Merge pull request #984 from rdmarsh2/rdmarsh/cpp/ir-stmtexpr

C++: add support for GNU StmtExpr in IR

Author: rdmarsh2

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

@@ -8,6 +8,8 @@ private import TranslatedDeclarationEntry
 private import TranslatedElement
 private import TranslatedFunction
 private import TranslatedInitialization
+private import TranslatedFunction
+private import TranslatedStmt
 import TranslatedCall
 
 /**
@@ -2727,3 +2729,53 @@ class TranslatedLambdaExpr extends TranslatedNonConstantExpr, InitializationCont
     result = getTranslatedInitialization(expr.getChild(0).getFullyConverted())
   }
 }
+
+/**
+ * The IR translation of `StmtExpr` (the GNU statement expression extension to C/C++), such as
+ * ``` ({ doSomething(); a + b; })```
+ */
+class TranslatedStmtExpr extends TranslatedNonConstantExpr {
+  override StmtExpr expr;
+  
+  override final Instruction getFirstInstruction() {
+    result = getStmt().getFirstInstruction()
+  }
+  
+  override final TranslatedElement getChild(int id) {
+    id = 0 and result = getStmt()
+  }
+  
+  override Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) {
+    tag instanceof OnlyInstructionTag and
+    kind instanceof GotoEdge and
+    result = getParent().getChildSuccessor(this)
+  }
+  
+  override Instruction getChildSuccessor(TranslatedElement child) {
+    child = getStmt() and
+    result = getInstruction(OnlyInstructionTag())
+  }
+  
+  override predicate hasInstruction(Opcode opcode, InstructionTag tag, Type resultType,
+        boolean isGLValue) {
+    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()
+  }
+  
+  TranslatedStmt getStmt() {
+    result = getTranslatedStmt(expr.getStmt())
+  }
+}

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

@@ -23,8 +23,6 @@
 | test.cpp:484:18:484:23 | test.cpp:485:8:485:12 | AST only |
 | test.cpp:489:7:489:11 | test.cpp:491:8:491:12 | 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 |