C++: Avoid generating IR for a few cases where we will be synthesizing assertions.

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/TranslatedStmt.qll

@@ -10,6 +10,7 @@ private import TranslatedElement
 private import TranslatedExpr
 private import TranslatedFunction
 private import TranslatedInitialization
+private import TranslatedAssertion
 
 TranslatedStmt getTranslatedStmt(Stmt stmt) { result.getAst() = stmt }
 
@@ -324,8 +325,16 @@ abstract class TranslatedStmt extends TranslatedElement, TTranslatedStmt {
 
 class TranslatedEmptyStmt extends TranslatedStmt {
   TranslatedEmptyStmt() {
-    stmt instanceof EmptyStmt or
-    stmt instanceof LabelStmt or
+    // An assertion macro invocation can expand to
+    // an empty statement in release builds. In that case
+    // we synthedsize the check that would have occured.
+    // This is handled by `TranslatedAssertion.qll` and so
+    // we exclude these statements here.
+    not assertion(_, stmt) and
+    stmt instanceof EmptyStmt
+    or
+    stmt instanceof LabelStmt
+    or
     stmt instanceof SwitchCase
   }
 
@@ -420,6 +429,15 @@ class TranslatedDeclStmt extends TranslatedStmt {
 class TranslatedExprStmt extends TranslatedStmt {
   override ExprStmt stmt;
 
+  TranslatedExprStmt() {
+    // An assertion macro invocation typically expand to the
+    // expression `((void)0)` in release builds. In that case
+    // we synthedsize the check that would have occured.
+    // This is handled by `TranslatedAssertion.qll` and so
+    // we exclude these statements here.
+    not assertion(_, stmt)
+  }
+
   TranslatedExpr getExpr() { result = getTranslatedExpr(stmt.getExpr().getFullyConverted()) }
 
   override TranslatedElement getChildInternal(int id) { id = 0 and result = this.getExpr() }