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

... as well as:
Revert "[DWARF] Defer creating declaration DIEs until we prepare call site info"

This reverts commit fa4701e.

This reverts commit 79daafc.

There have been reports of this assert getting hit:

CalleeDIE && "Could not find DIE for call site entry origin

(cherry picked from commit 802bec8)

Author: vedantk

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -968,8 +968,8 @@ 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);
   }

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -540,14 +540,6 @@ 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,
@@ -758,17 +750,6 @@ 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 {
-          // Create the declaration DIE if it is missing. This is required to
-          // support compilation of old bitcode with an incomplete list of
-          // retained metadata.
-          CU.getOrCreateSubprogramDIE(CalleeSP);
-        }
       }
 
       // TODO: Omit call site entries for runtime calls (objc_msgSend, etc).
@@ -924,6 +905,11 @@ DwarfDebug::getOrCreateDwarfCompileUnit(const DICompileUnit *DIUnit) {
     NewCU.setSection(Asm->getObjFileLowering().getDwarfInfoSection());
   }
 
+  // Create DIEs for function declarations used for call site debug info.
+  for (auto Scope : DIUnit->getRetainedTypes())
+    if (auto *SP = dyn_cast_or_null<DISubprogram>(Scope))
+      NewCU.getOrCreateSubprogramDIE(SP);
+
   CUMap.insert({DIUnit, &NewCU});
   CUDieMap.insert({&NewCU.getUnitDie(), &NewCU});
   return NewCU;

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -442,9 +442,6 @@ 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);

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -188,17 +188,18 @@ 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
   // building multiple independent libraries with LTO and then linking those
   // 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 {

llvm/test/DebugInfo/AArch64/unretained-declaration-subprogram.ll

@@ -159,7 +159,7 @@ body:             |
 ...
 
 # CHECK: DW_TAG_GNU_call_site
-# CHECK-NEXT: DW_AT_abstract_origin ({{.*}} "call_int")
+# CHECK-NEXT: DW_AT_abstract_origin (0x0000002a "call_int")
 #
 # CHECK: DW_TAG_GNU_call_site_parameter
 # CHECK-NEXT: DW_AT_location      (DW_OP_reg0 W0)
@@ -205,7 +205,7 @@ body:             |
 ...
 
 # CHECK: DW_TAG_GNU_call_site
-# CHECK-NEXT: DW_AT_abstract_origin ({{.*}} "call_long")
+# CHECK-NEXT: DW_AT_abstract_origin (0x0000003e "call_long")
 #
 # CHECK: DW_TAG_GNU_call_site_parameter
 # CHECK-NEXT: DW_AT_location      (DW_OP_reg0 W0)
@@ -265,7 +265,7 @@ body:             |
 ...
 
 # CHECK: DW_TAG_GNU_call_site
-# CHECK-NEXT: DW_AT_abstract_origin ({{.*}} "call_int_int")
+# CHECK-NEXT: DW_AT_abstract_origin (0x00000052 "call_int_int")
 #
 # CHECK: DW_TAG_GNU_call_site_parameter
 # FIXME: The DW_AT_location attribute should actually refer to W0! See PR44118.

llvm/test/DebugInfo/MIR/AArch64/dbgcall-site-orr-moves.mir

@@ -39,11 +39,17 @@
 # CHECK-GNU-NEXT:      DW_AT_location      (DW_OP_reg8 R8)
 # CHECK-GNU-NEXT:      DW_AT_GNU_call_site_value   (DW_OP_breg14 R14+3)
 
-# CHECK-DWARF5: DW_TAG_call_site
-# CHECK-DWARF5:   DW_AT_call_origin ([[getValue_SP:.*]])
+# CHECK-DWARF5: [[getValue_SP:.*]]: DW_TAG_subprogram
+# CHECK-DWARF5-NEXT: DW_AT_name      ("getVal")
 
+# CHECK-DWARF5: [[foo_SP:.*]]: DW_TAG_subprogram
+# CHECK-DWARF5-NEXT: DW_AT_name      ("foo")
+
+# CHECK-DWARF5: DW_TAG_call_site
+# CHECK-DWARF5:   DW_AT_call_origin ([[getValue_SP]])
+#
 # CHECK-DWARF5: DW_TAG_call_site
-# CHECK-DWARF5:   DW_AT_call_origin ([[foo_SP:.*]])
+# CHECK-DWARF5:   DW_AT_call_origin ([[foo_SP]])
 # CHECK-DWARF5:   DW_AT_call_return_pc {{.*}}
 # CHECK-DWARF5-EMPTY:
 # CHECK-DWARF5:         DW_TAG_call_site_parameter
@@ -65,12 +71,6 @@
 # CHECK-DWARF5-NEXT:      DW_AT_location      (DW_OP_reg8 R8)
 # CHECK-DWARF5-NEXT:      DW_AT_call_value   (DW_OP_breg14 R14+3)
 
-# CHECK-DWARF5: [[getValue_SP]]: DW_TAG_subprogram
-# CHECK-DWARF5-NEXT: DW_AT_name      ("getVal")
-
-# CHECK-DWARF5: [[foo_SP]]: DW_TAG_subprogram
-# CHECK-DWARF5-NEXT: DW_AT_name      ("foo")
-
 --- |
   ; ModuleID = 'test.c'
   source_filename = "test.c"