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Fix memory copy [Delivers #84703344]

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Paweł Bylica 2014-12-22 23:52:33 +01:00
parent 43e08ea32d
commit 4254b3fec1
1 changed files with 20 additions and 14 deletions
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34
libevmjit/Memory.cpp
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@ -189,8 +189,6 @@ void Memory::require(llvm::Value* _offset, llvm::Value* _size)
void Memory::copyBytes(llvm::Value* _srcPtr, llvm::Value* _srcSize, llvm::Value* _srcIdx, void Memory::copyBytes(llvm::Value* _srcPtr, llvm::Value* _srcSize, llvm::Value* _srcIdx,
llvm::Value* _destMemIdx, llvm::Value* _reqBytes) llvm::Value* _destMemIdx, llvm::Value* _reqBytes)
{ {
auto zero256 = llvm::ConstantInt::get(Type::Word, 0);
require(_destMemIdx, _reqBytes); require(_destMemIdx, _reqBytes);
// Additional copy cost // Additional copy cost
@ -198,20 +196,28 @@ void Memory::copyBytes(llvm::Value* _srcPtr, llvm::Value* _srcSize, llvm::Value*
auto copyWords = m_builder.CreateUDiv(m_builder.CreateAdd(_reqBytes, Constant::get(31)), Constant::get(32)); auto copyWords = m_builder.CreateUDiv(m_builder.CreateAdd(_reqBytes, Constant::get(31)), Constant::get(32));
m_gasMeter.countCopy(copyWords); m_gasMeter.countCopy(copyWords);
auto srcPtr = m_builder.CreateGEP(_srcPtr, _srcIdx, "src_idx"); // Algorithm:
// isOutsideData = idx256 >= size256
// idx64 = trunc idx256
// size64 = trunc size256
// dataLeftSize = size64 - idx64 // safe if not isOutsideData
// reqBytes64 = trunc _reqBytes // require() handles large values
// bytesToCopy0 = select(reqBytes64 > dataLeftSize, dataSizeLeft, reqBytes64) // min
// bytesToCopy = select(isOutsideData, 0, bytesToCopy0)
auto memPtr = getData(); auto isOutsideData = m_builder.CreateICmpUGE(_srcIdx, _srcSize);
auto destPtr = m_builder.CreateGEP(memPtr, _destMemIdx, "dest_mem_ptr"); auto idx64 = m_builder.CreateTrunc(_srcIdx, Type::lowPrecision);
auto size64 = m_builder.CreateTrunc(_srcSize, Type::lowPrecision);
auto dataLeftSize = m_builder.CreateSub(size64, idx64);
auto reqBytes64 = m_builder.CreateTrunc(_reqBytes, Type::lowPrecision);
auto outOfBound = m_builder.CreateICmpUGT(reqBytes64, dataLeftSize);
auto bytesToCopyInner = m_builder.CreateSelect(outOfBound, dataLeftSize, reqBytes64);
auto zero64 = llvm::ConstantInt::get(Type::lowPrecision, 0); // TODO: Cache common constants
auto bytesToCopy = m_builder.CreateSelect(isOutsideData, zero64, bytesToCopyInner);
// remaining source bytes: auto src = m_builder.CreateGEP(_srcPtr, idx64, "src");
auto remSrcSize = m_builder.CreateSub(_srcSize, _srcIdx); auto dst = m_builder.CreateGEP(getData(), _destMemIdx, "dst");
auto remSizeNegative = m_builder.CreateICmpSLT(remSrcSize, zero256); m_builder.CreateMemCpy(dst, src, bytesToCopy, 0);
auto remSrcBytes = m_builder.CreateSelect(remSizeNegative, zero256, remSrcSize, "rem_src_bytes");
auto tooFewSrcBytes = m_builder.CreateICmpULT(remSrcBytes, _reqBytes);
auto bytesToCopy = m_builder.CreateSelect(tooFewSrcBytes, remSrcBytes, _reqBytes, "bytes_to_copy");
m_builder.CreateMemCpy(destPtr, srcPtr, bytesToCopy, 0);
} }
} }