C#: Disjunctive barrier guards for free

Author: hvitved

csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll

@@ -1114,6 +1114,18 @@ private module DataFlowIntegrationInput implements Impl::DataFlowIntegrationInpu
     }
   }
 
+  class AndGuard extends Guard instanceof LogicalAndExpr {
+    Guard getLeftOperand() { result = LogicalAndExpr.super.getLeftOperand() }
+
+    Guard getRightOperand() { result = LogicalAndExpr.super.getRightOperand() }
+  }
+
+  class OrGuard extends Guard instanceof LogicalOrExpr {
+    Guard getLeftOperand() { result = LogicalOrExpr.super.getLeftOperand() }
+
+    Guard getRightOperand() { result = LogicalOrExpr.super.getRightOperand() }
+  }
+
   /** Holds if the guard `guard` controls block `bb` upon evaluating to `branch`. */
   predicate guardControlsBlock(Guard guard, ControlFlow::BasicBlock bb, boolean branch) {
     exists(ConditionBlock conditionBlock, ControlFlow::SuccessorTypes::ConditionalSuccessor s |

csharp/ql/test/library-tests/dataflow/barrier-guards/barrier-flow.expected

@@ -8,7 +8,6 @@ edges
 | BarrierFlow.cs:86:13:86:13 | access to local variable x : Object | BarrierFlow.cs:103:18:103:18 | access to local variable x | provenance |  |
 | BarrierFlow.cs:86:13:86:13 | access to local variable x : Object | BarrierFlow.cs:112:18:112:18 | access to local variable x | provenance |  |
 | BarrierFlow.cs:86:13:86:13 | access to local variable x : Object | BarrierFlow.cs:117:18:117:18 | access to local variable x | provenance |  |
-| BarrierFlow.cs:86:13:86:13 | access to local variable x : Object | BarrierFlow.cs:121:18:121:18 | access to local variable x | provenance |  |
 | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | BarrierFlow.cs:86:13:86:13 | access to local variable x : Object | provenance |  |
 | BarrierFlow.cs:127:13:127:13 | access to local variable x : Object | BarrierFlow.cs:135:18:135:18 | access to local variable x | provenance |  |
 | BarrierFlow.cs:127:13:127:13 | access to local variable x : Object | BarrierFlow.cs:140:18:140:18 | access to local variable x | provenance |  |
@@ -28,7 +27,6 @@ nodes
 | BarrierFlow.cs:103:18:103:18 | access to local variable x | semmle.label | access to local variable x |
 | BarrierFlow.cs:112:18:112:18 | access to local variable x | semmle.label | access to local variable x |
 | BarrierFlow.cs:117:18:117:18 | access to local variable x | semmle.label | access to local variable x |
-| BarrierFlow.cs:121:18:121:18 | access to local variable x | semmle.label | access to local variable x |
 | BarrierFlow.cs:127:13:127:13 | access to local variable x : Object | semmle.label | access to local variable x : Object |
 | BarrierFlow.cs:127:17:127:25 | call to method Source : Object | semmle.label | call to method Source : Object |
 | BarrierFlow.cs:135:18:135:18 | access to local variable x | semmle.label | access to local variable x |
@@ -37,15 +35,13 @@ nodes
 | BarrierFlow.cs:158:18:158:18 | access to local variable x | semmle.label | access to local variable x |
 subpaths
 testFailures
-| BarrierFlow.cs:121:18:121:18 | access to local variable x | Unexpected result: hasValueFlow=7 |
 #select
 | BarrierFlow.cs:12:14:12:14 | access to local variable x | BarrierFlow.cs:10:17:10:25 | call to method Source : Object | BarrierFlow.cs:12:14:12:14 | access to local variable x | $@ | BarrierFlow.cs:10:17:10:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:21:18:21:18 | access to local variable x | BarrierFlow.cs:17:17:17:25 | call to method Source : Object | BarrierFlow.cs:21:18:21:18 | access to local variable x | $@ | BarrierFlow.cs:17:17:17:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:94:18:94:18 | access to local variable x | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | BarrierFlow.cs:94:18:94:18 | access to local variable x | $@ | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:103:18:103:18 | access to local variable x | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | BarrierFlow.cs:103:18:103:18 | access to local variable x | $@ | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:112:18:112:18 | access to local variable x | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | BarrierFlow.cs:112:18:112:18 | access to local variable x | $@ | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:117:18:117:18 | access to local variable x | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | BarrierFlow.cs:117:18:117:18 | access to local variable x | $@ | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | call to method Source : Object |
-| BarrierFlow.cs:121:18:121:18 | access to local variable x | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | BarrierFlow.cs:121:18:121:18 | access to local variable x | $@ | BarrierFlow.cs:86:17:86:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:135:18:135:18 | access to local variable x | BarrierFlow.cs:127:17:127:25 | call to method Source : Object | BarrierFlow.cs:135:18:135:18 | access to local variable x | $@ | BarrierFlow.cs:127:17:127:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:140:18:140:18 | access to local variable x | BarrierFlow.cs:127:17:127:25 | call to method Source : Object | BarrierFlow.cs:140:18:140:18 | access to local variable x | $@ | BarrierFlow.cs:127:17:127:25 | call to method Source : Object | call to method Source : Object |
 | BarrierFlow.cs:149:18:149:18 | access to local variable x | BarrierFlow.cs:127:17:127:25 | call to method Source : Object | BarrierFlow.cs:149:18:149:18 | access to local variable x | $@ | BarrierFlow.cs:127:17:127:25 | call to method Source : Object | call to method Source : Object |