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https://github.com/c64scene-ar/llvm-6502.git
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This reverts commit r206707, reapplying r206704. The preceding commit to CalcSpillWeights should have sorted out the failing buildbots. <rdar://problem/14292693> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206766 91177308-0d34-0410-b5e6-96231b3b80d8
933 lines
29 KiB
C++
933 lines
29 KiB
C++
//===- BlockFrequencyImplInfo.cpp - Block Frequency Info Implementation ---===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Loops should be simplified before this analysis.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "block-freq"
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#include "llvm/Analysis/BlockFrequencyInfoImpl.h"
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#include "llvm/ADT/APFloat.h"
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#include "llvm/Support/raw_ostream.h"
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#include <deque>
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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//
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// PositiveFloat implementation.
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//
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//===----------------------------------------------------------------------===//
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#ifndef _MSC_VER
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const int32_t PositiveFloatBase::MaxExponent;
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const int32_t PositiveFloatBase::MinExponent;
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#endif
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static void appendDigit(std::string &Str, unsigned D) {
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assert(D < 10);
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Str += '0' + D % 10;
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}
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static void appendNumber(std::string &Str, uint64_t N) {
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while (N) {
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appendDigit(Str, N % 10);
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N /= 10;
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}
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}
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static bool doesRoundUp(char Digit) {
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switch (Digit) {
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case '5':
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case '6':
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case '7':
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case '8':
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case '9':
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return true;
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default:
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return false;
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}
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}
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static std::string toStringAPFloat(uint64_t D, int E, unsigned Precision) {
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assert(E >= PositiveFloatBase::MinExponent);
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assert(E <= PositiveFloatBase::MaxExponent);
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// Find a new E, but don't let it increase past MaxExponent.
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int LeadingZeros = PositiveFloatBase::countLeadingZeros64(D);
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int NewE = std::min(PositiveFloatBase::MaxExponent, E + 63 - LeadingZeros);
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int Shift = 63 - (NewE - E);
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assert(Shift <= LeadingZeros);
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assert(Shift == LeadingZeros || NewE == PositiveFloatBase::MaxExponent);
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D <<= Shift;
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E = NewE;
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// Check for a denormal.
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unsigned AdjustedE = E + 16383;
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if (!(D >> 63)) {
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assert(E == PositiveFloatBase::MaxExponent);
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AdjustedE = 0;
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}
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// Build the float and print it.
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uint64_t RawBits[2] = {D, AdjustedE};
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APFloat Float(APFloat::x87DoubleExtended, APInt(80, RawBits));
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SmallVector<char, 24> Chars;
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Float.toString(Chars, Precision, 0);
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return std::string(Chars.begin(), Chars.end());
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}
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static std::string stripTrailingZeros(const std::string &Float) {
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size_t NonZero = Float.find_last_not_of('0');
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assert(NonZero != std::string::npos && "no . in floating point string");
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if (Float[NonZero] == '.')
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++NonZero;
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return Float.substr(0, NonZero + 1);
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}
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std::string PositiveFloatBase::toString(uint64_t D, int16_t E, int Width,
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unsigned Precision) {
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if (!D)
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return "0.0";
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// Canonicalize exponent and digits.
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uint64_t Above0 = 0;
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uint64_t Below0 = 0;
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uint64_t Extra = 0;
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int ExtraShift = 0;
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if (E == 0) {
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Above0 = D;
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} else if (E > 0) {
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if (int Shift = std::min(int16_t(countLeadingZeros64(D)), E)) {
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D <<= Shift;
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E -= Shift;
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if (!E)
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Above0 = D;
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}
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} else if (E > -64) {
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Above0 = D >> -E;
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Below0 = D << (64 + E);
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} else if (E > -120) {
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Below0 = D >> (-E - 64);
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Extra = D << (128 + E);
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ExtraShift = -64 - E;
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}
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// Fall back on APFloat for very small and very large numbers.
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if (!Above0 && !Below0)
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return toStringAPFloat(D, E, Precision);
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// Append the digits before the decimal.
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std::string Str;
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size_t DigitsOut = 0;
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if (Above0) {
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appendNumber(Str, Above0);
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DigitsOut = Str.size();
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} else
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appendDigit(Str, 0);
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std::reverse(Str.begin(), Str.end());
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// Return early if there's nothing after the decimal.
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if (!Below0)
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return Str + ".0";
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// Append the decimal and beyond.
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Str += '.';
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uint64_t Error = UINT64_C(1) << (64 - Width);
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// We need to shift Below0 to the right to make space for calculating
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// digits. Save the precision we're losing in Extra.
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Extra = (Below0 & 0xf) << 56 | (Extra >> 8);
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Below0 >>= 4;
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size_t SinceDot = 0;
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size_t AfterDot = Str.size();
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do {
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if (ExtraShift) {
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--ExtraShift;
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Error *= 5;
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} else
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Error *= 10;
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Below0 *= 10;
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Extra *= 10;
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Below0 += (Extra >> 60);
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Extra = Extra & (UINT64_MAX >> 4);
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appendDigit(Str, Below0 >> 60);
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Below0 = Below0 & (UINT64_MAX >> 4);
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if (DigitsOut || Str.back() != '0')
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++DigitsOut;
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++SinceDot;
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} while (Error && (Below0 << 4 | Extra >> 60) >= Error / 2 &&
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(!Precision || DigitsOut <= Precision || SinceDot < 2));
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// Return early for maximum precision.
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if (!Precision || DigitsOut <= Precision)
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return stripTrailingZeros(Str);
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// Find where to truncate.
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size_t Truncate =
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std::max(Str.size() - (DigitsOut - Precision), AfterDot + 1);
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// Check if there's anything to truncate.
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if (Truncate >= Str.size())
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return stripTrailingZeros(Str);
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bool Carry = doesRoundUp(Str[Truncate]);
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if (!Carry)
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return stripTrailingZeros(Str.substr(0, Truncate));
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// Round with the first truncated digit.
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for (std::string::reverse_iterator I(Str.begin() + Truncate), E = Str.rend();
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I != E; ++I) {
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if (*I == '.')
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continue;
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if (*I == '9') {
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*I = '0';
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continue;
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}
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++*I;
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Carry = false;
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break;
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}
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// Add "1" in front if we still need to carry.
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return stripTrailingZeros(std::string(Carry, '1') + Str.substr(0, Truncate));
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}
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raw_ostream &PositiveFloatBase::print(raw_ostream &OS, uint64_t D, int16_t E,
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int Width, unsigned Precision) {
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return OS << toString(D, E, Width, Precision);
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}
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void PositiveFloatBase::dump(uint64_t D, int16_t E, int Width) {
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print(dbgs(), D, E, Width, 0) << "[" << Width << ":" << D << "*2^" << E
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<< "]";
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}
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static std::pair<uint64_t, int16_t>
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getRoundedFloat(uint64_t N, bool ShouldRound, int64_t Shift) {
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if (ShouldRound)
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if (!++N)
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// Rounding caused an overflow.
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return std::make_pair(UINT64_C(1), Shift + 64);
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return std::make_pair(N, Shift);
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}
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std::pair<uint64_t, int16_t> PositiveFloatBase::divide64(uint64_t Dividend,
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uint64_t Divisor) {
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// Input should be sanitized.
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assert(Divisor);
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assert(Dividend);
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// Minimize size of divisor.
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int16_t Shift = 0;
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if (int Zeros = countTrailingZeros(Divisor)) {
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Shift -= Zeros;
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Divisor >>= Zeros;
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}
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// Check for powers of two.
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if (Divisor == 1)
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return std::make_pair(Dividend, Shift);
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// Maximize size of dividend.
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if (int Zeros = countLeadingZeros64(Dividend)) {
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Shift -= Zeros;
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Dividend <<= Zeros;
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}
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// Start with the result of a divide.
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uint64_t Quotient = Dividend / Divisor;
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Dividend %= Divisor;
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// Continue building the quotient with long division.
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//
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// TODO: continue with largers digits.
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while (!(Quotient >> 63) && Dividend) {
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// Shift Dividend, and check for overflow.
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bool IsOverflow = Dividend >> 63;
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Dividend <<= 1;
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--Shift;
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// Divide.
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bool DoesDivide = IsOverflow || Divisor <= Dividend;
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Quotient = (Quotient << 1) | uint64_t(DoesDivide);
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Dividend -= DoesDivide ? Divisor : 0;
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}
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// Round.
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if (Dividend >= getHalf(Divisor))
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if (!++Quotient)
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// Rounding caused an overflow in Quotient.
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return std::make_pair(UINT64_C(1), Shift + 64);
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return getRoundedFloat(Quotient, Dividend >= getHalf(Divisor), Shift);
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}
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std::pair<uint64_t, int16_t> PositiveFloatBase::multiply64(uint64_t L,
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uint64_t R) {
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// Separate into two 32-bit digits (U.L).
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uint64_t UL = L >> 32, LL = L & UINT32_MAX, UR = R >> 32, LR = R & UINT32_MAX;
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// Compute cross products.
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uint64_t P1 = UL * UR, P2 = UL * LR, P3 = LL * UR, P4 = LL * LR;
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// Sum into two 64-bit digits.
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uint64_t Upper = P1, Lower = P4;
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auto addWithCarry = [&](uint64_t N) {
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uint64_t NewLower = Lower + (N << 32);
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Upper += (N >> 32) + (NewLower < Lower);
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Lower = NewLower;
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};
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addWithCarry(P2);
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addWithCarry(P3);
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// Check whether the upper digit is empty.
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if (!Upper)
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return std::make_pair(Lower, 0);
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// Shift as little as possible to maximize precision.
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unsigned LeadingZeros = countLeadingZeros64(Upper);
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int16_t Shift = 64 - LeadingZeros;
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if (LeadingZeros)
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Upper = Upper << LeadingZeros | Lower >> Shift;
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bool ShouldRound = Shift && (Lower & UINT64_C(1) << (Shift - 1));
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return getRoundedFloat(Upper, ShouldRound, Shift);
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}
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//===----------------------------------------------------------------------===//
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//
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// BlockMass implementation.
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//
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//===----------------------------------------------------------------------===//
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BlockMass &BlockMass::operator*=(const BranchProbability &P) {
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uint32_t N = P.getNumerator(), D = P.getDenominator();
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assert(D && "divide by 0");
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assert(N <= D && "fraction greater than 1");
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// Fast path for multiplying by 1.0.
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if (!Mass || N == D)
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return *this;
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// Get as much precision as we can.
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int Shift = countLeadingZeros(Mass);
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uint64_t ShiftedQuotient = (Mass << Shift) / D;
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uint64_t Product = ShiftedQuotient * N >> Shift;
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// Now check for what's lost.
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uint64_t Left = ShiftedQuotient * (D - N) >> Shift;
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uint64_t Lost = Mass - Product - Left;
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// TODO: prove this assertion.
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assert(Lost <= UINT32_MAX);
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// Take the product plus a portion of the spoils.
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Mass = Product + Lost * N / D;
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return *this;
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}
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PositiveFloat<uint64_t> BlockMass::toFloat() const {
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if (isFull())
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return PositiveFloat<uint64_t>(1, 0);
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return PositiveFloat<uint64_t>(getMass() + 1, -64);
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}
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void BlockMass::dump() const { print(dbgs()); }
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static char getHexDigit(int N) {
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assert(N < 16);
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if (N < 10)
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return '0' + N;
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return 'a' + N - 10;
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}
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raw_ostream &BlockMass::print(raw_ostream &OS) const {
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for (int Digits = 0; Digits < 16; ++Digits)
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OS << getHexDigit(Mass >> (60 - Digits * 4) & 0xf);
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return OS;
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}
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//===----------------------------------------------------------------------===//
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//
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// BlockFrequencyInfoImpl implementation.
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//
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//===----------------------------------------------------------------------===//
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namespace {
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typedef BlockFrequencyInfoImplBase::BlockNode BlockNode;
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typedef BlockFrequencyInfoImplBase::Distribution Distribution;
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typedef BlockFrequencyInfoImplBase::Distribution::WeightList WeightList;
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typedef BlockFrequencyInfoImplBase::Float Float;
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typedef BlockFrequencyInfoImplBase::PackagedLoopData PackagedLoopData;
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typedef BlockFrequencyInfoImplBase::Weight Weight;
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typedef BlockFrequencyInfoImplBase::FrequencyData FrequencyData;
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/// \brief Dithering mass distributer.
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///
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/// This class splits up a single mass into portions by weight, dithering to
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/// spread out error. No mass is lost. The dithering precision depends on the
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/// precision of the product of \a BlockMass and \a BranchProbability.
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///
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/// The distribution algorithm follows.
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///
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/// 1. Initialize by saving the sum of the weights in \a RemWeight and the
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/// mass to distribute in \a RemMass.
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///
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/// 2. For each portion:
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///
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/// 1. Construct a branch probability, P, as the portion's weight divided
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/// by the current value of \a RemWeight.
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/// 2. Calculate the portion's mass as \a RemMass times P.
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/// 3. Update \a RemWeight and \a RemMass at each portion by subtracting
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/// the current portion's weight and mass.
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///
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/// Mass is distributed in two ways: full distribution and forward
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/// distribution. The latter ignores backedges, and uses the parallel fields
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/// \a RemForwardWeight and \a RemForwardMass.
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struct DitheringDistributer {
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uint32_t RemWeight;
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uint32_t RemForwardWeight;
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BlockMass RemMass;
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BlockMass RemForwardMass;
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DitheringDistributer(Distribution &Dist, const BlockMass &Mass);
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BlockMass takeLocalMass(uint32_t Weight) {
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(void)takeMass(Weight);
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return takeForwardMass(Weight);
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}
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BlockMass takeExitMass(uint32_t Weight) {
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(void)takeForwardMass(Weight);
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return takeMass(Weight);
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}
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BlockMass takeBackedgeMass(uint32_t Weight) { return takeMass(Weight); }
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private:
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BlockMass takeForwardMass(uint32_t Weight);
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BlockMass takeMass(uint32_t Weight);
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};
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}
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DitheringDistributer::DitheringDistributer(Distribution &Dist,
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const BlockMass &Mass) {
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Dist.normalize();
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RemWeight = Dist.Total;
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RemForwardWeight = Dist.ForwardTotal;
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RemMass = Mass;
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RemForwardMass = Dist.ForwardTotal ? Mass : BlockMass();
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}
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BlockMass DitheringDistributer::takeForwardMass(uint32_t Weight) {
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// Compute the amount of mass to take.
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assert(Weight && "invalid weight");
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assert(Weight <= RemForwardWeight);
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BlockMass Mass = RemForwardMass * BranchProbability(Weight, RemForwardWeight);
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// Decrement totals (dither).
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RemForwardWeight -= Weight;
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RemForwardMass -= Mass;
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return Mass;
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}
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BlockMass DitheringDistributer::takeMass(uint32_t Weight) {
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assert(Weight && "invalid weight");
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assert(Weight <= RemWeight);
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BlockMass Mass = RemMass * BranchProbability(Weight, RemWeight);
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// Decrement totals (dither).
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RemWeight -= Weight;
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RemMass -= Mass;
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return Mass;
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}
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void Distribution::add(const BlockNode &Node, uint64_t Amount,
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Weight::DistType Type) {
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assert(Amount && "invalid weight of 0");
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uint64_t NewTotal = Total + Amount;
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// Check for overflow. It should be impossible to overflow twice.
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bool IsOverflow = NewTotal < Total;
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assert(!(DidOverflow && IsOverflow) && "unexpected repeated overflow");
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DidOverflow |= IsOverflow;
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// Update the total.
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Total = NewTotal;
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// Save the weight.
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Weight W;
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W.TargetNode = Node;
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W.Amount = Amount;
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W.Type = Type;
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Weights.push_back(W);
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if (Type == Weight::Backedge)
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return;
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// Update forward total. Don't worry about overflow here, since then Total
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// will exceed 32-bits and they'll both be recomputed in normalize().
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ForwardTotal += Amount;
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}
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static void combineWeight(Weight &W, const Weight &OtherW) {
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assert(OtherW.TargetNode.isValid());
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if (!W.Amount) {
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W = OtherW;
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return;
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}
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assert(W.Type == OtherW.Type);
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assert(W.TargetNode == OtherW.TargetNode);
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assert(W.Amount < W.Amount + OtherW.Amount);
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W.Amount += OtherW.Amount;
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}
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static void combineWeightsBySorting(WeightList &Weights) {
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// Sort so edges to the same node are adjacent.
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std::sort(Weights.begin(), Weights.end(),
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[](const Weight &L,
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const Weight &R) { return L.TargetNode < R.TargetNode; });
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// Combine adjacent edges.
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WeightList::iterator O = Weights.begin();
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for (WeightList::const_iterator I = O, L = O, E = Weights.end(); I != E;
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++O, (I = L)) {
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*O = *I;
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// Find the adjacent weights to the same node.
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for (++L; L != E && I->TargetNode == L->TargetNode; ++L)
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combineWeight(*O, *L);
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}
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// Erase extra entries.
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Weights.erase(O, Weights.end());
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return;
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}
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static void combineWeightsByHashing(WeightList &Weights) {
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// Collect weights into a DenseMap.
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typedef DenseMap<BlockNode::IndexType, Weight> HashTable;
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HashTable Combined(NextPowerOf2(2 * Weights.size()));
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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;
|
|
}
|