[PATCH] D45566: [CodeGen/Dwarf] Make debug_names compatible with split-dwarf

[Pavel Labath via Phabricator via llvm-commits]

labath created this revision.
labath added reviewers: JDevlieghere, aprantl, dblaikie.

Previously we crashed for the combination of the two features because we
tried to reference the dwo CU from the main object file. The fix
consists of two items:

- reference the skeleton CU from the name index (the consumer is expected to use the skeleton CU to find the real data).
- use the main object file string pool for the strings in the index


Repository:
  rL LLVM

https://reviews.llvm.org/D45566

Files:
  lib/CodeGen/AsmPrinter/AccelTable.cpp
  lib/CodeGen/AsmPrinter/DwarfDebug.cpp
  lib/CodeGen/AsmPrinter/DwarfDebug.h
  test/DebugInfo/Generic/debug-names-one-cu.ll


Index: test/DebugInfo/Generic/debug-names-one-cu.ll
===================================================================
--- test/DebugInfo/Generic/debug-names-one-cu.ll
+++ test/DebugInfo/Generic/debug-names-one-cu.ll
@@ -3,6 +3,10 @@
 ; RUN: llvm-dwarfdump -debug-names %t | FileCheck %s
 ; RUN: llvm-dwarfdump -debug-names -verify %t | FileCheck --check-prefix=VERIFY %s
 
+; Now try the same with split dwarf.
+; RUN: %llc_dwarf -split-dwarf-file=foo.dwo -accel-tables=Dwarf -filetype=obj -o %t < %s
+; RUN: llvm-dwarfdump -debug-names %t | FileCheck %s
+
 ; Check the header
 ; CHECK: CU count: 1
 ; CHECK: Local TU count: 0
Index: lib/CodeGen/AsmPrinter/DwarfDebug.h
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -339,6 +339,8 @@
   /// Construct a DIE for this abstract scope.
   void constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU, LexicalScope *Scope);
 
+  void addAccelDebugName(StringRef Name, const DIE &Die);
+
   void finishVariableDefinitions();
 
   void finishSubprogramDefinitions();
Index: lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2267,6 +2267,13 @@
   CU.addDIETypeSignature(RefDie, Signature);
 }
 
+void DwarfDebug::addAccelDebugName(StringRef Name, const DIE &Die) {
+  assert(getAccelTableKind() == AccelTableKind::Dwarf);
+
+  DwarfFile &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
+  AccelDebugNames.addName(Holder.getStringPool().getEntry(*Asm, Name), Die);
+}
+
 // Accelerator table mutators - add each name along with its companion
 // DIE to the proper table while ensuring that the name that we're going
 // to reference is in the string table. We do this since the names we
@@ -2277,8 +2284,7 @@
     AccelNames.addName(InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
     break;
   case AccelTableKind::Dwarf:
-    AccelDebugNames.addName(InfoHolder.getStringPool().getEntry(*Asm, Name),
-                            Die);
+    addAccelDebugName(Name, Die);
     break;
   case AccelTableKind::None:
     return;
@@ -2300,8 +2306,7 @@
                            &Die);
     break;
   case AccelTableKind::Dwarf:
-    AccelDebugNames.addName(InfoHolder.getStringPool().getEntry(*Asm, Name),
-                            Die);
+    addAccelDebugName(Name, Die);
     break;
   case AccelTableKind::None:
     return;
@@ -2316,8 +2321,7 @@
     AccelTypes.addName(InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
     break;
   case AccelTableKind::Dwarf:
-    AccelDebugNames.addName(InfoHolder.getStringPool().getEntry(*Asm, Name),
-                            Die);
+    addAccelDebugName(Name, Die);
     break;
   case AccelTableKind::None:
     return;
Index: lib/CodeGen/AsmPrinter/AccelTable.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/AccelTable.cpp
+++ lib/CodeGen/AsmPrinter/AccelTable.cpp
@@ -416,7 +416,9 @@
   for (const auto &CU : enumerate(CompUnits)) {
     assert(CU.index() == CU.value()->getUniqueID());
     Asm->OutStreamer->AddComment("Compilation unit " + Twine(CU.index()));
-    Asm->emitDwarfSymbolReference(CU.value()->getLabelBegin());
+    const DwarfCompileUnit *MainCU =
+        DD.useSplitDwarf() ? CU.value()->getSkeleton() : CU.value().get();
+    Asm->emitDwarfSymbolReference(MainCU->getLabelBegin());
   }
 }
 


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