[PATCH] D38136: [ELF] Simplify handling of removed sections

[ben via Phabricator via llvm-commits]

bd1976llvm created this revision.
Herald added a subscriber: emaste.

Simplify handling of removed sections by testing the Live bit to see if the section was removed.

The code is simpler, and the lack of this test caused confusion (see: https://reviews.llvm.org/D37718).


https://reviews.llvm.org/D38136

Files:
  ELF/LinkerScript.cpp
  ELF/Symbols.cpp
  ELF/Writer.cpp


Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -270,8 +270,10 @@
 
   Out::ElfHeader = make<OutputSection>("", 0, SHF_ALLOC);
   Out::ElfHeader->Size = sizeof(Elf_Ehdr);
+  Out::ElfHeader->Live = true;
   Out::ProgramHeaders = make<OutputSection>("", 0, SHF_ALLOC);
   Out::ProgramHeaders->updateAlignment(Config->Wordsize);
+  Out::ProgramHeaders->Live = true;
 
   if (needsInterpSection()) {
     InX::Interp = createInterpSection();
Index: ELF/Symbols.cpp
===================================================================
--- ELF/Symbols.cpp
+++ ELF/Symbols.cpp
@@ -48,17 +48,13 @@
     if (auto *ISB = dyn_cast_or_null<InputSectionBase>(IS))
       IS = ISB->Repl;
 
-    // According to the ELF spec reference to a local symbol from outside
-    // the group are not allowed. Unfortunately .eh_frame breaks that rule
-    // and must be treated specially. For now we just replace the symbol with
-    // 0.
-    if (IS == &InputSection::Discarded)
-      return 0;
-
     // This is an absolute symbol.
     if (!IS)
       return D.Value;
 
+    if (!IS->Live)
+      return 0;
+
     uint64_t Offset = D.Value;
 
     // An object in an SHF_MERGE section might be referenced via a
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -358,6 +358,7 @@
   // which will map to whatever the first actual section is.
   Aether = make<OutputSection>("", 0, SHF_ALLOC);
   Aether->SectionIndex = 1;
+  Aether->Live = true;
   auto State = make_unique<AddressState>(Opt);
   // CurAddressState captures the local AddressState and makes it accessible
   // deliberately. This is needed as there are some cases where we cannot just


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