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

[Michael Buch via lldb-commits]

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@@ -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);
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Michael137 wrote:

Also, I know we probably aren't very diligent about this in most places, but I just noticed it here so I'll mention it. I think it'd be nicer if we did `llvm::joinErrors(llvm::createStringError("Failed to perform pointer addition:"), err.takeError())`

Just thinking from a user-perspective. If the byte-size of the element type was failed to be read, an expression like `(5 + otherPtr) + offsets[0]` would just say: `failed to read byte-size`. Probably nicer to be more specific about what part failed.

Wdyt? I'm not sure how such failures would present today, so I might be off-base

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