C++: Fix handling of unreached instructions in IRGuards

jketema · jketema · commit 4390e4cad389 · 2023-12-06T10:23:27.000+01:00
diff --git a/cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll b/cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll
@@ -223,6 +223,9 @@ private class GuardConditionFromIR extends GuardCondition {
       or
       instr = tce.getInstruction(ConditionValueFalseTempAddressTag())
     )
+    or
+    // Exclude unreached instructions, as their AST is the whole function and not a block.
+    instr instanceof UnreachedInstruction
   }
 }
 
diff --git a/cpp/ql/test/library-tests/controlflow/guards-ir/tests.expected b/cpp/ql/test/library-tests/controlflow/guards-ir/tests.expected
@@ -257,7 +257,6 @@ astGuardsControl
 | test.c:175:13:175:32 | ... == ... | false | 175 | 175 |
 | test.c:175:13:175:32 | ... == ... | true | 175 | 175 |
 | test.c:181:9:181:9 | x | false | 183 | 184 |
-| test.c:181:9:181:9 | x | false | 186 | 180 |
 | test.c:181:9:181:9 | x | true | 181 | 182 |
 | test.c:181:9:181:9 | x | true | 186 | 180 |
 | test.cpp:18:8:18:10 | call to get | true | 19 | 19 |

Original file line number	Diff line number	Diff line change
`@@ -223,6 +223,9 @@ private class GuardConditionFromIR extends GuardCondition {`
`223`	`223`	`or`
`224`	`224`	`instr = tce.getInstruction(ConditionValueFalseTempAddressTag())`
`225`	`225`	`)`
	`226`	`+ or`
	`227`	`+ // Exclude unreached instructions, as their AST is the whole function and not a block.`
	`228`	`+ instr instanceof UnreachedInstruction`
`226`	`229`	`}`
`227`	`230`	`}`
`228`	`231`