[DebugInfo/DWARF] [1/4] De-templatize DWARFUnitSection. NFC

This is patch 1 of 4 NFC refactorings to handle type units and compile
units more consistently and with less concern about the object-file
section that they came from.

Patch 1 replaces the templated DWARFUnitSection with a non-templated
version. That is, instead of being a SmallVector of pointers to a
specific unit kind, it is not a SmallVector of pointers to the base
class for both type and compile units.  Virtual methods are magic.

Differential Revision: https://reviews.llvm.org/D49741

llvm-svn: 338628
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index 9d2554f..a26ebba0 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -584,11 +584,11 @@
 }
 
 DWARFCompileUnit *DWARFContext::getDWOCompileUnitForHash(uint64_t Hash) {
-  DWOCUs.parseDWO(*this, DObj->getInfoDWOSection(), true);
+  DWOCUs.parseDWO(*this, DObj->getInfoDWOSection(), DW_SECT_INFO, true);
 
   if (const auto &CUI = getCUIndex()) {
     if (const auto *R = CUI.getFromHash(Hash))
-      return DWOCUs.getUnitForIndexEntry(*R);
+      return dyn_cast_or_null<DWARFCompileUnit>(DWOCUs.getUnitForIndexEntry(*R));
     return nullptr;
   }
 
@@ -607,7 +607,7 @@
         continue;
     }
     if (DWOCU->getDWOId() == Hash)
-      return DWOCU.get();
+      return dyn_cast<DWARFCompileUnit>(DWOCU.get());
   }
   return nullptr;
 }
@@ -690,10 +690,10 @@
     return Loc.get();
 
   Loc.reset(new DWARFDebugLoc);
-  // Assume all compile units have the same address byte size.
+  // Assume all units have the same address byte size.
   if (getNumCompileUnits()) {
     DWARFDataExtractor LocData(*DObj, DObj->getLocSection(), isLittleEndian(),
-                               getCompileUnitAtIndex(0)->getAddressByteSize());
+                               getUnitAtIndex(0)->getAddressByteSize());
     Loc->parse(LocData);
   }
   return Loc.get();
@@ -707,7 +707,7 @@
   // Assume all compile units have the same address byte size.
   if (getNumCompileUnits()) {
     DataExtractor LocData(DObj->getLocDWOSection().Data, isLittleEndian(),
-                          getCompileUnitAtIndex(0)->getAddressByteSize());
+                          getUnitAtIndex(0)->getAddressByteSize());
     LocDWO->parse(LocData);
   }
   return LocDWO.get();
@@ -844,7 +844,7 @@
 }
 
 void DWARFContext::parseCompileUnits() {
-  CUs.parse(*this, DObj->getInfoSection());
+  CUs.parse(*this, DObj->getInfoSection(), DW_SECT_INFO);
 }
 
 void DWARFContext::parseTypeUnits() {
@@ -852,12 +852,12 @@
     return;
   DObj->forEachTypesSections([&](const DWARFSection &S) {
     TUs.emplace_back();
-    TUs.back().parse(*this, S);
+    TUs.back().parse(*this, S, DW_SECT_TYPES);
   });
 }
 
 void DWARFContext::parseDWOCompileUnits() {
-  DWOCUs.parseDWO(*this, DObj->getInfoDWOSection());
+  DWOCUs.parseDWO(*this, DObj->getInfoDWOSection(), DW_SECT_INFO);
 }
 
 void DWARFContext::parseDWOTypeUnits() {
@@ -865,13 +865,13 @@
     return;
   DObj->forEachTypesDWOSections([&](const DWARFSection &S) {
     DWOTUs.emplace_back();
-    DWOTUs.back().parseDWO(*this, S);
+    DWOTUs.back().parseDWO(*this, S, DW_SECT_TYPES);
   });
 }
 
 DWARFCompileUnit *DWARFContext::getCompileUnitForOffset(uint32_t Offset) {
   parseCompileUnits();
-  return CUs.getUnitForOffset(Offset);
+  return dyn_cast_or_null<DWARFCompileUnit>(CUs.getUnitForOffset(Offset));
 }
 
 DWARFCompileUnit *DWARFContext::getCompileUnitForAddress(uint64_t Address) {
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
index 3b40885..766234a 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
@@ -11,12 +11,14 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
+#include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugRnglists.h"
 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
+#include "llvm/DebugInfo/DWARF/DWARFTypeUnit.h"
 #include "llvm/Support/DataExtractor.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/WithColor.h"
@@ -31,21 +33,112 @@
 using namespace llvm;
 using namespace dwarf;
 
-void DWARFUnitSectionBase::parse(DWARFContext &C, const DWARFSection &Section) {
+void DWARFUnitSection::parse(DWARFContext &C, const DWARFSection &Section,
+                             DWARFSectionKind SectionKind) {
   const DWARFObject &D = C.getDWARFObj();
   parseImpl(C, D, Section, C.getDebugAbbrev(), &D.getRangeSection(),
             D.getStringSection(), D.getStringOffsetSection(),
             &D.getAddrSection(), D.getLineSection(), D.isLittleEndian(), false,
-            false);
+            false, SectionKind);
 }
 
-void DWARFUnitSectionBase::parseDWO(DWARFContext &C,
-                                    const DWARFSection &DWOSection, bool Lazy) {
+void DWARFUnitSection::parseDWO(DWARFContext &C,
+                                const DWARFSection &DWOSection,
+                                DWARFSectionKind SectionKind, bool Lazy) {
   const DWARFObject &D = C.getDWARFObj();
   parseImpl(C, D, DWOSection, C.getDebugAbbrevDWO(), &D.getRangeDWOSection(),
             D.getStringDWOSection(), D.getStringOffsetDWOSection(),
             &D.getAddrSection(), D.getLineDWOSection(), C.isLittleEndian(),
-            true, Lazy);
+            true, Lazy, SectionKind);
+}
+
+void DWARFUnitSection::parseImpl(DWARFContext &Context, const DWARFObject &Obj,
+               const DWARFSection &Section, const DWARFDebugAbbrev *DA,
+               const DWARFSection *RS, StringRef SS, const DWARFSection &SOS,
+               const DWARFSection *AOS, const DWARFSection &LS, bool LE,
+               bool IsDWO, bool Lazy, DWARFSectionKind SectionKind) {
+  if (Parsed)
+    return;
+  DWARFDataExtractor Data(Obj, Section, LE, 0);
+  // Lazy initialization of Parser, now that we have all section info.
+  if (!Parser) {
+    const DWARFUnitIndex *Index = nullptr;
+    if (IsDWO)
+      Index = &getDWARFUnitIndex(Context, SectionKind);
+    Parser = [=, &Context, &Section, &SOS,
+      &LS](uint32_t Offset) -> std::unique_ptr<DWARFUnit> {
+      if (!Data.isValidOffset(Offset))
+        return nullptr;
+      DWARFUnitHeader Header;
+      if (!Header.extract(Context, Data, &Offset, SectionKind, Index))
+        return nullptr;
+      std::unique_ptr<DWARFUnit> U;
+      if (Header.isTypeUnit())
+        U = llvm::make_unique<DWARFTypeUnit>(
+          Context, Section, Header, DA, RS, SS, SOS, AOS, LS, LE, IsDWO,
+          *this);
+      else
+        U = llvm::make_unique<DWARFCompileUnit>(
+          Context, Section, Header, DA, RS, SS, SOS, AOS, LS, LE, IsDWO,
+          *this);
+      return U;
+    };
+  }
+  if (Lazy)
+    return;
+  auto I = this->begin();
+  uint32_t Offset = 0;
+  while (Data.isValidOffset(Offset)) {
+    if (I != this->end() && (*I)->getOffset() == Offset) {
+      ++I;
+      continue;
+    }
+    auto U = Parser(Offset);
+    if (!U)
+      break;
+    Offset = U->getNextUnitOffset();
+    I = std::next(this->insert(I, std::move(U)));
+  }
+  Parsed = true;
+}
+
+DWARFUnit *DWARFUnitSection::getUnitForOffset(uint32_t Offset) const {
+  auto *CU = std::upper_bound(
+    this->begin(), this->end(), Offset,
+    [](uint32_t LHS, const std::unique_ptr<DWARFUnit> &RHS) {
+    return LHS < RHS->getNextUnitOffset();
+  });
+  if (CU != this->end() && (*CU)->getOffset() <= Offset)
+    return CU->get();
+  return nullptr;
+}
+
+DWARFUnit *
+DWARFUnitSection::getUnitForIndexEntry(const DWARFUnitIndex::Entry &E) {
+  const auto *CUOff = E.getOffset(DW_SECT_INFO);
+  if (!CUOff)
+    return nullptr;
+
+  auto Offset = CUOff->Offset;
+
+  auto *CU = std::upper_bound(
+    this->begin(), this->end(), CUOff->Offset,
+    [](uint32_t LHS, const std::unique_ptr<DWARFUnit> &RHS) {
+    return LHS < RHS->getNextUnitOffset();
+  });
+  if (CU != this->end() && (*CU)->getOffset() <= Offset)
+    return CU->get();
+
+  if (!Parser)
+    return nullptr;
+
+  auto U = Parser(Offset);
+  if (!U)
+    U = nullptr;
+
+  auto *NewCU = U.get();
+  this->insert(CU, std::move(U));
+  return NewCU;
 }
 
 DWARFUnit::DWARFUnit(DWARFContext &DC, const DWARFSection &Section,
@@ -53,7 +146,7 @@
                      const DWARFDebugAbbrev *DA, const DWARFSection *RS,
                      StringRef SS, const DWARFSection &SOS,
                      const DWARFSection *AOS, const DWARFSection &LS, bool LE,
-                     bool IsDWO, const DWARFUnitSectionBase &UnitSection)
+                     bool IsDWO, const DWARFUnitSection &UnitSection)
     : Context(DC), InfoSection(Section), Header(Header), Abbrev(DA),
       RangeSection(RS), LineSection(LS), StringSection(SS),
       StringOffsetSection(SOS),  AddrOffsetSection(AOS), isLittleEndian(LE),
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp b/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
index 82d52c4..cf1bdc2 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp
@@ -264,8 +264,7 @@
   bool isUnitDWARF64 = false;
   bool isHeaderChainValid = true;
   bool hasDIE = DebugInfoData.isValidOffset(Offset);
-  DWARFUnitSection<DWARFTypeUnit> TUSection{};
-  DWARFUnitSection<DWARFCompileUnit> CUSection{};
+  DWARFUnitSection UnitSection{};
   while (hasDIE) {
     OffsetStart = Offset;
     if (!verifyUnitHeader(DebugInfoData, &Offset, UnitIdx, UnitType,
@@ -284,7 +283,7 @@
             DCtx, DObj.getInfoSection(), Header, DCtx.getDebugAbbrev(),
             &DObj.getRangeSection(), DObj.getStringSection(),
             DObj.getStringOffsetSection(), &DObj.getAppleObjCSection(),
-            DObj.getLineSection(), DCtx.isLittleEndian(), false, TUSection));
+            DObj.getLineSection(), DCtx.isLittleEndian(), false, UnitSection));
         break;
       }
       case dwarf::DW_UT_skeleton:
@@ -298,7 +297,7 @@
             DCtx, DObj.getInfoSection(), Header, DCtx.getDebugAbbrev(),
             &DObj.getRangeSection(), DObj.getStringSection(),
             DObj.getStringOffsetSection(), &DObj.getAppleObjCSection(),
-            DObj.getLineSection(), DCtx.isLittleEndian(), false, CUSection));
+            DObj.getLineSection(), DCtx.isLittleEndian(), false, UnitSection));
         break;
       }
       default: { llvm_unreachable("Invalid UnitType."); }
@@ -1315,11 +1314,12 @@
   if (NumErrors > 0)
     return NumErrors;
 
-  for (const std::unique_ptr<DWARFCompileUnit> &CU : DCtx.compile_units()) {
+  for (const std::unique_ptr<DWARFUnit> &U : DCtx.compile_units()) {
     if (const DWARFDebugNames::NameIndex *NI =
-            AccelTable.getCUNameIndex(CU->getOffset())) {
+            AccelTable.getCUNameIndex(U->getOffset())) {
+      auto *CU = cast<DWARFCompileUnit>(U.get());
       for (const DWARFDebugInfoEntry &Die : CU->dies())
-        NumErrors += verifyNameIndexCompleteness(DWARFDie(CU.get(), &Die), *NI);
+        NumErrors += verifyNameIndexCompleteness(DWARFDie(CU, &Die), *NI);
     }
   }
   return NumErrors;