[llvm-commits] [llvm] r95242 - /llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

[Devang Patel]

Author: dpatel
Date: Wed Feb  3 14:08:48 2010
New Revision: 95242

URL: http://llvm.org/viewvc/llvm-project?rev=95242&view=rev
Log:
Emit appropriate expression to find virtual base offset.

Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=95242&r1=95241&r2=95242&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Feb  3 14:08:48 2010
@@ -1123,7 +1123,26 @@
     // This is not a bitfield.
     addUInt(MemLocationDie, 0, dwarf::DW_FORM_udata, DT.getOffsetInBits() >> 3);
 
-  addBlock(MemberDie, dwarf::DW_AT_data_member_location, 0, MemLocationDie);
+  if (DT.getTag() == dwarf::DW_TAG_inheritance
+      && DT.isVirtual()) {
+
+    // For C++, virtual base classes are not at fixed offset. Use following
+    // expression to extract appropriate offset from vtable.
+    // BaseAddr = ObAddr + *((*ObAddr) - Offset)
+
+    DIEBlock *VBaseLocationDie = new DIEBlock();
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_dup);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_udata, DT.getOffsetInBits());
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_minus);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
+
+    addBlock(MemberDie, dwarf::DW_AT_data_member_location, 0, 
+             VBaseLocationDie);
+  } else
+    addBlock(MemberDie, dwarf::DW_AT_data_member_location, 0, MemLocationDie);
 
   if (DT.isProtected())
     addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,