address comments related to const pointers

vgvassilev · Dec 22, 2023 · 3028b7c · 3028b7c
1 parent a2c1a70
commit 3028b7c
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Showing 2 changed files with 30 additions and 23 deletions.
diff --git a/lib/Differentiator/ReverseModeVisitor.cpp b/lib/Differentiator/ReverseModeVisitor.cpp
@@ -2125,7 +2125,9 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       return {cloneE, derivedE};
     } else {
       if (opCode != UO_LNot)
-        // We should not output any warning on visiting boolean conditions
+        // We should only output warnings on visiting boolean conditions
+        // when it is related to some indepdendent variable and causes
+        // discontinuity in the function space.
         // FIXME: We should support boolean differentiation or ignore it
         // completely
         unsupportedOpWarn(UnOp->getEndLoc());
@@ -2329,7 +2331,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       utils::GetInnermostReturnExpr(Ldiff.getExpr(), ExprsToStore);
 
       // We need to store values of derivative pointer variables in forward pass
-      // and restore them in reverese pass.
+      // and restore them in reverse pass.
       if (isPointerOp) {
         Expr* Edx = Ldiff.getExpr_dx();
         ExprsToStore.push_back(Edx);
@@ -2595,8 +2597,17 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
       // expression of the corresponding pointer type.
       else if (isPointerType && VD->getInit()) {
         initDiff = Visit(VD->getInit());
-        if (initDiff.getExpr_dx())
-          VDDerivedInit = initDiff.getExpr_dx();
+        VDDerivedType = getNonConstType(VDDerivedType, m_Context, m_Sema);
+        // If it's a pointer to a constant type, then remove the constness.
+        if (VD->getType()->getPointeeType().isConstQualified()) {
+          // first extract the pointee type
+          auto pointeeType = VD->getType()->getPointeeType();
+          // then remove the constness
+          pointeeType.removeLocalConst();
+          // then create a new pointer type with the new pointee type
+          VDDerivedType = m_Context.getPointerType(pointeeType);
+        }
+        VDDerivedInit = getZeroInit(VDDerivedType);
       }
       // Here separate behaviour for record and non-record types is only
       // necessary to preserve the old tests.
@@ -2681,6 +2692,11 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
         derivedVDE = BuildOp(UnaryOperatorKind::UO_Deref, derivedVDE);
       }
     }
+    if (isPointerType) {
+      Expr* assignDerivativeE = BuildOp(BinaryOperatorKind::BO_Assign,
+                                        derivedVDE, initDiff.getExpr_dx());
+      addToCurrentBlock(assignDerivativeE, direction::forward);
+    }
     m_Variables.emplace(VDClone, derivedVDE);
 
     return VarDeclDiff(VDClone, VDDerived);

diff --git a/test/Gradient/Pointers.C b/test/Gradient/Pointers.C
@@ -21,44 +21,34 @@ double nonMemFn(double i) {
 // CHECK-NEXT: }
 
 double minimalPointer(double x) {
-  double *p;
-  p = &x;
+  double* const p = &x;
   *p = (*p)*(*p);
   return *p; // x*x
 }
 
 // CHECK: void minimalPointer_grad(double x, clad::array_ref<double> _d_x) {
 // CHECK-NEXT:     double *_d_p = 0;
-// CHECK-NEXT:     double *_t0;
-// CHECK-NEXT:     double *_t1;
-// CHECK-NEXT:     double _t2;
-// CHECK-NEXT:     double *p;
-// CHECK-NEXT:     _t0 = p;
-// CHECK-NEXT:     _t1 = _d_p;
+// CHECK-NEXT:     double _t0;
 // CHECK-NEXT:     _d_p = &* _d_x;
-// CHECK-NEXT:     p = &x;
-// CHECK-NEXT:     _t2 = *p;
+// CHECK-NEXT:     double *const p = &x;
+// CHECK-NEXT:     _t0 = *p;
 // CHECK-NEXT:     *p = *p * (*p);
 // CHECK-NEXT:     goto _label0;
 // CHECK-NEXT:   _label0:
 // CHECK-NEXT:     *_d_p += 1;
 // CHECK-NEXT:     {
-// CHECK-NEXT:         *p = _t2;
+// CHECK-NEXT:         *p = _t0;
 // CHECK-NEXT:         double _r_d0 = *_d_p;
 // CHECK-NEXT:         double _r0 = _r_d0 * (*p);
 // CHECK-NEXT:         *_d_p += _r0;
 // CHECK-NEXT:         double _r1 = *p * _r_d0;
 // CHECK-NEXT:         *_d_p += _r1;
 // CHECK-NEXT:         *_d_p -= _r_d0;
 // CHECK-NEXT:     }
-// CHECK-NEXT:     {
-// CHECK-NEXT:         p = _t0;
-// CHECK-NEXT:         _d_p = _t1;
-// CHECK-NEXT:     }
 // CHECK-NEXT: }
 
-double arrayPointer(double* arr) {
-  double *p = arr;
+double arrayPointer(const double* arr) {
+  const double *p = arr;
   p = p + 1;
   double sum = *p;
   p++;
@@ -73,8 +63,8 @@ double arrayPointer(double* arr) {
   return sum; // 5*arr[0] + arr[1] + 2*arr[2] + 4*arr[3] + 3*arr[4]
 }
 
-// CHECK: void arrayPointer_grad(double *arr, clad::array_ref<double> _d_arr) {
-// CHECK-NEXT:    double *_d_p = _d_arr;
+// CHECK: void arrayPointer_grad(const double *arr, clad::array_ref<double> _d_arr) {
+// CHECK-NEXT:    double *_d_p = 0;
 // CHECK-NEXT:    double *_t0;
 // CHECK-NEXT:    double *_t1;
 // CHECK-NEXT:    double _d_sum = 0;
@@ -88,6 +78,7 @@ double arrayPointer(double* arr) {
 // CHECK-NEXT:    double *_t9;
 // CHECK-NEXT:    double *_t10;
 // CHECK-NEXT:    double _t11;
+// CHECK-NEXT:    _d_p = _d_arr;
 // CHECK-NEXT:    double *p = arr;
 // CHECK-NEXT:    _t0 = p;
 // CHECK-NEXT:    _t1 = _d_p;