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New LaneDescription methods, refactor TransformVar initialize

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This commit is contained in:
caheckman 2019-10-17 09:49:24 -04:00
parent ad87a8d40f
commit 4f925923c5
2 changed files with 148 additions and 55 deletions
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176
Ghidra/Features/Decompiler/src/decompile/cpp/transform.cc
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@ -49,6 +49,81 @@ LaneDescription::LaneDescription(int4 origSize,int4 lo,int4 hi)
lanePosition[1] = lo;
}
/// Position 0 will map to index 0 and a position equal to whole size will
/// map to the number of lanes. Positions that are out of bounds or that do
/// not fall on a lane boundary will return -1.
/// \param bytePos is the given byte position to test
/// \return the index of the lane that start at the given position
int4 LaneDescription::getBoundary(int4 bytePos) const
{
if (bytePos < 0 || bytePos > wholeSize)
return -1;
if (bytePos == wholeSize)
return lanePosition.size();
int4 min = 0;
int4 max = lanePosition.size() - 1;
while(min < max) {
int4 index = (min + max) / 2;
int4 pos = lanePosition[index];
if (pos == bytePos) return index;
if (pos < bytePos)
min = pos + 1;
else
max = pos - 1;
}
return -1;
}
/// \brief Decide if a given truncation is natural for \b this description
///
/// A subset of lanes are specified and a truncation (given by a byte position and byte size).
/// If the truncation, relative to the subset, contains at least 1 lane and does not split any
/// lanes, then return \b true and pass back the number of lanes and starting lane of the truncation.
/// \param numLanes is the number of lanes in the original subset
/// \param skipLanes is the starting (least significant) lane index of the original subset
/// \param bytePos is the number of bytes to truncate from the front (least significant portion) of the subset
/// \param size is the number of bytes to include in the truncation
/// \param resNumLanes will hold the number of lanes in the truncation
/// \param resSkipLanes will hold the starting lane in the truncation
/// \return \b true if the truncation is natural
bool LaneDescription::restriction(int4 numLanes,int4 skipLanes,int4 bytePos,int4 size,
int4 &resNumLanes,int4 &resSkipLanes) const
{
resSkipLanes = getBoundary(lanePosition[skipLanes] + bytePos);
if (resSkipLanes < 0) return false;
int4 finalIndex = getBoundary(lanePosition[skipLanes] + bytePos + size);
if (finalIndex < 0) return false;
resNumLanes = finalIndex - resSkipLanes;
return (resNumLanes != 0);
}
/// \brief Decide if a given subset of lanes can be extended naturally for \b this description
///
/// A subset of lanes are specified and their position within an extension (given by a byte position).
/// The size in bytes of the extension is also given. If the extension is contained within \b this description,
/// and the boundaries of the extension don't split any lanes, then return \b true and pass back
/// the number of lanes and starting lane of the extension.
/// \param numLanes is the number of lanes in the original subset
/// \param skipLanes is the starting (least significant) lane index of the original subset
/// \param bytePos is the number of bytes to truncate from the front (least significant portion) of the extension
/// \param size is the number of bytes in the extension
/// \param resNumLanes will hold the number of lanes in the extension
/// \param resSkipLanes will hold the starting lane in the extension
/// \return \b true if the extension is natural
bool LaneDescription::extension(int4 numLanes,int4 skipLanes,int4 bytePos,int4 size,
int4 &resNumLanes,int4 &resSkipLanes) const
{
resSkipLanes = getBoundary(lanePosition[skipLanes] - bytePos);
if (resSkipLanes < 0) return false;
int4 finalIndex = getBoundary(lanePosition[skipLanes] - bytePos + size);
if (finalIndex < 0) return false;
resNumLanes = finalIndex - resSkipLanes;
return (resNumLanes != 0);
}
/// Create the Varnode object (constant, unique, vector piece) described by the
/// given placeholder. If the Varnode is an output, assume the op already exists
/// and create the Varnode as an output. Set the \b replacement field with the
@ -193,14 +268,10 @@ TransformVar *TransformManager::newPreexistingVarnode(Varnode *vn)
{
TransformVar *res = new TransformVar[1];
pieceMap[vn->getCreateIndex()] = res; // Enter preexisting Varnode into map, so we don't make another placeholder
res->vn = vn;
res->replacement = (Varnode *)0;
res->byteSize = vn->getSize();
res->bitSize = res->byteSize * 8;
res->def = (TransformOp *)0;
res->type = TransformVar::preexisting;
// value of 0 treats this as "piece" of itself at offset 0, allows getPiece() to find it
res->initialize(TransformVar::preexisting,vn,vn->getSize()*8,vn->getSize(),0);
res->flags = TransformVar::split_terminator;
res->val = 0; // Treat this as "piece" of itself at offset 0, allows getPiece() to find this
return res;
}
@ -211,13 +282,7 @@ TransformVar *TransformManager::newUnique(int4 size)
{
newVarnodes.push_back(TransformVar());
TransformVar *res = &newVarnodes.back();
res->vn = (Varnode *)0;
res->replacement = (Varnode *)0;
res->byteSize = size;
res->bitSize = size * 8;
res->def = (TransformOp *)0;
res->type = TransformVar::normal_temp;
res->flags = 0;
res->initialize(TransformVar::normal_temp,(Varnode *)0,size*8,size,0);
return res;
}
@ -232,30 +297,19 @@ TransformVar *TransformManager::newConstant(int4 size,int4 lsbOffset,uintb val)
{
newVarnodes.push_back(TransformVar());
TransformVar *res = &newVarnodes.back();
res->vn = (Varnode *)0;
res->replacement = (Varnode *)0;
res->byteSize = size;
res->bitSize = size * 8;
res->val = (val >> lsbOffset) & calc_mask(size);
res->def = (TransformOp *)0;
res->type = TransformVar::constant;
res->flags = 0;
res->initialize(TransformVar::constant,(Varnode *)0,size*8,size,(val >> lsbOffset) & calc_mask(size));
return res;
}
/// Used for creating INDIRECT placeholders.
/// \param vn is the original iop parameter to the INDIRECT
/// \return the new placeholder node
TransformVar *TransformManager::newIop(Varnode *vn)
{
newVarnodes.push_back(TransformVar());
TransformVar *res = &newVarnodes.back();
res->vn = (Varnode *)0;
res->replacement = (Varnode *)0;
res->byteSize = vn->getSize();
res->bitSize = res->byteSize * 8;
res->val = vn->getOffset(); // The encoded iop
res->def = (TransformOp *)0;
res->type = TransformVar::constant_iop;
res->flags = 0;
res->initialize(TransformVar::constant_iop,(Varnode *)0,vn->getSize()*8,vn->getSize(),vn->getOffset());
return res;
}
@ -270,17 +324,10 @@ TransformVar *TransformManager::newPiece(Varnode *vn,int4 bitSize,int4 lsbOffset
{
TransformVar *res = new TransformVar[1];
pieceMap[vn->getCreateIndex()] = res;
res->vn = vn;
res->replacement = (Varnode *)0;
res->bitSize = bitSize;
res->byteSize = (bitSize + 7) / 8;
res->def = (TransformOp *)0;
if (preserveAddress(vn, bitSize, lsbOffset))
res->type = TransformVar::piece;
else
res->type = TransformVar::piece_temp;
int4 byteSize = (bitSize + 7) / 8;
uint4 type = preserveAddress(vn, bitSize, lsbOffset) ? TransformVar::piece : TransformVar::piece_temp;
res->initialize(type, vn, bitSize, byteSize, lsbOffset);
res->flags = TransformVar::split_terminator;
res->val = lsbOffset;
return res;
}
@ -300,28 +347,47 @@ TransformVar *TransformManager::newSplit(Varnode *vn,const LaneDescription &desc
for(int4 i=0;i<num;++i) {
int4 bitpos = description.getPosition(i) * 8;
TransformVar *newVar = &res[i];
newVar->vn = vn;
newVar->replacement = (Varnode *)0;
newVar->byteSize = description.getSize(i);
newVar->bitSize = newVar->byteSize * 8;
newVar->def = (TransformOp *)0;
newVar->flags = 0;
if (vn->isConstant()) {
newVar->type = TransformVar::constant;
newVar->val = (vn->getOffset() >> bitpos) & calc_mask(newVar->byteSize);
}
int4 byteSize = description.getSize(i);
if (vn->isConstant())
newVar->initialize(TransformVar::constant,vn,byteSize * 8,byteSize, (vn->getOffset() >> bitpos) & calc_mask(byteSize));
else {
if (preserveAddress(vn, newVar->bitSize, bitpos))
newVar->type = TransformVar::piece;
else
newVar->type = TransformVar::piece_temp;
newVar->val = bitpos;
uint4 type = preserveAddress(vn, byteSize * 8, bitpos) ? TransformVar::piece : TransformVar::piece_temp;
newVar->initialize(type,vn,byteSize * 8, byteSize, bitpos);
}
}
res[num-1].flags = TransformVar::split_terminator;
return res;
}
/// \brief Create placeholder nodes splitting a Varnode into a subset of lanes in the given description
///
/// Given a big Varnode and specific subset of a lane description, create placeholders for all
/// the explicit pieces that the big Varnode will be split into.
/// \param vn is the big Varnode to split
/// \param description gives a list of potentional lanes
/// \param numLanes is the number of lanes in the subset
/// \param startLane is the starting (least significant) lane in the subset
/// \return an array of the new TransformVar placeholders from least to most significant
TransformVar *TransformManager::newSplit(Varnode *vn,const LaneDescription &description,int4 numLanes,int4 startLane)
{
TransformVar *res = new TransformVar[numLanes];
pieceMap[vn->getCreateIndex()] = res;
for(int4 i=0;i<numLanes;++i) {
int4 bitpos = description.getPosition(startLane + i) * 8;
int4 byteSize = description.getSize(startLane + i);
TransformVar *newVar = &res[i];
if (vn->isConstant())
newVar->initialize(TransformVar::constant,vn,byteSize * 8, byteSize, (vn->getOffset() >> bitpos) & calc_mask(byteSize));
else {
uint4 type = preserveAddress(vn, byteSize * 8, bitpos) ? TransformVar::piece : TransformVar::piece_temp;
newVar->initialize(type,vn,byteSize * 8, byteSize, bitpos);
}
}
res[numLanes-1].flags = TransformVar::split_terminator;
return res;
}
/// \brief Create a new placeholder op intended to replace an existing op
///
/// An uninitialized placeholder for the new op is created.