Emit abstract subprogram DIE referenced from a global variable in the correct CU.

Author: dzhidzhoev

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -1836,8 +1836,12 @@ DIE *DwarfCompileUnit::getOrCreateSubprogramDIE(const DISubprogram *SP,
   if (!F && SP->isDefinition()) {
     F = DD->getLexicalScopes().getFunction(SP);
 
-    if (!F)
-      return &getCU().getOrCreateAbstractSubprogramDIE(SP);
+    if (!F) {
+      // SP may belong to another CU. Determine the CU similarly
+      // to DwarfDebug::constructAbstractSubprogramScopeDIE.
+      return &DD->getOrCreateAbstractSubprogramCU(SP, *this)
+                  .getOrCreateAbstractSubprogramDIE(SP);
+    }
   }
 
   return DwarfUnit::getOrCreateSubprogramDIE(SP, F, Minimal);

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -548,6 +548,16 @@ bool DwarfDebug::shareAcrossDWOCUs() const {
   return SplitDwarfCrossCuReferences;
 }
 
+DwarfCompileUnit &
+DwarfDebug::getOrCreateAbstractSubprogramCU(const DISubprogram *SP,
+                                            DwarfCompileUnit &SrcCU) {
+  auto &CU = getOrCreateDwarfCompileUnit(SP->getUnit());
+  if (CU.getSkeleton())
+    return shareAcrossDWOCUs() ? CU : SrcCU;
+
+  return CU;
+}
+
 void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU,
                                                      LexicalScope *Scope) {
   assert(Scope && Scope->getScopeNode());
@@ -559,14 +569,11 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU,
   // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
   // was inlined from another compile unit.
   auto &CU = getOrCreateDwarfCompileUnit(SP->getUnit());
-  if (auto *SkelCU = CU.getSkeleton()) {
-    (shareAcrossDWOCUs() ? CU : SrcCU)
-        .constructAbstractSubprogramScopeDIE(Scope);
+  auto &TargetCU = getOrCreateAbstractSubprogramCU(SP, SrcCU);
+  TargetCU.constructAbstractSubprogramScopeDIE(Scope);
+  if (auto *SkelCU = CU.getSkeleton())
     if (CU.getCUNode()->getSplitDebugInlining())
       SkelCU->constructAbstractSubprogramScopeDIE(Scope);
-  } else {
-    CU.constructAbstractSubprogramScopeDIE(Scope);
-  }
 }
 
 /// Represents a parameter whose call site value can be described by applying a

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -906,6 +906,10 @@ class DwarfDebug : public DebugHandlerBase {
     return CUDieMap.lookup(Die);
   }
 
+  /// Find the matching DwarfCompileUnit for the given SP referenced from SrcCU.
+  DwarfCompileUnit &getOrCreateAbstractSubprogramCU(const DISubprogram *SP,
+                                                    DwarfCompileUnit &SrcCU);
+
   unsigned getStringTypeLoc(const DIStringType *ST) const {
     return StringTypeLocMap.lookup(ST);
   }

llvm/test/DebugInfo/AArch64/abstract-sp-unit.ll

@@ -0,0 +1,43 @@
+; RUN: llc --filetype=obj -O0 -o - %s | llvm-dwarfdump --verify -
+
+; Check that abstract DIE for a subprogram referenced from another compile unit
+; is emitted in the correct CU.
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64"
+
+define void @a() !dbg !10 {
+  br label %for.b.c.c, !dbg !13
+  for.b.c.c:
+    br label %for.b.c.c
+}
+
+!llvm.dbg.cu = !{!0, !6}
+!llvm.module.flags = !{!8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_20, file: !1, emissionKind: FullDebug, globals: !2)
+!1 = !DIFile(filename: "foo.cpp", directory: "")
+!2 = !{!3}
+!3 = !DIGlobalVariableExpression(var: !4, expr: !DIExpression())
+!4 = !DIGlobalVariable(type: !5)
+!5 = !DICompositeType(tag: DW_TAG_class_type)
+!6 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_20, file: !7, emissionKind: FullDebug)
+!7 = !DIFile(filename: "bar.cpp", directory: "")
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!10 = distinct !DISubprogram(type: !11, unit: !6)
+!11 = !DISubroutineType(types: !12)
+!12 = !{}
+!13 = !DILocation(scope: !14, inlinedAt: !15)
+!14 = distinct !DISubprogram(unit: !6)
+!15 = !DILocation(scope: !16, inlinedAt: !25)
+!16 = distinct !DISubprogram(type: !11, unit: !6, declaration: !17)
+!17 = !DISubprogram(scope: !5, type: !11, spFlags: DISPFlagOptimized, templateParams: !18)
+!18 = !{!19}
+!19 = !DITemplateTypeParameter(type: !20)
+!20 = !DICompositeType(tag: DW_TAG_class_type, scope: !21)
+!21 = distinct !DISubprogram(unit: !6, retainedNodes: !22)
+!22 = !{!23}
+!23 = !DILocalVariable(scope: !21, type: !24)
+!24 = !DIBasicType()
+!25 = !DILocation(scope: !21, inlinedAt: !26)
+!26 = !DILocation(scope: !10)