From 89e3fdea7da028243eef4b198e762acfb5be165f Mon Sep 17 00:00:00 2001
From: Vaibhav Thakkar <vaibhav.thakkar.22.12.99@gmail.com>
Date: Mon, 26 Feb 2024 12:41:46 +0100
Subject: [PATCH] Fix builtin macros and zero init for memory operations

---
 lib/Differentiator/CladUtils.cpp          | 30 ++++++++++++++++++++---
 lib/Differentiator/ReverseModeVisitor.cpp | 17 ++++++++++---
 test/Gradient/Pointers.C                  |  4 +--
 3 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/lib/Differentiator/CladUtils.cpp b/lib/Differentiator/CladUtils.cpp
index 3d1a872c9..51b8d44d4 100644
--- a/lib/Differentiator/CladUtils.cpp
+++ b/lib/Differentiator/CladUtils.cpp
@@ -6,6 +6,7 @@
 #include "clang/AST/Decl.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/Basic/Builtins.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Sema/Lookup.h"
 #include "llvm/ADT/SmallVector.h"
@@ -400,6 +401,13 @@ namespace clad {
       auto& C = semaRef.getASTContext();
       if (!TSI)
         TSI = C.getTrivialTypeSourceInfo(qType);
+      bool implicitInit = false;
+      if (initializer && isa<ImplicitValueInitExpr>(initializer))
+        // If the initializer is an implicit value init expression, then
+        // we don't need to pass it explicitly to the CXXNewExpr. As, clang
+        // internally adds it when initializer is nullptr and DirectInitRange
+        // is valid.
+        implicitInit = true;
       auto newExpr =
           semaRef
               .BuildCXXNew(
@@ -407,7 +415,7 @@ namespace clad {
                   SourceRange(), qType, TSI,
                   (arraySize ? arraySize : clad_compat::ArraySize_None()),
                   initializer ? GetValidSRange(semaRef) : SourceRange(),
-                  initializer)
+                  implicitInit ? nullptr : initializer)
               .getAs<CXXNewExpr>();
       return newExpr;
     }
@@ -643,17 +651,31 @@ namespace clad {
     }
 
     bool IsMemoryAllocationFunction(const clang::FunctionDecl* FD) {
+
+#if CLANG_VERSION_MAJOR > 12
       if (FD->getBuiltinID() == Builtin::BImalloc)
         return true;
-      if (FD->getBuiltinID() == Builtin::BIcalloc)
+      if (FD->getBuiltinID() == Builtin::ID::BIcalloc)
+        return true;
+      if (FD->getBuiltinID() == Builtin::ID::BIrealloc)
+        return true;
+#else
+      if (FD->getNameAsString() == "malloc")
         return true;
-      if (FD->getBuiltinID() == Builtin::BIrealloc)
+      if (FD->getNameAsString() == "calloc")
         return true;
+      if (FD->getNameAsString() == "realloc")
+        return true;
+#endif
       return false;
     }
 
     bool IsMemoryDeallocationFunction(const clang::FunctionDecl* FD) {
-      return FD->getBuiltinID() == Builtin::BIfree;
+#if CLANG_VERSION_MAJOR > 12
+      return FD->getBuiltinID() == Builtin::ID::BIfree;
+#else
+      return FD->getNameAsString() == "free";
+#endif
     }
   } // namespace utils
 } // namespace clad
diff --git a/lib/Differentiator/ReverseModeVisitor.cpp b/lib/Differentiator/ReverseModeVisitor.cpp
index c0acb6f0f..360e5b24b 100644
--- a/lib/Differentiator/ReverseModeVisitor.cpp
+++ b/lib/Differentiator/ReverseModeVisitor.cpp
@@ -2649,8 +2649,7 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     bool isPointerType = VD->getType()->isPointerType();
     bool isInitializedByNewExpr = false;
     // Check if the variable is pointer type and initialized by new expression
-    if (isPointerType && (VD->getInit() != nullptr) &&
-        isa<CXXNewExpr>(VD->getInit()))
+    if (isPointerType && VD->getInit() && isa<CXXNewExpr>(VD->getInit()))
       isInitializedByNewExpr = true;
 
     // VDDerivedInit now serves two purposes -- as the initial derivative value
@@ -3824,9 +3823,19 @@ Expr* getArraySizeExpr(const ArrayType* AT, ASTContext& context,
     Expr* clonedNewE = utils::BuildCXXNewExpr(
         m_Sema, CNE->getAllocatedType(), clonedArraySizeE,
         initializerDiff.getExpr(), CNE->getAllocatedTypeSourceInfo());
+    Expr* diffInit = initializerDiff.getExpr_dx();
+    if (!diffInit) {
+      // we should initialize it implicitly using ImplicitValueInitExpr
+      QualType type = CNE->getAllocatedType();
+      if (CNE->isArray()) {
+        type = m_Context.getVariableArrayType(
+            type, derivedArraySizeE, ArrayType::Normal, 0, SourceRange());
+      }
+      diffInit = new (m_Context) ImplicitValueInitExpr(type);
+    }
     Expr* derivedNewE = utils::BuildCXXNewExpr(
-        m_Sema, CNE->getAllocatedType(), derivedArraySizeE,
-        initializerDiff.getExpr_dx(), CNE->getAllocatedTypeSourceInfo());
+        m_Sema, CNE->getAllocatedType(), derivedArraySizeE, diffInit,
+        CNE->getAllocatedTypeSourceInfo());
     return {clonedNewE, derivedNewE};
   }
 
diff --git a/test/Gradient/Pointers.C b/test/Gradient/Pointers.C
index c216aba6e..049b18769 100644
--- a/test/Gradient/Pointers.C
+++ b/test/Gradient/Pointers.C
@@ -363,7 +363,7 @@ double newAndDeletePointer(double i, double j) {
 // CHECK-NEXT:     double *p = new double(i);
 // CHECK-NEXT:     _d_q = new double(* _d_j);
 // CHECK-NEXT:     double *q = new double(j);
-// CHECK-NEXT:     _d_r = new double [2];
+// CHECK-NEXT:     _d_r = new double [2](/*implicit*/(double[2])0);
 // CHECK-NEXT:     double *r = new double [2];
 // CHECK-NEXT:     _t0 = r[0];
 // CHECK-NEXT:     r[0] = i + j;
@@ -418,7 +418,7 @@ double structPointer (double x) {
 // CHECK: void structPointer_grad(double x, clad::array_ref<double> _d_x) {
 // CHECK-NEXT:     T *_d_t = 0;
 // CHECK-NEXT:     double _d_res = 0;
-// CHECK-NEXT:     _d_t = new T;
+// CHECK-NEXT:     _d_t = new T();
 // CHECK-NEXT:     T *t = new T({x, /*implicit*/(int)0});
 // CHECK-NEXT:     double res = t->x;
 // CHECK-NEXT:     goto _label0;