Merge pull request #15021 from jketema/ir-guards-unreached-fix

C++: Fix handling of unreached instructions in IRGuards

Author: jketema

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
   }
 }
 

cpp/ql/test/library-tests/controlflow/guards-ir/test.c

@@ -174,3 +174,13 @@ int ternary_test(const char *path, int mode)
 {
     return (foo(path, mode) == 0 ? 1 : 0);
 }
+
+void abort(void);
+
+int abort_test(int x) {
+    if (x) {
+        x += 1;
+    } else {
+        abort();
+    }
+}

cpp/ql/test/library-tests/controlflow/guards-ir/tests.expected

@@ -35,6 +35,7 @@ astGuards
 | test.c:162:9:162:18 | ... < ... |
 | test.c:165:9:165:18 | ... < ... |
 | test.c:175:13:175:32 | ... == ... |
+| test.c:181:9:181:9 | x |
 | test.cpp:18:8:18:10 | call to get |
 | test.cpp:31:7:31:13 | ... == ... |
 | test.cpp:42:13:42:20 | call to getABool |
@@ -255,6 +256,9 @@ astGuardsControl
 | test.c:165:9:165:18 | ... < ... | true | 165 | 166 |
 | 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 | 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 |
 | test.cpp:31:7:31:13 | ... == ... | false | 30 | 30 |
 | test.cpp:31:7:31:13 | ... == ... | false | 34 | 34 |
@@ -470,6 +474,7 @@ irGuards
 | test.c:162:9:162:18 | CompareLT: ... < ... |
 | test.c:165:9:165:18 | CompareLT: ... < ... |
 | test.c:175:13:175:32 | CompareEQ: ... == ... |
+| test.c:181:9:181:9 | Load: x |
 | test.cpp:18:8:18:12 | CompareNE: (bool)... |
 | test.cpp:31:7:31:13 | CompareEQ: ... == ... |
 | test.cpp:42:13:42:20 | Call: call to getABool |
@@ -667,6 +672,8 @@ irGuardsControl
 | test.c:165:9:165:18 | CompareLT: ... < ... | true | 165 | 166 |
 | test.c:175:13:175:32 | CompareEQ: ... == ... | false | 175 | 175 |
 | test.c:175:13:175:32 | CompareEQ: ... == ... | true | 175 | 175 |
+| test.c:181:9:181:9 | Load: x | false | 184 | 184 |
+| test.c:181:9:181:9 | Load: x | true | 182 | 182 |
 | test.cpp:18:8:18:12 | CompareNE: (bool)... | true | 19 | 19 |
 | test.cpp:31:7:31:13 | CompareEQ: ... == ... | false | 34 | 34 |
 | test.cpp:31:7:31:13 | CompareEQ: ... == ... | true | 30 | 30 |