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Fix undefined behavior in Block access

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(cherry picked from commit a1cdcdb038cda474aefb900171222254599e9dd8)
This commit is contained in:
Jeremy Nimmer 2023-02-01 00:40:45 +00:00 committed by Antonio Sanchez
parent b26ada1e03
commit 90dce8dfa3
2 changed files with 20 additions and 4 deletions
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23
Eigen/src/Core/Block.h
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@ -334,6 +334,17 @@ class BlockImpl_dense<XprType,BlockRows,BlockCols, InnerPanel,true>
enum {
XprTypeIsRowMajor = (int(traits<XprType>::Flags)&RowMajorBit) != 0
};
/** \internal Returns base+offset (unless base is null, in which case returns null).
* Adding an offset to nullptr is undefined behavior, so we must avoid it.
*/
template <typename Scalar>
EIGEN_DEVICE_FUNC EIGEN_CONSTEXPR EIGEN_ALWAYS_INLINE
static Scalar* add_to_nullable_pointer(Scalar* base, Index offset)
{
return base != NULL ? base+offset : NULL;
}
public:
typedef MapBase<BlockType> Base;
@ -344,8 +355,9 @@ class BlockImpl_dense<XprType,BlockRows,BlockCols, InnerPanel,true>
*/
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
BlockImpl_dense(XprType& xpr, Index i)
: Base(xpr.data() + i * ( ((BlockRows==1) && (BlockCols==XprType::ColsAtCompileTime) && (!XprTypeIsRowMajor))
|| ((BlockRows==XprType::RowsAtCompileTime) && (BlockCols==1) && ( XprTypeIsRowMajor)) ? xpr.innerStride() : xpr.outerStride()),
: Base(add_to_nullable_pointer(xpr.data(),
i * ( ((BlockRows==1) && (BlockCols==XprType::ColsAtCompileTime) && (!XprTypeIsRowMajor))
|| ((BlockRows==XprType::RowsAtCompileTime) && (BlockCols==1) && ( XprTypeIsRowMajor)) ? xpr.innerStride() : xpr.outerStride())),
BlockRows==1 ? 1 : xpr.rows(),
BlockCols==1 ? 1 : xpr.cols()),
m_xpr(xpr),
@ -359,7 +371,8 @@ class BlockImpl_dense<XprType,BlockRows,BlockCols, InnerPanel,true>
*/
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
BlockImpl_dense(XprType& xpr, Index startRow, Index startCol)
: Base(xpr.data()+xpr.innerStride()*(XprTypeIsRowMajor?startCol:startRow) + xpr.outerStride()*(XprTypeIsRowMajor?startRow:startCol)),
: Base(add_to_nullable_pointer(xpr.data(),
xpr.innerStride()*(XprTypeIsRowMajor?startCol:startRow) + xpr.outerStride()*(XprTypeIsRowMajor?startRow:startCol))),
m_xpr(xpr), m_startRow(startRow), m_startCol(startCol)
{
init();
@ -371,7 +384,9 @@ class BlockImpl_dense<XprType,BlockRows,BlockCols, InnerPanel,true>
BlockImpl_dense(XprType& xpr,
Index startRow, Index startCol,
Index blockRows, Index blockCols)
: Base(xpr.data()+xpr.innerStride()*(XprTypeIsRowMajor?startCol:startRow) + xpr.outerStride()*(XprTypeIsRowMajor?startRow:startCol), blockRows, blockCols),
: Base(add_to_nullable_pointer(xpr.data(),
xpr.innerStride()*(XprTypeIsRowMajor?startCol:startRow) + xpr.outerStride()*(XprTypeIsRowMajor?startRow:startCol)),
blockRows, blockCols),
m_xpr(xpr), m_startRow(startRow), m_startCol(startCol)
{
init();

1
Eigen/src/Core/StlIterators.h
View File

@ -196,6 +196,7 @@ public:
pointer_based_stl_iterator() EIGEN_NO_THROW : m_ptr(0) {}
pointer_based_stl_iterator(XprType& xpr, Index index) EIGEN_NO_THROW : m_incr(xpr.innerStride())
{
eigen_assert(xpr.data() != NULL || index == 0 || m_incr.value() == 0);
m_ptr = xpr.data() + index * m_incr.value();
}