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//===-------------------- Bitcastbuffer.cpp ---------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "BitcastBuffer.h"
#include "llvm/ADT/STLExtras.h"
using namespace clang;
using namespace clang::interp;
/// Returns the value of the bit in the given sequence of bytes.
static inline bool bitof(const std::byte *B, Bits BitIndex) {
return (B[BitIndex.roundToBytes()] &
(std::byte{1} << BitIndex.getOffsetInByte())) != std::byte{0};
}
void BitcastBuffer::pushData(const std::byte *In, Bits BitOffset, Bits BitWidth,
Endian TargetEndianness) {
for (unsigned It = 0; It != BitWidth.getQuantity(); ++It) {
bool BitValue = bitof(In, Bits(It));
if (!BitValue)
continue;
Bits DstBit;
if (TargetEndianness == Endian::Little)
DstBit = BitOffset + Bits(It);
else
DstBit = size() - BitOffset - BitWidth + Bits(It);
size_t DstByte = DstBit.roundToBytes();
Data[DstByte] |= std::byte{1} << DstBit.getOffsetInByte();
}
}
std::unique_ptr<std::byte[]>
BitcastBuffer::copyBits(Bits BitOffset, Bits BitWidth, Bits FullBitWidth,
Endian TargetEndianness) const {
assert(BitWidth.getQuantity() <= FullBitWidth.getQuantity());
assert(FullBitWidth.isFullByte());
auto Out = std::make_unique<std::byte[]>(FullBitWidth.roundToBytes());
for (unsigned It = 0; It != BitWidth.getQuantity(); ++It) {
Bits BitIndex;
if (TargetEndianness == Endian::Little)
BitIndex = BitOffset + Bits(It);
else
BitIndex = size() - BitWidth - BitOffset + Bits(It);
bool BitValue = bitof(Data.get(), BitIndex);
if (!BitValue)
continue;
Bits DstBit = Bits(It);
size_t DstByte = DstBit.roundToBytes();
Out[DstByte] |= std::byte{1} << DstBit.getOffsetInByte();
}
return Out;
}
bool BitcastBuffer::allInitialized() const {
return rangeInitialized(Bits::zero(), FinalBitSize);
}
void BitcastBuffer::markInitialized(Bits Offset, Bits Length) {
if (Length.isZero())
return;
BitRange Element(Offset, Offset + Length - Bits(1));
if (InitializedBits.empty()) {
InitializedBits.push_back(Element);
return;
}
assert(InitializedBits.size() >= 1);
// Common case of just appending.
Bits End = InitializedBits.back().End;
if (End <= Offset) {
// Merge this range with the last one.
// In the best-case scenario, this means we only ever have
// one single bit range covering all bits.
if (End == (Offset - Bits(1))) {
InitializedBits.back().End = Element.End;
return;
}
// Otherwise, we can simply append.
InitializedBits.push_back(Element);
} else {
// Insert sorted.
auto It = std::upper_bound(InitializedBits.begin(), InitializedBits.end(),
Element);
InitializedBits.insert(It, Element);
}
#ifndef NDEBUG
// Ensure ranges are sorted and non-overlapping.
assert(llvm::is_sorted(InitializedBits));
for (unsigned I = 1; I != InitializedBits.size(); ++I) {
[[maybe_unused]] auto Prev = InitializedBits[I - 1];
[[maybe_unused]] auto Cur = InitializedBits[I];
assert(Prev.End.N < Cur.Start.N);
}
#endif
}
bool BitcastBuffer::rangeInitialized(Bits Offset, Bits Length) const {
if (Length.isZero())
return true;
BitRange Range(Offset, Offset + Length - Bits(1));
Bits Sum;
bool FoundStart = false;
for (BitRange BR : InitializedBits) {
if (FoundStart) {
if (BR.contains(Range.End)) {
Sum += (Range.End - BR.Start + Bits(1));
break;
}
// Else, BR is completely inside Range.
Sum += BR.size();
}
if (BR.contains(Range.Start)) {
Sum += (BR.End - Range.Start + Bits(1));
FoundStart = true;
}
}
// Note that Sum can be larger than Range, e.g. when Range is fully
// contained in one range.
return Sum >= Range.size();
}
#if 0
template<typename T>
static std::string hex(T t) {
std::stringstream stream;
stream << std::hex << (int)t;
return std::string(stream.str());
}
void BitcastBuffer::dump(bool AsHex = true) const {
llvm::errs() << "LSB\n ";
unsigned LineLength = 0;
for (unsigned I = 0; I != (FinalBitSize / 8); ++I) {
std::byte B = Data[I];
if (AsHex) {
std::stringstream stream;
stream << std::hex << (int)B;
llvm::errs() << stream.str();
LineLength += stream.str().size() + 1;
} else {
llvm::errs() << std::bitset<8>((int)B).to_string();
LineLength += 8 + 1;
// llvm::errs() << (int)B;
}
llvm::errs() << ' ';
}
llvm::errs() << '\n';
for (unsigned I = 0; I != LineLength; ++I)
llvm::errs() << ' ';
llvm::errs() << "MSB\n";
}
#endif
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