commit dabd2622a86900718ce5ba22e787333265375d4a
author Evgenii Stepanov <eugenis@google.com> Mon Nov 25 17:47:30 2019 -0800
committer Evgenii Stepanov <eugenis@google.com> Thu Dec 12 16:18:54 2019 -0800
tree ad16725186d458409867f242bb0294071f08bf6b
parent 479868646a6a3a83dda482e8da26f77a1a39c58d

hwasan: add tag_offset DWARF attribute to optimized debug info

Summary:
Support alloca-referencing dbg.value in hwasan instrumentation.
Update AsmPrinter to emit DW_AT_LLVM_tag_offset when location is in
loclist format.

Reviewers: pcc

Subscribers: srhines, aprantl, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70753

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 4e90c10..0f3d8c6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -615,6 +615,10 @@
   unsigned Offset = DV.getDebugLocListIndex();
   if (Offset != ~0U) {
     addLocationList(*VariableDie, dwarf::DW_AT_location, Offset);
+    auto TagOffset = DV.getDebugLocListTagOffset();
+    if (TagOffset)
+      addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
+              *TagOffset);
     return VariableDie;
   }
 
@@ -632,6 +636,10 @@
         DwarfExpr.addUnsignedConstant(DVal->getInt());
         DwarfExpr.addExpression(Expr);
         addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
+        if (DwarfExpr.TagOffset)
+          addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset,
+                  dwarf::DW_FORM_data1, *DwarfExpr.TagOffset);
+
       } else
         addConstantValue(*VariableDie, DVal->getInt(), DV.getType());
     } else if (DVal->isConstantFP()) {
@@ -1198,6 +1206,10 @@
 
   // Now attach the location information to the DIE.
   addBlock(Die, Attribute, DwarfExpr.finalize());
+
+  if (DwarfExpr.TagOffset)
+    addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
+            *DwarfExpr.TagOffset);
 }
 
 /// Start with the address based on the location provided, and generate the
@@ -1228,6 +1240,10 @@
 
   // Now attach the location information to the DIE.
   addBlock(Die, Attribute, DwarfExpr.finalize());
+
+  if (DwarfExpr.TagOffset)
+    addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
+            *DwarfExpr.TagOffset);
 }
 
 /// Add a Dwarf loclistptr attribute data and value.