[lld] r308492 - Bring back r307364.
Rafael Espindola via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 19 09:45:05 PDT 2017
Author: rafael
Date: Wed Jul 19 09:45:05 2017
New Revision: 308492
URL: http://llvm.org/viewvc/llvm-project?rev=308492&view=rev
Log:
Bring back r307364.
In addition this includes a change to prefer symbols with a default
version @@ over unversioned symbols.
Original commit message:
[ELF] - Handle symbols with default version early.
This fixes last testcase provided in PR28414.
In short issue is next: when we had X@@Version symbol in object A,
we did not resolve it to X early. Then when in another object B
we had reference to undefined X, symbol X from archive was fetched.
Since both archive and object A contains another symbol Z, duplicate
symbol definition was triggered as a result.
Correct behavior is to use X@@Version from object A instead and do not fetch
any symbols from archive.
Differential revision: https://reviews.llvm.org/D35059
Added:
lld/trunk/test/ELF/Inputs/symver-archive1.s
lld/trunk/test/ELF/Inputs/symver-archive2.s
lld/trunk/test/ELF/symver-archive.s
Modified:
lld/trunk/ELF/SymbolTable.cpp
Modified: lld/trunk/ELF/SymbolTable.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=308492&r1=308491&r2=308492&view=diff
==============================================================================
--- lld/trunk/ELF/SymbolTable.cpp (original)
+++ lld/trunk/ELF/SymbolTable.cpp Wed Jul 19 09:45:05 2017
@@ -211,6 +211,12 @@ static uint8_t getMinVisibility(uint8_t
// Find an existing symbol or create and insert a new one.
template <class ELFT>
std::pair<Symbol *, bool> SymbolTable<ELFT>::insert(StringRef Name) {
+ // <name>@@<version> means the symbol is the default version. In that
+ // case <name>@@<version> will be used to resolve references to <name>.
+ size_t Pos = Name.find("@@");
+ if (Pos != StringRef::npos)
+ Name = Name.take_front(Pos);
+
auto P = Symtab.insert(
{CachedHashStringRef(Name), SymIndex((int)SymVector.size(), false)});
SymIndex &V = P.first->second;
@@ -312,15 +318,36 @@ Symbol *SymbolTable<ELFT>::addUndefined(
return S;
}
+// Using .symver foo,foo@@VER unfortunately creates two symbols: foo and
+// foo@@VER. We want to effectively ignore foo, so give precedence to
+// foo@@VER.
+// FIXME: If users can transition to using
+// .symver foo,foo@@@VER
+// we can delete this hack.
+static int compareVersion(Symbol *S, StringRef Name) {
+ if (Name.find("@@") != StringRef::npos &&
+ S->body()->getName().find("@@") == StringRef::npos)
+ return 1;
+ if (Name.find("@@") == StringRef::npos &&
+ S->body()->getName().find("@@") != StringRef::npos)
+ return -1;
+ return 0;
+}
+
// We have a new defined symbol with the specified binding. Return 1 if the new
// symbol should win, -1 if the new symbol should lose, or 0 if both symbols are
// strong defined symbols.
-static int compareDefined(Symbol *S, bool WasInserted, uint8_t Binding) {
+static int compareDefined(Symbol *S, bool WasInserted, uint8_t Binding,
+ StringRef Name) {
if (WasInserted)
return 1;
SymbolBody *Body = S->body();
if (!Body->isInCurrentDSO())
return 1;
+
+ if (int R = compareVersion(S, Name))
+ return R;
+
if (Binding == STB_WEAK)
return -1;
if (S->isWeak())
@@ -333,8 +360,9 @@ static int compareDefined(Symbol *S, boo
// is a conflict. If the new symbol wins, also update the binding.
template <typename ELFT>
static int compareDefinedNonCommon(Symbol *S, bool WasInserted, uint8_t Binding,
- bool IsAbsolute, typename ELFT::uint Value) {
- if (int Cmp = compareDefined(S, WasInserted, Binding)) {
+ bool IsAbsolute, typename ELFT::uint Value,
+ StringRef Name) {
+ if (int Cmp = compareDefined(S, WasInserted, Binding, Name)) {
if (Cmp > 0)
S->Binding = Binding;
return Cmp;
@@ -362,7 +390,7 @@ Symbol *SymbolTable<ELFT>::addCommon(Str
bool WasInserted;
std::tie(S, WasInserted) = insert(N, Type, getVisibility(StOther),
/*CanOmitFromDynSym*/ false, File);
- int Cmp = compareDefined(S, WasInserted, Binding);
+ int Cmp = compareDefined(S, WasInserted, Binding, N);
if (Cmp > 0) {
S->Binding = Binding;
replaceBody<DefinedCommon>(S, N, Size, Alignment, StOther, Type, File);
@@ -439,7 +467,7 @@ Symbol *SymbolTable<ELFT>::addRegular(St
std::tie(S, WasInserted) = insert(Name, Type, getVisibility(StOther),
/*CanOmitFromDynSym*/ false, File);
int Cmp = compareDefinedNonCommon<ELFT>(S, WasInserted, Binding,
- Section == nullptr, Value);
+ Section == nullptr, Value, Name);
if (Cmp > 0)
replaceBody<DefinedRegular>(S, Name, /*IsLocal=*/false, StOther, Type,
Value, Size, Section, File);
@@ -485,7 +513,7 @@ Symbol *SymbolTable<ELFT>::addBitcode(St
std::tie(S, WasInserted) =
insert(Name, Type, getVisibility(StOther), CanOmitFromDynSym, F);
int Cmp = compareDefinedNonCommon<ELFT>(S, WasInserted, Binding,
- /*IsAbs*/ false, /*Value*/ 0);
+ /*IsAbs*/ false, /*Value*/ 0, Name);
if (Cmp > 0)
replaceBody<DefinedRegular>(S, Name, /*IsLocal=*/false, StOther, Type, 0, 0,
nullptr, F);
@@ -717,32 +745,9 @@ void SymbolTable<ELFT>::assignWildcardVe
B->symbol()->VersionId = VersionId;
}
-static bool isDefaultVersion(SymbolBody *B) {
- return B->isInCurrentDSO() && B->getName().find("@@") != StringRef::npos;
-}
-
// This function processes version scripts by updating VersionId
// member of symbols.
template <class ELFT> void SymbolTable<ELFT>::scanVersionScript() {
- // Symbol themselves might know their versions because symbols
- // can contain versions in the form of <name>@<version>.
- // Let them parse and update their names to exclude version suffix.
- for (Symbol *Sym : SymVector) {
- SymbolBody *Body = Sym->body();
- bool IsDefault = isDefaultVersion(Body);
- Body->parseSymbolVersion();
-
- if (!IsDefault)
- continue;
-
- // <name>@@<version> means the symbol is the default version. If that's the
- // case, the symbol is not used only to resolve <name> of version <version>
- // but also undefined unversioned symbols with name <name>.
- SymbolBody *S = find(Body->getName());
- if (S && S->isUndefined())
- S->copy(Body);
- }
-
// Handle edge cases first.
handleAnonymousVersion();
Added: lld/trunk/test/ELF/Inputs/symver-archive1.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/symver-archive1.s?rev=308492&view=auto
==============================================================================
--- lld/trunk/test/ELF/Inputs/symver-archive1.s (added)
+++ lld/trunk/test/ELF/Inputs/symver-archive1.s Wed Jul 19 09:45:05 2017
@@ -0,0 +1,6 @@
+.text
+.globl x
+.type x, @function
+x:
+
+.symver x, xx@@VER
Added: lld/trunk/test/ELF/Inputs/symver-archive2.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/symver-archive2.s?rev=308492&view=auto
==============================================================================
--- lld/trunk/test/ELF/Inputs/symver-archive2.s (added)
+++ lld/trunk/test/ELF/Inputs/symver-archive2.s Wed Jul 19 09:45:05 2017
@@ -0,0 +1 @@
+call xx at PLT
Added: lld/trunk/test/ELF/symver-archive.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/symver-archive.s?rev=308492&view=auto
==============================================================================
--- lld/trunk/test/ELF/symver-archive.s (added)
+++ lld/trunk/test/ELF/symver-archive.s Wed Jul 19 09:45:05 2017
@@ -0,0 +1,15 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t1
+# RUN: rm -f %t.a
+# RUN: llvm-ar rcs %t.a %t1
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/symver-archive1.s -o %t2.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/symver-archive2.s -o %t3.o
+# RUN: ld.lld -o %t.out %t2.o %t3.o %t.a
+
+.text
+.globl x
+.type x, @function
+x:
+
+.globl xx
+xx = x
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