C++: Fix join-order in 'phi_node' predicate.

MathiasVP · MathiasVP · commit d84079649458 · 2021-12-17T07:50:04.000Z
diff --git a/cpp/ql/lib/semmle/code/cpp/controlflow/SSAUtils.qll b/cpp/ql/lib/semmle/code/cpp/controlflow/SSAUtils.qll
@@ -153,7 +153,7 @@ library class SSAHelper extends int {
    * Modern Compiler Implementation by Andrew Appel.
    */
   private predicate frontier_phi_node(StackVariable v, BasicBlock b) {
-    exists(BasicBlock x | dominanceFrontier(x, b) and ssa_defn_rec(v, x)) and
+    exists(BasicBlock x | dominanceFrontier(pragma[only_bind_into](x), b) and ssa_defn_rec(v, x)) and
     /* We can also eliminate those nodes where the variable is not live on any incoming edge */
     live_at_start_of_bb(v, b)
   }

Original file line number	Diff line number	Diff line change
`@@ -153,7 +153,7 @@ library class SSAHelper extends int {`
`153`	`153`	`* Modern Compiler Implementation by Andrew Appel.`
`154`	`154`	`*/`
`155`	`155`	`private predicate frontier_phi_node(StackVariable v, BasicBlock b) {`
`156`		`- exists(BasicBlock x \| dominanceFrontier(x, b) and ssa_defn_rec(v, x)) and`
	`156`	`+ exists(BasicBlock x \| dominanceFrontier(pragma[only_bind_into](x), b) and ssa_defn_rec(v, x)) and`
`157`	`157`	`/* We can also eliminate those nodes where the variable is not live on any incoming edge */`
`158`	`158`	`live_at_start_of_bb(v, b)`
`159`	`159`	`}`