C++: Make the pre update node for ExplicitFieldStoreQualifierNode an operand node. This fixes the IR dataflow consistency errors.

MathiasVP · MathiasVP · commit 5aa1b131369e · 2020-06-24T18:27:53.000+02:00
diff --git a/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll b/cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll
@@ -317,7 +317,7 @@ abstract class PostUpdateNode extends InstructionNode {
  * setY(&x); // a partial definition of the object `x`.
  * ```
  */
-abstract private class PartialDefinitionNode extends PostUpdateNode, TInstructionNode {
+abstract private class PartialDefinitionNode extends PostUpdateNode {
   abstract Expr getDefinedExpr();
 }
 
@@ -332,11 +332,7 @@ private class ExplicitFieldStoreQualifierNode extends PartialDefinitionNode {
     )
   }
 
-  // There might be multiple `ChiInstructions` that has a particular instruction as
-  // the total operand - so this definition gives consistency errors in
-  // DataFlowImplConsistency::Consistency. However, it's not clear what (if any) implications
-  // this consistency failure has.
-  override Node getPreUpdateNode() { result.asInstruction() = instr.getTotal() }
+  override Node getPreUpdateNode() { result.asOperand() = instr.getTotalOperand() }
 
   override Expr getDefinedExpr() {
     result = field.getObjectAddress().getUnconvertedResultExpression()

Original file line number	Diff line number	Diff line change
`@@ -317,7 +317,7 @@ abstract class PostUpdateNode extends InstructionNode {`
`317`	`317`	* setY(&x); // a partial definition of the object `x`.
`318`	`318`	* ```
`319`	`319`	`*/`
`320`		`-abstract private class PartialDefinitionNode extends PostUpdateNode, TInstructionNode {`
	`320`	`+abstract private class PartialDefinitionNode extends PostUpdateNode {`
`321`	`321`	`abstract Expr getDefinedExpr();`
`322`	`322`	`}`
`323`	`323`
`@@ -332,11 +332,7 @@ private class ExplicitFieldStoreQualifierNode extends PartialDefinitionNode {`
`332`	`332`	`)`
`333`	`333`	`}`
`334`	`334`
`335`		- // There might be multiple `ChiInstructions` that has a particular instruction as
`336`		`- // the total operand - so this definition gives consistency errors in`
`337`		`- // DataFlowImplConsistency::Consistency. However, it's not clear what (if any) implications`
`338`		`- // this consistency failure has.`
`339`		`- override Node getPreUpdateNode() { result.asInstruction() = instr.getTotal() }`
	`335`	`+ override Node getPreUpdateNode() { result.asOperand() = instr.getTotalOperand() }`
`340`	`336`
`341`	`337`	`override Expr getDefinedExpr() {`
`342`	`338`	`result = field.getObjectAddress().getUnconvertedResultExpression()`