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Java: Adjust caching of BasicBlocks, BaseSSA, and CompileTimeConstants #19093

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Merged
aschackmull merged 4 commits into from
Mar 31, 2025
Merged

Java: Adjust caching of BasicBlocks, BaseSSA, and CompileTimeConstants #19093

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3313533
Java: Merge cached stages for BasicBlocks.
aschackmull Mar 21, 2025
e75ed5a
Java: Merge BaseSSA cached stages.
aschackmull Mar 21, 2025
3c6db09
Java: Cache the other compiletimeconstant value predicates
aschackmull Mar 21, 2025
dc0ca1a
Java: Fix TC magic in SystemProperty.
aschackmull Mar 24, 2025
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18 changes: 12 additions & 6 deletions java/ql/lib/semmle/code/java/environment/SystemProperty.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -269,18 +269,24 @@ private MethodCall getSystemPropertyFromSpringProperties(string propertyName) {
* for final variables.
*/
private predicate localExprFlowPlusInitializers(Expr e1, Expr e2) {
e1 = e2 or
localFlowPlusInitializers(DataFlow::exprNode(e1), DataFlow::exprNode(e2))
}

private predicate localFlowPlusInitializers(DataFlow::Node pred, DataFlow::Node succ) =
fastTC(localFlowStepPlusInitializers/2)(pred, succ)

/**
* Holds if data can flow from `pred` to `succ` in zero or more
* local (intra-procedural) steps or via instance or static variable intializers
* Holds if data can flow from `pred` to `succ` in a
* local (intra-procedural) step or via instance or static variable intializers
* for final variables.
*/
private predicate localFlowPlusInitializers(DataFlow::Node pred, DataFlow::Node succ) {
exists(Variable v | v.isFinal() and pred.asExpr() = v.getInitializer() |
DataFlow::localFlow(DataFlow::exprNode(v.getAnAccess()), succ)
private predicate localFlowStepPlusInitializers(DataFlow::Node pred, DataFlow::Node succ) {
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@hvitved hvitved Mar 31, 2025

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Is this rewrite semantics preserving? It looks like before it would calculate flow as

pred --initializer--> access --local--*> succ

and now it is

pred --initializer/local--*> succ

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@aschackmull aschackmull Mar 31, 2025

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Correct, it's not 100% semantics preserving, but I think the tweaked version makes more sense: If we're doing local flow plus initialization of final fields, then it seems like a mistake to rule out local flow prior to the initialization, like e.g. a cast or something like that.

exists(Variable v |
v.isFinal() and
pred.asExpr() = v.getInitializer() and
succ.asExpr() = v.getAnAccess()
)
or
DataFlow::localFlow(pred, succ)
DataFlow::localFlowStep(pred, succ)
}
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