Revert "[DWARF] Allow cross-CU references of subprogram definitions"

This reverts commit 30038da15b18ac4e34b9ea7a648382ae481e4770. It causes
the stage2 thinLTO bot to fail with:

Assertion failed: (CU.getDIE(CalleeSP) && "Expected declaration subprogram DIE for callee")

rdar://57840415

4 files changed, 7 insertions, 26 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index e40541e57d5..4e90c10e3e9 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -964,8 +964,8 @@ DIE &DwarfCompileUnit::constructCallSiteEntryDIE(
     addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
                MachineLocation(CallReg));
   } else {
-    DIE *CalleeDIE = getDIE(CalleeSP);
-    assert(CalleeDIE && "Could not find DIE for call site entry origin");
+    DIE *CalleeDIE = getOrCreateSubprogramDIE(CalleeSP);
+    assert(CalleeDIE && "Could not create DIE for call site entry origin");
     addDIEEntry(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_origin),
                 *CalleeDIE);
   }
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 74133280bf2..0a20de505a1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -535,14 +535,6 @@ void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU,
   }
 }
 
-DIE &DwarfDebug::constructSubprogramDefinitionDIE(const DISubprogram *SP) {
-  DICompileUnit *Unit = SP->getUnit();
-  assert(SP->isDefinition() && "Subprogram not a definition");
-  assert(Unit && "Subprogram definition without parent unit");
-  auto &CU = getOrCreateDwarfCompileUnit(Unit);
-  return *CU.getOrCreateSubprogramDIE(SP);
-}
-
 /// Try to interpret values loaded into registers that forward parameters
 /// for \p CallMI. Store parameters with interpreted value into \p Params.
 static void collectCallSiteParameters(const MachineInstr *CallMI,
@@ -753,15 +745,6 @@ void DwarfDebug::constructCallSiteEntryDIEs(const DISubprogram &SP,
         if (!CalleeDecl || !CalleeDecl->getSubprogram())
           continue;
         CalleeSP = CalleeDecl->getSubprogram();
-
-        if (CalleeSP->isDefinition()) {
-          // Ensure that a subprogram DIE for the callee is available in the
-          // appropriate CU.
-          constructSubprogramDefinitionDIE(CalleeSP);
-        } else {
-          assert(CU.getDIE(CalleeSP) &&
-                 "Expected declaration subprogram DIE for callee");
-        }
       }
 
       // TODO: Omit call site entries for runtime calls (objc_msgSend, etc).
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 4d7bf0c54de..03949dbddea 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -437,9 +437,6 @@ class DwarfDebug : public DebugHandlerBase {
   /// Construct a DIE for this abstract scope.
   void constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU, LexicalScope *Scope);
 
-  /// Construct a DIE for the subprogram definition \p SP and return it.
-  DIE &constructSubprogramDefinitionDIE(const DISubprogram *SP);
-
   /// Construct DIEs for call site entries describing the calls in \p MF.
   void constructCallSiteEntryDIEs(const DISubprogram &SP, DwarfCompileUnit &CU,
                                   DIE &ScopeDIE, const MachineFunction &MF);
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 58d7a4eaa7e..86522a85427 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -188,9 +188,8 @@ int64_t DwarfUnit::getDefaultLowerBound() const {
 
 /// Check whether the DIE for this MDNode can be shared across CUs.
 bool DwarfUnit::isShareableAcrossCUs(const DINode *D) const {
-  // When the MDNode can be part of the type system (this includes subprogram
-  // declarations *and* subprogram definitions, even local definitions), the
-  // DIE must be shared across CUs.
+  // When the MDNode can be part of the type system, the DIE can be shared
+  // across CUs.
   // Combining type units and cross-CU DIE sharing is lower value (since
   // cross-CU DIE sharing is used in LTO and removes type redundancy at that
   // level already) but may be implementable for some value in projects
@@ -198,7 +197,9 @@ bool DwarfUnit::isShareableAcrossCUs(const DINode *D) const {
   // together.
   if (isDwoUnit() && !DD->shareAcrossDWOCUs())
     return false;
-  return (isa<DIType>(D) || isa<DISubprogram>(D)) && !DD->generateTypeUnits();
+  return (isa<DIType>(D) ||
+          (isa<DISubprogram>(D) && !cast<DISubprogram>(D)->isDefinition())) &&
+         !DD->generateTypeUnits();
 }
 
 DIE *DwarfUnit::getDIE(const DINode *D) const {