Move unwrapIfSingleStmt to the clad::utils namespace

This commit moves the `unwrapIfSingleStmt` function that
was previously defined as a helper function for the reverse
mode differentiation only.

include/clad/Differentiator/CladUtils.h

@@ -27,6 +27,10 @@ namespace clad {
     /// function `FD`.
     std::string ComputeEffectiveFnName(const clang::FunctionDecl* FD);
 
+    // Unwraps S to a single statement if it's a compound statement only
+    // containing 1 statement.
+    clang::Stmt* unwrapIfSingleStmt(clang::Stmt* S);
+
     /// Creates and returns a compound statement having statements as follows:
     /// {`S`, all the statement of `initial` in sequence}
     clang::CompoundStmt* PrependAndCreateCompoundStmt(clang::ASTContext& C,

lib/Differentiator/BaseForwardModeVisitor.cpp

@@ -764,11 +764,7 @@ StmtDiff BaseForwardModeVisitor::VisitForStmt(const ForStmt* FS) {
   StmtDiff bodyVisited = Visit(body);
   for (Stmt* S : bodyVisited.getBothStmts())
     addToCurrentBlock(S);
-  CompoundStmt* bodyResultCmpd = endBlock();
-  if (bodyResultCmpd->size() == 1)
-    bodyResult = bodyResultCmpd->body_front();
-  else
-    bodyResult = bodyResultCmpd;
+  bodyResult = utils::unwrapIfSingleStmt(endBlock());
   endScope();
 
   Stmt* forStmtDiff = new (m_Context)

lib/Differentiator/CladUtils.cpp

@@ -102,6 +102,19 @@ namespace clad {
       }
     }
 
+    Stmt* unwrapIfSingleStmt(Stmt* S) {
+      if (!S)
+        return nullptr;
+      if (!isa<CompoundStmt>(S))
+        return S;
+      auto* CS = cast<CompoundStmt>(S);
+      if (CS->size() == 0)
+        return nullptr;
+      if (CS->size() == 1)
+        return CS->body_front();
+      return CS;
+    }
+
     CompoundStmt* PrependAndCreateCompoundStmt(ASTContext& C, Stmt* initial,
                                                Stmt* S) {
       llvm::SmallVector<Stmt*, 16> block;

lib/Differentiator/ReverseModeVisitor.cpp

@@ -783,19 +783,6 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     return StmtDiff(Forward, Reverse);
   }
 
-  static Stmt* unwrapIfSingleStmt(Stmt* S) {
-    if (!S)
-      return nullptr;
-    if (!isa<CompoundStmt>(S))
-      return S;
-    auto* CS = cast<CompoundStmt>(S);
-    if (CS->size() == 0)
-      return nullptr;
-    if (CS->size() == 1)
-      return CS->body_front();
-    return CS;
-  }
-
   StmtDiff ReverseModeVisitor::VisitIfStmt(const clang::IfStmt* If) {
     // Control scope of the IfStmt. E.g., in if (double x = ...) {...}, x goes
     // to this scope.
@@ -888,8 +875,8 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
         m_ExternalSource
             ->ActBeforeFinalizingVisitBranchSingleStmtInIfVisitStmt();
 
-      Stmt* Forward = unwrapIfSingleStmt(endBlock(direction::forward));
-      Stmt* Reverse = unwrapIfSingleStmt(BranchDiff.getStmt_dx());
+      Stmt* Forward = utils::unwrapIfSingleStmt(endBlock(direction::forward));
+      Stmt* Reverse = utils::unwrapIfSingleStmt(BranchDiff.getStmt_dx());
       return StmtDiff(Forward, Reverse);
     };
 
@@ -914,8 +901,8 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     CompoundStmt* ForwardBlock = endBlock(direction::forward);
     CompoundStmt* ReverseBlock = endBlock(direction::reverse);
     endScope();
-    return StmtDiff(unwrapIfSingleStmt(ForwardBlock),
-                    unwrapIfSingleStmt(ReverseBlock));
+    return StmtDiff(utils::unwrapIfSingleStmt(ForwardBlock),
+                    utils::unwrapIfSingleStmt(ReverseBlock));
   }
 
   StmtDiff ReverseModeVisitor::VisitConditionalOperator(
@@ -941,8 +928,8 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       auto Result = DifferentiateSingleExpr(Branch, dfdx);
       StmtDiff BranchDiff = Result.first;
       StmtDiff ExprDiff = Result.second;
-      Stmt* Forward = unwrapIfSingleStmt(BranchDiff.getStmt());
-      Stmt* Reverse = unwrapIfSingleStmt(BranchDiff.getStmt_dx());
+      Stmt* Forward = utils::unwrapIfSingleStmt(BranchDiff.getStmt());
+      Stmt* Reverse = utils::unwrapIfSingleStmt(BranchDiff.getStmt_dx());
       return {StmtDiff(Forward, Reverse), ExprDiff};
     };
 
@@ -1128,7 +1115,8 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     Reverse = endBlock(direction::reverse);
     endScope();
 
-    return {unwrapIfSingleStmt(Forward), unwrapIfSingleStmt(Reverse)};
+    return {utils::unwrapIfSingleStmt(Forward),
+            utils::unwrapIfSingleStmt(Reverse)};
   }
 
   StmtDiff
@@ -2766,7 +2754,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       addToCurrentBlock(SDiff.getStmt_dx(), direction::reverse);
     CompoundStmt* RCS = endBlock(direction::reverse);
     std::reverse(RCS->body_begin(), RCS->body_end());
-    Stmt* ReverseResult = unwrapIfSingleStmt(RCS);
+    Stmt* ReverseResult = utils::unwrapIfSingleStmt(RCS);
     return StmtDiff(SDiff.getStmt(), ReverseResult);
   }
 
@@ -2780,7 +2768,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     CompoundStmt* RCS = endBlock(direction::reverse);
     Stmt* ForwardResult = endBlock(direction::forward);
     std::reverse(RCS->body_begin(), RCS->body_end());
-    Stmt* ReverseResult = unwrapIfSingleStmt(RCS);
+    Stmt* ReverseResult = utils::unwrapIfSingleStmt(RCS);
     return {StmtDiff(ForwardResult, ReverseResult), EDiff};
   }
 
@@ -2929,7 +2917,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       for (Decl* decl : decls)
         addToBlock(BuildDeclStmt(decl), m_Globals);
       Stmt* initAssignments = MakeCompoundStmt(inits);
-      initAssignments = unwrapIfSingleStmt(initAssignments);
+      initAssignments = utils::unwrapIfSingleStmt(initAssignments);
       return StmtDiff(initAssignments);
     }
 
@@ -3574,7 +3562,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       if (m_ExternalSource)
         m_ExternalSource->ActAfterProcessingSingleStmtBodyInVisitForLoop();
 
-      Stmt* reverseBlock = unwrapIfSingleStmt(bodyDiff.getStmt_dx());
+      Stmt* reverseBlock = utils::unwrapIfSingleStmt(bodyDiff.getStmt_dx());
       bodyDiff = {endBlock(direction::forward), reverseBlock};
       // for forward-pass loop statement body
       endScope();
@@ -3619,7 +3607,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     addToCurrentBlock(condVarDiff, direction::reverse);
     addToCurrentBlock(bodyDiff.getStmt_dx(), direction::reverse);
     bodyDiff = {bodyDiff.getStmt(),
-                unwrapIfSingleStmt(endBlock(direction::reverse))};
+                utils::unwrapIfSingleStmt(endBlock(direction::reverse))};
     return bodyDiff;
   }