[llvm] r347134 - llvm-symbolizer: Avoid calling getFromOffset when the index entry is already available

[David Blaikie via llvm-commits]

Author: dblaikie
Date: Fri Nov 16 21:57:58 2018
New Revision: 347134

URL: http://llvm.org/viewvc/llvm-project?rev=347134&view=rev
Log:
llvm-symbolizer: Avoid calling getFromOffset when the index entry is already available

Especially for symbolizer it can be efficient to have to search through
the entire index when it isn't needed - llvm-symbolizer looks up only a
few CUs & already has an index available in getUnitForEntry, once it's
passed down to DWARFUnitHeader::extract then there's no need for it to
call getFromOffset.

Modified:
    llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFUnit.h
    llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp

Modified: llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFUnit.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFUnit.h?rev=347134&r1=347133&r2=347134&view=diff
==============================================================================
--- llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFUnit.h (original)
+++ llvm/trunk/include/llvm/DebugInfo/DWARF/DWARFUnit.h Fri Nov 16 21:57:58 2018
@@ -72,7 +72,8 @@ public:
   /// Parse a unit header from \p debug_info starting at \p offset_ptr.
   bool extract(DWARFContext &Context, const DWARFDataExtractor &debug_info,
                uint32_t *offset_ptr, DWARFSectionKind Kind = DW_SECT_INFO,
-               const DWARFUnitIndex *Index = nullptr);
+               const DWARFUnitIndex *Index = nullptr,
+               const DWARFUnitIndex::Entry *Entry = nullptr);
   uint32_t getOffset() const { return Offset; }
   const dwarf::FormParams &getFormParams() const { return FormParams; }
   uint16_t getVersion() const { return FormParams.Version; }
@@ -108,7 +109,8 @@ const DWARFUnitIndex &getDWARFUnitIndex(
 /// .debug_info and .debug_types, or from .debug_info.dwo and .debug_types.dwo.
 class DWARFUnitVector final : public SmallVector<std::unique_ptr<DWARFUnit>, 1> {
   std::function<std::unique_ptr<DWARFUnit>(uint32_t, DWARFSectionKind,
-                                           const DWARFSection *)>
+                                           const DWARFSection *,
+                                           const DWARFUnitIndex::Entry *)>
       Parser;
   int NumInfoUnits = -1;
 

Modified: llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp?rev=347134&r1=347133&r2=347134&view=diff
==============================================================================
--- llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp (original)
+++ llvm/trunk/lib/DebugInfo/DWARF/DWARFUnit.cpp Fri Nov 16 21:57:58 2018
@@ -66,9 +66,11 @@ void DWARFUnitVector::addUnitsImpl(
   DWARFDataExtractor Data(Obj, Section, LE, 0);
   // Lazy initialization of Parser, now that we have all section info.
   if (!Parser) {
-    Parser = [=, &Context, &Obj, &Section, &SOS, &LS](
-                 uint32_t Offset, DWARFSectionKind SectionKind,
-                 const DWARFSection *CurSection) -> std::unique_ptr<DWARFUnit> {
+    Parser = [=, &Context, &Obj, &Section, &SOS,
+              &LS](uint32_t Offset, DWARFSectionKind SectionKind,
+                   const DWARFSection *CurSection,
+                   const DWARFUnitIndex::Entry *IndexEntry)
+        -> std::unique_ptr<DWARFUnit> {
       const DWARFSection &InfoSection = CurSection ? *CurSection : Section;
       DWARFDataExtractor Data(Obj, InfoSection, LE, 0);
       if (!Data.isValidOffset(Offset))
@@ -77,7 +79,8 @@ void DWARFUnitVector::addUnitsImpl(
       if (IsDWO)
         Index = &getDWARFUnitIndex(Context, SectionKind);
       DWARFUnitHeader Header;
-      if (!Header.extract(Context, Data, &Offset, SectionKind, Index))
+      if (!Header.extract(Context, Data, &Offset, SectionKind, Index,
+                          IndexEntry))
         return nullptr;
       std::unique_ptr<DWARFUnit> U;
       if (Header.isTypeUnit())
@@ -106,7 +109,7 @@ void DWARFUnitVector::addUnitsImpl(
       ++I;
       continue;
     }
-    auto U = Parser(Offset, SectionKind, &Section);
+    auto U = Parser(Offset, SectionKind, &Section, nullptr);
     // If parsing failed, we're done with this section.
     if (!U)
       break;
@@ -156,7 +159,7 @@ DWARFUnitVector::getUnitForIndexEntry(co
   if (!Parser)
     return nullptr;
 
-  auto U = Parser(Offset, DW_SECT_INFO, nullptr);
+  auto U = Parser(Offset, DW_SECT_INFO, nullptr, &E);
   if (!U)
     U = nullptr;
 
@@ -233,9 +236,12 @@ bool DWARFUnitHeader::extract(DWARFConte
                               const DWARFDataExtractor &debug_info,
                               uint32_t *offset_ptr,
                               DWARFSectionKind SectionKind,
-                              const DWARFUnitIndex *Index) {
+                              const DWARFUnitIndex *Index,
+                              const DWARFUnitIndex::Entry *Entry) {
   Offset = *offset_ptr;
-  IndexEntry = Index ? Index->getFromOffset(*offset_ptr) : nullptr;
+  IndexEntry = Entry;
+  if (!IndexEntry && Index)
+    IndexEntry = Index->getFromOffset(*offset_ptr);
   Length = debug_info.getU32(offset_ptr);
   // FIXME: Support DWARF64.
   unsigned SizeOfLength = 4;