[llvm] 0d71782 - [DebugInfo]: Allow DwarfCompileUnit to have line table symbol

[Sourabh Singh Tomar via llvm-commits]

Author: Sourabh Singh Tomar
Date: 2020-04-06T00:14:29+05:30
New Revision: 0d71782f4e29784873080571f7aebd5bdd163f3f

URL: https://github.com/llvm/llvm-project/commit/0d71782f4e29784873080571f7aebd5bdd163f3f
DIFF: https://github.com/llvm/llvm-project/commit/0d71782f4e29784873080571f7aebd5bdd163f3f.diff

LOG: [DebugInfo]: Allow DwarfCompileUnit to have line table symbol

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`.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D77489

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 889303b4278e..c3b2a0dc4070 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -351,8 +351,6 @@ void DwarfCompileUnit::initStmtList() {
   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 @@ void DwarfCompileUnit::initStmtList() {
   // 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,

diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index 5d0afee4c3df..4ccd8c96dd0d 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -47,9 +47,9 @@ class DwarfCompileUnit final : public DwarfUnit {
   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 @@ class DwarfCompileUnit final : public DwarfUnit {
   /// 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;