C++: add CopyValueInstruction for StmtExpr result

Author: Robert Marsh

cpp/ql/src/semmle/code/cpp/ir/implementation/raw/internal/TranslatedExpr.qll

@@ -2746,20 +2746,32 @@ class TranslatedStmtExpr extends TranslatedNonConstantExpr {
   }
 
   override Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) {
-    none()
+    tag instanceof OnlyInstructionTag and
+    kind instanceof GotoEdge and
+    result = getParent().getChildSuccessor(this)
   }
 
   override Instruction getChildSuccessor(TranslatedElement child) {
     child = getStmt() and
-    result = getParent().getChildSuccessor(this)
+    result = getInstruction(OnlyInstructionTag())
   }
 
   override predicate hasInstruction(Opcode opcode, InstructionTag tag, Type resultType,
         boolean isGLValue) {
-    none()
+    opcode instanceof Opcode::CopyValue and
+    tag instanceof OnlyInstructionTag and
+    resultType = expr.getType() and
+    isGLValue = false
   }
 
   override Instruction getResult() {
+    result = getInstruction(OnlyInstructionTag())
+  }
+  
+  override Instruction getInstructionOperand(InstructionTag tag,
+      OperandTag operandTag) {
+    tag instanceof OnlyInstructionTag and
+    operandTag instanceof UnaryOperandTag and
     result = getTranslatedExpr(expr.getResultExpr().getFullyConverted()).getResult()
   }
 

cpp/ql/test/library-tests/dataflow/dataflow-tests/test_diff.expected

@@ -16,8 +16,6 @@
 | test.cpp:477:20:477:24 | test.cpp:478:8:478:12 | AST only |
 | test.cpp:484:18:484:23 | test.cpp:485:8:485:12 | AST only |
 | test.cpp:490:18:490:22 | test.cpp:491:8:491:12 | AST only |
-| test.cpp:497:26:497:32 | test.cpp:498:9:498:22 | AST only |
-| test.cpp:497:26:497:32 | test.cpp:509:8:509:12 | AST only |
 | true_upon_entry.cpp:9:11:9:16 | true_upon_entry.cpp:13:8:13:8 | IR only |
 | true_upon_entry.cpp:62:11:62:16 | true_upon_entry.cpp:66:8:66:8 | IR only |
 | true_upon_entry.cpp:98:11:98:16 | true_upon_entry.cpp:105:8:105:8 | IR only |

cpp/ql/test/library-tests/dataflow/dataflow-tests/test_ir.expected

@@ -27,6 +27,8 @@
 | test.cpp:314:12:314:12 | Load: x | test.cpp:313:22:313:27 | Call: call to source |
 | test.cpp:337:14:337:14 | Load: x | test.cpp:353:17:353:22 | Call: call to source |
 | test.cpp:366:7:366:7 | Load: x | test.cpp:362:4:362:9 | Call: call to source |
+| test.cpp:498:9:498:22 | CopyValue: (statement expression) | test.cpp:497:26:497:32 | InitializeParameter: source1 |
+| test.cpp:509:8:509:12 | Load: local | test.cpp:497:26:497:32 | InitializeParameter: source1 |
 | true_upon_entry.cpp:13:8:13:8 | Load: x | true_upon_entry.cpp:9:11:9:16 | Call: call to source |
 | true_upon_entry.cpp:21:8:21:8 | Load: x | true_upon_entry.cpp:17:11:17:16 | Call: call to source |
 | true_upon_entry.cpp:29:8:29:8 | Load: x | true_upon_entry.cpp:27:9:27:14 | Call: call to source |

cpp/ql/test/library-tests/ir/ir/raw_ir.expected

@@ -4406,15 +4406,17 @@ ir.cpp:
 #  999|   Block 3
 #  999|     r3_0(glval<int>) = VariableAddress[w]       : 
 #  999|     r3_1(int)        = Load                     : r3_0, mu0_2
-#  992|     mu3_2(int)       = Store                    : r0_9, r3_1
-# 1002|     r3_3(glval<int>) = VariableAddress[#return] : 
-# 1002|     r3_4(glval<int>) = VariableAddress[x]       : 
-# 1002|     r3_5(int)        = Load                     : r3_4, mu0_2
-# 1002|     mu3_6(int)       = Store                    : r3_3, r3_5
-#  991|     r3_7(glval<int>) = VariableAddress[#return] : 
-#  991|     v3_8(void)       = ReturnValue              : r3_7, mu0_2
-#  991|     v3_9(void)       = UnmodeledUse             : mu*
-#  991|     v3_10(void)      = ExitFunction             : 
+#  992|     r3_2(int)        = CopyValue                : r3_1
+#  992|     mu3_3(int)       = Store                    : r0_9, r3_2
+# 1002|     r3_4(glval<int>) = VariableAddress[#return] : 
+# 1002|     r3_5(glval<int>) = VariableAddress[x]       : 
+# 1002|     r3_6(int)        = Load                     : r3_5, mu0_2
+# 1002|     r3_7(int)        = CopyValue                : r3_6
+# 1002|     mu3_8(int)       = Store                    : r3_4, r3_7
+#  991|     r3_9(glval<int>) = VariableAddress[#return] : 
+#  991|     v3_10(void)      = ReturnValue              : r3_9, mu0_2
+#  991|     v3_11(void)      = UnmodeledUse             : mu*
+#  991|     v3_12(void)      = ExitFunction             : 
 
 # 1025| void EmptyStructInit()
 # 1025|   Block 0