170 lines · cpp
1//===-------------------- Bitcastbuffer.cpp ---------------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8#include "BitcastBuffer.h"9#include "llvm/ADT/STLExtras.h"10 11using namespace clang;12using namespace clang::interp;13 14/// Returns the value of the bit in the given sequence of bytes.15static inline bool bitof(const std::byte *B, Bits BitIndex) {16 return (B[BitIndex.roundToBytes()] &17 (std::byte{1} << BitIndex.getOffsetInByte())) != std::byte{0};18}19 20void BitcastBuffer::pushData(const std::byte *In, Bits BitOffset, Bits BitWidth,21 Endian TargetEndianness) {22 for (unsigned It = 0; It != BitWidth.getQuantity(); ++It) {23 bool BitValue = bitof(In, Bits(It));24 if (!BitValue)25 continue;26 27 Bits DstBit;28 if (TargetEndianness == Endian::Little)29 DstBit = BitOffset + Bits(It);30 else31 DstBit = size() - BitOffset - BitWidth + Bits(It);32 33 size_t DstByte = DstBit.roundToBytes();34 Data[DstByte] |= std::byte{1} << DstBit.getOffsetInByte();35 }36}37 38std::unique_ptr<std::byte[]>39BitcastBuffer::copyBits(Bits BitOffset, Bits BitWidth, Bits FullBitWidth,40 Endian TargetEndianness) const {41 assert(BitWidth.getQuantity() <= FullBitWidth.getQuantity());42 assert(FullBitWidth.isFullByte());43 auto Out = std::make_unique<std::byte[]>(FullBitWidth.roundToBytes());44 45 for (unsigned It = 0; It != BitWidth.getQuantity(); ++It) {46 Bits BitIndex;47 if (TargetEndianness == Endian::Little)48 BitIndex = BitOffset + Bits(It);49 else50 BitIndex = size() - BitWidth - BitOffset + Bits(It);51 52 bool BitValue = bitof(Data.get(), BitIndex);53 if (!BitValue)54 continue;55 56 Bits DstBit = Bits(It);57 size_t DstByte = DstBit.roundToBytes();58 Out[DstByte] |= std::byte{1} << DstBit.getOffsetInByte();59 }60 61 return Out;62}63 64bool BitcastBuffer::allInitialized() const {65 return rangeInitialized(Bits::zero(), FinalBitSize);66}67 68void BitcastBuffer::markInitialized(Bits Offset, Bits Length) {69 if (Length.isZero())70 return;71 72 BitRange Element(Offset, Offset + Length - Bits(1));73 if (InitializedBits.empty()) {74 InitializedBits.push_back(Element);75 return;76 }77 78 assert(InitializedBits.size() >= 1);79 // Common case of just appending.80 Bits End = InitializedBits.back().End;81 if (End <= Offset) {82 // Merge this range with the last one.83 // In the best-case scenario, this means we only ever have84 // one single bit range covering all bits.85 if (End == (Offset - Bits(1))) {86 InitializedBits.back().End = Element.End;87 return;88 }89 90 // Otherwise, we can simply append.91 InitializedBits.push_back(Element);92 } else {93 // Insert sorted.94 auto It = llvm::upper_bound(InitializedBits, Element);95 InitializedBits.insert(It, Element);96 }97 98#ifndef NDEBUG99 // Ensure ranges are sorted and non-overlapping.100 assert(llvm::is_sorted(InitializedBits));101 for (unsigned I = 1; I != InitializedBits.size(); ++I) {102 [[maybe_unused]] auto Prev = InitializedBits[I - 1];103 [[maybe_unused]] auto Cur = InitializedBits[I];104 assert(Prev.End.N < Cur.Start.N);105 }106#endif107}108 109bool BitcastBuffer::rangeInitialized(Bits Offset, Bits Length) const {110 if (Length.isZero())111 return true;112 113 BitRange Range(Offset, Offset + Length - Bits(1));114 Bits Sum;115 bool FoundStart = false;116 for (BitRange BR : InitializedBits) {117 if (FoundStart) {118 if (BR.contains(Range.End)) {119 Sum += (Range.End - BR.Start + Bits(1));120 break;121 }122 123 // Else, BR is completely inside Range.124 Sum += BR.size();125 }126 if (BR.contains(Range.Start)) {127 Sum += (BR.End - Range.Start + Bits(1));128 FoundStart = true;129 }130 }131 132 // Note that Sum can be larger than Range, e.g. when Range is fully133 // contained in one range.134 return Sum >= Range.size();135}136 137#if 0138 template<typename T>139 static std::string hex(T t) {140 std::stringstream stream;141 stream << std::hex << (int)t;142 return std::string(stream.str());143 }144 145 146 void BitcastBuffer::dump(bool AsHex = true) const {147 llvm::errs() << "LSB\n ";148 unsigned LineLength = 0;149 for (unsigned I = 0; I != (FinalBitSize / 8); ++I) {150 std::byte B = Data[I];151 if (AsHex) {152 std::stringstream stream;153 stream << std::hex << (int)B;154 llvm::errs() << stream.str();155 LineLength += stream.str().size() + 1;156 } else {157 llvm::errs() << std::bitset<8>((int)B).to_string();158 LineLength += 8 + 1;159 // llvm::errs() << (int)B;160 }161 llvm::errs() << ' ';162 }163 llvm::errs() << '\n';164 165 for (unsigned I = 0; I != LineLength; ++I)166 llvm::errs() << ' ';167 llvm::errs() << "MSB\n";168 }169#endif170