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Performance improvements suggested

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This commit is contained in:
Philippe Antoine
2020-07-09 11:31:47 +02:00
parent 8f7ff1a537
commit 5eff8d3165
1 changed files with 5 additions and 8 deletions
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13
cpp/ql/src/Likely Bugs/RedundantNullCheckParam.ql
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@@ -28,21 +28,17 @@ predicate isCheckedInstruction(VariableAccess unchecked, VariableAccess checked)
blockDominates(checked.getEnclosingBlock(), unchecked.getEnclosingBlock())
}
pragma[noinline]
predicate candidateResultUnchecked(VariableAccess unchecked) {
not isCheckedInstruction(unchecked, _)
}
pragma[noinline]
predicate candidateResultChecked(VariableAccess check, EqualityOperation eqop, Parameter param) {
predicate candidateResultChecked(VariableAccess check, EqualityOperation eqop) {
//not dereferenced to check against pointer, not its pointed value
not dereferenced(check) and
//assert macros are not taken into account
not check.isInMacroExpansion() and
// is part of a comarison against some constant NULL
eqop.getAnOperand() = check and eqop.getAnOperand() instanceof NullValue and
// this function parameter is not overwritten
count(param.getAnAssignment()) = 0
eqop.getAnOperand() = check and eqop.getAnOperand() instanceof NullValue
}
from VariableAccess unchecked, VariableAccess check, EqualityOperation eqop, Parameter param
@@ -51,9 +47,10 @@ where
dereferenced(unchecked) and
// for a function parameter
unchecked.getTarget() = param and
check.getTarget() = param and
// this function parameter is not overwritten
count(param.getAnAssignment()) = 0 and
// which is once checked
candidateResultChecked(check, eqop, param) and
candidateResultChecked(check, eqop) and
// and which has not been checked before in this code path
candidateResultUnchecked(unchecked)
select check, "This null check is redundant because the value is $@ ", unchecked, "dereferenced here"