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C++: Improve performance by not calling getDef, but instead refer to isDefinitionInexact. This gives roughly the same tuple numbers we had with only instruction nodes.

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This commit is contained in:
Mathias Vorreiter Pedersen
2020-06-25 12:55:57 +02:00
parent 8c6753a3cc
commit a0bfbda51c
1 changed files with 8 additions and 6 deletions
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14
cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll
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@@ -521,9 +521,9 @@ private predicate getFieldSizeOfClass(Class c, Type type, int size) {
cached
private predicate simpleInstructionLocalFlowStep(Operand opFrom, Instruction iTo) {
iTo.(CopyInstruction).getSourceValue() = opFrom.getDef()
iTo.(CopyInstruction).getSourceValueOperand() = opFrom and not opFrom.isDefinitionInexact()
or
iTo.(PhiInstruction).getAnInput() = opFrom.getDef()
iTo.(PhiInstruction).getAnInputOperand() = opFrom and not opFrom.isDefinitionInexact()
or
// A read side effect is almost never exact since we don't know exactly how
// much memory the callee will read.
@@ -542,7 +542,7 @@ private predicate simpleInstructionLocalFlowStep(Operand opFrom, Instruction iTo
// leads to a phi node.
exists(InitializeIndirectionInstruction init |
opFrom.getAnyDef() = init and
iTo.(LoadInstruction).getSourceValueOperand().getAnyDef() = init and
iTo.(LoadInstruction).getSourceValueOperand() = opFrom and
// Check that the types match. Otherwise we can get flow from an object to
// its fields, which leads to field conflation when there's flow from other
// fields to the object elsewhere.
@@ -551,11 +551,13 @@ private predicate simpleInstructionLocalFlowStep(Operand opFrom, Instruction iTo
)
or
// Treat all conversions as flow, even conversions between different numeric types.
iTo.(ConvertInstruction).getUnary() = opFrom.getDef()
iTo.(ConvertInstruction).getUnaryOperand() = opFrom and not opFrom.isDefinitionInexact()
or
iTo.(CheckedConvertOrNullInstruction).getUnary() = opFrom.getDef()
iTo.(CheckedConvertOrNullInstruction).getUnaryOperand() = opFrom and
not opFrom.isDefinitionInexact()
or
iTo.(InheritanceConversionInstruction).getUnary() = opFrom.getDef()
iTo.(InheritanceConversionInstruction).getUnaryOperand() = opFrom and
not opFrom.isDefinitionInexact()
or
// A chi instruction represents a point where a new value (the _partial_
// operand) may overwrite an old value (the _total_ operand), but the alias