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C++: data flow AlwaysTrueUponEntryLoop perf fix #598

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Merged
geoffw0 merged 1 commit into from
Dec 3, 2018
Merged

C++: data flow AlwaysTrueUponEntryLoop perf fix #598

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14 changes: 10 additions & 4 deletions cpp/ql/src/semmle/code/cpp/dataflow/internal/FlowVar.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -292,17 +292,23 @@ module FlowVar_internal {
* Gets a variable that is assigned in this loop and read outside the loop.
*/
private Variable getARelevantVariable() {
exists(BasicBlock bbAssign |
assignmentLikeOperation(bbAssign.getANode(), result, _) and
this.bbInLoop(bbAssign)
) and
result = this.getAVariableAssignedInLoop() and
exists(VariableAccess va |
va.getTarget() = result and
readAccess(va) and
bbNotInLoop(va.getBasicBlock())
)
}

/** Gets a variable that is assigned in this loop. */
pragma[noinline]
private Variable getAVariableAssignedInLoop() {
exists(BasicBlock bbAssign |
assignmentLikeOperation(bbAssign.getANode(), result, _) and
this.bbInLoop(bbAssign)
)
}

private predicate bbInLoopCondition(BasicBlock bb) {
getCFNParent*(bb.getANode()) = this.(Loop).getCondition()
}
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