Remove unnecessary DeclRefExpr from for loop condition.

vgvassilev · Nov 24, 2023 · 628f71e · 628f71e
1 parent 3a1dad0
commit 628f71e
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Showing 2 changed files with 8 additions and 2 deletions.
diff --git a/lib/Differentiator/ReverseModeVisitor.cpp b/lib/Differentiator/ReverseModeVisitor.cpp
@@ -1124,8 +1124,14 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     /// This is a temporary measure to avoid the bug that arises from overwriting
     /// local variables on different loop passes.
     Expr* forwardCond = cond.getExpr();
+    /// If there is a declaration in the condition, `cond` will be
+    /// a DeclRefExpr of the declared variable. There is no point in
+    /// inserting it since condVarRes.getExpr() represents an assignment with
+    /// that variable on the LHS.
+    /// e.g. for condition `int x = y`,
+    /// condVarRes.getExpr() will represent `x = y`
     if (condVarRes.getExpr() != nullptr && isa<Expr>(condVarRes.getExpr())) {
-      forwardCond = BuildOp(BO_Comma, cond.getExpr(), cast<Expr>(condVarRes.getExpr()));
+      forwardCond = cast<Expr>(condVarRes.getExpr());
     }
 
     Stmt* Forward = new (m_Context) ForStmt(m_Context,

diff --git a/test/Gradient/Loops.C b/test/Gradient/Loops.C
@@ -958,7 +958,7 @@ double fn13(double i, double j) {
 // CHECK-NEXT:     double res = 0;
 // CHECK-NEXT:     int counter = 3;
 // CHECK-NEXT:     _t0 = 0;
-// CHECK-NEXT:     for (; k , clad::push(_t1, k) , k = counter; clad::push(_t2, counter) , (counter -= 1)) {
+// CHECK-NEXT:     for (; clad::push(_t1, k) , k = counter; clad::push(_t2, counter) , (counter -= 1)) {
 // CHECK-NEXT:         _t0++;
 // CHECK-NEXT:         clad::push(_t3, k);
 // CHECK-NEXT:         k += i + 2 * clad::push(_t4, j);