DWARFExpression: Convert file addresses to load addresses early on.

This is a change that only affects Swift and is NFC for the language
plugins on llvm.org. In Swift, we can have global variables with a
location such as DW_OP_addr <addr> DW_OP_deref. The DWARF expression
evaluator doesn't know how to apply a DW_OP_deref to a file address,
but at the very end we convert the file address into a load address.

This patch moves the file->load address conversion to right after the
result of the DW_OP_addr is pushed onto the stack so that a subsequent
DW_OP_deref (and potentially other operations) can be interpreted.

rdar://problem/39767528

Differential revision: https://reviews.llvm.org/D46362

llvm-svn: 331492

4 files changed, 30 insertions, 19 deletions

diff --git a/lldb/include/lldb/Core/Value.h b/lldb/include/lldb/Core/Value.h
index 6ef2b7d9667..801e818c6f5 100644
--- a/lldb/include/lldb/Core/Value.h
+++ b/lldb/include/lldb/Core/Value.h
@@ -228,6 +228,9 @@ public:
 
   static const char *GetContextTypeAsCString(ContextType context_type);
 
+  /// Convert this value's file address to a load address, if possible.
+  void ConvertToLoadAddress(Module *module, Target *target);
+
   bool GetData(DataExtractor &data);
 
   void Clear();
diff --git a/lldb/source/Core/Value.cpp b/lldb/source/Core/Value.cpp
index 292ba0725ff..254c9008bab 100644
--- a/lldb/source/Core/Value.cpp
+++ b/lldb/source/Core/Value.cpp
@@ -669,6 +669,25 @@ const char *Value::GetContextTypeAsCString(ContextType context_type) {
   return "???";
 }
 
+void Value::ConvertToLoadAddress(Module *module, Target *target) {
+  if (!module || !target || (GetValueType() != eValueTypeFileAddress))
+    return;
+
+  lldb::addr_t file_addr = GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
+  if (file_addr == LLDB_INVALID_ADDRESS)
+    return;
+
+  Address so_addr;
+  if (!module->ResolveFileAddress(file_addr, so_addr))
+    return;
+  lldb::addr_t load_addr = so_addr.GetLoadAddress(target);
+  if (load_addr == LLDB_INVALID_ADDRESS)
+    return;
+
+  SetValueType(Value::eValueTypeLoadAddress);
+  GetScalar() = load_addr;
+}
+
 ValueList::ValueList(const ValueList &rhs) { m_values = rhs.m_values; }
 
 const ValueList &ValueList::operator=(const ValueList &rhs) {
diff --git a/lldb/source/Core/ValueObjectVariable.cpp b/lldb/source/Core/ValueObjectVariable.cpp
index e08963210ec..95b58b3336c 100644
--- a/lldb/source/Core/ValueObjectVariable.cpp
+++ b/lldb/source/Core/ValueObjectVariable.cpp
@@ -235,25 +235,8 @@ bool ValueObjectVariable::UpdateValue() {
         // m_data. Make sure this type has a value before we try and read it
 
         // If we have a file address, convert it to a load address if we can.
-        if (value_type == Value::eValueTypeFileAddress && process_is_alive) {
-          lldb::addr_t file_addr =
-              m_value.GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
-          if (file_addr != LLDB_INVALID_ADDRESS) {
-            SymbolContext var_sc;
-            variable->CalculateSymbolContext(&var_sc);
-            if (var_sc.module_sp) {
-              ObjectFile *objfile = var_sc.module_sp->GetObjectFile();
-              if (objfile) {
-                Address so_addr(file_addr, objfile->GetSectionList());
-                lldb::addr_t load_addr = so_addr.GetLoadAddress(target);
-                if (load_addr != LLDB_INVALID_ADDRESS) {
-                  m_value.SetValueType(Value::eValueTypeLoadAddress);
-                  m_value.GetScalar() = load_addr;
-                }
-              }
-            }
-          }
-        }
+        if (value_type == Value::eValueTypeFileAddress && process_is_alive)
+          m_value.ConvertToLoadAddress(GetModule().get(), target);
 
         if (!CanProvideValue()) {
           // this value object represents an aggregate type whose children have
diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index 71495715e75..8f54bf37ea0 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -1374,6 +1374,7 @@ bool DWARFExpression::Evaluate(
       }
       log->Printf("0x%8.8" PRIx64 ": %s", op_offset, DW_OP_value_to_name(op));
     }
+
     switch (op) {
     //----------------------------------------------------------------------
     // The DW_OP_addr operation has a single operand that encodes a machine
@@ -1382,6 +1383,11 @@ bool DWARFExpression::Evaluate(
     case DW_OP_addr:
       stack.push_back(Scalar(opcodes.GetAddress(&offset)));
       stack.back().SetValueType(Value::eValueTypeFileAddress);
+      // Convert the file address to a load address, so subsequent
+      // DWARF operators can operate on it.
+      if (frame)
+        stack.back().ConvertToLoadAddress(module_sp.get(),
+                                          frame->CalculateTarget().get());
       break;
 
     //----------------------------------------------------------------------