[PATCH] D77489: [DebugInfo]: Allow DwarfCompileUnit to have line table symbol

[Sourabh Singh Tomar via Phabricator via llvm-commits]

SouraVX created this revision.
SouraVX added reviewers: dblaikie, probinson, jini.susan.george.
SouraVX added a project: debug-info.
Herald added subscribers: llvm-commits, hiraditya, aprantl.
Herald added a project: LLVM.

Previously line table symbol was represented as `DIE::value_iterator` inside `DwarfCompileUnit` and subsequent function `intStmtList` was used to create a local `MCSymbol` to initialize it.

This patch removes `DIE::value_iterator` from `DwarfCompileUnit` and intoduce `MCSymbol` for representing this units symbol for `debug_line` section. As a result `applyStmtList` is also modified  to utilize this. Further more a helper function `getLineTableStartSym` is also introduced to get this symbol, this would be used by clients which need to access this line table, i.e `debug_macro`.

This patch is based on @dblaikie comment https://reviews.llvm.org/D72828#1958625 on D72828 <https://reviews.llvm.org/D72828>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77489

Files:
  llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
  llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h


Index: llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -47,9 +47,9 @@
   unsigned UniqueID;
   bool HasRangeLists = false;
 
-  /// The attribute index of DW_AT_stmt_list in the compile unit DIE, avoiding
-  /// the need to search for it in applyStmtList.
-  DIE::value_iterator StmtListValue;
+  /// The start of the unit line section, this is also
+  /// reused in appyStmtList.
+  MCSymbol *LineTableStartSym;
 
   /// Skeleton unit associated with this unit.
   DwarfCompileUnit *Skeleton = nullptr;
@@ -123,6 +123,9 @@
   /// Apply the DW_AT_stmt_list from this compile unit to the specified DIE.
   void applyStmtList(DIE &D);
 
+  /// Get line table start symbol for this unit.
+  MCSymbol *getLineTableStartSym() const { return LineTableStartSym; }
+
   /// A pair of GlobalVariable and DIExpression.
   struct GlobalExpr {
     const GlobalVariable *Var;
Index: llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -351,8 +351,6 @@
   if (CUNode->isDebugDirectivesOnly())
     return;
 
-  // Define start line table label for each Compile Unit.
-  MCSymbol *LineTableStartSym;
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
   if (DD->useSectionsAsReferences()) {
     LineTableStartSym = TLOF.getDwarfLineSection()->getBeginSymbol();
@@ -366,13 +364,14 @@
   // left in the skeleton CU and so not included.
   // The line table entries are not always emitted in assembly, so it
   // is not okay to use line_table_start here.
-  StmtListValue =
       addSectionLabel(getUnitDie(), dwarf::DW_AT_stmt_list, LineTableStartSym,
                       TLOF.getDwarfLineSection()->getBeginSymbol());
 }
 
 void DwarfCompileUnit::applyStmtList(DIE &D) {
-  D.addValue(DIEValueAllocator, *StmtListValue);
+  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
+  addSectionLabel(D, dwarf::DW_AT_stmt_list, LineTableStartSym,
+                  TLOF.getDwarfLineSection()->getBeginSymbol());
 }
 
 void DwarfCompileUnit::attachLowHighPC(DIE &D, const MCSymbol *Begin,


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