[Lldb-commits] [lldb] [lldb] Extract DW_OP_deref evaluation code (NFC) (PR #146801)

[Adrian Prantl via lldb-commits]

================
@@ -860,6 +860,64 @@ ResolveLoadAddress(ExecutionContext *exe_ctx, lldb::ModuleSP &module_sp,
   return load_addr;
 }
 
+static llvm::Error Evaluate_DW_OP_deref(DWARFExpression::Stack &stack,
+                                        ExecutionContext *exe_ctx,
+                                        lldb::ModuleSP module_sp,
+                                        Process *process) {
+  if (stack.empty())
+    return llvm::createStringError("expression stack empty for DW_OP_deref");
+
+  const Value::ValueType value_type = stack.back().GetValueType();
+  switch (value_type) {
+  case Value::ValueType::HostAddress: {
+    void *src = (void *)stack.back().GetScalar().ULongLong();
+    intptr_t ptr;
+    ::memcpy(&ptr, src, sizeof(void *));
+    stack.back().GetScalar() = ptr;
+    stack.back().ClearContext();
+  } break;
+  case Value::ValueType::FileAddress: {
+    auto file_addr = stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
+    Address so_addr;
+    auto maybe_load_addr = ResolveLoadAddress(exe_ctx, module_sp, "DW_OP_deref",
+                                              file_addr, so_addr);
+    if (!maybe_load_addr)
+      return maybe_load_addr.takeError();
+    stack.back().GetScalar() = *maybe_load_addr;
+    // Fall through to load address promotion code below.
+  }
+    [[fallthrough]];
+  case Value::ValueType::Scalar:
+    // Promote Scalar to LoadAddress and fall through.
+    stack.back().SetValueType(Value::ValueType::LoadAddress);
+    [[fallthrough]];
+  case Value::ValueType::LoadAddress: {
+    if (!exe_ctx)
+      return llvm::createStringError("NULL execution context for DW_OP_deref");
+    if (!process)
+      return llvm::createStringError("NULL process for DW_OP_deref");
+    lldb::addr_t pointer_addr =
+        stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
+    Status error;
+    lldb::addr_t pointer_value =
+        process->ReadPointerFromMemory(pointer_addr, error);
+    if (pointer_value == LLDB_INVALID_ADDRESS)
+      return llvm::createStringError(
+          "Failed to dereference pointer from 0x%" PRIx64
+          " for DW_OP_deref: %s\n",
+          pointer_addr, error.AsCString());
----------------
adrian-prantl wrote:

Status is an llvm::Error, so this should be
`return llvm::joinErrors(llvm::createStringError("Failed to dereference pointer from 0x%" PRIx64 " for DW_OP_deref", pointer_addr, error.takeError())`


https://github.com/llvm/llvm-project/pull/146801