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C++: Eliminate dead code, uncertain is always false.

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This commit is contained in:
Anders Schack-Mulligen
2025-03-20 13:12:48 +01:00
parent e8e9403b4c
commit 133f08784f
1 changed files with 9 additions and 35 deletions
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44
cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowPrivate.qll
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@@ -1879,15 +1879,6 @@ module IteratorFlow {
phi.definesAt(sv, bb2, i2, _) phi.definesAt(sv, bb2, i2, _)
) )
} }
cached
Node getAPriorDefinition(IteratorSsa::DefinitionExt next) {
exists(IRBlock bb, int i, SourceVariable sv, IteratorSsa::DefinitionExt def |
IteratorSsa::lastRefRedefExt(pragma[only_bind_into](def), pragma[only_bind_into](sv),
pragma[only_bind_into](bb), pragma[only_bind_into](i), next) and
nodeToDefOrUse(result, sv, bb, i, _)
)
}
} }
/** The set of nodes necessary for iterator flow. */ /** The set of nodes necessary for iterator flow. */
@@ -1912,25 +1903,19 @@ module IteratorFlow {
private import IteratorSsaCached private import IteratorSsaCached
private predicate defToNode(Node node, Def def, boolean uncertain) { private predicate defToNode(Node node, Def def) {
( nodeHasOperand(node, def.getValue().asOperand(), def.getIndirectionIndex())
nodeHasOperand(node, def.getValue().asOperand(), def.getIndirectionIndex()) or
or nodeHasInstruction(node, def.getValue().asInstruction(), def.getIndirectionIndex())
nodeHasInstruction(node, def.getValue().asInstruction(), def.getIndirectionIndex())
) and
uncertain = false
} }
private predicate nodeToDefOrUse( private predicate nodeToDefOrUse(Node node, SourceVariable sv, IRBlock bb, int i) {
Node node, SourceVariable sv, IRBlock bb, int i, boolean uncertain
) {
exists(Def def | exists(Def def |
def.hasIndexInBlock(bb, i, sv) and def.hasIndexInBlock(bb, i, sv) and
defToNode(node, def, uncertain) defToNode(node, def)
) )
or or
useToNode(bb, i, sv, node) and useToNode(bb, i, sv, node)
uncertain = false
} }
private predicate useToNode(IRBlock bb, int i, SourceVariable sv, Node nodeTo) { private predicate useToNode(IRBlock bb, int i, SourceVariable sv, Node nodeTo) {
@@ -1949,21 +1934,10 @@ module IteratorFlow {
* Holds if `nodeFrom` flows to `nodeTo` in a single step. * Holds if `nodeFrom` flows to `nodeTo` in a single step.
*/ */
predicate localFlowStep(Node nodeFrom, Node nodeTo) { predicate localFlowStep(Node nodeFrom, Node nodeTo) {
exists( exists(SourceVariable sv, IRBlock bb1, int i1, IRBlock bb2, int i2 |
Node nFrom, SourceVariable sv, IRBlock bb1, int i1, IRBlock bb2, int i2, boolean uncertain
|
adjacentDefRead(bb1, i1, sv, bb2, i2) and adjacentDefRead(bb1, i1, sv, bb2, i2) and
nodeToDefOrUse(nFrom, sv, bb1, i1, uncertain) and nodeToDefOrUse(nodeFrom, sv, bb1, i1) and
useToNode(bb2, i2, sv, nodeTo) useToNode(bb2, i2, sv, nodeTo)
|
if uncertain = true
then
nodeFrom =
[
nFrom,
getAPriorDefinition(any(IteratorSsa::DefinitionExt next | next.definesAt(sv, bb1, i1, _)))
]
else nFrom = nodeFrom
) )
} }
} }