Delay creating an alias for @@@.
With this we only create an alias for @@@ once we know if it should
use @ or @@. This avoids last minutes renames and hacks to handle MS
names.
This only handles the ELF writer. LTO still has issues with @@@
aliases.
llvm-svn: 327160
diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index e11eaaa..989d4bb 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -128,8 +128,6 @@
/// @name Symbol Table Data
/// @{
- BumpPtrAllocator Alloc;
- StringSaver VersionSymSaver{Alloc};
StringTableBuilder StrTabBuilder{StringTableBuilder::ELF};
/// @}
@@ -391,27 +389,29 @@
const MCAsmLayout &Layout) {
// The presence of symbol versions causes undefined symbols and
// versions declared with @@@ to be renamed.
- for (const MCSymbol &A : Asm.symbols()) {
- const auto &Alias = cast<MCSymbolELF>(A);
- // Not an alias.
- if (!Alias.isVariable())
- continue;
- auto *Ref = dyn_cast<MCSymbolRefExpr>(Alias.getVariableValue());
- if (!Ref)
- continue;
- const auto &Symbol = cast<MCSymbolELF>(Ref->getSymbol());
-
- StringRef AliasName = Alias.getName();
+ for (const std::pair<StringRef, const MCSymbol *> &P : Asm.Symvers) {
+ StringRef AliasName = P.first;
+ const auto &Symbol = cast<MCSymbolELF>(*P.second);
size_t Pos = AliasName.find('@');
- if (Pos == StringRef::npos)
- continue;
+ assert(Pos != StringRef::npos);
+
+ StringRef Prefix = AliasName.substr(0, Pos);
+ StringRef Rest = AliasName.substr(Pos);
+ StringRef Tail = Rest;
+ if (Rest.startswith("@@@"))
+ Tail = Rest.substr(Symbol.isUndefined() ? 2 : 1);
+
+ auto *Alias =
+ cast<MCSymbolELF>(Asm.getContext().getOrCreateSymbol(Prefix + Tail));
+ Asm.registerSymbol(*Alias);
+ const MCExpr *Value = MCSymbolRefExpr::create(&Symbol, Asm.getContext());
+ Alias->setVariableValue(Value);
// Aliases defined with .symvar copy the binding from the symbol they alias.
// This is the first place we are able to copy this information.
- Alias.setExternal(Symbol.isExternal());
- Alias.setBinding(Symbol.getBinding());
+ Alias->setExternal(Symbol.isExternal());
+ Alias->setBinding(Symbol.getBinding());
- StringRef Rest = AliasName.substr(Pos);
if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
continue;
@@ -420,7 +420,7 @@
!Rest.startswith("@@@"))
report_fatal_error("A @@ version cannot be undefined");
- Renames.insert(std::make_pair(&Symbol, &Alias));
+ Renames.insert(std::make_pair(&Symbol, Alias));
}
}
@@ -836,44 +836,7 @@
HasLargeSectionIndex = true;
}
- // The @@@ in symbol version is replaced with @ in undefined symbols and @@
- // in defined ones.
- //
- // FIXME: All name handling should be done before we get to the writer,
- // including dealing with GNU-style version suffixes. Fixing this isn't
- // trivial.
- //
- // We thus have to be careful to not perform the symbol version replacement
- // blindly:
- //
- // The ELF format is used on Windows by the MCJIT engine. Thus, on
- // Windows, the ELFObjectWriter can encounter symbols mangled using the MS
- // Visual Studio C++ name mangling scheme. Symbols mangled using the MSVC
- // C++ name mangling can legally have "@@@" as a sub-string. In that case,
- // the EFLObjectWriter should not interpret the "@@@" sub-string as
- // specifying GNU-style symbol versioning. The ELFObjectWriter therefore
- // checks for the MSVC C++ name mangling prefix which is either "?", "@?",
- // "__imp_?" or "__imp_@?".
- //
- // It would have been interesting to perform the MS mangling prefix check
- // only when the target triple is of the form *-pc-windows-elf. But, it
- // seems that this information is not easily accessible from the
- // ELFObjectWriter.
StringRef Name = Symbol.getName();
- SmallString<32> Buf;
- if (!Name.startswith("?") && !Name.startswith("@?") &&
- !Name.startswith("__imp_?") && !Name.startswith("__imp_@?")) {
- // This symbol isn't following the MSVC C++ name mangling convention. We
- // can thus safely interpret the @@@ in symbol names as specifying symbol
- // versioning.
- size_t Pos = Name.find("@@@");
- if (Pos != StringRef::npos) {
- Buf += Name.substr(0, Pos);
- unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
- Buf += Name.substr(Pos + Skip);
- Name = VersionSymSaver.save(Buf.c_str());
- }
- }
// Sections have their own string table
if (Symbol.getType() != ELF::STT_SECTION) {