[lld] r342007 - [ELF] Revert "Also demote lazy symbols."
Chih-Hung Hsieh via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 11 16:00:37 PDT 2018
Author: chh
Date: Tue Sep 11 16:00:36 2018
New Revision: 342007
URL: http://llvm.org/viewvc/llvm-project?rev=342007&view=rev
Log:
[ELF] Revert "Also demote lazy symbols."
This reverts commit https://reviews.llvm.org/rL330869
for a regression to link Android dex2oatds.
Differential Revision: https://reviews.llvm.org/D51892
Added:
lld/trunk/test/ELF/Inputs/i386-linkonce.s
lld/trunk/test/ELF/i386-linkonce.s
Modified:
lld/trunk/ELF/Driver.cpp
lld/trunk/ELF/Symbols.cpp
lld/trunk/ELF/Symbols.h
Modified: lld/trunk/ELF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.cpp?rev=342007&r1=342006&r2=342007&view=diff
==============================================================================
--- lld/trunk/ELF/Driver.cpp (original)
+++ lld/trunk/ELF/Driver.cpp Tue Sep 11 16:00:36 2018
@@ -1231,33 +1231,19 @@ template <class ELFT> static void handle
Symtab->fetchLazy<ELFT>(Sym);
}
-template <class ELFT> static bool shouldDemote(Symbol &Sym) {
- // If all references to a DSO happen to be weak, the DSO is not added to
- // DT_NEEDED. If that happens, we need to eliminate shared symbols created
- // from the DSO. Otherwise, they become dangling references that point to a
- // non-existent DSO.
- if (auto *S = dyn_cast<SharedSymbol>(&Sym))
- return !S->getFile<ELFT>().IsNeeded;
-
- // We are done processing archives, so lazy symbols that were used but not
- // found can be converted to undefined. We could also just delete the other
- // lazy symbols, but that seems to be more work than it is worth.
- return Sym.isLazy() && Sym.IsUsedInRegularObj;
-}
-
-// Some files, such as .so or files between -{start,end}-lib may be removed
-// after their symbols are added to the symbol table. If that happens, we
-// need to remove symbols that refer files that no longer exist, so that
-// they won't appear in the symbol table of the output file.
-//
-// We remove symbols by demoting them to undefined symbol.
-template <class ELFT> static void demoteSymbols() {
+// If all references to a DSO happen to be weak, the DSO is not added
+// to DT_NEEDED. If that happens, we need to eliminate shared symbols
+// created from the DSO. Otherwise, they become dangling references
+// that point to a non-existent DSO.
+template <class ELFT> static void demoteSharedSymbols() {
for (Symbol *Sym : Symtab->getSymbols()) {
- if (shouldDemote<ELFT>(*Sym)) {
- bool Used = Sym->Used;
- replaceSymbol<Undefined>(Sym, nullptr, Sym->getName(), Sym->Binding,
- Sym->StOther, Sym->Type);
- Sym->Used = Used;
+ if (auto *S = dyn_cast<SharedSymbol>(Sym)) {
+ if (!S->getFile<ELFT>().IsNeeded) {
+ bool Used = S->Used;
+ replaceSymbol<Undefined>(S, nullptr, S->getName(), STB_WEAK, S->StOther,
+ S->Type);
+ S->Used = Used;
+ }
}
}
}
@@ -1592,7 +1578,7 @@ template <class ELFT> void LinkerDriver:
decompressSections();
splitSections<ELFT>();
markLive<ELFT>();
- demoteSymbols<ELFT>();
+ demoteSharedSymbols<ELFT>();
mergeSections();
if (Config->ICF != ICFLevel::None) {
findKeepUniqueSections<ELFT>(Args);
Modified: lld/trunk/ELF/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.cpp?rev=342007&r1=342006&r2=342007&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.cpp (original)
+++ lld/trunk/ELF/Symbols.cpp Tue Sep 11 16:00:36 2018
@@ -103,7 +103,8 @@ static uint64_t getSymVA(const Symbol &S
return 0;
case Symbol::LazyArchiveKind:
case Symbol::LazyObjectKind:
- llvm_unreachable("lazy symbol reached writer");
+ assert(Sym.IsUsedInRegularObj && "lazy symbol reached writer");
+ return 0;
}
llvm_unreachable("invalid symbol kind");
}
Modified: lld/trunk/ELF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.h?rev=342007&r1=342006&r2=342007&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.h (original)
+++ lld/trunk/ELF/Symbols.h Tue Sep 11 16:00:36 2018
@@ -128,8 +128,12 @@ public:
return SymbolKind == LazyArchiveKind || SymbolKind == LazyObjectKind;
}
- // True if this is an undefined weak symbol.
- bool isUndefWeak() const { return isWeak() && isUndefined(); }
+ // True if this is an undefined weak symbol. This only works once
+ // all input files have been added.
+ bool isUndefWeak() const {
+ // See comment on lazy symbols for details.
+ return isWeak() && (isUndefined() || isLazy());
+ }
StringRef getName() const {
if (NameSize == (uint32_t)-1)
Added: lld/trunk/test/ELF/Inputs/i386-linkonce.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/i386-linkonce.s?rev=342007&view=auto
==============================================================================
--- lld/trunk/test/ELF/Inputs/i386-linkonce.s (added)
+++ lld/trunk/test/ELF/Inputs/i386-linkonce.s Tue Sep 11 16:00:36 2018
@@ -0,0 +1,11 @@
+.section .gnu.linkonce.t.__i686.get_pc_thunk.bx
+.global __i686.get_pc_thunk.bx
+__i686.get_pc_thunk.bx:
+ mov (%esp),%ebx
+ ret
+
+.section .text
+.global _strchr1
+_strchr1:
+ call __i686.get_pc_thunk.bx
+ ret
Added: lld/trunk/test/ELF/i386-linkonce.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/i386-linkonce.s?rev=342007&view=auto
==============================================================================
--- lld/trunk/test/ELF/i386-linkonce.s (added)
+++ lld/trunk/test/ELF/i386-linkonce.s Tue Sep 11 16:00:36 2018
@@ -0,0 +1,9 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=i386-linux-gnu %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=i386-linux-gnu %p/Inputs/i386-linkonce.s -o %t2.o
+// RUN: llvm-ar rcs %t2.a %t2.o
+// RUN: ld.lld %t.o %t2.a -o %t
+
+ .globl _start
+_start:
+ call _strchr1
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