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Code Issues Releases Wiki Activity

Rearrange MULTIEQUAL equation generation

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This commit is contained in:
caheckman 2019-06-15 00:52:51 -04:00
parent 3433400d76
commit e506f27b31
2 changed files with 62 additions and 24 deletions
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84
Ghidra/Features/Decompiler/src/decompile/cpp/rangeutil.cc
View file

@ -2035,6 +2035,44 @@ void ValueSetSolver::establishTopologicalOrder(void)
orderPartition.startNode = orderPartition.startNode->next; // Remove simulated root
}
/// \brief Generate an equation given a \b true constraint and the input/output Varnodes it affects
///
/// The equation is expressed as: only \b true values can reach the indicated input to a specific PcodeOp.
/// The equation is attached to the output of the PcodeOp.
/// \param vn is the output Varnode the equation will be attached to
/// \param op is the specific PcodeOp
/// \param slot is the input slot of the constrained input Varnode
/// \param type is the type of values
/// \param range is the range of \b true values
void ValueSetSolver::generateTrueEquation(Varnode *vn,PcodeOp *op,int4 slot,int4 type,const CircleRange &range)
{
if (vn != (Varnode *) 0)
vn->getValueSet()->addEquation(slot, type, range);
else
readNodes[op->getSeqNum()].addEquation(slot, type, range);// Special read site
}
/// \brief Generate the complementary equation given a \b true constraint and the input/output Varnodes it affects
///
/// The equation is expressed as: only \b false values can reach the indicated input to a specific PcodeOp.
/// The equation is attached to the output of the PcodeOp.
/// \param vn is the output Varnode the equation will be attached to
/// \param op is the specific PcodeOp
/// \param slot is the input slot of the constrained input Varnode
/// \param type is the type of values
/// \param range is the range of \b true values, which must be complemented
void ValueSetSolver::generateFalseEquation(Varnode *vn,PcodeOp *op,int4 slot,int4 type,const CircleRange &range)
{
CircleRange falseRange(range);
falseRange.invert();
if (vn != (Varnode *) 0)
vn->getValueSet()->addEquation(slot, type, falseRange);
else
readNodes[op->getSeqNum()].addEquation(slot, type, falseRange);// Special read site
}
/// \brief Look for PcodeOps where the given constraint range applies and instantiate an equation
///
/// If a read of the given Varnode is in a basic block dominated by the condition producing the
@ -2079,35 +2117,33 @@ void ValueSetSolver::applyConstraints(Varnode *vn,int4 type,const CircleRange &r
}
FlowBlock *curBlock = op->getParent();
int4 slot = op->getSlot(vn);
if (op->code() == CPUI_MULTIEQUAL) {
if (curBlock == trueBlock) {
// If its possible that both the true and false edges can reach trueBlock
// then the only input we can restrict is a MULTIEQUAL input along the exact true edge
if (trueIsRestricted || trueBlock->getIn(slot) == splitPoint)
generateTrueEquation(outVn, op, slot, type, range);
continue;
}
else if (curBlock == falseBlock) {
// If its possible that both the true and false edges can reach falseBlock
// then the only input we can restrict is a MULTIEQUAL input along the exact false edge
if (falseIsRestricted || falseBlock->getIn(slot) == splitPoint)
generateFalseEquation(outVn, op, slot, type, range);
continue;
}
// else
// curBlock = curBlock->getIn(slot); // MULTIEQUAL input is really only from one in-block
}
for(;;) {
if (curBlock == trueBlock) {
if (!trueIsRestricted) {
// If its possible that both the true and false edges can reach trueBlock
// then the only input we can restrict is a MULTIEQUAL input along the exact true edge
if (op->code() != CPUI_MULTIEQUAL) break;
if (op->getParent() != trueBlock) break;
if (trueBlock->getIn(slot) != splitPoint) break;
}
if (outVn != (Varnode *)0)
outVn->getValueSet()->addEquation(slot, type, range);
else
readNodes[op->getSeqNum()].addEquation(slot, type, range); // Special read site
if (trueIsRestricted)
generateTrueEquation(outVn, op, slot, type, range);
break;
}
else if (curBlock == falseBlock) {
if (!falseIsRestricted) {
// If its possible that both the true and false edges can reach falseBlock
// then the only input we can restrict is a MULTIEQUAL input along the exact false edge
if (op->code() != CPUI_MULTIEQUAL) break;
if (op->getParent() != falseBlock) break;
if (falseBlock->getIn(slot) != splitPoint) break;
}
CircleRange falseRange(range);
falseRange.invert();
if (outVn != (Varnode *)0)
outVn->getValueSet()->addEquation(slot, type, falseRange);
else
readNodes[op->getSeqNum()].addEquation(slot, type, falseRange); // Special read site
if (falseIsRestricted)
generateFalseEquation(outVn, op, slot, type, range);
break;
}
else if (curBlock == splitPoint || curBlock == (FlowBlock *)0)

2
Ghidra/Features/Decompiler/src/decompile/cpp/rangeutil.hh
View file

@ -287,6 +287,8 @@ class ValueSetSolver {
void component(ValueSet *vertex,Partition &part); ///< Generate a partition component given its head
int4 visit(ValueSet *vertex,Partition &part); ///< Recursively walk the data-flow graph finding partitions
void establishTopologicalOrder(void); ///< Find the optimal order for iterating through the ValueSets
void generateTrueEquation(Varnode *vn,PcodeOp *op,int4 slot,int4 type,const CircleRange &range);
void generateFalseEquation(Varnode *vn,PcodeOp *op,int4 slot,int4 type,const CircleRange &range);
void applyConstraints(Varnode *vn,int4 type,const CircleRange &range,PcodeOp *cbranch);
void constraintsFromPath(int4 type,CircleRange &lift,Varnode *startVn,Varnode *endVn,PcodeOp *cbranch);
void constraintsFromCBranch(PcodeOp *cbranch); ///< Generate constraints arising from the given branch