AsmPrinter: Change DIEValue to be stored by value

Change `DIEValue` to be stored/passed/etc. by value, instead of
reference.  It's now a discriminated union, with a `Val` field storing
the actual type.  The classes that used to inherit from `DIEValue` no
longer do.  There are two categories of these:

  - Small values fit in a single pointer and are stored by value.
  - Large values require auxiliary storage, and are stored by reference.

The only non-mechanical change is to tools/dsymutil/DwarfLinker.cpp.  It
was relying on `DIEInteger`s being passed around by reference, so I
replaced that assumption with a `PatchLocation` type that stores a safe
reference to where the `DIEInteger` lives instead.

This commit causes a temporary regression in memory usage, since I've
left merging `DIEAbbrevData` into `DIEValue` for a follow-up commit.  I
measured an increase from 845 MB to 879 MB, around 3.9%.  The follow-up
drops it lower than the starting point, and I've only recently brought
the memory this low anyway, so I'm committing these changes separately
to keep them incremental.  (I also considered swapping the commits, but
the other one first would cause a lot more code churn.)

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

llvm-svn: 238349

1 files changed, 51 insertions, 49 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
index 1ccffe97b80..a3c79d938b6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -128,8 +128,8 @@ const DIE *DIE::getUnitOrNull() const {
   return nullptr;
 }
 
-DIEValue *DIE::findAttribute(dwarf::Attribute Attribute) const {
-  const SmallVectorImpl<DIEValue *> &Values = getValues();
+DIEValue DIE::findAttribute(dwarf::Attribute Attribute) const {
+  const SmallVectorImpl<DIEValue> &Values = getValues();
   const DIEAbbrev &Abbrevs = getAbbrev();
 
   // Iterate through all the attributes until we find the one we're
@@ -137,7 +137,7 @@ DIEValue *DIE::findAttribute(dwarf::Attribute Attribute) const {
   for (size_t i = 0; i < Values.size(); ++i)
     if (Abbrevs.getData()[i].getAttribute() == Attribute)
       return Values[i];
-  return nullptr;
+  return DIEValue();
 }
 
 #ifndef NDEBUG
@@ -174,7 +174,7 @@ void DIE::print(raw_ostream &O, unsigned IndentCount) const {
     O <<  "  "
       << dwarf::FormEncodingString(Data[i].getForm())
       << " ";
-    Values[i]->print(O);
+    Values[i].print(O);
     O << "\n";
   }
   IndentCount -= 2;
@@ -193,9 +193,11 @@ void DIE::dump() {
 
 void DIEValue::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
   switch (Ty) {
+  case isNone:
+    llvm_unreachable("Expected valid DIEValue");
 #define EMIT_VALUE_IMPL(Kind)                                                  \
   case is##Kind:                                                               \
-    cast<DIE##Kind>(this)->EmitValueImpl(AP, Form);                            \
+    getDIE##Kind().EmitValue(AP, Form);                                        \
     break;
     EMIT_VALUE_IMPL(Integer)
     EMIT_VALUE_IMPL(String)
@@ -213,9 +215,11 @@ void DIEValue::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
 
 unsigned DIEValue::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   switch (Ty) {
+  case isNone:
+    llvm_unreachable("Expected valid DIEValue");
 #define SIZE_OF_IMPL(Kind)                                                     \
   case is##Kind:                                                               \
-    return cast<DIE##Kind>(this)->SizeOfImpl(AP, Form);
+    return getDIE##Kind().SizeOf(AP, Form);
     SIZE_OF_IMPL(Integer)
     SIZE_OF_IMPL(String)
     SIZE_OF_IMPL(Expr)
@@ -234,9 +238,11 @@ unsigned DIEValue::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
 #ifndef NDEBUG
 void DIEValue::print(raw_ostream &O) const {
   switch (Ty) {
+  case isNone:
+    llvm_unreachable("Expected valid DIEValue");
 #define PRINT_IMPL(Kind)                                                       \
   case is##Kind:                                                               \
-    cast<DIE##Kind>(this)->printImpl(O);                                       \
+    getDIE##Kind().print(O);                                                   \
     break;
     PRINT_IMPL(Integer)
     PRINT_IMPL(String)
@@ -263,7 +269,7 @@ void DIEValue::dump() const {
 
 /// EmitValue - Emit integer of appropriate size.
 ///
-void DIEInteger::EmitValueImpl(const AsmPrinter *Asm, dwarf::Form Form) const {
+void DIEInteger::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
   unsigned Size = ~0U;
   switch (Form) {
   case dwarf::DW_FORM_flag_present:
@@ -299,7 +305,7 @@ void DIEInteger::EmitValueImpl(const AsmPrinter *Asm, dwarf::Form Form) const {
 
 /// SizeOf - Determine size of integer value in bytes.
 ///
-unsigned DIEInteger::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIEInteger::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   switch (Form) {
   case dwarf::DW_FORM_flag_present: return 0;
   case dwarf::DW_FORM_flag:  // Fall thru
@@ -328,7 +334,7 @@ unsigned DIEInteger::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIEInteger::printImpl(raw_ostream &O) const {
+void DIEInteger::print(raw_ostream &O) const {
   O << "Int: " << (int64_t)Integer << "  0x";
   O.write_hex(Integer);
 }
@@ -340,13 +346,13 @@ void DIEInteger::printImpl(raw_ostream &O) const {
 
 /// EmitValue - Emit expression value.
 ///
-void DIEExpr::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+void DIEExpr::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
   AP->OutStreamer->EmitValue(Expr, SizeOf(AP, Form));
 }
 
 /// SizeOf - Determine size of expression value in bytes.
 ///
-unsigned DIEExpr::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIEExpr::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   if (Form == dwarf::DW_FORM_data4) return 4;
   if (Form == dwarf::DW_FORM_sec_offset) return 4;
   if (Form == dwarf::DW_FORM_strp) return 4;
@@ -354,7 +360,7 @@ unsigned DIEExpr::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIEExpr::printImpl(raw_ostream &O) const { O << "Expr: " << *Expr; }
+void DIEExpr::print(raw_ostream &O) const { O << "Expr: " << *Expr; }
 #endif
 
 //===----------------------------------------------------------------------===//
@@ -363,7 +369,7 @@ void DIEExpr::printImpl(raw_ostream &O) const { O << "Expr: " << *Expr; }
 
 /// EmitValue - Emit label value.
 ///
-void DIELabel::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+void DIELabel::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
   AP->EmitLabelReference(Label, SizeOf(AP, Form),
                          Form == dwarf::DW_FORM_strp ||
                              Form == dwarf::DW_FORM_sec_offset ||
@@ -372,7 +378,7 @@ void DIELabel::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 
 /// SizeOf - Determine size of label value in bytes.
 ///
-unsigned DIELabel::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIELabel::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   if (Form == dwarf::DW_FORM_data4) return 4;
   if (Form == dwarf::DW_FORM_sec_offset) return 4;
   if (Form == dwarf::DW_FORM_strp) return 4;
@@ -380,9 +386,7 @@ unsigned DIELabel::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIELabel::printImpl(raw_ostream &O) const {
-  O << "Lbl: " << Label->getName();
-}
+void DIELabel::print(raw_ostream &O) const { O << "Lbl: " << Label->getName(); }
 #endif
 
 //===----------------------------------------------------------------------===//
@@ -391,13 +395,13 @@ void DIELabel::printImpl(raw_ostream &O) const {
 
 /// EmitValue - Emit delta value.
 ///
-void DIEDelta::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+void DIEDelta::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
   AP->EmitLabelDifference(LabelHi, LabelLo, SizeOf(AP, Form));
 }
 
 /// SizeOf - Determine size of delta value in bytes.
 ///
-unsigned DIEDelta::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIEDelta::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   if (Form == dwarf::DW_FORM_data4) return 4;
   if (Form == dwarf::DW_FORM_sec_offset) return 4;
   if (Form == dwarf::DW_FORM_strp) return 4;
@@ -405,7 +409,7 @@ unsigned DIEDelta::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIEDelta::printImpl(raw_ostream &O) const {
+void DIEDelta::print(raw_ostream &O) const {
   O << "Del: " << LabelHi->getName() << "-" << LabelLo->getName();
 }
 #endif
@@ -416,7 +420,7 @@ void DIEDelta::printImpl(raw_ostream &O) const {
 
 /// EmitValue - Emit string value.
 ///
-void DIEString::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+void DIEString::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
   assert(
       (Form == dwarf::DW_FORM_strp || Form == dwarf::DW_FORM_GNU_str_index) &&
       "Expected valid string form");
@@ -440,7 +444,7 @@ void DIEString::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 
 /// SizeOf - Determine size of delta value in bytes.
 ///
-unsigned DIEString::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIEString::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   assert(
       (Form == dwarf::DW_FORM_strp || Form == dwarf::DW_FORM_GNU_str_index) &&
       "Expected valid string form");
@@ -458,7 +462,7 @@ unsigned DIEString::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIEString::printImpl(raw_ostream &O) const {
+void DIEString::print(raw_ostream &O) const {
   O << "String: " << S.getString();
 }
 #endif
@@ -469,16 +473,16 @@ void DIEString::printImpl(raw_ostream &O) const {
 
 /// EmitValue - Emit debug information entry offset.
 ///
-void DIEEntry::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+void DIEEntry::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
 
   if (Form == dwarf::DW_FORM_ref_addr) {
     const DwarfDebug *DD = AP->getDwarfDebug();
-    unsigned Addr = Entry.getOffset();
+    unsigned Addr = Entry->getOffset();
     assert(!DD->useSplitDwarf() && "TODO: dwo files can't have relocations.");
     // For DW_FORM_ref_addr, output the offset from beginning of debug info
     // section. Entry->getOffset() returns the offset from start of the
     // compile unit.
-    DwarfCompileUnit *CU = DD->lookupUnit(Entry.getUnit());
+    DwarfCompileUnit *CU = DD->lookupUnit(Entry->getUnit());
     assert(CU && "CUDie should belong to a CU.");
     Addr += CU->getDebugInfoOffset();
     if (AP->MAI->doesDwarfUseRelocationsAcrossSections())
@@ -487,7 +491,7 @@ void DIEEntry::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
     else
       AP->OutStreamer->EmitIntValue(Addr, DIEEntry::getRefAddrSize(AP));
   } else
-    AP->EmitInt32(Entry.getOffset());
+    AP->EmitInt32(Entry->getOffset());
 }
 
 unsigned DIEEntry::getRefAddrSize(const AsmPrinter *AP) {
@@ -503,7 +507,7 @@ unsigned DIEEntry::getRefAddrSize(const AsmPrinter *AP) {
 }
 
 #ifndef NDEBUG
-void DIEEntry::printImpl(raw_ostream &O) const {
+void DIEEntry::print(raw_ostream &O) const {
   O << format("Die: 0x%lx", (long)(intptr_t)&Entry);
 }
 #endif
@@ -511,14 +515,15 @@ void DIEEntry::printImpl(raw_ostream &O) const {
 //===----------------------------------------------------------------------===//
 // DIETypeSignature Implementation
 //===----------------------------------------------------------------------===//
-void DIETypeSignature::EmitValueImpl(const AsmPrinter *Asm, dwarf::Form Form) const {
+void DIETypeSignature::EmitValue(const AsmPrinter *Asm,
+                                 dwarf::Form Form) const {
   assert(Form == dwarf::DW_FORM_ref_sig8);
-  Asm->OutStreamer->EmitIntValue(Unit.getTypeSignature(), 8);
+  Asm->OutStreamer->EmitIntValue(Unit->getTypeSignature(), 8);
 }
 
 #ifndef NDEBUG
-void DIETypeSignature::printImpl(raw_ostream &O) const {
-  O << format("Type Unit: 0x%lx", Unit.getTypeSignature());
+void DIETypeSignature::print(raw_ostream &O) const {
+  O << format("Type Unit: 0x%lx", Unit->getTypeSignature());
 }
 #endif
 
@@ -532,7 +537,7 @@ unsigned DIELoc::ComputeSize(const AsmPrinter *AP) const {
   if (!Size) {
     const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
     for (unsigned i = 0, N = Values.size(); i < N; ++i)
-      Size += Values[i]->SizeOf(AP, AbbrevData[i].getForm());
+      Size += Values[i].SizeOf(AP, AbbrevData[i].getForm());
   }
 
   return Size;
@@ -540,7 +545,7 @@ unsigned DIELoc::ComputeSize(const AsmPrinter *AP) const {
 
 /// EmitValue - Emit location data.
 ///
-void DIELoc::EmitValueImpl(const AsmPrinter *Asm, dwarf::Form Form) const {
+void DIELoc::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
   switch (Form) {
   default: llvm_unreachable("Improper form for block");
   case dwarf::DW_FORM_block1: Asm->EmitInt8(Size);    break;
@@ -553,12 +558,12 @@ void DIELoc::EmitValueImpl(const AsmPrinter *Asm, dwarf::Form Form) const {
 
   const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
   for (unsigned i = 0, N = Values.size(); i < N; ++i)
-    Values[i]->EmitValue(Asm, AbbrevData[i].getForm());
+    Values[i].EmitValue(Asm, AbbrevData[i].getForm());
 }
 
 /// SizeOf - Determine size of location data in bytes.
 ///
-unsigned DIELoc::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIELoc::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   switch (Form) {
   case dwarf::DW_FORM_block1: return Size + sizeof(int8_t);
   case dwarf::DW_FORM_block2: return Size + sizeof(int16_t);
@@ -571,7 +576,7 @@ unsigned DIELoc::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIELoc::printImpl(raw_ostream &O) const {
+void DIELoc::print(raw_ostream &O) const {
   O << "ExprLoc: ";
   DIE::print(O, 5);
 }
@@ -587,7 +592,7 @@ unsigned DIEBlock::ComputeSize(const AsmPrinter *AP) const {
   if (!Size) {
     const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
     for (unsigned i = 0, N = Values.size(); i < N; ++i)
-      Size += Values[i]->SizeOf(AP, AbbrevData[i].getForm());
+      Size += Values[i].SizeOf(AP, AbbrevData[i].getForm());
   }
 
   return Size;
@@ -595,7 +600,7 @@ unsigned DIEBlock::ComputeSize(const AsmPrinter *AP) const {
 
 /// EmitValue - Emit block data.
 ///
-void DIEBlock::EmitValueImpl(const AsmPrinter *Asm, dwarf::Form Form) const {
+void DIEBlock::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
   switch (Form) {
   default: llvm_unreachable("Improper form for block");
   case dwarf::DW_FORM_block1: Asm->EmitInt8(Size);    break;
@@ -606,12 +611,12 @@ void DIEBlock::EmitValueImpl(const AsmPrinter *Asm, dwarf::Form Form) const {
 
   const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
   for (unsigned i = 0, N = Values.size(); i < N; ++i)
-    Values[i]->EmitValue(Asm, AbbrevData[i].getForm());
+    Values[i].EmitValue(Asm, AbbrevData[i].getForm());
 }
 
 /// SizeOf - Determine size of block data in bytes.
 ///
-unsigned DIEBlock::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIEBlock::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   switch (Form) {
   case dwarf::DW_FORM_block1: return Size + sizeof(int8_t);
   case dwarf::DW_FORM_block2: return Size + sizeof(int16_t);
@@ -622,7 +627,7 @@ unsigned DIEBlock::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIEBlock::printImpl(raw_ostream &O) const {
+void DIEBlock::print(raw_ostream &O) const {
   O << "Blk: ";
   DIE::print(O, 5);
 }
@@ -632,7 +637,7 @@ void DIEBlock::printImpl(raw_ostream &O) const {
 // DIELocList Implementation
 //===----------------------------------------------------------------------===//
 
-unsigned DIELocList::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+unsigned DIELocList::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   if (Form == dwarf::DW_FORM_data4)
     return 4;
   if (Form == dwarf::DW_FORM_sec_offset)
@@ -642,7 +647,7 @@ unsigned DIELocList::SizeOfImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 
 /// EmitValue - Emit label value.
 ///
-void DIELocList::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
+void DIELocList::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
   DwarfDebug *DD = AP->getDwarfDebug();
   MCSymbol *Label = DD->getDebugLocs().getList(Index).Label;
 
@@ -653,8 +658,5 @@ void DIELocList::EmitValueImpl(const AsmPrinter *AP, dwarf::Form Form) const {
 }
 
 #ifndef NDEBUG
-void DIELocList::printImpl(raw_ostream &O) const {
-  O << "LocList: " << Index;
-
-}
+void DIELocList::print(raw_ostream &O) const { O << "LocList: " << Index; }
 #endif