[PATCH] D137082: [clang][Interp] Fix dereferencing arrays with no offset applied

[Timm Bäder via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGad2fb01cb68d: [clang][Interp] Fix dereferencing arrays with no offset applied (authored by tbaeder).

Changed prior to commit:
  https://reviews.llvm.org/D137082?vs=472887&id=492041#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137082/new/

https://reviews.llvm.org/D137082

Files:
  clang/lib/AST/Interp/Pointer.h
  clang/test/AST/Interp/arrays.cpp


Index: clang/test/AST/Interp/arrays.cpp
===================================================================
--- clang/test/AST/Interp/arrays.cpp
+++ clang/test/AST/Interp/arrays.cpp
@@ -42,6 +42,21 @@
   return *(Arr + index);
 }
 
+constexpr int derefPtr(const int *d) {
+  return *d;
+}
+static_assert(derefPtr(data) == 5, "");
+
+constexpr int storePtr() {
+  int b[] = {1,2,3,4};
+  int *c = b;
+
+  *c = 4;
+  return *c;
+}
+static_assert(storePtr() == 4, "");
+
+
 static_assert(getElement(data, 1) == 4, "");
 static_assert(getElement(data, 4) == 1, "");
 
Index: clang/lib/AST/Interp/Pointer.h
===================================================================
--- clang/lib/AST/Interp/Pointer.h
+++ clang/lib/AST/Interp/Pointer.h
@@ -225,6 +225,10 @@
     return Offset - Base - Adjust;
   }
 
+  /// Whether this array refers to an array, but not
+  /// to the first element.
+  bool isArrayRoot() const { return inArray() && Offset == Base; }
+
   /// Checks if the innermost field is an array.
   bool inArray() const { return getFieldDesc()->IsArray; }
   /// Checks if the structure is a primitive array.
@@ -306,6 +310,10 @@
   /// Dereferences the pointer, if it's live.
   template <typename T> T &deref() const {
     assert(isLive() && "Invalid pointer");
+    if (isArrayRoot())
+      return *reinterpret_cast<T *>(Pointee->rawData() + Base +
+                                    sizeof(InitMap *));
+
     return *reinterpret_cast<T *>(Pointee->rawData() + Offset);
   }
 


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