[PATCH] D45302: Initialize OffsetMap earlier

[Rafael Avila de Espindola via Phabricator via llvm-commits]

espindola created this revision.
espindola added a reviewer: ruiu.
Herald added subscribers: arichardson, emaste.

Sorry for the noise, but now that getSectionPiece uses OffsetMap, it is advantageous to initialize it earlier.

It is also the simplest so far.


https://reviews.llvm.org/D45302

Files:
  ELF/InputSection.cpp
  ELF/SyntheticSections.cpp


Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -2440,15 +2440,10 @@
   // finalize() fixed tail-optimized strings, so we can now get
   // offsets of strings. Get an offset for each string and save it
   // to a corresponding StringPiece for easy access.
-  for (MergeInputSection *Sec : Sections) {
-    Sec->OffsetMap.reserve(Sec->Pieces.size());
-    for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I) {
-      SectionPiece &P = Sec->Pieces[I];
-      Sec->OffsetMap[P.InputOff] = I;
-      if (P.Live)
-        P.OutputOff = Builder.getOffset(Sec->getData(I));
-    }
-  }
+  for (MergeInputSection *Sec : Sections)
+    for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I)
+      if (Sec->Pieces[I].Live)
+        Sec->Pieces[I].OutputOff = Builder.getOffset(Sec->getData(I));
 }
 
 void MergeNoTailSection::writeTo(uint8_t *Buf) {
@@ -2501,13 +2496,10 @@
   // So far, section pieces have offsets from beginning of shards, but
   // we want offsets from beginning of the whole section. Fix them.
   parallelForEach(Sections, [&](MergeInputSection *Sec) {
-    Sec->OffsetMap.reserve(Sec->Pieces.size());
-    for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I) {
-      SectionPiece &P = Sec->Pieces[I];
-      Sec->OffsetMap[P.InputOff] = I;
-      if (P.Live)
-        P.OutputOff += ShardOffsets[getShardId(P.Hash)];
-    }
+    for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I)
+      if (Sec->Pieces[I].Live)
+        Sec->Pieces[I].OutputOff +=
+            ShardOffsets[getShardId(Sec->Pieces[I].Hash)];
   });
 }
 
Index: ELF/InputSection.cpp
===================================================================
--- ELF/InputSection.cpp
+++ ELF/InputSection.cpp
@@ -920,6 +920,10 @@
   else
     splitNonStrings(Data, Entsize);
 
+  OffsetMap.reserve(Pieces.size());
+  for (size_t I = 0, E = Pieces.size(); I != E; ++I)
+    OffsetMap[Pieces[I].InputOff] = I;
+
   if (Config->GcSections && (Flags & SHF_ALLOC))
     for (uint32_t Off : LiveOffsets)
       getSectionPiece(Off)->Live = true;


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