[PATCH] D25033: [ELF] GC: Mark all pieces of mergeable section live.

[Eugene Leviant via llvm-commits]

evgeny777 created this revision.
evgeny777 added reviewers: ruiu, grimar, rafael.
evgeny777 added subscribers: ikudrin, llvm-commits.
evgeny777 set the repository for this revision to rL LLVM.
evgeny777 added a project: lld.

The .comment section may have multiple pieces. Current revision will only live the very first piece alive

Repository:
  rL LLVM

https://reviews.llvm.org/D25033

Files:
  ELF/InputSection.cpp
  ELF/MarkLive.cpp
  test/ELF/debug-gc.s

Index: test/ELF/debug-gc.s
===================================================================
--- test/ELF/debug-gc.s
+++ test/ELF/debug-gc.s
@@ -4,7 +4,7 @@
 # RUN: llvm-objdump -s %t1 | FileCheck %s
 
 # CHECK:      Contents of section .debug_str:
-# CHECK-NEXT:  0000 41414100 42424200   AAA.BBB.
+# CHECK-NEXT:  0000 41414100 42424200 43434300           AAA.BBB.CCC.
 # CHECK:      Contents of section .debug_info:
 # CHECK-NEXT:  0000 00000000 04000000
 
Index: ELF/MarkLive.cpp
===================================================================
--- ELF/MarkLive.cpp
+++ ELF/MarkLive.cpp
@@ -64,20 +64,13 @@
   return Rel.r_addend;
 }
 
-template <class ELFT> static bool IsAlloc(InputSectionBase<ELFT> &Sec) {
-  return (&Sec != &InputSection<ELFT>::Discarded) &&
-         (Sec.getSectionHdr()->sh_flags & SHF_ALLOC);
-}
-
 template <class ELFT, class RelT>
 static ResolvedReloc<ELFT> resolveReloc(InputSectionBase<ELFT> &Sec,
                                         RelT &Rel) {
   SymbolBody &B = Sec.getFile()->getRelocTargetSym(Rel);
   auto *D = dyn_cast<DefinedRegular<ELFT>>(&B);
   if (!D || !D->Section)
     return {nullptr, 0};
-  if (!IsAlloc<ELFT>(Sec) && IsAlloc<ELFT>(*D->Section))
-    return {nullptr, 0};
   typename ELFT::uint Offset = D->Value;
   if (D->isSection())
     Offset += getAddend(Sec, Rel);
@@ -215,7 +208,8 @@
       return;
     R.Sec->Live = true;
     if (InputSection<ELFT> *S = dyn_cast<InputSection<ELFT>>(R.Sec))
-      Q.push_back(S);
+      if (S->getSectionHdr()->sh_flags & SHF_ALLOC)
+        Q.push_back(S);
   };
 
   auto MarkSymbol = [&](const SymbolBody *Sym) {
Index: ELF/InputSection.cpp
===================================================================
--- ELF/InputSection.cpp
+++ ELF/InputSection.cpp
@@ -572,9 +572,16 @@
   else
     this->Pieces = splitNonStrings(Data, EntSize);
 
-  if (Config->GcSections)
-    for (uintX_t Off : LiveOffsets)
-      this->getSectionPiece(Off)->Live = true;
+  if (Config->GcSections) {
+    if (this->getSectionHdr()->sh_flags & SHF_ALLOC) {
+      for (uintX_t Off : LiveOffsets)
+        this->getSectionPiece(Off)->Live = true;
+      return;
+    }
+
+    for (SectionPiece &Piece : this->Pieces)
+      Piece.Live = true;
+  }
 }
 
 template <class ELFT>


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