[Lldb-commits] [lldb] [lldb] Add pointer arithmetics for addition and subtraction to DIL (PR #184652)

[Michael Buch via lldb-commits]

================
@@ -602,6 +642,62 @@ llvm::Expected<lldb::ValueObjectSP> Interpreter::EvaluateBinarySubtraction(
   if (result_type.IsScalarType())
     return EvaluateScalarOp(BinaryOpKind::Sub, lhs, rhs, result_type, location);
 
+  auto lhs_type = lhs->GetCompilerType();
+  auto rhs_type = rhs->GetCompilerType();
+
+  // "pointer - integer" operation.
+  if (lhs_type.IsPointerType() && rhs_type.IsInteger())
+    return PointerAdd(lhs, -rhs->GetValueAsUnsigned(0), location);
+
+  // "pointer - pointer" operation.
+  if (lhs_type.IsPointerType() && rhs_type.IsPointerType()) {
+    if (lhs_type.IsPointerToVoid() && rhs_type.IsPointerToVoid()) {
+      return llvm::make_error<DILDiagnosticError>(
+          m_expr, "arithmetic on pointers to void", location);
+    }
+    // Compare canonical unqualified pointer types.
+    CompilerType lhs_unqualified_type =
+        lhs_type.GetCanonicalType().GetFullyUnqualifiedType();
+    CompilerType rhs_unqualified_type =
+        rhs_type.GetCanonicalType().GetFullyUnqualifiedType();
----------------
Michael137 wrote:

Looks like `CompareTypes` already calls `GetFullyUnqualifiedType()` on both

Can we drop it from here? Also we should probably make `CompareTypes` call `GetCanonicalType`

https://github.com/llvm/llvm-project/pull/184652