[Lldb-commits] [lldb] r331462 - DWARFExpression: Convert file addresses to load addresses early on.

[Adrian Prantl via lldb-commits]

Author: adrian
Date: Thu May  3 09:51:37 2018
New Revision: 331462

URL: http://llvm.org/viewvc/llvm-project?rev=331462&view=rev
Log:
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

Modified:
    lldb/trunk/include/lldb/Core/Value.h
    lldb/trunk/source/Core/Value.cpp
    lldb/trunk/source/Core/ValueObjectVariable.cpp
    lldb/trunk/source/Expression/DWARFExpression.cpp

Modified: lldb/trunk/include/lldb/Core/Value.h
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Core/Value.h?rev=331462&r1=331461&r2=331462&view=diff
==============================================================================
--- lldb/trunk/include/lldb/Core/Value.h (original)
+++ lldb/trunk/include/lldb/Core/Value.h Thu May  3 09:51:37 2018
@@ -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(SymbolContext sc);
+
   bool GetData(DataExtractor &data);
 
   void Clear();

Modified: lldb/trunk/source/Core/Value.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Core/Value.cpp?rev=331462&r1=331461&r2=331462&view=diff
==============================================================================
--- lldb/trunk/source/Core/Value.cpp (original)
+++ lldb/trunk/source/Core/Value.cpp Thu May  3 09:51:37 2018
@@ -669,6 +669,28 @@ const char *Value::GetContextTypeAsCStri
   return "???";
 }
 
+void Value::ConvertToLoadAddress(SymbolContext sc) {
+  if (GetValueType() != eValueTypeFileAddress)
+    return;
+
+  if (!sc.module_sp)
+    return;
+
+  lldb::addr_t file_addr = GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
+  if (file_addr == LLDB_INVALID_ADDRESS)
+    return;
+
+  Address so_addr;
+  if (!sc.module_sp->ResolveFileAddress(file_addr, so_addr))
+    return;
+  lldb::addr_t load_addr = so_addr.GetLoadAddress(sc.target_sp.get());
+  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) {

Modified: lldb/trunk/source/Core/ValueObjectVariable.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Core/ValueObjectVariable.cpp?rev=331462&r1=331461&r2=331462&view=diff
==============================================================================
--- lldb/trunk/source/Core/ValueObjectVariable.cpp (original)
+++ lldb/trunk/source/Core/ValueObjectVariable.cpp Thu May  3 09:51:37 2018
@@ -234,26 +234,10 @@ bool ValueObjectVariable::UpdateValue()
         // If this variable is a simple type, we read all data for it into
         // m_data. Make sure this type has a value before we try and read it
 
+        SymbolContext var_sc;
+        variable->CalculateSymbolContext(&var_sc);
         // 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;
-                }
-              }
-            }
-          }
-        }
+        m_value.ConvertToLoadAddress(var_sc);
 
         if (!CanProvideValue()) {
           // this value object represents an aggregate type whose children have

Modified: lldb/trunk/source/Expression/DWARFExpression.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Expression/DWARFExpression.cpp?rev=331462&r1=331461&r2=331462&view=diff
==============================================================================
--- lldb/trunk/source/Expression/DWARFExpression.cpp (original)
+++ lldb/trunk/source/Expression/DWARFExpression.cpp Thu May  3 09:51:37 2018
@@ -1379,10 +1379,13 @@ bool DWARFExpression::Evaluate(
     // The DW_OP_addr operation has a single operand that encodes a machine
     // address and whose size is the size of an address on the target machine.
     //----------------------------------------------------------------------
-    case DW_OP_addr:
+    case DW_OP_addr: {
       stack.push_back(Scalar(opcodes.GetAddress(&offset)));
       stack.back().SetValueType(Value::eValueTypeFileAddress);
+      auto sc = frame->GetSymbolContext(eSymbolContextFunction);
+      stack.back().ConvertToLoadAddress(sc);
       break;
+    }
 
     //----------------------------------------------------------------------
     // The DW_OP_addr_sect_offset4 is used for any location expressions in