Add support for DebugFission to DWARF parser

Summary:
1) Make llvm-symbolizer properly symbolize
files with split debug info (by using stanalone .dwo files).
2) Make DWARFCompileUnit parse and store corresponding .dwo file,
if necessary.
3) Make bits of DWARF parsing more CompileUnit-oriented.

Reviewers: echristo

Reviewed By: echristo

CC: bkramer, llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1164

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189329 91177308-0d34-0410-b5e6-96231b3b80d8

lib/DebugInfo/DWARFCompileUnit.cpp

@@ -12,12 +12,31 @@
 #include "llvm/DebugInfo/DWARFFormValue.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 using namespace dwarf;
 
-DataExtractor DWARFCompileUnit::getDebugInfoExtractor() const {
-  return DataExtractor(InfoSection, isLittleEndian, AddrSize);
+bool DWARFCompileUnit::getAddrOffsetSectionItem(uint32_t Index,
+                                                uint64_t &Result) const {
+  uint32_t Offset = AddrOffsetSectionBase + Index * AddrSize;
+  if (AddrOffsetSection.size() < Offset + AddrSize)
+    return false;
+  DataExtractor DA(AddrOffsetSection, isLittleEndian, AddrSize);
+  Result = DA.getAddress(&Offset);
+  return true;
+}
+
+bool DWARFCompileUnit::getStringOffsetSectionItem(uint32_t Index,
+                                                  uint32_t &Result) const {
+  // FIXME: string offset section entries are 8-byte for DWARF64.
+  const uint32_t ItemSize = 4;
+  uint32_t Offset = Index * ItemSize;
+  if (StringOffsetSection.size() < Offset + ItemSize)
+    return false;
+  DataExtractor DA(StringOffsetSection, isLittleEndian, 0);
+  Result = DA.getU32(&Offset);
+  return true;
 }
 
 bool DWARFCompileUnit::extract(DataExtractor debug_info, uint32_t *offset_ptr) {
@@ -78,7 +97,8 @@ bool DWARFCompileUnit::extractRangeList(uint32_t RangeListOffset,
   // Require that compile unit is extracted.
   assert(DieArray.size() > 0);
   DataExtractor RangesData(RangeSection, isLittleEndian, AddrSize);
-  return RangeList.extract(RangesData, &RangeListOffset);
+  uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
+  return RangeList.extract(RangesData, &ActualRangeListOffset);
 }
 
 void DWARFCompileUnit::clear() {
@@ -88,7 +108,10 @@ void DWARFCompileUnit::clear() {
   Abbrevs = 0;
   AddrSize = 0;
   BaseAddr = 0;
+  RangeSectionBase = 0;
+  AddrOffsetSectionBase = 0;
   clearDIEs(false);
+  DWO.reset();
 }
 
 void DWARFCompileUnit::dump(raw_ostream &OS) {
@@ -112,6 +135,15 @@ const char *DWARFCompileUnit::getCompilationDir() {
   return DieArray[0].getAttributeValueAsString(this, DW_AT_comp_dir, 0);
 }
 
+uint64_t DWARFCompileUnit::getDWOId() {
+  extractDIEsIfNeeded(true);
+  const uint64_t FailValue = -1ULL;
+  if (DieArray.empty())
+    return FailValue;
+  return DieArray[0]
+      .getAttributeValueAsUnsigned(this, DW_AT_GNU_dwo_id, FailValue);
+}
+
 void DWARFCompileUnit::setDIERelations() {
   if (DieArray.empty())
     return;
@@ -207,21 +239,72 @@ size_t DWARFCompileUnit::extractDIEsIfNeeded(bool CUDieOnly) {
       DieArray.size() > 1)
     return 0; // Already parsed.
 
-  extractDIEsToVector(DieArray.empty(), !CUDieOnly, DieArray);
+  bool HasCUDie = DieArray.size() > 0;
+  extractDIEsToVector(!HasCUDie, !CUDieOnly, DieArray);
 
-  // Set the base address of current compile unit.
-  if (!DieArray.empty()) {
+  if (DieArray.empty())
+    return 0;
+
+  // If CU DIE was just parsed, copy several attribute values from it.
+  if (!HasCUDie) {
     uint64_t BaseAddr =
       DieArray[0].getAttributeValueAsUnsigned(this, DW_AT_low_pc, -1U);
     if (BaseAddr == -1U)
       BaseAddr = DieArray[0].getAttributeValueAsUnsigned(this, DW_AT_entry_pc, 0);
     setBaseAddress(BaseAddr);
+    AddrOffsetSectionBase =
+        DieArray[0].getAttributeValueAsReference(this, DW_AT_GNU_addr_base, 0);
+    RangeSectionBase =
+        DieArray[0].getAttributeValueAsReference(this, DW_AT_GNU_ranges_base, 0);
   }
 
   setDIERelations();
   return DieArray.size();
 }
 
+DWARFCompileUnit::DWOHolder::DWOHolder(object::ObjectFile *DWOFile)
+    : DWOFile(DWOFile),
+      DWOContext(cast<DWARFContext>(DIContext::getDWARFContext(DWOFile))),
+      DWOCU(0) {
+  if (DWOContext->getNumDWOCompileUnits() > 0)
+    DWOCU = DWOContext->getDWOCompileUnitAtIndex(0);
+}
+
+bool DWARFCompileUnit::parseDWO() {
+  if (DWO.get() != 0)
+    return false;
+  extractDIEsIfNeeded(true);
+  if (DieArray.empty())
+    return false;
+  const char *DWOFileName =
+      DieArray[0].getAttributeValueAsString(this, DW_AT_GNU_dwo_name, 0);
+  if (DWOFileName == 0)
+    return false;
+  const char *CompilationDir =
+      DieArray[0].getAttributeValueAsString(this, DW_AT_comp_dir, 0);
+  SmallString<16> AbsolutePath;
+  if (sys::path::is_relative(DWOFileName) && CompilationDir != 0) {
+    sys::path::append(AbsolutePath, CompilationDir);
+  }
+  sys::path::append(AbsolutePath, DWOFileName);
+  object::ObjectFile *DWOFile =
+      object::ObjectFile::createObjectFile(AbsolutePath);
+  if (!DWOFile)
+    return false;
+  // Reset DWOHolder.
+  DWO.reset(new DWOHolder(DWOFile));
+  DWARFCompileUnit *DWOCU = DWO->getCU();
+  // Verify that compile unit in .dwo file is valid.
+  if (DWOCU == 0 || DWOCU->getDWOId() != getDWOId()) {
+    DWO.reset();
+    return false;
+  }
+  // Share .debug_addr and .debug_ranges section with compile unit in .dwo
+  DWOCU->setAddrOffsetSection(AddrOffsetSection, AddrOffsetSectionBase);
+  DWOCU->setRangesSection(RangeSection, RangeSectionBase);
+  return true;
+}
+
 void DWARFCompileUnit::clearDIEs(bool KeepCUDie) {
   if (DieArray.size() > (unsigned)KeepCUDie) {
     // std::vectors never get any smaller when resized to a smaller size,
@@ -241,7 +324,8 @@ void DWARFCompileUnit::clearDIEs(bool KeepCUDie) {
 
 void
 DWARFCompileUnit::buildAddressRangeTable(DWARFDebugAranges *debug_aranges,
-                                         bool clear_dies_if_already_not_parsed){
+                                         bool clear_dies_if_already_not_parsed,
+                                         uint32_t CUOffsetInAranges) {
   // This function is usually called if there in no .debug_aranges section
   // in order to produce a compile unit level set of address ranges that
   // is accurate. If the DIEs weren't parsed, then we don't want all dies for
@@ -250,7 +334,17 @@ DWARFCompileUnit::buildAddressRangeTable(DWARFDebugAranges *debug_aranges,
   // down.
   const bool clear_dies = extractDIEsIfNeeded(false) > 1 &&
                           clear_dies_if_already_not_parsed;
-  DieArray[0].buildAddressRangeTable(this, debug_aranges);
+  DieArray[0].buildAddressRangeTable(this, debug_aranges, CUOffsetInAranges);
+  bool DWOCreated = parseDWO();
+  if (DWO.get()) {
+    // If there is a .dwo file for this compile unit, then skeleton CU DIE
+    // doesn't have children, and we should instead build address range table
+    // from DIEs in the .debug_info.dwo section of .dwo file.
+    DWO->getCU()->buildAddressRangeTable(
+        debug_aranges, clear_dies_if_already_not_parsed, CUOffsetInAranges);
+  }
+  if (DWOCreated && clear_dies_if_already_not_parsed)
+    DWO.reset();
 
   // Keep memory down by clearing DIEs if this generate function
   // caused them to be parsed.
@@ -258,21 +352,38 @@ DWARFCompileUnit::buildAddressRangeTable(DWARFDebugAranges *debug_aranges,
     clearDIEs(true);
 }
 
+const DWARFDebugInfoEntryMinimal *
+DWARFCompileUnit::getSubprogramForAddress(uint64_t Address) {
+  extractDIEsIfNeeded(false);
+  for (size_t i = 0, n = DieArray.size(); i != n; i++)
+    if (DieArray[i].isSubprogramDIE() &&
+        DieArray[i].addressRangeContainsAddress(this, Address)) {
+      return &DieArray[i];
+    }
+  return 0;
+}
+
 DWARFDebugInfoEntryInlinedChain
 DWARFCompileUnit::getInlinedChainForAddress(uint64_t Address) {
   // First, find a subprogram that contains the given address (the root
   // of inlined chain).
-  extractDIEsIfNeeded(false);
-  const DWARFDebugInfoEntryMinimal *SubprogramDIE = 0;
-  for (size_t i = 0, n = DieArray.size(); i != n; i++) {
-    if (DieArray[i].isSubprogramDIE() &&
-        DieArray[i].addressRangeContainsAddress(this, Address)) {
-      SubprogramDIE = &DieArray[i];
-      break;
+  const DWARFCompileUnit *ChainCU = 0;
+  const DWARFDebugInfoEntryMinimal *SubprogramDIE =
+      getSubprogramForAddress(Address);
+  if (SubprogramDIE) {
+    ChainCU = this;
+  } else {
+    // Try to look for subprogram DIEs in the DWO file.
+    parseDWO();
+    if (DWO.get()) {
+      SubprogramDIE = DWO->getCU()->getSubprogramForAddress(Address);
+      if (SubprogramDIE)
+        ChainCU = DWO->getCU();
     }
   }
+
   // Get inlined chain rooted at this subprogram DIE.
   if (!SubprogramDIE)
     return DWARFDebugInfoEntryInlinedChain();
-  return SubprogramDIE->getInlinedChainForAddress(this, Address);
-}
+  return SubprogramDIE->getInlinedChainForAddress(ChainCU, Address);
+ }