[Lldb-commits] [lldb] [lldb-dap] Support inspecting memory (PR #104317)

[Greg Clayton via lldb-commits]

================
@@ -1085,6 +1085,19 @@ std::string VariableDescription::GetResult(llvm::StringRef context) {
   return description.trim().str();
 }
 
+lldb::addr_t GetMemoryReference(lldb::SBValue v) {
+  if (!v.GetType().IsPointerType() && !v.GetType().IsArrayType()) {
+    return LLDB_INVALID_ADDRESS;
+  }
+
+  lldb::SBValue deref = v.Dereference();
+  if (!deref.IsValid()) {
+    return LLDB_INVALID_ADDRESS;
+  }
+
+  return deref.GetLoadAddress();
----------------
clayborg wrote:

We can return the address of a SBValue by calling `v.GetLoadAddress();`. But as you know, if the value is a pointer, then we want to dereference it. We want to dereference reference values as well. This code should be:
```
std::optional<lldb::addr_t> GetMemoryReference(lldb::SBValue v) {
  SBType v_type =  v.GetType();
  // Dereference and pointers or C++ references.
  if (v_type.IsPointerType() || v_type.IsReferenceType())
    v = v.Dereference();
  lldb::addr_t load_addr = v.GetLoadAddress();
  if (load_addr != LLDB_INVALID_ADDRESS)
    return load_addr;
  return std::nullopt;
}
```
Any value that lives in memory should return a valid load address. If a variable lives in a register, or is a constant, then `v.GetLoadAddress()` will return `LLDB_INVALID_ADDRESS`. Also, no need to check if `v.Dereference();` succeeded, because if it doesn't, then the `SBValue` will be invalid and also return `LLDB_INVALID_ADDRESS`

https://github.com/llvm/llvm-project/pull/104317