[PATCH] D54968: [ELF] --gdb-index: use const char *, uint32_t to replace CachedHashStringRef

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added a reviewer: ruiu.
Herald added subscribers: llvm-commits, arphaman, arichardson, emaste.
Herald added a reviewer: espindola.

This decreases the size of NameAttrEntry from 20 bytes to 16 bytes on 64-bit platforms.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D54968

Files:
  ELF/SyntheticSections.cpp
  ELF/SyntheticSections.h


Index: ELF/SyntheticSections.h
===================================================================
--- ELF/SyntheticSections.h
+++ ELF/SyntheticSections.h
@@ -684,7 +684,8 @@
   };
 
   struct NameAttrEntry {
-    llvm::CachedHashStringRef Name;
+    const char *Name;
+    uint32_t NameHash;
     uint32_t CuIndexAndAttrs;
   };
 
Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -2433,7 +2433,7 @@
       while (I < CUs.size() && CUs[I].CuOffset < Set.Offset)
         ++I;
       for (const DWARFDebugPubTable::Entry &Ent : Set.Entries)
-        Ret.push_back({{Ent.Name, computeGdbHash(Ent.Name)},
+        Ret.push_back({Ent.Name.data(), computeGdbHash(Ent.Name),
                        (Ent.Descriptor.toBits() << 24) | I});
     }
   }
@@ -2475,19 +2475,20 @@
     uint32_t I = 0;
     for (ArrayRef<NameAttrEntry> Entries : NameAttrs) {
       for (const NameAttrEntry &Ent : Entries) {
-        size_t ShardId = Ent.Name.hash() >> Shift;
+        size_t ShardId = Ent.NameHash >> Shift;
         if ((ShardId & (Concurrency - 1)) != ThreadId)
           continue;
 
+        CachedHashStringRef Name(Ent.Name, Ent.NameHash);
         uint32_t V = Ent.CuIndexAndAttrs + CuIdxs[I];
-        size_t &Idx = Map[ShardId][Ent.Name];
+        size_t &Idx = Map[ShardId][Name];
         if (Idx) {
           Symbols[ShardId][Idx - 1].CuVector.push_back(V);
           continue;
         }
 
         Idx = Symbols[ShardId].size() + 1;
-        Symbols[ShardId].push_back({Ent.Name, {V}, 0, 0});
+        Symbols[ShardId].push_back({Name, {V}, 0, 0});
       }
       ++I;
     }


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