r1 = rem(2p,abs(nc)) - q2 = signedMin.udiv(ad); // initialize q2 = 2p/abs(d) - r2 = signedMin - q2*ad; // initialize r2 = rem(2p,abs(d)) - do { - p = p + 1; - q1 = q1<<1; // update q1 = 2p/abs(nc) - r1 = r1<<1; // update r1 = rem(2p/abs(nc)) - if (r1.uge(anc)) { // must be unsigned comparison - q1 = q1 + 1; - r1 = r1 - anc; - } - q2 = q2<<1; // update q2 = 2p/abs(d) - r2 = r2<<1; // update r2 = rem(2p/abs(d)) - if (r2.uge(ad)) { // must be unsigned comparison - q2 = q2 + 1; - r2 = r2 - ad; - } - delta = ad - r2; - } while (q1.ult(delta) || (q1 == delta && r1 == 0)); - - mag.m = q2 + 1; - if (d.isNegative()) mag.m = -mag.m; // resulting magic number - mag.s = p - d.getBitWidth(); // resulting shift - return mag; -} - -/// Calculate the magic numbers required to implement an unsigned integer -/// division by a constant as a sequence of multiplies, adds and shifts. -/// Requires that the divisor not be 0. Taken from "Hacker's Delight", Henry -/// S. Warren, Jr., chapter 10. -/// LeadingZeros can be used to simplify the calculation if the upper bits -/// of the divided value are known zero. -APInt::mu APInt::magicu(unsigned LeadingZeros) const { - const APInt& d = *this; - unsigned p; - APInt nc, delta, q1, r1, q2, r2; - struct mu magu; - magu.a = 0; // initialize "add" indicator - APInt allOnes = APInt::getAllOnesValue(d.getBitWidth()).lshr(LeadingZeros); - APInt signedMin = APInt::getSignedMinValue(d.getBitWidth()); - APInt signedMax = APInt::getSignedMaxValue(d.getBitWidth()); - - nc = allOnes - (allOnes - d).urem(d); - p = d.getBitWidth() - 1; // initialize p - q1 = signedMin.udiv(nc); // initialize q1 = 2p/nc - r1 = signedMin - q1*nc; // initialize r1 = rem(2p,nc) - q2 = signedMax.udiv(d); // initialize q2 = (2p-1)/d - r2 = signedMax - q2*d; // initialize r2 = rem((2p-1),d) - do { - p = p + 1; - if (r1.uge(nc - r1)) { - q1 = q1 + q1 + 1; // update q1 - r1 = r1 + r1 - nc; // update r1 - } - else { - q1 = q1+q1; // update q1 - r1 = r1+r1; // update r1 - } - if ((r2 + 1).uge(d - r2)) { - if (q2.uge(signedMax)) magu.a = 1; - q2 = q2+q2 + 1; // update q2 - r2 = r2+r2 + 1 - d; // update r2 - } - else { - if (q2.uge(signedMin)) magu.a = 1; - q2 = q2+q2; // update q2 - r2 = r2+r2 + 1; // update r2 - } - delta = d - 1 - r2; - } while (p < d.getBitWidth()*2 && - (q1.ult(delta) || (q1 == delta && r1 == 0))); - magu.m = q2 + 1; // resulting magic number - magu.s = p - d.getBitWidth(); // resulting shift - return magu; -} - -/// Implementation of Knuth's Algorithm D (Division of nonnegative integers) -/// from "Art of Computer Programming, Volume 2", section 4.3.1, p. 272. The -/// variables here have the same names as in the algorithm. Comments explain -/// the algorithm and any deviation from it. -static void KnuthDiv(uint32_t *u, uint32_t *v, uint32_t *q, uint32_t* r, - unsigned m, unsigned n) { - assert(u && "Must provide dividend"); - assert(v && "Must provide divisor"); - assert(q && "Must provide quotient"); - assert(u != v && u != q && v != q && "Must use different memory"); - assert(n>1 && "n must be > 1"); - - // b denotes the base of the number system. In our case b is 2^32. - const uint64_t b = uint64_t(1) << 32; - -// The DEBUG macros here tend to be spam in the debug output if you're not -// debugging this code. Disable them unless KNUTH_DEBUG is defined. -#ifdef KNUTH_DEBUG -#define DEBUG_KNUTH(X) LLVM_DEBUG(X) -#else -#define DEBUG_KNUTH(X) do {} while(false) -#endif - - DEBUG_KNUTH(dbgs() << "KnuthDiv: m=" << m << " n=" << n << '\n'); - DEBUG_KNUTH(dbgs() << "KnuthDiv: original:"); - DEBUG_KNUTH(for (int i = m + n; i >= 0; i--) dbgs() << " " << u[i]); - DEBUG_KNUTH(dbgs() << " by"); - DEBUG_KNUTH(for (int i = n; i > 0; i--) dbgs() << " " << v[i - 1]); - DEBUG_KNUTH(dbgs() << '\n'); - // D1. [Normalize.] Set d = b / (v[n-1] + 1) and multiply all the digits of - // u and v by d. Note that we have taken Knuth's advice here to use a power - // of 2 value for d such that d * v[n-1] >= b/2 (b is the base). A power of - // 2 allows us to shift instead of multiply and it is easy to determine the - // shift amount from the leading zeros. We are basically normalizing the u - // and v so that its high bits are shifted to the top of v's range without - // overflow. Note that this can require an extra word in u so that u must - // be of length m+n+1. - unsigned shift = countLeadingZeros(v[n-1]); - uint32_t v_carry = 0; - uint32_t u_carry = 0; - if (shift) { - for (unsigned i = 0; i < m+n; ++i) { - uint32_t u_tmp = u[i] >> (32 - shift); - u[i] = (u[i] << shift) | u_carry; - u_carry = u_tmp; - } - for (unsigned i = 0; i < n; ++i) { - uint32_t v_tmp = v[i] >> (32 - shift); - v[i] = (v[i] << shift) | v_carry; - v_carry = v_tmp; - } - } - u[m+n] = u_carry; - - DEBUG_KNUTH(dbgs() << "KnuthDiv: normal:"); - DEBUG_KNUTH(for (int i = m + n; i >= 0; i--) dbgs() << " " << u[i]); - DEBUG_KNUTH(dbgs() << " by"); - DEBUG_KNUTH(for (int i = n; i > 0; i--) dbgs() << " " << v[i - 1]); - DEBUG_KNUTH(dbgs() << '\n'); - - // D2. [Initialize j.] Set j to m. This is the loop counter over the places. - int j = m; - do { - DEBUG_KNUTH(dbgs() << "KnuthDiv: quotient digit #" << j << '\n'); - // D3. [Calculate q'.]. - // Set qp = (u[j+n]*b + u[j+n-1]) / v[n-1]. (qp=qprime=q') - // Set rp = (u[j+n]*b + u[j+n-1]) % v[n-1]. (rp=rprime=r') - // Now test if qp == b or qp*v[n-2] > b*rp + u[j+n-2]; if so, decrease - // qp by 1, increase rp by v[n-1], and repeat this test if rp < b. The test - // on v[n-2] determines at high speed most of the cases in which the trial - // value qp is one too large, and it eliminates all cases where qp is two - // too large. - uint64_t dividend = Make_64(u[j+n], u[j+n-1]); - DEBUG_KNUTH(dbgs() << "KnuthDiv: dividend == " << dividend << '\n'); - uint64_t qp = dividend / v[n-1]; - uint64_t rp = dividend % v[n-1]; - if (qp == b || qp*v[n-2] > b*rp + u[j+n-2]) { - qp--; - rp += v[n-1]; - if (rp < b && (qp == b || qp*v[n-2] > b*rp + u[j+n-2])) - qp--; - } - DEBUG_KNUTH(dbgs() << "KnuthDiv: qp == " << qp << ", rp == " << rp << '\n'); - - // D4. [Multiply and subtract.] Replace (u[j+n]u[j+n-1]...u[j]) with - // (u[j+n]u[j+n-1]..u[j]) - qp * (v[n-1]...v[1]v[0]). This computation - // consists of a simple multiplication by a one-place number, combined with - // a subtraction. - // The digits (u[j+n]...u[j]) should be kept positive; if the result of - // this step is actually negative, (u[j+n]...u[j]) should be left as the - // true value plus b**(n+1), namely as the b's complement of - // the true value, and a "borrow" to the left should be remembered. - int64_t borrow = 0; - for (unsigned i = 0; i < n; ++i) { - uint64_t p = uint64_t(qp) * uint64_t(v[i]); - int64_t subres = int64_t(u[j+i]) - borrow - Lo_32(p); - u[j+i] = Lo_32(subres); - borrow = Hi_32(p) - Hi_32(subres); - DEBUG_KNUTH(dbgs() << "KnuthDiv: u[j+i] = " << u[j + i] - << ", borrow = " << borrow << '\n'); - } - bool isNeg = u[j+n] < borrow; - u[j+n] -= Lo_32(borrow); - - DEBUG_KNUTH(dbgs() << "KnuthDiv: after subtraction:"); - DEBUG_KNUTH(for (int i = m + n; i >= 0; i--) dbgs() << " " << u[i]); - DEBUG_KNUTH(dbgs() << '\n'); - - // D5. [Test remainder.] Set q[j] = qp. If the result of step D4 was - // negative, go to step D6; otherwise go on to step D7. - q[j] = Lo_32(qp); - if (isNeg) { - // D6. [Add back]. The probability that this step is necessary is very - // small, on the order of only 2/b. Make sure that test data accounts for - // this possibility. Decrease q[j] by 1 - q[j]--; - // and add (0v[n-1]...v[1]v[0]) to (u[j+n]u[j+n-1]...u[j+1]u[j]). - // A carry will occur to the left of u[j+n], and it should be ignored - // since it cancels with the borrow that occurred in D4. - bool carry = false; - for (unsigned i = 0; i < n; i++) { - uint32_t limit = std::min(u[j+i],v[i]); - u[j+i] += v[i] + carry; - carry = u[j+i] < limit || (carry && u[j+i] == limit); - } - u[j+n] += carry; - } - DEBUG_KNUTH(dbgs() << "KnuthDiv: after correction:"); - DEBUG_KNUTH(for (int i = m + n; i >= 0; i--) dbgs() << " " << u[i]); - DEBUG_KNUTH(dbgs() << "\nKnuthDiv: digit result = " << q[j] << '\n'); - - // D7. [Loop on j.] Decrease j by one. Now if j >= 0, go back to D3. - } while (--j >= 0); - - DEBUG_KNUTH(dbgs() << "KnuthDiv: quotient:"); - DEBUG_KNUTH(for (int i = m; i >= 0; i--) dbgs() << " " << q[i]); - DEBUG_KNUTH(dbgs() << '\n'); - - // D8. [Unnormalize]. Now q[...] is the desired quotient, and the desired - // remainder may be obtained by dividing u[...] by d. If r is non-null we - // compute the remainder (urem uses this). - if (r) { - // The value d is expressed by the "shift" value above since we avoided - // multiplication by d by using a shift left. So, all we have to do is - // shift right here. - if (shift) { - uint32_t carry = 0; - DEBUG_KNUTH(dbgs() << "KnuthDiv: remainder:"); - for (int i = n-1; i >= 0; i--) { - r[i] = (u[i] >> shift) | carry; - carry = u[i] << (32 - shift); - DEBUG_KNUTH(dbgs() << " " << r[i]); - } - } else { - for (int i = n-1; i >= 0; i--) { - r[i] = u[i]; - DEBUG_KNUTH(dbgs() << " " << r[i]); - } - } - DEBUG_KNUTH(dbgs() << '\n'); - } - DEBUG_KNUTH(dbgs() << '\n'); -} - -void APInt::divide(const WordType *LHS, unsigned lhsWords, const WordType *RHS, - unsigned rhsWords, WordType *Quotient, WordType *Remainder) { - assert(lhsWords >= rhsWords && "Fractional result"); - - // First, compose the values into an array of 32-bit words instead of - // 64-bit words. This is a necessity of both the "short division" algorithm - // and the Knuth "classical algorithm" which requires there to be native - // operations for +, -, and * on an m bit value with an m*2 bit result. We - // can't use 64-bit operands here because we don't have native results of - // 128-bits. Furthermore, casting the 64-bit values to 32-bit values won't - // work on large-endian machines. - unsigned n = rhsWords * 2; - unsigned m = (lhsWords * 2) - n; - - // Allocate space for the temporary values we need either on the stack, if - // it will fit, or on the heap if it won't. - uint32_t SPACE[128]; - uint32_t *U = nullptr; - uint32_t *V = nullptr; - uint32_t *Q = nullptr; - uint32_t *R = nullptr; - if ((Remainder?4:3)*n+2*m+1 <= 128) { - U = &SPACE[0]; - V = &SPACE[m+n+1]; - Q = &SPACE[(m+n+1) + n]; - if (Remainder) - R = &SPACE[(m+n+1) + n + (m+n)]; - } else { - U = new uint32_t[m + n + 1]; - V = new uint32_t[n]; - Q = new uint32_t[m+n]; - if (Remainder) - R = new uint32_t[n]; - } - - // Initialize the dividend - memset(U, 0, (m+n+1)*sizeof(uint32_t)); - for (unsigned i = 0; i < lhsWords; ++i) { - uint64_t tmp = LHS[i]; - U[i * 2] = Lo_32(tmp); - U[i * 2 + 1] = Hi_32(tmp); - } - U[m+n] = 0; // this extra word is for "spill" in the Knuth algorithm. - - // Initialize the divisor - memset(V, 0, (n)*sizeof(uint32_t)); - for (unsigned i = 0; i < rhsWords; ++i) { - uint64_t tmp = RHS[i]; - V[i * 2] = Lo_32(tmp); - V[i * 2 + 1] = Hi_32(tmp); - } - - // initialize the quotient and remainder - memset(Q, 0, (m+n) * sizeof(uint32_t)); - if (Remainder) - memset(R, 0, n * sizeof(uint32_t)); - - // Now, adjust m and n for the Knuth division. n is the number of words in - // the divisor. m is the number of words by which the dividend exceeds the - // divisor (i.e. m+n is the length of the dividend). These sizes must not - // contain any zero words or the Knuth algorithm fails. - for (unsigned i = n; i > 0 && V[i-1] == 0; i--) { - n--; - m++; - } - for (unsigned i = m+n; i > 0 && U[i-1] == 0; i--) - m--; - - // If we're left with only a single word for the divisor, Knuth doesn't work - // so we implement the short division algorithm here. This is much simpler - // and faster because we are certain that we can divide a 64-bit quantity - // by a 32-bit quantity at hardware speed and short division is simply a - // series of such operations. This is just like doing short division but we - // are using base 2^32 instead of base 10. - assert(n != 0 && "Divide by zero?"); - if (n == 1) { - uint32_t divisor = V[0]; - uint32_t remainder = 0; - for (int i = m; i >= 0; i--) { - uint64_t partial_dividend = Make_64(remainder, U[i]); - if (partial_dividend == 0) { - Q[i] = 0; - remainder = 0; - } else if (partial_dividend < divisor) { - Q[i] = 0; - remainder = Lo_32(partial_dividend); - } else if (partial_dividend == divisor) { - Q[i] = 1; - remainder = 0; - } else { - Q[i] = Lo_32(partial_dividend / divisor); - remainder = Lo_32(partial_dividend - (Q[i] * divisor)); - } - } - if (R) - R[0] = remainder; - } else { - // Now we're ready to invoke the Knuth classical divide algorithm. In this - // case n > 1. - KnuthDiv(U, V, Q, R, m, n); - } - - // If the caller wants the quotient - if (Quotient) { - for (unsigned i = 0; i < lhsWords; ++i) - Quotient[i] = Make_64(Q[i*2+1], Q[i*2]); - } - - // If the caller wants the remainder - if (Remainder) { - for (unsigned i = 0; i < rhsWords; ++i) - Remainder[i] = Make_64(R[i*2+1], R[i*2]); - } - - // Clean up the memory we allocated. - if (U != &SPACE[0]) { - delete [] U; - delete [] V; - delete [] Q; - delete [] R; - } -} - -APInt APInt::udiv(const APInt &RHS) const { - assert(BitWidth == RHS.BitWidth && "Bit widths must be the same"); - - // First, deal with the easy case - if (isSingleWord()) { - assert(RHS.U.VAL != 0 && "Divide by zero?"); - return APInt(BitWidth, U.VAL / RHS.U.VAL); - } - - // Get some facts about the LHS and RHS number of bits and words - unsigned lhsWords = getNumWords(getActiveBits()); - unsigned rhsBits = RHS.getActiveBits(); - unsigned rhsWords = getNumWords(rhsBits); - assert(rhsWords && "Divided by zero???"); - - // Deal with some degenerate cases - if (!lhsWords) - // 0 / X ===> 0 - return APInt(BitWidth, 0); - if (rhsBits == 1) - // X / 1 ===> X - return *this; - if (lhsWords < rhsWords || this->ult(RHS)) - // X / Y ===> 0, iff X < Y - return APInt(BitWidth, 0); - if (*this == RHS) - // X / X ===> 1 - return APInt(BitWidth, 1); - if (lhsWords == 1) // rhsWords is 1 if lhsWords is 1. - // All high words are zero, just use native divide - return APInt(BitWidth, this->U.pVal[0] / RHS.U.pVal[0]); - - // We have to compute it the hard way. Invoke the Knuth divide algorithm. - APInt Quotient(BitWidth, 0); // to hold result. - divide(U.pVal, lhsWords, RHS.U.pVal, rhsWords, Quotient.U.pVal, nullptr); - return Quotient; -} - -APInt APInt::udiv(uint64_t RHS) const { - assert(RHS != 0 && "Divide by zero?"); - - // First, deal with the easy case - if (isSingleWord()) - return APInt(BitWidth, U.VAL / RHS); - - // Get some facts about the LHS words. - unsigned lhsWords = getNumWords(getActiveBits()); - - // Deal with some degenerate cases - if (!lhsWords) - // 0 / X ===> 0 - return APInt(BitWidth, 0); - if (RHS == 1) - // X / 1 ===> X - return *this; - if (this->ult(RHS)) - // X / Y ===> 0, iff X < Y - return APInt(BitWidth, 0); - if (*this == RHS) - // X / X ===> 1 - return APInt(BitWidth, 1); - if (lhsWords == 1) // rhsWords is 1 if lhsWords is 1. - // All high words are zero, just use native divide - return APInt(BitWidth, this->U.pVal[0] / RHS); - - // We have to compute it the hard way. Invoke the Knuth divide algorithm. - APInt Quotient(BitWidth, 0); // to hold result. - divide(U.pVal, lhsWords, &RHS, 1, Quotient.U.pVal, nullptr); - return Quotient; -} - -APInt APInt::sdiv(const APInt &RHS) const { - if (isNegative()) { - if (RHS.isNegative()) - return (-(*this)).udiv(-RHS); - return -((-(*this)).udiv(RHS)); - } - if (RHS.isNegative()) - return -(this->udiv(-RHS)); - return this->udiv(RHS); -} - -APInt APInt::sdiv(int64_t RHS) const { - if (isNegative()) { - if (RHS < 0) - return (-(*this)).udiv(-RHS); - return -((-(*this)).udiv(RHS)); - } - if (RHS < 0) - return -(this->udiv(-RHS)); - return this->udiv(RHS); -} - -APInt APInt::urem(const APInt &RHS) const { - assert(BitWidth == RHS.BitWidth && "Bit widths must be the same"); - if (isSingleWord()) { - assert(RHS.U.VAL != 0 && "Remainder by zero?"); - return APInt(BitWidth, U.VAL % RHS.U.VAL); - } - - // Get some facts about the LHS - unsigned lhsWords = getNumWords(getActiveBits()); - - // Get some facts about the RHS - unsigned rhsBits = RHS.getActiveBits(); - unsigned rhsWords = getNumWords(rhsBits); - assert(rhsWords && "Performing remainder operation by zero ???"); - - // Check the degenerate cases - if (lhsWords == 0) - // 0 % Y ===> 0 - return APInt(BitWidth, 0); - if (rhsBits == 1) - // X % 1 ===> 0 - return APInt(BitWidth, 0); - if (lhsWords < rhsWords || this->ult(RHS)) - // X % Y ===> X, iff X < Y - return *this; - if (*this == RHS) - // X % X == 0; - return APInt(BitWidth, 0); - if (lhsWords == 1) - // All high words are zero, just use native remainder - return APInt(BitWidth, U.pVal[0] % RHS.U.pVal[0]); - - // We have to compute it the hard way. Invoke the Knuth divide algorithm. - APInt Remainder(BitWidth, 0); - divide(U.pVal, lhsWords, RHS.U.pVal, rhsWords, nullptr, Remainder.U.pVal); - return Remainder; -} - -uint64_t APInt::urem(uint64_t RHS) const { - assert(RHS != 0 && "Remainder by zero?"); - - if (isSingleWord()) - return U.VAL % RHS; - - // Get some facts about the LHS - unsigned lhsWords = getNumWords(getActiveBits()); - - // Check the degenerate cases - if (lhsWords == 0) - // 0 % Y ===> 0 - return 0; - if (RHS == 1) - // X % 1 ===> 0 - return 0; - if (this->ult(RHS)) - // X % Y ===> X, iff X < Y - return getZExtValue(); - if (*this == RHS) - // X % X == 0; - return 0; - if (lhsWords == 1) - // All high words are zero, just use native remainder - return U.pVal[0] % RHS; - - // We have to compute it the hard way. Invoke the Knuth divide algorithm. - uint64_t Remainder; - divide(U.pVal, lhsWords, &RHS, 1, nullptr, &Remainder); - return Remainder; -} - -APInt APInt::srem(const APInt &RHS) const { - if (isNegative()) { - if (RHS.isNegative()) - return -((-(*this)).urem(-RHS)); - return -((-(*this)).urem(RHS)); - } - if (RHS.isNegative()) - return this->urem(-RHS); - return this->urem(RHS); -} - -int64_t APInt::srem(int64_t RHS) const { - if (isNegative()) { - if (RHS < 0) - return -((-(*this)).urem(-RHS)); - return -((-(*this)).urem(RHS)); - } - if (RHS < 0) - return this->urem(-RHS); - return this->urem(RHS); -} - -void APInt::udivrem(const APInt &LHS, const APInt &RHS, - APInt &Quotient, APInt &Remainder) { - assert(LHS.BitWidth == RHS.BitWidth && "Bit widths must be the same"); - unsigned BitWidth = LHS.BitWidth; - - // First, deal with the easy case - if (LHS.isSingleWord()) { - assert(RHS.U.VAL != 0 && "Divide by zero?"); - uint64_t QuotVal = LHS.U.VAL / RHS.U.VAL; - uint64_t RemVal = LHS.U.VAL % RHS.U.VAL; - Quotient = APInt(BitWidth, QuotVal); - Remainder = APInt(BitWidth, RemVal); - return; - } - - // Get some size facts about the dividend and divisor - unsigned lhsWords = getNumWords(LHS.getActiveBits()); - unsigned rhsBits = RHS.getActiveBits(); - unsigned rhsWords = getNumWords(rhsBits); - assert(rhsWords && "Performing divrem operation by zero ???"); - - // Check the degenerate cases - if (lhsWords == 0) { - Quotient = APInt(BitWidth, 0); // 0 / Y ===> 0 - Remainder = APInt(BitWidth, 0); // 0 % Y ===> 0 - return; - } - - if (rhsBits == 1) { - Quotient = LHS; // X / 1 ===> X - Remainder = APInt(BitWidth, 0); // X % 1 ===> 0 - } - - if (lhsWords < rhsWords || LHS.ult(RHS)) { - Remainder = LHS; // X % Y ===> X, iff X < Y - Quotient = APInt(BitWidth, 0); // X / Y ===> 0, iff X < Y - return; - } - - if (LHS == RHS) { - Quotient = APInt(BitWidth, 1); // X / X ===> 1 - Remainder = APInt(BitWidth, 0); // X % X ===> 0; - return; - } - - // Make sure there is enough space to hold the results. - // NOTE: This assumes that reallocate won't affect any bits if it doesn't - // change the size. This is necessary if Quotient or Remainder is aliased - // with LHS or RHS. - Quotient.reallocate(BitWidth); - Remainder.reallocate(BitWidth); - - if (lhsWords == 1) { // rhsWords is 1 if lhsWords is 1. - // There is only one word to consider so use the native versions. - uint64_t lhsValue = LHS.U.pVal[0]; - uint64_t rhsValue = RHS.U.pVal[0]; - Quotient = lhsValue / rhsValue; - Remainder = lhsValue % rhsValue; - return; - } - - // Okay, lets do it the long way - divide(LHS.U.pVal, lhsWords, RHS.U.pVal, rhsWords, Quotient.U.pVal, - Remainder.U.pVal); - // Clear the rest of the Quotient and Remainder. - std::memset(Quotient.U.pVal + lhsWords, 0, - (getNumWords(BitWidth) - lhsWords) * APINT_WORD_SIZE); - std::memset(Remainder.U.pVal + rhsWords, 0, - (getNumWords(BitWidth) - rhsWords) * APINT_WORD_SIZE); -} - -void APInt::udivrem(const APInt &LHS, uint64_t RHS, APInt &Quotient, - uint64_t &Remainder) { - assert(RHS != 0 && "Divide by zero?"); - unsigned BitWidth = LHS.BitWidth; - - // First, deal with the easy case - if (LHS.isSingleWord()) { - uint64_t QuotVal = LHS.U.VAL / RHS; - Remainder = LHS.U.VAL % RHS; - Quotient = APInt(BitWidth, QuotVal); - return; - } - - // Get some size facts about the dividend and divisor - unsigned lhsWords = getNumWords(LHS.getActiveBits()); - - // Check the degenerate cases - if (lhsWords == 0) { - Quotient = APInt(BitWidth, 0); // 0 / Y ===> 0 - Remainder = 0; // 0 % Y ===> 0 - return; - } - - if (RHS == 1) { - Quotient = LHS; // X / 1 ===> X - Remainder = 0; // X % 1 ===> 0 - return; - } - - if (LHS.ult(RHS)) { - Remainder = LHS.getZExtValue(); // X % Y ===> X, iff X < Y - Quotient = APInt(BitWidth, 0); // X / Y ===> 0, iff X < Y - return; - } - - if (LHS == RHS) { - Quotient = APInt(BitWidth, 1); // X / X ===> 1 - Remainder = 0; // X % X ===> 0; - return; - } - - // Make sure there is enough space to hold the results. - // NOTE: This assumes that reallocate won't affect any bits if it doesn't - // change the size. This is necessary if Quotient is aliased with LHS. - Quotient.reallocate(BitWidth); - - if (lhsWords == 1) { // rhsWords is 1 if lhsWords is 1. - // There is only one word to consider so use the native versions. - uint64_t lhsValue = LHS.U.pVal[0]; - Quotient = lhsValue / RHS; - Remainder = lhsValue % RHS; - return; - } - - // Okay, lets do it the long way - divide(LHS.U.pVal, lhsWords, &RHS, 1, Quotient.U.pVal, &Remainder); - // Clear the rest of the Quotient. - std::memset(Quotient.U.pVal + lhsWords, 0, - (getNumWords(BitWidth) - lhsWords) * APINT_WORD_SIZE); -} - -void APInt::sdivrem(const APInt &LHS, const APInt &RHS, - APInt &Quotient, APInt &Remainder) { - if (LHS.isNegative()) { - if (RHS.isNegative()) - APInt::udivrem(-LHS, -RHS, Quotient, Remainder); - else { - APInt::udivrem(-LHS, RHS, Quotient, Remainder); - Quotient.negate(); - } - Remainder.negate(); - } else if (RHS.isNegative()) { - APInt::udivrem(LHS, -RHS, Quotient, Remainder); - Quotient.negate(); - } else { - APInt::udivrem(LHS, RHS, Quotient, Remainder); - } -} - -void APInt::sdivrem(const APInt &LHS, int64_t RHS, - APInt &Quotient, int64_t &Remainder) { - uint64_t R = Remainder; - if (LHS.isNegative()) { - if (RHS < 0) - APInt::udivrem(-LHS, -RHS, Quotient, R); - else { - APInt::udivrem(-LHS, RHS, Quotient, R); - Quotient.negate(); - } - R = -R; - } else if (RHS < 0) { - APInt::udivrem(LHS, -RHS, Quotient, R); - Quotient.negate(); - } else { - APInt::udivrem(LHS, RHS, Quotient, R); - } - Remainder = R; -} - -APInt APInt::sadd_ov(const APInt &RHS, bool &Overflow) const { - APInt Res = *this+RHS; - Overflow = isNonNegative() == RHS.isNonNegative() && - Res.isNonNegative() != isNonNegative(); - return Res; -} - -APInt APInt::uadd_ov(const APInt &RHS, bool &Overflow) const { - APInt Res = *this+RHS; - Overflow = Res.ult(RHS); - return Res; -} - -APInt APInt::ssub_ov(const APInt &RHS, bool &Overflow) const { - APInt Res = *this - RHS; - Overflow = isNonNegative() != RHS.isNonNegative() && - Res.isNonNegative() != isNonNegative(); - return Res; -} - -APInt APInt::usub_ov(const APInt &RHS, bool &Overflow) const { - APInt Res = *this-RHS; - Overflow = Res.ugt(*this); - return Res; -} - -APInt APInt::sdiv_ov(const APInt &RHS, bool &Overflow) const { - // MININT/-1 --> overflow. - Overflow = isMinSignedValue() && RHS.isAllOnesValue(); - return sdiv(RHS); -} - -APInt APInt::smul_ov(const APInt &RHS, bool &Overflow) const { - APInt Res = *this * RHS; - - if (*this != 0 && RHS != 0) - Overflow = Res.sdiv(RHS) != *this || Res.sdiv(*this) != RHS; - else - Overflow = false; - return Res; -} - -APInt APInt::umul_ov(const APInt &RHS, bool &Overflow) const { - if (countLeadingZeros() + RHS.countLeadingZeros() + 2 <= BitWidth) { - Overflow = true; - return *this * RHS; - } - - APInt Res = lshr(1) * RHS; - Overflow = Res.isNegative(); - Res <<= 1; - if ((*this)[0]) { - Res += RHS; - if (Res.ult(RHS)) - Overflow = true; - } - return Res; -} - -APInt APInt::sshl_ov(const APInt &ShAmt, bool &Overflow) const { - Overflow = ShAmt.uge(getBitWidth()); - if (Overflow) - return APInt(BitWidth, 0); - - if (isNonNegative()) // Don't allow sign change. - Overflow = ShAmt.uge(countLeadingZeros()); - else - Overflow = ShAmt.uge(countLeadingOnes()); - - return *this << ShAmt; -} - -APInt APInt::ushl_ov(const APInt &ShAmt, bool &Overflow) const { - Overflow = ShAmt.uge(getBitWidth()); - if (Overflow) - return APInt(BitWidth, 0); - - Overflow = ShAmt.ugt(countLeadingZeros()); - - return *this << ShAmt; -} - -APInt APInt::sadd_sat(const APInt &RHS) const { - bool Overflow; - APInt Res = sadd_ov(RHS, Overflow); - if (!Overflow) - return Res; - - return isNegative() ? APInt::getSignedMinValue(BitWidth) - : APInt::getSignedMaxValue(BitWidth); -} - -APInt APInt::uadd_sat(const APInt &RHS) const { - bool Overflow; - APInt Res = uadd_ov(RHS, Overflow); - if (!Overflow) - return Res; - - return APInt::getMaxValue(BitWidth); -} - -APInt APInt::ssub_sat(const APInt &RHS) const { - bool Overflow; - APInt Res = ssub_ov(RHS, Overflow); - if (!Overflow) - return Res; - - return isNegative() ? APInt::getSignedMinValue(BitWidth) - : APInt::getSignedMaxValue(BitWidth); -} - -APInt APInt::usub_sat(const APInt &RHS) const { - bool Overflow; - APInt Res = usub_ov(RHS, Overflow); - if (!Overflow) - return Res; - - return APInt(BitWidth, 0); -} - - -void APInt::fromString(unsigned numbits, StringRef str, uint8_t radix) { - // Check our assumptions here - assert(!str.empty() && "Invalid string length"); - assert((radix == 10 || radix == 8 || radix == 16 || radix == 2 || - radix == 36) && - "Radix should be 2, 8, 10, 16, or 36!"); - - StringRef::iterator p = str.begin(); - size_t slen = str.size(); - bool isNeg = *p == '-'; - if (*p == '-' || *p == '+') { - p++; - slen--; - assert(slen && "String is only a sign, needs a value."); - } - assert((slen <= numbits || radix != 2) && "Insufficient bit width"); - assert(((slen-1)*3 <= numbits || radix != 8) && "Insufficient bit width"); - assert(((slen-1)*4 <= numbits || radix != 16) && "Insufficient bit width"); - assert((((slen-1)*64)/22 <= numbits || radix != 10) && - "Insufficient bit width"); - - // Allocate memory if needed - if (isSingleWord()) - U.VAL = 0; - else - U.pVal = getClearedMemory(getNumWords()); - - // Figure out if we can shift instead of multiply - unsigned shift = (radix == 16 ? 4 : radix == 8 ? 3 : radix == 2 ? 1 : 0); - - // Enter digit traversal loop - for (StringRef::iterator e = str.end(); p != e; ++p) { - unsigned digit = getDigit(*p, radix); - assert(digit < radix && "Invalid character in digit string"); - - // Shift or multiply the value by the radix - if (slen > 1) { - if (shift) - *this <<= shift; - else - *this *= radix; - } - - // Add in the digit we just interpreted - *this += digit; - } - // If its negative, put it in two's complement form - if (isNeg) - this->negate(); -} - -void APInt::toString(SmallVectorImpl<char> &Str, unsigned Radix, - bool Signed, bool formatAsCLiteral) const { - assert((Radix == 10 || Radix == 8 || Radix == 16 || Radix == 2 || - Radix == 36) && - "Radix should be 2, 8, 10, 16, or 36!"); - - const char *Prefix = ""; - if (formatAsCLiteral) { - switch (Radix) { - case 2: - // Binary literals are a non-standard extension added in gcc 4.3: - // http://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Binary-constants.html - Prefix = "0b"; - break; - case 8: - Prefix = "0"; - break; - case 10: - break; // No prefix - case 16: - Prefix = "0x"; - break; - default: - llvm_unreachable("Invalid radix!"); - } - } - - // First, check for a zero value and just short circuit the logic below. - if (*this == 0) { - while (*Prefix) { - Str.push_back(*Prefix); - ++Prefix; - }; - Str.push_back('0'); - return; - } - - static const char Digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; - - if (isSingleWord()) { - char Buffer[65]; - char *BufPtr = std::end(Buffer); - - uint64_t N; - if (!Signed) { - N = getZExtValue(); - } else { - int64_t I = getSExtValue(); - if (I >= 0) { - N = I; - } else { - Str.push_back('-'); - N = -(uint64_t)I; - } - } - - while (*Prefix) { - Str.push_back(*Prefix); - ++Prefix; - }; - - while (N) { - *--BufPtr = Digits[N % Radix]; - N /= Radix; - } - Str.append(BufPtr, std::end(Buffer)); - return; - } - - APInt Tmp(*this); - - if (Signed && isNegative()) { - // They want to print the signed version and it is a negative value - // Flip the bits and add one to turn it into the equivalent positive - // value and put a '-' in the result. - Tmp.negate(); - Str.push_back('-'); - } - - while (*Prefix) { - Str.push_back(*Prefix); - ++Prefix; - }; - - // We insert the digits backward, then reverse them to get the right order. - unsigned StartDig = Str.size(); - - // For the 2, 8 and 16 bit cases, we can just shift instead of divide - // because the number of bits per digit (1, 3 and 4 respectively) divides - // equally. We just shift until the value is zero. - if (Radix == 2 || Radix == 8 || Radix == 16) { - // Just shift tmp right for each digit width until it becomes zero - unsigned ShiftAmt = (Radix == 16 ? 4 : (Radix == 8 ? 3 : 1)); - unsigned MaskAmt = Radix - 1; - - while (Tmp.getBoolValue()) { - unsigned Digit = unsigned(Tmp.getRawData()[0]) & MaskAmt; - Str.push_back(Digits[Digit]); - Tmp.lshrInPlace(ShiftAmt); - } - } else { - while (Tmp.getBoolValue()) { - uint64_t Digit; - udivrem(Tmp, Radix, Tmp, Digit); - assert(Digit < Radix && "divide failed"); - Str.push_back(Digits[Digit]); - } - } - - // Reverse the digits before returning. - std::reverse(Str.begin()+StartDig, Str.end()); -} - -/// Returns the APInt as a std::string. Note that this is an inefficient method. -/// It is better to pass in a SmallVector/SmallString to the methods above. -std::string APInt::toString(unsigned Radix = 10, bool Signed = true) const { - SmallString<40> S; - toString(S, Radix, Signed, /* formatAsCLiteral = */false); - return S.str(); -} - -#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) -LLVM_DUMP_METHOD void APInt::dump() const { - SmallString<40> S, U; - this->toStringUnsigned(U); - this->toStringSigned(S); - dbgs() << "APInt(" << BitWidth << "b, " - << U << "u " << S << "s)\n"; -} -#endif - -void APInt::print(raw_ostream &OS, bool isSigned) const { - SmallString<40> S; - this->toString(S, 10, isSigned, /* formatAsCLiteral = */false); - OS << S; -} - -// This implements a variety of operations on a representation of -// arbitrary precision, two's-complement, bignum integer values. - -// Assumed by lowHalf, highHalf, partMSB and partLSB. A fairly safe -// and unrestricting assumption. -static_assert(APInt::APINT_BITS_PER_WORD % 2 == 0, - "Part width must be divisible by 2!"); - -/* Some handy functions local to this file. */ - -/* Returns the integer part with the least significant BITS set. - BITS cannot be zero. */ -static inline APInt::WordType lowBitMask(unsigned bits) { - assert(bits != 0 && bits <= APInt::APINT_BITS_PER_WORD); - - return ~(APInt::WordType) 0 >> (APInt::APINT_BITS_PER_WORD - bits); -} - -/* Returns the value of the lower half of PART. */ -static inline APInt::WordType lowHalf(APInt::WordType part) { - return part & lowBitMask(APInt::APINT_BITS_PER_WORD / 2); -} - -/* Returns the value of the upper half of PART. */ -static inline APInt::WordType highHalf(APInt::WordType part) { - return part >> (APInt::APINT_BITS_PER_WORD / 2); -} - -/* Returns the bit number of the most significant set bit of a part. - If the input number has no bits set -1U is returned. */ -static unsigned partMSB(APInt::WordType value) { - return findLastSet(value, ZB_Max); -} - -/* Returns the bit number of the least significant set bit of a - part. If the input number has no bits set -1U is returned. */ -static unsigned partLSB(APInt::WordType value) { - return findFirstSet(value, ZB_Max); -} - -/* Sets the least significant part of a bignum to the input value, and - zeroes out higher parts. */ -void APInt::tcSet(WordType *dst, WordType part, unsigned parts) { - assert(parts > 0); - - dst[0] = part; - for (unsigned i = 1; i < parts; i++) - dst[i] = 0; -} - -/* Assign one bignum to another. */ -void APInt::tcAssign(WordType *dst, const WordType *src, unsigned parts) { - for (unsigned i = 0; i < parts; i++) - dst[i] = src[i]; -} - -/* Returns true if a bignum is zero, false otherwise. */ -bool APInt::tcIsZero(const WordType *src, unsigned parts) { - for (unsigned i = 0; i < parts; i++) - if (src[i]) - return false; - - return true; -} - -/* Extract the given bit of a bignum; returns 0 or 1. */ -int APInt::tcExtractBit(const WordType *parts, unsigned bit) { - return (parts[whichWord(bit)] & maskBit(bit)) != 0; -} - -/* Set the given bit of a bignum. */ -void APInt::tcSetBit(WordType *parts, unsigned bit) { - parts[whichWord(bit)] |= maskBit(bit); -} - -/* Clears the given bit of a bignum. */ -void APInt::tcClearBit(WordType *parts, unsigned bit) { - parts[whichWord(bit)] &= ~maskBit(bit); -} - -/* Returns the bit number of the least significant set bit of a - number. If the input number has no bits set -1U is returned. */ -unsigned APInt::tcLSB(const WordType *parts, unsigned n) { - for (unsigned i = 0; i < n; i++) { - if (parts[i] != 0) { - unsigned lsb = partLSB(parts[i]); - - return lsb + i * APINT_BITS_PER_WORD; - } - } - - return -1U; -} - -/* Returns the bit number of the most significant set bit of a number. - If the input number has no bits set -1U is returned. */ -unsigned APInt::tcMSB(const WordType *parts, unsigned n) { - do { - --n; - - if (parts[n] != 0) { - unsigned msb = partMSB(parts[n]); - - return msb + n * APINT_BITS_PER_WORD; - } - } while (n); - - return -1U; -} - -/* Copy the bit vector of width srcBITS from SRC, starting at bit - srcLSB, to DST, of dstCOUNT parts, such that the bit srcLSB becomes - the least significant bit of DST. All high bits above srcBITS in - DST are zero-filled. */ -void -APInt::tcExtract(WordType *dst, unsigned dstCount, const WordType *src, - unsigned srcBits, unsigned srcLSB) { - unsigned dstParts = (srcBits + APINT_BITS_PER_WORD - 1) / APINT_BITS_PER_WORD; - assert(dstParts <= dstCount); - - unsigned firstSrcPart = srcLSB / APINT_BITS_PER_WORD; - tcAssign (dst, src + firstSrcPart, dstParts); - - unsigned shift = srcLSB % APINT_BITS_PER_WORD; - tcShiftRight (dst, dstParts, shift); - - /* We now have (dstParts * APINT_BITS_PER_WORD - shift) bits from SRC - in DST. If this is less that srcBits, append the rest, else - clear the high bits. */ - unsigned n = dstParts * APINT_BITS_PER_WORD - shift; - if (n < srcBits) { - WordType mask = lowBitMask (srcBits - n); - dst[dstParts - 1] |= ((src[firstSrcPart + dstParts] & mask) - << n % APINT_BITS_PER_WORD); - } else if (n > srcBits) { - if (srcBits % APINT_BITS_PER_WORD) - dst[dstParts - 1] &= lowBitMask (srcBits % APINT_BITS_PER_WORD); - } - - /* Clear high parts. */ - while (dstParts < dstCount) - dst[dstParts++] = 0; -} - -/* DST += RHS + C where C is zero or one. Returns the carry flag. */ -APInt::WordType APInt::tcAdd(WordType *dst, const WordType *rhs, - WordType c, unsigned parts) { - assert(c <= 1); - - for (unsigned i = 0; i < parts; i++) { - WordType l = dst[i]; - if (c) { - dst[i] += rhs[i] + 1; - c = (dst[i] <= l); - } else { - dst[i] += rhs[i]; - c = (dst[i] < l); - } - } - - return c; -} - -/// This function adds a single "word" integer, src, to the multiple -/// "word" integer array, dst[]. dst[] is modified to reflect the addition and -/// 1 is returned if there is a carry out, otherwise 0 is returned. -/// @returns the carry of the addition. -APInt::WordType APInt::tcAddPart(WordType *dst, WordType src, - unsigned parts) { - for (unsigned i = 0; i < parts; ++i) { - dst[i] += src; - if (dst[i] >= src) - return 0; // No need to carry so exit early. - src = 1; // Carry one to next digit. - } - - return 1; -} - -/* DST -= RHS + C where C is zero or one. Returns the carry flag. */ -APInt::WordType APInt::tcSubtract(WordType *dst, const WordType *rhs, - WordType c, unsigned parts) { - assert(c <= 1); - - for (unsigned i = 0; i < parts; i++) { - WordType l = dst[i]; - if (c) { - dst[i] -= rhs[i] + 1; - c = (dst[i] >= l); - } else { - dst[i] -= rhs[i]; - c = (dst[i] > l); - } - } - - return c; -} - -/// This function subtracts a single "word" (64-bit word), src, from -/// the multi-word integer array, dst[], propagating the borrowed 1 value until -/// no further borrowing is needed or it runs out of "words" in dst. The result -/// is 1 if "borrowing" exhausted the digits in dst, or 0 if dst was not -/// exhausted. In other words, if src > dst then this function returns 1, -/// otherwise 0. -/// @returns the borrow out of the subtraction -APInt::WordType APInt::tcSubtractPart(WordType *dst, WordType src, - unsigned parts) { - for (unsigned i = 0; i < parts; ++i) { - WordType Dst = dst[i]; - dst[i] -= src; - if (src <= Dst) - return 0; // No need to borrow so exit early. - src = 1; // We have to "borrow 1" from next "word" - } - - return 1; -} - -/* Negate a bignum in-place. */ -void APInt::tcNegate(WordType *dst, unsigned parts) { - tcComplement(dst, parts); - tcIncrement(dst, parts); -} - -/* DST += SRC * MULTIPLIER + CARRY if add is true - DST = SRC * MULTIPLIER + CARRY if add is false - - Requires 0 <= DSTPARTS <= SRCPARTS + 1. If DST overlaps SRC - they must start at the same point, i.e. DST == SRC. - - If DSTPARTS == SRCPARTS + 1 no overflow occurs and zero is - returned. Otherwise DST is filled with the least significant - DSTPARTS parts of the result, and if all of the omitted higher - parts were zero return zero, otherwise overflow occurred and - return one. */ -int APInt::tcMultiplyPart(WordType *dst, const WordType *src, - WordType multiplier, WordType carry, - unsigned srcParts, unsigned dstParts, - bool add) { - /* Otherwise our writes of DST kill our later reads of SRC. */ - assert(dst <= src || dst >= src + srcParts); - assert(dstParts <= srcParts + 1); - - /* N loops; minimum of dstParts and srcParts. */ - unsigned n = std::min(dstParts, srcParts); - - for (unsigned i = 0; i < n; i++) { - WordType low, mid, high, srcPart; - - /* [ LOW, HIGH ] = MULTIPLIER * SRC[i] + DST[i] + CARRY. - - This cannot overflow, because - - (n - 1) * (n - 1) + 2 (n - 1) = (n - 1) * (n + 1) - - which is less than n^2. */ - - srcPart = src[i]; - - if (multiplier == 0 || srcPart == 0) { - low = carry; - high = 0; - } else { - low = lowHalf(srcPart) * lowHalf(multiplier); - high = highHalf(srcPart) * highHalf(multiplier); - - mid = lowHalf(srcPart) * highHalf(multiplier); - high += highHalf(mid); - mid <<= APINT_BITS_PER_WORD / 2; - if (low + mid < low) - high++; - low += mid; - - mid = highHalf(srcPart) * lowHalf(multiplier); - high += highHalf(mid); - mid <<= APINT_BITS_PER_WORD / 2; - if (low + mid < low) - high++; - low += mid; - - /* Now add carry. */ - if (low + carry < low) - high++; - low += carry; - } - - if (add) { - /* And now DST[i], and store the new low part there. */ - if (low + dst[i] < low) - high++; - dst[i] += low; - } else - dst[i] = low; - - carry = high; - } - - if (srcParts < dstParts) { - /* Full multiplication, there is no overflow. */ - assert(srcParts + 1 == dstParts); - dst[srcParts] = carry; - return 0; - } - - /* We overflowed if there is carry. */ - if (carry) - return 1; - - /* We would overflow if any significant unwritten parts would be - non-zero. This is true if any remaining src parts are non-zero - and the multiplier is non-zero. */ - if (multiplier) - for (unsigned i = dstParts; i < srcParts; i++) - if (src[i]) - return 1; - - /* We fitted in the narrow destination. */ - return 0; -} - -/* DST = LHS * RHS, where DST has the same width as the operands and - is filled with the least significant parts of the result. Returns - one if overflow occurred, otherwise zero. DST must be disjoint - from both operands. */ -int APInt::tcMultiply(WordType *dst, const WordType *lhs, - const WordType *rhs, unsigned parts) { - assert(dst != lhs && dst != rhs); - - int overflow = 0; - tcSet(dst, 0, parts); - - for (unsigned i = 0; i < parts; i++) - overflow |= tcMultiplyPart(&dst[i], lhs, rhs[i], 0, parts, - parts - i, true); - - return overflow; -} - -/// DST = LHS * RHS, where DST has width the sum of the widths of the -/// operands. No overflow occurs. DST must be disjoint from both operands. -void APInt::tcFullMultiply(WordType *dst, const WordType *lhs, - const WordType *rhs, unsigned lhsParts, - unsigned rhsParts) { - /* Put the narrower number on the LHS for less loops below. */ - if (lhsParts > rhsParts) - return tcFullMultiply (dst, rhs, lhs, rhsParts, lhsParts); - - assert(dst != lhs && dst != rhs); - - tcSet(dst, 0, rhsParts); - - for (unsigned i = 0; i < lhsParts; i++) - tcMultiplyPart(&dst[i], rhs, lhs[i], 0, rhsParts, rhsParts + 1, true); -} - -/* If RHS is zero LHS and REMAINDER are left unchanged, return one. - Otherwise set LHS to LHS / RHS with the fractional part discarded, - set REMAINDER to the remainder, return zero. i.e. - - OLD_LHS = RHS * LHS + REMAINDER - - SCRATCH is a bignum of the same size as the operands and result for - use by the routine; its contents need not be initialized and are - destroyed. LHS, REMAINDER and SCRATCH must be distinct. -*/ -int APInt::tcDivide(WordType *lhs, const WordType *rhs, - WordType *remainder, WordType *srhs, - unsigned parts) { - assert(lhs != remainder && lhs != srhs && remainder != srhs); - - unsigned shiftCount = tcMSB(rhs, parts) + 1; - if (shiftCount == 0) - return true; - - shiftCount = parts * APINT_BITS_PER_WORD - shiftCount; - unsigned n = shiftCount / APINT_BITS_PER_WORD; - WordType mask = (WordType) 1 << (shiftCount % APINT_BITS_PER_WORD); - - tcAssign(srhs, rhs, parts); - tcShiftLeft(srhs, parts, shiftCount); - tcAssign(remainder, lhs, parts); - tcSet(lhs, 0, parts); - - /* Loop, subtracting SRHS if REMAINDER is greater and adding that to - the total. */ - for (;;) { - int compare = tcCompare(remainder, srhs, parts); - if (compare >= 0) { - tcSubtract(remainder, srhs, 0, parts); - lhs[n] |= mask; - } - - if (shiftCount == 0) - break; - shiftCount--; - tcShiftRight(srhs, parts, 1); - if ((mask >>= 1) == 0) { - mask = (WordType) 1 << (APINT_BITS_PER_WORD - 1); - n--; - } - } - - return false; -} - -/// Shift a bignum left Cound bits in-place. Shifted in bits are zero. There are -/// no restrictions on Count. -void APInt::tcShiftLeft(WordType *Dst, unsigned Words, unsigned Count) { - // Don't bother performing a no-op shift. - if (!Count) - return; - - // WordShift is the inter-part shift; BitShift is the intra-part shift. - unsigned WordShift = std::min(Count / APINT_BITS_PER_WORD, Words); - unsigned BitShift = Count % APINT_BITS_PER_WORD; - - // Fastpath for moving by whole words. - if (BitShift == 0) { - std::memmove(Dst + WordShift, Dst, (Words - WordShift) * APINT_WORD_SIZE); - } else { - while (Words-- > WordShift) { - Dst[Words] = Dst[Words - WordShift] << BitShift; - if (Words > WordShift) - Dst[Words] |= - Dst[Words - WordShift - 1] >> (APINT_BITS_PER_WORD - BitShift); - } - } - - // Fill in the remainder with 0s. - std::memset(Dst, 0, WordShift * APINT_WORD_SIZE); -} - -/// Shift a bignum right Count bits in-place. Shifted in bits are zero. There -/// are no restrictions on Count. -void APInt::tcShiftRight(WordType *Dst, unsigned Words, unsigned Count) { - // Don't bother performing a no-op shift. - if (!Count) - return; - - // WordShift is the inter-part shift; BitShift is the intra-part shift. - unsigned WordShift = std::min(Count / APINT_BITS_PER_WORD, Words); - unsigned BitShift = Count % APINT_BITS_PER_WORD; - - unsigned WordsToMove = Words - WordShift; - // Fastpath for moving by whole words. - if (BitShift == 0) { - std::memmove(Dst, Dst + WordShift, WordsToMove * APINT_WORD_SIZE); - } else { - for (unsigned i = 0; i != WordsToMove; ++i) { - Dst[i] = Dst[i + WordShift] >> BitShift; - if (i + 1 != WordsToMove) - Dst[i] |= Dst[i + WordShift + 1] << (APINT_BITS_PER_WORD - BitShift); - } - } - - // Fill in the remainder with 0s. - std::memset(Dst + WordsToMove, 0, WordShift * APINT_WORD_SIZE); -} - -/* Bitwise and of two bignums. */ -void APInt::tcAnd(WordType *dst, const WordType *rhs, unsigned parts) { - for (unsigned i = 0; i < parts; i++) - dst[i] &= rhs[i]; -} - -/* Bitwise inclusive or of two bignums. */ -void APInt::tcOr(WordType *dst, const WordType *rhs, unsigned parts) { - for (unsigned i = 0; i < parts; i++) - dst[i] |= rhs[i]; -} - -/* Bitwise exclusive or of two bignums. */ -void APInt::tcXor(WordType *dst, const WordType *rhs, unsigned parts) { - for (unsigned i = 0; i < parts; i++) - dst[i] ^= rhs[i]; -} - -/* Complement a bignum in-place. */ -void APInt::tcComplement(WordType *dst, unsigned parts) { - for (unsigned i = 0; i < parts; i++) - dst[i] = ~dst[i]; -} - -/* Comparison (unsigned) of two bignums. */ -int APInt::tcCompare(const WordType *lhs, const WordType *rhs, - unsigned parts) { - while (parts) { - parts--; - if (lhs[parts] != rhs[parts]) - return (lhs[parts] > rhs[parts]) ? 1 : -1; - } - - return 0; -} - -/* Set the least significant BITS bits of a bignum, clear the - rest. */ -void APInt::tcSetLeastSignificantBits(WordType *dst, unsigned parts, - unsigned bits) { - unsigned i = 0; - while (bits > APINT_BITS_PER_WORD) { - dst[i++] = ~(WordType) 0; - bits -= APINT_BITS_PER_WORD; - } - - if (bits) - dst[i++] = ~(WordType) 0 >> (APINT_BITS_PER_WORD - bits); - - while (i < parts) - dst[i++] = 0; -} - -APInt llvm::APIntOps::RoundingUDiv(const APInt &A, const APInt &B, - APInt::Rounding RM) { - // Currently udivrem always rounds down. - switch (RM) { - case APInt::Rounding::DOWN: - case APInt::Rounding::TOWARD_ZERO: - return A.udiv(B); - case APInt::Rounding::UP: { - APInt Quo, Rem; - APInt::udivrem(A, B, Quo, Rem); - if (Rem == 0) - return Quo; - return Quo + 1; - } - } - llvm_unreachable("Unknown APInt::Rounding enum"); -} - -APInt llvm::APIntOps::RoundingSDiv(const APInt &A, const APInt &B, - APInt::Rounding RM) { - switch (RM) { - case APInt::Rounding::DOWN: - case APInt::Rounding::UP: { - APInt Quo, Rem; - APInt::sdivrem(A, B, Quo, Rem); - if (Rem == 0) - return Quo; - // This algorithm deals with arbitrary rounding mode used by sdivrem. - // We want to check whether the non-integer part of the mathematical value - // is negative or not. If the non-integer part is negative, we need to round - // down from Quo; otherwise, if it's positive or 0, we return Quo, as it's - // already rounded down. - if (RM == APInt::Rounding::DOWN) { - if (Rem.isNegative() != B.isNegative()) - return Quo - 1; - return Quo; - } - if (Rem.isNegative() != B.isNegative()) - return Quo; - return Quo + 1; - } - // Currently sdiv rounds twards zero. - case APInt::Rounding::TOWARD_ZERO: - return A.sdiv(B); - } - llvm_unreachable("Unknown APInt::Rounding enum"); -} - -Optional<APInt> -llvm::APIntOps::SolveQuadraticEquationWrap(APInt A, APInt B, APInt C, - unsigned RangeWidth) { - unsigned CoeffWidth = A.getBitWidth(); - assert(CoeffWidth == B.getBitWidth() && CoeffWidth == C.getBitWidth()); - assert(RangeWidth <= CoeffWidth && - "Value range width should be less than coefficient width"); - assert(RangeWidth > 1 && "Value range bit width should be > 1"); - - LLVM_DEBUG(dbgs() << __func__ << ": solving " << A << "x^2 + " << B - << "x + " << C << ", rw:" << RangeWidth << '\n'); - - // Identify 0 as a (non)solution immediately. - if (C.sextOrTrunc(RangeWidth).isNullValue() ) { - LLVM_DEBUG(dbgs() << __func__ << ": zero solution\n"); - return APInt(CoeffWidth, 0); - } - - // The result of APInt arithmetic has the same bit width as the operands, - // so it can actually lose high bits. A product of two n-bit integers needs - // 2n-1 bits to represent the full value. - // The operation done below (on quadratic coefficients) that can produce - // the largest value is the evaluation of the equation during bisection, - // which needs 3 times the bitwidth of the coefficient, so the total number - // of required bits is 3n. - // - // The purpose of this extension is to simulate the set Z of all integers, - // where n+1 > n for all n in Z. In Z it makes sense to talk about positive - // and negative numbers (not so much in a modulo arithmetic). The method - // used to solve the equation is based on the standard formula for real - // numbers, and uses the concepts of "positive" and "negative" with their - // usual meanings. - CoeffWidth *= 3; - A = A.sext(CoeffWidth); - B = B.sext(CoeffWidth); - C = C.sext(CoeffWidth); - - // Make A > 0 for simplicity. Negate cannot overflow at this point because - // the bit width has increased. - if (A.isNegative()) { - A.negate(); - B.negate(); - C.negate(); - } - - // Solving an equation q(x) = 0 with coefficients in modular arithmetic - // is really solving a set of equations q(x) = kR for k = 0, 1, 2, ..., - // and R = 2^BitWidth. - // Since we're trying not only to find exact solutions, but also values - // that "wrap around", such a set will always have a solution, i.e. an x - // that satisfies at least one of the equations, or such that |q(x)| - // exceeds kR, while |q(x-1)| for the same k does not. - // - // We need to find a value k, such that Ax^2 + Bx + C = kR will have a - // positive solution n (in the above sense), and also such that the n - // will be the least among all solutions corresponding to k = 0, 1, ... - // (more precisely, the least element in the set - // { n(k) | k is such that a solution n(k) exists }). - // - // Consider the parabola (over real numbers) that corresponds to the - // quadratic equation. Since A > 0, the arms of the parabola will point - // up. Picking different values of k will shift it up and down by R. - // - // We want to shift the parabola in such a way as to reduce the problem - // of solving q(x) = kR to solving shifted_q(x) = 0. - // (The interesting solutions are the ceilings of the real number - // solutions.) - APInt R = APInt::getOneBitSet(CoeffWidth, RangeWidth); - APInt TwoA = 2 * A; - APInt SqrB = B * B; - bool PickLow; - - auto RoundUp = [] (const APInt &V, const APInt &A) -> APInt { - assert(A.isStrictlyPositive()); - APInt T = V.abs().urem(A); - if (T.isNullValue()) - return V; - return V.isNegative() ? V+T : V+(A-T); - }; - - // The vertex of the parabola is at -B/2A, but since A > 0, it's negative - // iff B is positive. - if (B.isNonNegative()) { - // If B >= 0, the vertex it at a negative location (or at 0), so in - // order to have a non-negative solution we need to pick k that makes - // C-kR negative. To satisfy all the requirements for the solution - // that we are looking for, it needs to be closest to 0 of all k. - C = C.srem(R); - if (C.isStrictlyPositive()) - C -= R; - // Pick the greater solution. - PickLow = false; - } else { - // If B < 0, the vertex is at a positive location. For any solution - // to exist, the discriminant must be non-negative. This means that - // C-kR <= B^2/4A is a necessary condition for k, i.e. there is a - // lower bound on values of k: kR >= C - B^2/4A. - APInt LowkR = C - SqrB.udiv(2*TwoA); // udiv because all values > 0. - // Round LowkR up (towards +inf) to the nearest kR. - LowkR = RoundUp(LowkR, R); - - // If there exists k meeting the condition above, and such that - // C-kR > 0, there will be two positive real number solutions of - // q(x) = kR. Out of all such values of k, pick the one that makes - // C-kR closest to 0, (i.e. pick maximum k such that C-kR > 0). - // In other words, find maximum k such that LowkR <= kR < C. - if (C.sgt(LowkR)) { - // If LowkR < C, then such a k is guaranteed to exist because - // LowkR itself is a multiple of R. - C -= -RoundUp(-C, R); // C = C - RoundDown(C, R) - // Pick the smaller solution. - PickLow = true; - } else { - // If C-kR < 0 for all potential k's, it means that one solution - // will be negative, while the other will be positive. The positive - // solution will shift towards 0 if the parabola is moved up. - // Pick the kR closest to the lower bound (i.e. make C-kR closest - // to 0, or in other words, out of all parabolas that have solutions, - // pick the one that is the farthest "up"). - // Since LowkR is itself a multiple of R, simply take C-LowkR. - C -= LowkR; - // Pick the greater solution. - PickLow = false; - } - } - - LLVM_DEBUG(dbgs() << __func__ << ": updated coefficients " << A << "x^2 + " - << B << "x + " << C << ", rw:" << RangeWidth << '\n'); - - APInt D = SqrB - 4*A*C; - assert(D.isNonNegative() && "Negative discriminant"); - APInt SQ = D.sqrt(); - - APInt Q = SQ * SQ; - bool InexactSQ = Q != D; - // The calculated SQ may actually be greater than the exact (non-integer) - // value. If that's the case, decremement SQ to get a value that is lower. - if (Q.sgt(D)) - SQ -= 1; - - APInt X; - APInt Rem; - - // SQ is rounded down (i.e SQ * SQ <= D), so the roots may be inexact. - // When using the quadratic formula directly, the calculated low root - // may be greater than the exact one, since we would be subtracting SQ. - // To make sure that the calculated root is not greater than the exact - // one, subtract SQ+1 when calculating the low root (for inexact value - // of SQ). - if (PickLow) - APInt::sdivrem(-B - (SQ+InexactSQ), TwoA, X, Rem); - else - APInt::sdivrem(-B + SQ, TwoA, X, Rem); - - // The updated coefficients should be such that the (exact) solution is - // positive. Since APInt division rounds towards 0, the calculated one - // can be 0, but cannot be negative. - assert(X.isNonNegative() && "Solution should be non-negative"); - - if (!InexactSQ && Rem.isNullValue()) { - LLVM_DEBUG(dbgs() << __func__ << ": solution (root): " << X << '\n'); - return X; - } - - assert((SQ*SQ).sle(D) && "SQ = |_sqrt(D)_|, so SQ*SQ <= D"); - // The exact value of the square root of D should be between SQ and SQ+1. - // This implies that the solution should be between that corresponding to - // SQ (i.e. X) and that corresponding to SQ+1. - // - // The calculated X cannot be greater than the exact (real) solution. - // Actually it must be strictly less than the exact solution, while - // X+1 will be greater than or equal to it. - - APInt VX = (A*X + B)*X + C; - APInt VY = VX + TwoA*X + A + B; - bool SignChange = VX.isNegative() != VY.isNegative() || - VX.isNullValue() != VY.isNullValue(); - // If the sign did not change between X and X+1, X is not a valid solution. - // This could happen when the actual (exact) roots don't have an integer - // between them, so they would both be contained between X and X+1. - if (!SignChange) { - LLVM_DEBUG(dbgs() << __func__ << ": no valid solution\n"); - return None; - } - - X += 1; - LLVM_DEBUG(dbgs() << __func__ << ": solution (wrap): " << X << '\n'); - return X; -} - -/// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst -/// with the integer held in IntVal. -void llvm::StoreIntToMemory(const APInt &IntVal, uint8_t *Dst, - unsigned StoreBytes) { - assert((IntVal.getBitWidth()+7)/8 >= StoreBytes && "Integer too small!"); - const uint8_t *Src = (const uint8_t *)IntVal.getRawData(); - - if (sys::IsLittleEndianHost) { - // Little-endian host - the source is ordered from LSB to MSB. Order the - // destination from LSB to MSB: Do a straight copy. - memcpy(Dst, Src, StoreBytes); - } else { - // Big-endian host - the source is an array of 64 bit words ordered from - // LSW to MSW. Each word is ordered from MSB to LSB. Order the destination - // from MSB to LSB: Reverse the word order, but not the bytes in a word. - while (StoreBytes > sizeof(uint64_t)) { - StoreBytes -= sizeof(uint64_t); - // May not be aligned so use memcpy. - memcpy(Dst + StoreBytes, Src, sizeof(uint64_t)); - Src += sizeof(uint64_t); - } - - memcpy(Dst, Src + sizeof(uint64_t) - StoreBytes, StoreBytes); - } -} - -/// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting -/// from Src into IntVal, which is assumed to be wide enough and to hold zero. -void llvm::LoadIntFromMemory(APInt &IntVal, uint8_t *Src, unsigned LoadBytes) { - assert((IntVal.getBitWidth()+7)/8 >= LoadBytes && "Integer too small!"); - uint8_t *Dst = reinterpret_cast<uint8_t *>( - const_cast<uint64_t *>(IntVal.getRawData())); - - if (sys::IsLittleEndianHost) - // Little-endian host - the destination must be ordered from LSB to MSB. - // The source is ordered from LSB to MSB: Do a straight copy. - memcpy(Dst, Src, LoadBytes); - else { - // Big-endian - the destination is an array of 64 bit words ordered from - // LSW to MSW. Each word must be ordered from MSB to LSB. The source is - // ordered from MSB to LSB: Reverse the word order, but not the bytes in - // a word. - while (LoadBytes > sizeof(uint64_t)) { - LoadBytes -= sizeof(uint64_t); - // May not be aligned so use memcpy. - memcpy(Dst, Src + LoadBytes, sizeof(uint64_t)); - Dst += sizeof(uint64_t); - } - - memcpy(Dst + sizeof(uint64_t) - LoadBytes, Src, LoadBytes); - } -} |
