Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206707, reapplying r206704. The preceding commit
to CalcSpillWeights should have sorted out the failing buildbots.
<rdar://problem/14292693>
llvm-svn: 206766
diff --git a/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp b/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
new file mode 100644
index 0000000..e7424aeb
--- /dev/null
+++ b/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
@@ -0,0 +1,932 @@
+//===- BlockFrequencyImplInfo.cpp - Block Frequency Info Implementation ---===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Loops should be simplified before this analysis.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "block-freq"
+#include "llvm/Analysis/BlockFrequencyInfoImpl.h"
+#include "llvm/ADT/APFloat.h"
+#include "llvm/Support/raw_ostream.h"
+#include <deque>
+
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//
+// PositiveFloat implementation.
+//
+//===----------------------------------------------------------------------===//
+#ifndef _MSC_VER
+const int32_t PositiveFloatBase::MaxExponent;
+const int32_t PositiveFloatBase::MinExponent;
+#endif
+
+static void appendDigit(std::string &Str, unsigned D) {
+ assert(D < 10);
+ Str += '0' + D % 10;
+}
+
+static void appendNumber(std::string &Str, uint64_t N) {
+ while (N) {
+ appendDigit(Str, N % 10);
+ N /= 10;
+ }
+}
+
+static bool doesRoundUp(char Digit) {
+ switch (Digit) {
+ case '5':
+ case '6':
+ case '7':
+ case '8':
+ case '9':
+ return true;
+ default:
+ return false;
+ }
+}
+
+static std::string toStringAPFloat(uint64_t D, int E, unsigned Precision) {
+ assert(E >= PositiveFloatBase::MinExponent);
+ assert(E <= PositiveFloatBase::MaxExponent);
+
+ // Find a new E, but don't let it increase past MaxExponent.
+ int LeadingZeros = PositiveFloatBase::countLeadingZeros64(D);
+ int NewE = std::min(PositiveFloatBase::MaxExponent, E + 63 - LeadingZeros);
+ int Shift = 63 - (NewE - E);
+ assert(Shift <= LeadingZeros);
+ assert(Shift == LeadingZeros || NewE == PositiveFloatBase::MaxExponent);
+ D <<= Shift;
+ E = NewE;
+
+ // Check for a denormal.
+ unsigned AdjustedE = E + 16383;
+ if (!(D >> 63)) {
+ assert(E == PositiveFloatBase::MaxExponent);
+ AdjustedE = 0;
+ }
+
+ // Build the float and print it.
+ uint64_t RawBits[2] = {D, AdjustedE};
+ APFloat Float(APFloat::x87DoubleExtended, APInt(80, RawBits));
+ SmallVector<char, 24> Chars;
+ Float.toString(Chars, Precision, 0);
+ return std::string(Chars.begin(), Chars.end());
+}
+
+static std::string stripTrailingZeros(const std::string &Float) {
+ size_t NonZero = Float.find_last_not_of('0');
+ assert(NonZero != std::string::npos && "no . in floating point string");
+
+ if (Float[NonZero] == '.')
+ ++NonZero;
+
+ return Float.substr(0, NonZero + 1);
+}
+
+std::string PositiveFloatBase::toString(uint64_t D, int16_t E, int Width,
+ unsigned Precision) {
+ if (!D)
+ return "0.0";
+
+ // Canonicalize exponent and digits.
+ uint64_t Above0 = 0;
+ uint64_t Below0 = 0;
+ uint64_t Extra = 0;
+ int ExtraShift = 0;
+ if (E == 0) {
+ Above0 = D;
+ } else if (E > 0) {
+ if (int Shift = std::min(int16_t(countLeadingZeros64(D)), E)) {
+ D <<= Shift;
+ E -= Shift;
+
+ if (!E)
+ Above0 = D;
+ }
+ } else if (E > -64) {
+ Above0 = D >> -E;
+ Below0 = D << (64 + E);
+ } else if (E > -120) {
+ Below0 = D >> (-E - 64);
+ Extra = D << (128 + E);
+ ExtraShift = -64 - E;
+ }
+
+ // Fall back on APFloat for very small and very large numbers.
+ if (!Above0 && !Below0)
+ return toStringAPFloat(D, E, Precision);
+
+ // Append the digits before the decimal.
+ std::string Str;
+ size_t DigitsOut = 0;
+ if (Above0) {
+ appendNumber(Str, Above0);
+ DigitsOut = Str.size();
+ } else
+ appendDigit(Str, 0);
+ std::reverse(Str.begin(), Str.end());
+
+ // Return early if there's nothing after the decimal.
+ if (!Below0)
+ return Str + ".0";
+
+ // Append the decimal and beyond.
+ Str += '.';
+ uint64_t Error = UINT64_C(1) << (64 - Width);
+
+ // We need to shift Below0 to the right to make space for calculating
+ // digits. Save the precision we're losing in Extra.
+ Extra = (Below0 & 0xf) << 56 | (Extra >> 8);
+ Below0 >>= 4;
+ size_t SinceDot = 0;
+ size_t AfterDot = Str.size();
+ do {
+ if (ExtraShift) {
+ --ExtraShift;
+ Error *= 5;
+ } else
+ Error *= 10;
+
+ Below0 *= 10;
+ Extra *= 10;
+ Below0 += (Extra >> 60);
+ Extra = Extra & (UINT64_MAX >> 4);
+ appendDigit(Str, Below0 >> 60);
+ Below0 = Below0 & (UINT64_MAX >> 4);
+ if (DigitsOut || Str.back() != '0')
+ ++DigitsOut;
+ ++SinceDot;
+ } while (Error && (Below0 << 4 | Extra >> 60) >= Error / 2 &&
+ (!Precision || DigitsOut <= Precision || SinceDot < 2));
+
+ // Return early for maximum precision.
+ if (!Precision || DigitsOut <= Precision)
+ return stripTrailingZeros(Str);
+
+ // Find where to truncate.
+ size_t Truncate =
+ std::max(Str.size() - (DigitsOut - Precision), AfterDot + 1);
+
+ // Check if there's anything to truncate.
+ if (Truncate >= Str.size())
+ return stripTrailingZeros(Str);
+
+ bool Carry = doesRoundUp(Str[Truncate]);
+ if (!Carry)
+ return stripTrailingZeros(Str.substr(0, Truncate));
+
+ // Round with the first truncated digit.
+ for (std::string::reverse_iterator I(Str.begin() + Truncate), E = Str.rend();
+ I != E; ++I) {
+ if (*I == '.')
+ continue;
+ if (*I == '9') {
+ *I = '0';
+ continue;
+ }
+
+ ++*I;
+ Carry = false;
+ break;
+ }
+
+ // Add "1" in front if we still need to carry.
+ return stripTrailingZeros(std::string(Carry, '1') + Str.substr(0, Truncate));
+}
+
+raw_ostream &PositiveFloatBase::print(raw_ostream &OS, uint64_t D, int16_t E,
+ int Width, unsigned Precision) {
+ return OS << toString(D, E, Width, Precision);
+}
+
+void PositiveFloatBase::dump(uint64_t D, int16_t E, int Width) {
+ print(dbgs(), D, E, Width, 0) << "[" << Width << ":" << D << "*2^" << E
+ << "]";
+}
+
+static std::pair<uint64_t, int16_t>
+getRoundedFloat(uint64_t N, bool ShouldRound, int64_t Shift) {
+ if (ShouldRound)
+ if (!++N)
+ // Rounding caused an overflow.
+ return std::make_pair(UINT64_C(1), Shift + 64);
+ return std::make_pair(N, Shift);
+}
+
+std::pair<uint64_t, int16_t> PositiveFloatBase::divide64(uint64_t Dividend,
+ uint64_t Divisor) {
+ // Input should be sanitized.
+ assert(Divisor);
+ assert(Dividend);
+
+ // Minimize size of divisor.
+ int16_t Shift = 0;
+ if (int Zeros = countTrailingZeros(Divisor)) {
+ Shift -= Zeros;
+ Divisor >>= Zeros;
+ }
+
+ // Check for powers of two.
+ if (Divisor == 1)
+ return std::make_pair(Dividend, Shift);
+
+ // Maximize size of dividend.
+ if (int Zeros = countLeadingZeros64(Dividend)) {
+ Shift -= Zeros;
+ Dividend <<= Zeros;
+ }
+
+ // Start with the result of a divide.
+ uint64_t Quotient = Dividend / Divisor;
+ Dividend %= Divisor;
+
+ // Continue building the quotient with long division.
+ //
+ // TODO: continue with largers digits.
+ while (!(Quotient >> 63) && Dividend) {
+ // Shift Dividend, and check for overflow.
+ bool IsOverflow = Dividend >> 63;
+ Dividend <<= 1;
+ --Shift;
+
+ // Divide.
+ bool DoesDivide = IsOverflow || Divisor <= Dividend;
+ Quotient = (Quotient << 1) | uint64_t(DoesDivide);
+ Dividend -= DoesDivide ? Divisor : 0;
+ }
+
+ // Round.
+ if (Dividend >= getHalf(Divisor))
+ if (!++Quotient)
+ // Rounding caused an overflow in Quotient.
+ return std::make_pair(UINT64_C(1), Shift + 64);
+
+ return getRoundedFloat(Quotient, Dividend >= getHalf(Divisor), Shift);
+}
+
+std::pair<uint64_t, int16_t> PositiveFloatBase::multiply64(uint64_t L,
+ uint64_t R) {
+ // Separate into two 32-bit digits (U.L).
+ uint64_t UL = L >> 32, LL = L & UINT32_MAX, UR = R >> 32, LR = R & UINT32_MAX;
+
+ // Compute cross products.
+ uint64_t P1 = UL * UR, P2 = UL * LR, P3 = LL * UR, P4 = LL * LR;
+
+ // Sum into two 64-bit digits.
+ uint64_t Upper = P1, Lower = P4;
+ auto addWithCarry = [&](uint64_t N) {
+ uint64_t NewLower = Lower + (N << 32);
+ Upper += (N >> 32) + (NewLower < Lower);
+ Lower = NewLower;
+ };
+ addWithCarry(P2);
+ addWithCarry(P3);
+
+ // Check whether the upper digit is empty.
+ if (!Upper)
+ return std::make_pair(Lower, 0);
+
+ // Shift as little as possible to maximize precision.
+ unsigned LeadingZeros = countLeadingZeros64(Upper);
+ int16_t Shift = 64 - LeadingZeros;
+ if (LeadingZeros)
+ Upper = Upper << LeadingZeros | Lower >> Shift;
+ bool ShouldRound = Shift && (Lower & UINT64_C(1) << (Shift - 1));
+ return getRoundedFloat(Upper, ShouldRound, Shift);
+}
+
+//===----------------------------------------------------------------------===//
+//
+// BlockMass implementation.
+//
+//===----------------------------------------------------------------------===//
+BlockMass &BlockMass::operator*=(const BranchProbability &P) {
+ uint32_t N = P.getNumerator(), D = P.getDenominator();
+ assert(D && "divide by 0");
+ assert(N <= D && "fraction greater than 1");
+
+ // Fast path for multiplying by 1.0.
+ if (!Mass || N == D)
+ return *this;
+
+ // Get as much precision as we can.
+ int Shift = countLeadingZeros(Mass);
+ uint64_t ShiftedQuotient = (Mass << Shift) / D;
+ uint64_t Product = ShiftedQuotient * N >> Shift;
+
+ // Now check for what's lost.
+ uint64_t Left = ShiftedQuotient * (D - N) >> Shift;
+ uint64_t Lost = Mass - Product - Left;
+
+ // TODO: prove this assertion.
+ assert(Lost <= UINT32_MAX);
+
+ // Take the product plus a portion of the spoils.
+ Mass = Product + Lost * N / D;
+ return *this;
+}
+
+PositiveFloat<uint64_t> BlockMass::toFloat() const {
+ if (isFull())
+ return PositiveFloat<uint64_t>(1, 0);
+ return PositiveFloat<uint64_t>(getMass() + 1, -64);
+}
+
+void BlockMass::dump() const { print(dbgs()); }
+
+static char getHexDigit(int N) {
+ assert(N < 16);
+ if (N < 10)
+ return '0' + N;
+ return 'a' + N - 10;
+}
+raw_ostream &BlockMass::print(raw_ostream &OS) const {
+ for (int Digits = 0; Digits < 16; ++Digits)
+ OS << getHexDigit(Mass >> (60 - Digits * 4) & 0xf);
+ return OS;
+}
+
+//===----------------------------------------------------------------------===//
+//
+// BlockFrequencyInfoImpl implementation.
+//
+//===----------------------------------------------------------------------===//
+namespace {
+
+typedef BlockFrequencyInfoImplBase::BlockNode BlockNode;
+typedef BlockFrequencyInfoImplBase::Distribution Distribution;
+typedef BlockFrequencyInfoImplBase::Distribution::WeightList WeightList;
+typedef BlockFrequencyInfoImplBase::Float Float;
+typedef BlockFrequencyInfoImplBase::PackagedLoopData PackagedLoopData;
+typedef BlockFrequencyInfoImplBase::Weight Weight;
+typedef BlockFrequencyInfoImplBase::FrequencyData FrequencyData;
+
+/// \brief Dithering mass distributer.
+///
+/// This class splits up a single mass into portions by weight, dithering to
+/// spread out error. No mass is lost. The dithering precision depends on the
+/// precision of the product of \a BlockMass and \a BranchProbability.
+///
+/// The distribution algorithm follows.
+///
+/// 1. Initialize by saving the sum of the weights in \a RemWeight and the
+/// mass to distribute in \a RemMass.
+///
+/// 2. For each portion:
+///
+/// 1. Construct a branch probability, P, as the portion's weight divided
+/// by the current value of \a RemWeight.
+/// 2. Calculate the portion's mass as \a RemMass times P.
+/// 3. Update \a RemWeight and \a RemMass at each portion by subtracting
+/// the current portion's weight and mass.
+///
+/// Mass is distributed in two ways: full distribution and forward
+/// distribution. The latter ignores backedges, and uses the parallel fields
+/// \a RemForwardWeight and \a RemForwardMass.
+struct DitheringDistributer {
+ uint32_t RemWeight;
+ uint32_t RemForwardWeight;
+
+ BlockMass RemMass;
+ BlockMass RemForwardMass;
+
+ DitheringDistributer(Distribution &Dist, const BlockMass &Mass);
+
+ BlockMass takeLocalMass(uint32_t Weight) {
+ (void)takeMass(Weight);
+ return takeForwardMass(Weight);
+ }
+ BlockMass takeExitMass(uint32_t Weight) {
+ (void)takeForwardMass(Weight);
+ return takeMass(Weight);
+ }
+ BlockMass takeBackedgeMass(uint32_t Weight) { return takeMass(Weight); }
+
+private:
+ BlockMass takeForwardMass(uint32_t Weight);
+ BlockMass takeMass(uint32_t Weight);
+};
+}
+
+DitheringDistributer::DitheringDistributer(Distribution &Dist,
+ const BlockMass &Mass) {
+ Dist.normalize();
+ RemWeight = Dist.Total;
+ RemForwardWeight = Dist.ForwardTotal;
+ RemMass = Mass;
+ RemForwardMass = Dist.ForwardTotal ? Mass : BlockMass();
+}
+
+BlockMass DitheringDistributer::takeForwardMass(uint32_t Weight) {
+ // Compute the amount of mass to take.
+ assert(Weight && "invalid weight");
+ assert(Weight <= RemForwardWeight);
+ BlockMass Mass = RemForwardMass * BranchProbability(Weight, RemForwardWeight);
+
+ // Decrement totals (dither).
+ RemForwardWeight -= Weight;
+ RemForwardMass -= Mass;
+ return Mass;
+}
+BlockMass DitheringDistributer::takeMass(uint32_t Weight) {
+ assert(Weight && "invalid weight");
+ assert(Weight <= RemWeight);
+ BlockMass Mass = RemMass * BranchProbability(Weight, RemWeight);
+
+ // Decrement totals (dither).
+ RemWeight -= Weight;
+ RemMass -= Mass;
+ return Mass;
+}
+
+void Distribution::add(const BlockNode &Node, uint64_t Amount,
+ Weight::DistType Type) {
+ assert(Amount && "invalid weight of 0");
+ uint64_t NewTotal = Total + Amount;
+
+ // Check for overflow. It should be impossible to overflow twice.
+ bool IsOverflow = NewTotal < Total;
+ assert(!(DidOverflow && IsOverflow) && "unexpected repeated overflow");
+ DidOverflow |= IsOverflow;
+
+ // Update the total.
+ Total = NewTotal;
+
+ // Save the weight.
+ Weight W;
+ W.TargetNode = Node;
+ W.Amount = Amount;
+ W.Type = Type;
+ Weights.push_back(W);
+
+ if (Type == Weight::Backedge)
+ return;
+
+ // Update forward total. Don't worry about overflow here, since then Total
+ // will exceed 32-bits and they'll both be recomputed in normalize().
+ ForwardTotal += Amount;
+}
+
+static void combineWeight(Weight &W, const Weight &OtherW) {
+ assert(OtherW.TargetNode.isValid());
+ if (!W.Amount) {
+ W = OtherW;
+ return;
+ }
+ assert(W.Type == OtherW.Type);
+ assert(W.TargetNode == OtherW.TargetNode);
+ assert(W.Amount < W.Amount + OtherW.Amount);
+ W.Amount += OtherW.Amount;
+}
+static void combineWeightsBySorting(WeightList &Weights) {
+ // Sort so edges to the same node are adjacent.
+ std::sort(Weights.begin(), Weights.end(),
+ [](const Weight &L,
+ const Weight &R) { return L.TargetNode < R.TargetNode; });
+
+ // Combine adjacent edges.
+ WeightList::iterator O = Weights.begin();
+ for (WeightList::const_iterator I = O, L = O, E = Weights.end(); I != E;
+ ++O, (I = L)) {
+ *O = *I;
+
+ // Find the adjacent weights to the same node.
+ for (++L; L != E && I->TargetNode == L->TargetNode; ++L)
+ combineWeight(*O, *L);
+ }
+
+ // Erase extra entries.
+ Weights.erase(O, Weights.end());
+ return;
+}
+static void combineWeightsByHashing(WeightList &Weights) {
+ // Collect weights into a DenseMap.
+ typedef DenseMap<BlockNode::IndexType, Weight> HashTable;
+ HashTable Combined(NextPowerOf2(2 * Weights.size()));
+ for (const Weight &W : Weights)
+ combineWeight(Combined[W.TargetNode.Index], W);
+
+ // Check whether anything changed.
+ if (Weights.size() == Combined.size())
+ return;
+
+ // Fill in the new weights.
+ Weights.clear();
+ Weights.reserve(Combined.size());
+ for (const auto &I : Combined)
+ Weights.push_back(I.second);
+}
+static void combineWeights(WeightList &Weights) {
+ // Use a hash table for many successors to keep this linear.
+ if (Weights.size() > 128) {
+ combineWeightsByHashing(Weights);
+ return;
+ }
+
+ combineWeightsBySorting(Weights);
+}
+static uint64_t shiftRightAndRound(uint64_t N, int Shift) {
+ assert(Shift >= 0);
+ assert(Shift < 64);
+ if (!Shift)
+ return N;
+ return (N >> Shift) + (UINT64_C(1) & N >> (Shift - 1));
+}
+void Distribution::normalize() {
+ // Early exit for termination nodes.
+ if (Weights.empty())
+ return;
+
+ // Only bother if there are multiple successors.
+ if (Weights.size() > 1)
+ combineWeights(Weights);
+
+ // Early exit when combined into a single successor.
+ if (Weights.size() == 1) {
+ Total = 1;
+ ForwardTotal = Weights.front().Type != Weight::Backedge;
+ Weights.front().Amount = 1;
+ return;
+ }
+
+ // Determine how much to shift right so that the total fits into 32-bits.
+ //
+ // If we shift at all, shift by 1 extra. Otherwise, the lower limit of 1
+ // for each weight can cause a 32-bit overflow.
+ int Shift = 0;
+ if (DidOverflow)
+ Shift = 33;
+ else if (Total > UINT32_MAX)
+ Shift = 33 - countLeadingZeros(Total);
+
+ // Early exit if nothing needs to be scaled.
+ if (!Shift)
+ return;
+
+ // Recompute the total through accumulation (rather than shifting it) so that
+ // it's accurate after shifting. ForwardTotal is dirty here anyway.
+ Total = 0;
+ ForwardTotal = 0;
+
+ // Sum the weights to each node and shift right if necessary.
+ for (Weight &W : Weights) {
+ // Scale down below UINT32_MAX. Since Shift is larger than necessary, we
+ // can round here without concern about overflow.
+ assert(W.TargetNode.isValid());
+ W.Amount = std::max(UINT64_C(1), shiftRightAndRound(W.Amount, Shift));
+ assert(W.Amount <= UINT32_MAX);
+
+ // Update the total.
+ Total += W.Amount;
+ if (W.Type == Weight::Backedge)
+ continue;
+
+ // Update the forward total.
+ ForwardTotal += W.Amount;
+ }
+ assert(Total <= UINT32_MAX);
+}
+
+void BlockFrequencyInfoImplBase::clear() {
+ *this = BlockFrequencyInfoImplBase();
+}
+
+/// \brief Clear all memory not needed downstream.
+///
+/// Releases all memory not used downstream. In particular, saves Freqs.
+static void cleanup(BlockFrequencyInfoImplBase &BFI) {
+ std::vector<FrequencyData> SavedFreqs(std::move(BFI.Freqs));
+ BFI.clear();
+ BFI.Freqs = std::move(SavedFreqs);
+}
+
+/// \brief Get a possibly packaged node.
+///
+/// Get the node currently representing Node, which could be a containing
+/// loop.
+///
+/// This function should only be called when distributing mass. As long as
+/// there are no irreducilbe edges to Node, then it will have complexity O(1)
+/// in this context.
+///
+/// In general, the complexity is O(L), where L is the number of loop headers
+/// Node has been packaged into. Since this method is called in the context
+/// of distributing mass, L will be the number of loop headers an early exit
+/// edge jumps out of.
+static BlockNode getPackagedNode(const BlockFrequencyInfoImplBase &BFI,
+ const BlockNode &Node) {
+ assert(Node.isValid());
+ if (!BFI.Working[Node.Index].IsPackaged)
+ return Node;
+ if (!BFI.Working[Node.Index].ContainingLoop.isValid())
+ return Node;
+ return getPackagedNode(BFI, BFI.Working[Node.Index].ContainingLoop);
+}
+
+/// \brief Get the appropriate mass for a possible pseudo-node loop package.
+///
+/// Get appropriate mass for Node. If Node is a loop-header (whose loop has
+/// been packaged), returns the mass of its pseudo-node. If it's a node inside
+/// a packaged loop, it returns the loop's pseudo-node.
+static BlockMass &getPackageMass(BlockFrequencyInfoImplBase &BFI,
+ const BlockNode &Node) {
+ assert(Node.isValid());
+ assert(!BFI.Working[Node.Index].IsPackaged);
+ if (!BFI.Working[Node.Index].IsAPackage)
+ return BFI.Working[Node.Index].Mass;
+
+ return BFI.getLoopPackage(Node).Mass;
+}
+
+void BlockFrequencyInfoImplBase::addToDist(Distribution &Dist,
+ const BlockNode &LoopHead,
+ const BlockNode &Pred,
+ const BlockNode &Succ,
+ uint64_t Weight) {
+ if (!Weight)
+ Weight = 1;
+
+#ifndef NDEBUG
+ auto debugSuccessor = [&](const char *Type, const BlockNode &Resolved) {
+ dbgs() << " =>"
+ << " [" << Type << "] weight = " << Weight;
+ if (Succ != LoopHead)
+ dbgs() << ", succ = " << getBlockName(Succ);
+ if (Resolved != Succ)
+ dbgs() << ", resolved = " << getBlockName(Resolved);
+ dbgs() << "\n";
+ };
+ (void)debugSuccessor;
+#endif
+
+ if (Succ == LoopHead) {
+ DEBUG(debugSuccessor("backedge", Succ));
+ Dist.addBackedge(LoopHead, Weight);
+ return;
+ }
+ BlockNode Resolved = getPackagedNode(*this, Succ);
+ assert(Resolved != LoopHead);
+
+ if (Working[Resolved.Index].ContainingLoop != LoopHead) {
+ DEBUG(debugSuccessor(" exit ", Resolved));
+ Dist.addExit(Resolved, Weight);
+ return;
+ }
+
+ if (!LoopHead.isValid() && Resolved < Pred) {
+ // Irreducible backedge. Skip this edge in the distribution.
+ DEBUG(debugSuccessor("skipped ", Resolved));
+ return;
+ }
+
+ DEBUG(debugSuccessor(" local ", Resolved));
+ Dist.addLocal(Resolved, Weight);
+}
+
+void BlockFrequencyInfoImplBase::addLoopSuccessorsToDist(
+ const BlockNode &LoopHead, const BlockNode &LocalLoopHead,
+ Distribution &Dist) {
+ PackagedLoopData &LoopPackage = getLoopPackage(LocalLoopHead);
+ const PackagedLoopData::ExitMap &Exits = LoopPackage.Exits;
+
+ // Copy the exit map into Dist.
+ for (const auto &I : Exits)
+ addToDist(Dist, LoopHead, LocalLoopHead, I.first, I.second.getMass());
+
+ // We don't need this map any more. Clear it to prevent quadratic memory
+ // usage in deeply nested loops with irreducible control flow.
+ LoopPackage.Exits.clear();
+}
+
+/// \brief Get the maximum allowed loop scale.
+///
+/// Gives the maximum number of estimated iterations allowed for a loop.
+/// Downstream users have trouble with very large numbers (even within
+/// 64-bits). Perhaps they can be changed to use PositiveFloat.
+///
+/// TODO: change downstream users so that this can be increased or removed.
+static Float getMaxLoopScale() { return Float(1, 12); }
+
+/// \brief Compute the loop scale for a loop.
+void BlockFrequencyInfoImplBase::computeLoopScale(const BlockNode &LoopHead) {
+ // Compute loop scale.
+ DEBUG(dbgs() << "compute-loop-scale: " << getBlockName(LoopHead) << "\n");
+
+ // LoopScale == 1 / ExitMass
+ // ExitMass == HeadMass - BackedgeMass
+ PackagedLoopData &LoopPackage = getLoopPackage(LoopHead);
+ BlockMass ExitMass = BlockMass::getFull() - LoopPackage.BackedgeMass;
+
+ // Block scale stores the inverse of the scale.
+ LoopPackage.Scale = ExitMass.toFloat().inverse();
+
+ DEBUG(dbgs() << " - exit-mass = " << ExitMass << " (" << BlockMass::getFull()
+ << " - " << LoopPackage.BackedgeMass << ")\n"
+ << " - scale = " << LoopPackage.Scale << "\n");
+
+ if (LoopPackage.Scale > getMaxLoopScale()) {
+ LoopPackage.Scale = getMaxLoopScale();
+ DEBUG(dbgs() << " - reduced-to-max-scale: " << getMaxLoopScale() << "\n");
+ }
+}
+
+/// \brief Package up a loop.
+void BlockFrequencyInfoImplBase::packageLoop(const BlockNode &LoopHead) {
+ DEBUG(dbgs() << "packaging-loop: " << getBlockName(LoopHead) << "\n");
+ Working[LoopHead.Index].IsAPackage = true;
+ for (const BlockNode &M : getLoopPackage(LoopHead).Members) {
+ DEBUG(dbgs() << " - node: " << getBlockName(M.Index) << "\n");
+ Working[M.Index].IsPackaged = true;
+ }
+}
+
+void BlockFrequencyInfoImplBase::distributeMass(const BlockNode &Source,
+ const BlockNode &LoopHead,
+ Distribution &Dist) {
+ BlockMass Mass = getPackageMass(*this, Source);
+ DEBUG(dbgs() << " => mass: " << Mass
+ << " ( general | forward )\n");
+
+ // Distribute mass to successors as laid out in Dist.
+ DitheringDistributer D(Dist, Mass);
+
+#ifndef NDEBUG
+ auto debugAssign = [&](const BlockNode &T, const BlockMass &M,
+ const char *Desc) {
+ dbgs() << " => assign " << M << " (" << D.RemMass << "|"
+ << D.RemForwardMass << ")";
+ if (Desc)
+ dbgs() << " [" << Desc << "]";
+ if (T.isValid())
+ dbgs() << " to " << getBlockName(T);
+ dbgs() << "\n";
+ };
+ (void)debugAssign;
+#endif
+
+ PackagedLoopData *LoopPackage = 0;
+ if (LoopHead.isValid())
+ LoopPackage = &getLoopPackage(LoopHead);
+ for (const Weight &W : Dist.Weights) {
+ // Check for a local edge (forward and non-exit).
+ if (W.Type == Weight::Local) {
+ BlockMass Local = D.takeLocalMass(W.Amount);
+ getPackageMass(*this, W.TargetNode) += Local;
+ DEBUG(debugAssign(W.TargetNode, Local, nullptr));
+ continue;
+ }
+
+ // Backedges and exits only make sense if we're processing a loop.
+ assert(LoopPackage && "backedge or exit outside of loop");
+
+ // Check for a backedge.
+ if (W.Type == Weight::Backedge) {
+ BlockMass Back = D.takeBackedgeMass(W.Amount);
+ LoopPackage->BackedgeMass += Back;
+ DEBUG(debugAssign(BlockNode(), Back, "back"));
+ continue;
+ }
+
+ // This must be an exit.
+ assert(W.Type == Weight::Exit);
+ BlockMass Exit = D.takeExitMass(W.Amount);
+ LoopPackage->Exits.push_back(std::make_pair(W.TargetNode, Exit));
+ DEBUG(debugAssign(W.TargetNode, Exit, "exit"));
+ }
+}
+
+static void convertFloatingToInteger(BlockFrequencyInfoImplBase &BFI,
+ const Float &Min, const Float &Max) {
+ // Scale the Factor to a size that creates integers. Ideally, integers would
+ // be scaled so that Max == UINT64_MAX so that they can be best
+ // differentiated. However, the register allocator currently deals poorly
+ // with large numbers. Instead, push Min up a little from 1 to give some
+ // room to differentiate small, unequal numbers.
+ //
+ // TODO: fix issues downstream so that ScalingFactor can be Float(1,64)/Max.
+ Float ScalingFactor = Min.inverse();
+ if ((Max / Min).lg() < 60)
+ ScalingFactor <<= 3;
+
+ // Translate the floats to integers.
+ DEBUG(dbgs() << "float-to-int: min = " << Min << ", max = " << Max
+ << ", factor = " << ScalingFactor << "\n");
+ for (size_t Index = 0; Index < BFI.Freqs.size(); ++Index) {
+ Float Scaled = BFI.Freqs[Index].Floating * ScalingFactor;
+ BFI.Freqs[Index].Integer = std::max(UINT64_C(1), Scaled.toInt<uint64_t>());
+ DEBUG(dbgs() << " - " << BFI.getBlockName(Index) << ": float = "
+ << BFI.Freqs[Index].Floating << ", scaled = " << Scaled
+ << ", int = " << BFI.Freqs[Index].Integer << "\n");
+ }
+}
+
+static void scaleBlockData(BlockFrequencyInfoImplBase &BFI,
+ const BlockNode &Node,
+ const PackagedLoopData &Loop) {
+ Float F = Loop.Mass.toFloat() * Loop.Scale;
+
+ Float &Current = BFI.Freqs[Node.Index].Floating;
+ Float Updated = Current * F;
+
+ DEBUG(dbgs() << " - " << BFI.getBlockName(Node) << ": " << Current << " => "
+ << Updated << "\n");
+
+ Current = Updated;
+}
+
+/// \brief Unwrap a loop package.
+///
+/// Visits all the members of a loop, adjusting their BlockData according to
+/// the loop's pseudo-node.
+static void unwrapLoopPackage(BlockFrequencyInfoImplBase &BFI,
+ const BlockNode &Head) {
+ assert(Head.isValid());
+
+ PackagedLoopData &LoopPackage = BFI.getLoopPackage(Head);
+ DEBUG(dbgs() << "unwrap-loop-package: " << BFI.getBlockName(Head)
+ << ": mass = " << LoopPackage.Mass
+ << ", scale = " << LoopPackage.Scale << "\n");
+ scaleBlockData(BFI, Head, LoopPackage);
+
+ // Propagate the head scale through the loop. Since members are visited in
+ // RPO, the head scale will be updated by the loop scale first, and then the
+ // final head scale will be used for updated the rest of the members.
+ for (const BlockNode &M : LoopPackage.Members) {
+ const FrequencyData &HeadData = BFI.Freqs[Head.Index];
+ FrequencyData &Freqs = BFI.Freqs[M.Index];
+ Float NewFreq = Freqs.Floating * HeadData.Floating;
+ DEBUG(dbgs() << " - " << BFI.getBlockName(M) << ": " << Freqs.Floating
+ << " => " << NewFreq << "\n");
+ Freqs.Floating = NewFreq;
+ }
+}
+
+void BlockFrequencyInfoImplBase::finalizeMetrics() {
+ // Set initial frequencies from loop-local masses.
+ for (size_t Index = 0; Index < Working.size(); ++Index)
+ Freqs[Index].Floating = Working[Index].Mass.toFloat();
+
+ // Unwrap loop packages in reverse post-order, tracking min and max
+ // frequencies.
+ auto Min = Float::getLargest();
+ auto Max = Float::getZero();
+ for (size_t Index = 0; Index < Working.size(); ++Index) {
+ if (Working[Index].isLoopHeader())
+ unwrapLoopPackage(*this, BlockNode(Index));
+
+ // Update max scale.
+ Min = std::min(Min, Freqs[Index].Floating);
+ Max = std::max(Max, Freqs[Index].Floating);
+ }
+
+ // Convert to integers.
+ convertFloatingToInteger(*this, Min, Max);
+
+ // Clean up data structures.
+ cleanup(*this);
+
+ // Print out the final stats.
+ DEBUG(dump());
+}
+
+BlockFrequency
+BlockFrequencyInfoImplBase::getBlockFreq(const BlockNode &Node) const {
+ if (!Node.isValid())
+ return 0;
+ return Freqs[Node.Index].Integer;
+}
+Float
+BlockFrequencyInfoImplBase::getFloatingBlockFreq(const BlockNode &Node) const {
+ if (!Node.isValid())
+ return Float::getZero();
+ return Freqs[Node.Index].Floating;
+}
+
+std::string
+BlockFrequencyInfoImplBase::getBlockName(const BlockNode &Node) const {
+ return std::string();
+}
+
+raw_ostream &
+BlockFrequencyInfoImplBase::printBlockFreq(raw_ostream &OS,
+ const BlockNode &Node) const {
+ return OS << getFloatingBlockFreq(Node);
+}
+
+raw_ostream &
+BlockFrequencyInfoImplBase::printBlockFreq(raw_ostream &OS,
+ const BlockFrequency &Freq) const {
+ Float Block(Freq.getFrequency(), 0);
+ Float Entry(getEntryFreq(), 0);
+
+ return OS << Block / Entry;
+}