Fix pr24486.

This extends the work done in r233995 so that now getFragment (in addition to
getSection) also works for variable symbols.

With that the existing logic to decide if a-b can be computed works even if
a or b are variables. Given that, the expression evaluation can avoid expanding
variables as aggressively and that in turn lets the relocation code see the
original variable.

In order for this to work with the asm streamer, there is now a dummy fragment
per section. It is used to assign a section to a symbol when no other fragment
exists.

This patch is a joint work by Maxim Ostapenko andy myself.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249303 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/MC/MCAssembler.h b/include/llvm/MC/MCAssembler.h
index 6becda88ebf68e3373235fb0f61b874e58ce207c..d69472bf2ec21e55d2ea316836f54349128840e6 100644 (file)
--- a/include/llvm/MC/MCAssembler.h
+++ b/include/llvm/MC/MCAssembler.h
@@ -52,7 +52,8 @@ public:
     FT_Dwarf,
     FT_DwarfFrame,
     FT_LEB,
-    FT_SafeSEH
+    FT_SafeSEH,
+    FT_Dummy
   };
 
 private:
@@ -136,9 +137,19 @@ public:
   /// and only some fragments have a meaningful implementation.
   void setBundlePadding(uint8_t N) { BundlePadding = N; }
 
+  /// \brief Return true if given frgment has FT_Dummy type.
+  bool isDummy() const { return Kind == FT_Dummy; }
+
   void dump();
 };
 
+class MCDummyFragment : public MCFragment {
+public:
+  explicit MCDummyFragment(MCSection *Sec)
+      : MCFragment(FT_Dummy, false, 0, Sec){};
+  static bool classof(const MCFragment *F) { return F->getKind() == FT_Dummy; }
+};
+
 /// Interface implemented by fragments that contain encoded instructions and/or
 /// data.
 ///

diff --git a/include/llvm/MC/MCExpr.h b/include/llvm/MC/MCExpr.h
index b3a607351a826304396700c27a1afe25a230b197..76da86cd7d6376f6529f5d7a819ee2e41d0f25d2 100644 (file)
--- a/include/llvm/MC/MCExpr.h
+++ b/include/llvm/MC/MCExpr.h
@@ -20,6 +20,7 @@ class MCAsmLayout;
 class MCAssembler;
 class MCContext;
 class MCFixup;
+class MCFragment;
 class MCSection;
 class MCStreamer;
 class MCSymbol;
@@ -115,7 +116,7 @@ public:
   /// currently defined as the absolute section for constants, or
   /// otherwise the section associated with the first defined symbol in the
   /// expression.
-  MCSection *findAssociatedSection() const;
+  MCFragment *findAssociatedFragment() const;
 
   /// @}
 };
@@ -556,7 +557,7 @@ public:
                                          const MCAsmLayout *Layout,
                                          const MCFixup *Fixup) const = 0;
   virtual void visitUsedExpr(MCStreamer& Streamer) const = 0;
-  virtual MCSection *findAssociatedSection() const = 0;
+  virtual MCFragment *findAssociatedFragment() const = 0;
 
   virtual void fixELFSymbolsInTLSFixups(MCAssembler &) const = 0;
 

diff --git a/include/llvm/MC/MCMachObjectWriter.h b/include/llvm/MC/MCMachObjectWriter.h
index 7eccd562af39a62b06578b6328770cbc911e4e41..fe1227fe3dd92d141d19eec086cfb2c73152c49c 100644 (file)
--- a/include/llvm/MC/MCMachObjectWriter.h
+++ b/include/llvm/MC/MCMachObjectWriter.h
@@ -247,6 +247,11 @@ public:
   void executePostLayoutBinding(MCAssembler &Asm,
                                 const MCAsmLayout &Layout) override;
 
+  bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
+                                              const MCSymbol &A,
+                                              const MCSymbol &B,
+                                              bool InSet) const override;
+
   bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
                                               const MCSymbol &SymA,
                                               const MCFragment &FB, bool InSet,

diff --git a/include/llvm/MC/MCObjectWriter.h b/include/llvm/MC/MCObjectWriter.h
index 406831aae810e3531e62e30847bd40bff0f0b132..ed1f493d74e79c2dcd56626e3c539dfc1f4471f9 100644 (file)
--- a/include/llvm/MC/MCObjectWriter.h
+++ b/include/llvm/MC/MCObjectWriter.h
@@ -92,6 +92,11 @@ public:
                                           const MCSymbolRefExpr *B,
                                           bool InSet) const;
 
+  virtual bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
+                                                      const MCSymbol &A,
+                                                      const MCSymbol &B,
+                                                      bool InSet) const;
+
   virtual bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
                                                       const MCSymbol &SymA,
                                                       const MCFragment &FB,

diff --git a/include/llvm/MC/MCSection.h b/include/llvm/MC/MCSection.h
index 2d0d4dfc59137dded9bfff83134b4a253b0603d7..f5490fcd173a1b9cd9d2f77bc290f9a1ce54348c 100644 (file)
--- a/include/llvm/MC/MCSection.h
+++ b/include/llvm/MC/MCSection.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/ilist.h"
 #include "llvm/ADT/ilist_node.h"
+#include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/SectionKind.h"
 #include "llvm/Support/Compiler.h"
 
@@ -92,6 +93,8 @@ private:
 
   unsigned IsRegistered : 1;
 
+  MCDummyFragment DummyFragment;
+
   FragmentListType Fragments;
 
   /// Mapping from subsection number to insertion point for subsection numbers
@@ -152,6 +155,9 @@ public:
     return const_cast<MCSection *>(this)->getFragmentList();
   }
 
+  const MCDummyFragment &getDummyFragment() const { return DummyFragment; }
+  MCDummyFragment &getDummyFragment() { return DummyFragment; }
+
   MCSection::iterator begin();
   MCSection::const_iterator begin() const {
     return const_cast<MCSection *>(this)->begin();

diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index 6beeaa9dd77d214a2b0c0cb6ba82c09d2715b040..209bfe5801f696de024dbe45aff9cd6e6f46f9cb 100644 (file)
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -358,7 +358,7 @@ public:
   ///
   /// Each emitted symbol will be tracked in the ordering table,
   /// so we can sort on them later.
-  void AssignSection(MCSymbol *Symbol, MCSection *Section);
+  void AssignFragment(MCSymbol *Symbol, MCFragment *Fragment);
 
   /// \brief Emit a label for \p Symbol into the current section.
   ///

diff --git a/include/llvm/MC/MCSymbol.h b/include/llvm/MC/MCSymbol.h
index 563fa803b0e4b2bc1f30d41891babae3585f1727..c51ecfcb0c5c9c018552c97f1315260cc8d23063 100644 (file)
--- a/include/llvm/MC/MCSymbol.h
+++ b/include/llvm/MC/MCSymbol.h
@@ -56,19 +56,17 @@ protected:
     SymContentsCommon,
   };
 
-  // Special sentinal value for the absolute pseudo section.
-  //
-  // FIXME: Use a PointerInt wrapper for this?
-  static MCSection *AbsolutePseudoSection;
+  // Special sentinal value for the absolute pseudo fragment.
+  static MCFragment *AbsolutePseudoFragment;
 
   /// If a symbol has a Fragment, the section is implied, so we only need
   /// one pointer.
+  /// The special AbsolutePseudoFragment value is for absolute symbols.
+  /// If this is a variable symbol, this caches the variable value's fragment.
   /// FIXME: We might be able to simplify this by having the asm streamer create
   /// dummy fragments.
   /// If this is a section, then it gives the symbol is defined in. This is null
-  /// for undefined symbols, and the special AbsolutePseudoSection value for
-  /// absolute symbols. If this is a variable symbol, this caches the variable
-  /// value's section.
+  /// for undefined symbols.
   ///
   /// If this is a fragment, then it gives the fragment this symbol's value is
   /// relative to, if any.
@@ -76,8 +74,7 @@ protected:
   /// For the 'HasName' integer, this is true if this symbol is named.
   /// A named symbol will have a pointer to the name allocated in the bytes
   /// immediately prior to the MCSymbol.
-  mutable PointerIntPair<PointerUnion<MCSection *, MCFragment *>, 1>
-      SectionOrFragmentAndHasName;
+  mutable PointerIntPair<MCFragment *, 1> FragmentAndHasName;
 
   /// IsTemporary - True if this is an assembler temporary label, which
   /// typically does not survive in the .o file's symbol table.  Usually
@@ -155,7 +152,7 @@ protected: // MCContext creates and uniques these.
         Kind(Kind), IsUsedInReloc(false), SymbolContents(SymContentsUnset),
         CommonAlignLog2(0), Flags(0) {
     Offset = 0;
-    SectionOrFragmentAndHasName.setInt(!!Name);
+    FragmentAndHasName.setInt(!!Name);
     if (Name)
       getNameEntryPtr() = Name;
   }
@@ -180,19 +177,16 @@ private:
   MCSymbol(const MCSymbol &) = delete;
   void operator=(const MCSymbol &) = delete;
   MCSection *getSectionPtr(bool SetUsed = true) const {
-    if (MCFragment *F = getFragment())
+    if (MCFragment *F = getFragment(SetUsed)) {
+      assert(F != AbsolutePseudoFragment);
       return F->getParent();
-    const auto &SectionOrFragment = SectionOrFragmentAndHasName.getPointer();
-    assert(!SectionOrFragment.is<MCFragment *>() && "Section or null expected");
-    MCSection *Section = SectionOrFragment.dyn_cast<MCSection *>();
-    if (Section || !isVariable())
-      return Section;
-    return Section = getVariableValue(SetUsed)->findAssociatedSection();
+    }
+    return nullptr;
   }
 
   /// \brief Get a reference to the name field.  Requires that we have a name
   const StringMapEntry<bool> *&getNameEntryPtr() {
-    assert(SectionOrFragmentAndHasName.getInt() && "Name is required");
+    assert(FragmentAndHasName.getInt() && "Name is required");
     NameEntryStorageTy *Name = reinterpret_cast<NameEntryStorageTy *>(this);
     return (*(Name - 1)).NameEntry;
   }
@@ -203,7 +197,7 @@ private:
 public:
   /// getName - Get the symbol name.
   StringRef getName() const {
-    if (!SectionOrFragmentAndHasName.getInt())
+    if (!FragmentAndHasName.getInt())
       return StringRef();
 
     return getNameEntryPtr()->first();
@@ -249,7 +243,7 @@ public:
   ///
   /// Defined symbols are either absolute or in some section.
   bool isDefined(bool SetUsed = true) const {
-    return getSectionPtr(SetUsed) != nullptr;
+    return getFragment(SetUsed) != nullptr;
   }
 
   /// isInSection - Check if this symbol is defined in some section (i.e., it
@@ -263,7 +257,7 @@ public:
 
   /// isAbsolute - Check if this is an absolute symbol.
   bool isAbsolute(bool SetUsed = true) const {
-    return getSectionPtr(SetUsed) == AbsolutePseudoSection;
+    return getFragment(SetUsed) == AbsolutePseudoFragment;
   }
 
   /// Get the section associated with a defined, non-absolute symbol.
@@ -272,19 +266,14 @@ public:
     return *getSectionPtr(SetUsed);
   }
 
-  /// Mark the symbol as defined in the section \p S.
-  void setSection(MCSection &S) {
-    assert(!isVariable() && "Cannot set section of variable");
-    assert(!SectionOrFragmentAndHasName.getPointer().is<MCFragment *>() &&
-           "Section or null expected");
-    SectionOrFragmentAndHasName.setPointer(&S);
+  /// Mark the symbol as defined in the fragment \p F.
+  void setFragment(MCFragment *F) const {
+    assert(!isVariable() && "Cannot set fragment of variable");
+    FragmentAndHasName.setPointer(F);
   }
 
   /// Mark the symbol as undefined.
-  void setUndefined() {
-    SectionOrFragmentAndHasName.setPointer(
-        PointerUnion<MCSection *, MCFragment *>());
-  }
+  void setUndefined() { FragmentAndHasName.setPointer(nullptr); }
 
   bool isELF() const { return Kind == SymbolKindELF; }
 
@@ -385,11 +374,13 @@ public:
     return SymbolContents == SymContentsCommon;
   }
 
-  MCFragment *getFragment() const {
-    return SectionOrFragmentAndHasName.getPointer().dyn_cast<MCFragment *>();
-  }
-  void setFragment(MCFragment *Value) const {
-    SectionOrFragmentAndHasName.setPointer(Value);
+  MCFragment *getFragment(bool SetUsed = true) const {
+    MCFragment *Fragment = FragmentAndHasName.getPointer();
+    if (Fragment || !isVariable())
+      return Fragment;
+    Fragment = getVariableValue(SetUsed)->findAssociatedFragment();
+    FragmentAndHasName.setPointer(Fragment);
+    return Fragment;
   }
 
   bool isExternal() const { return IsExternal; }

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 16f299c8fd88e27e3572255bea6c0eb9296ef3aa..f1acc1d75fbd5a29b2247becde3da6e019ffd4dd 100644 (file)
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -447,9 +447,6 @@ void ELFObjectWriter::writeSymbol(SymbolTableWriter &Writer,
                                   uint32_t StringIndex, ELFSymbolData &MSD,
                                   const MCAsmLayout &Layout) {
   const auto &Symbol = cast<MCSymbolELF>(*MSD.Symbol);
-  assert((!Symbol.getFragment() ||
-          (Symbol.getFragment()->getParent() == &Symbol.getSection())) &&
-         "The symbol's section doesn't match the fragment's symbol");
   const MCSymbolELF *Base =
       cast_or_null<MCSymbolELF>(Layout.getBaseSymbol(Symbol));
 

diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 7a30075bac95a7dcd931a5c91a452c132fb37153..f9dbd5ad3f0492eb153997bfbaedcd8030065612 100644 (file)
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -575,7 +575,7 @@ void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
                                  uint64_t Size, unsigned ByteAlignment) {
   if (Symbol)
-    AssignSection(Symbol, Section);
+    AssignFragment(Symbol, &Section->getDummyFragment());
 
   // Note: a .zerofill directive does not switch sections.
   OS << ".zerofill ";
@@ -599,7 +599,7 @@ void MCAsmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
 // e.g. _a.
 void MCAsmStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
                                    uint64_t Size, unsigned ByteAlignment) {
-  AssignSection(Symbol, Section);
+  AssignFragment(Symbol, &Section->getDummyFragment());
 
   assert(Symbol && "Symbol shouldn't be NULL!");
   // Instead of using the Section we'll just use the shortcut.

diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index d93bf44928ddc2057f80129a1b7dd34d3a127ebf..143d284897f3d93494db12fa2cac5dfd7a0f05ae 100644 (file)
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -277,7 +277,7 @@ MCFragment::MCFragment(FragmentType Kind, bool HasInstructions,
     : Kind(Kind), HasInstructions(HasInstructions), AlignToBundleEnd(false),
       BundlePadding(BundlePadding), Parent(Parent), Atom(nullptr),
       Offset(~UINT64_C(0)) {
-  if (Parent)
+  if (Parent && !isDummy())
     Parent->getFragmentList().push_back(this);
 }
 
@@ -319,6 +319,9 @@ void MCFragment::destroy() {
     case FT_SafeSEH:
       delete cast<MCSafeSEHFragment>(this);
       return;
+    case FT_Dummy:
+      delete cast<MCDummyFragment>(this);
+      return;
   }
 }
 
@@ -411,7 +414,7 @@ const MCSymbol *MCAssembler::getAtom(const MCSymbol &S) const {
     return &S;
 
   // Absolute and undefined symbols have no defining atom.
-  if (!S.getFragment())
+  if (!S.isInSection())
     return nullptr;
 
   // Non-linker visible symbols in sections which can't be atomized have no
@@ -547,6 +550,8 @@ uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
     return cast<MCDwarfLineAddrFragment>(F).getContents().size();
   case MCFragment::FT_DwarfFrame:
     return cast<MCDwarfCallFrameFragment>(F).getContents().size();
+  case MCFragment::FT_Dummy:
+    llvm_unreachable("Should not have been added");
   }
 
   llvm_unreachable("invalid fragment kind");
@@ -780,6 +785,8 @@ static void writeFragment(const MCAssembler &Asm, const MCAsmLayout &Layout,
     OW->writeBytes(CF.getContents());
     break;
   }
+  case MCFragment::FT_Dummy:
+    llvm_unreachable("Should not have been added");
   }
 
   assert(OW->getStream().tell() - Start == FragmentSize &&
@@ -1147,6 +1154,9 @@ void MCFragment::dump() {
   case MCFragment::FT_DwarfFrame: OS << "MCDwarfCallFrameFragment"; break;
   case MCFragment::FT_LEB:   OS << "MCLEBFragment"; break;
   case MCFragment::FT_SafeSEH:    OS << "MCSafeSEHFragment"; break;
+  case MCFragment::FT_Dummy:
+    OS << "MCDummyFragment";
+    break;
   }
 
   OS << "<MCFragment " << (void*) this << " LayoutOrder:" << LayoutOrder
@@ -1245,6 +1255,8 @@ void MCFragment::dump() {
     OS << " Sym:" << F->getSymbol();
     break;
   }
+  case MCFragment::FT_Dummy:
+    break;
   }
   OS << ">";
 }

diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index f0b3ec699fe941a4b443a29e20e383e838a13b49..fc4f8a6281b41e1687de09ae59008bfd39a24e96 100644 (file)
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -111,7 +111,7 @@ void MCELFStreamer::EmitLabel(MCSymbol *S) {
   MCObjectStreamer::EmitLabel(Symbol);
 
   const MCSectionELF &Section =
-    static_cast<const MCSectionELF&>(Symbol->getSection());
+      static_cast<const MCSectionELF &>(*getCurrentSectionOnly());
   if (Section.getFlags() & ELF::SHF_TLS)
     Symbol->setType(ELF::STT_TLS);
 }
@@ -311,11 +311,6 @@ void MCELFStreamer::EmitCommonSymbol(MCSymbol *S, uint64_t Size,
   Symbol->setType(ELF::STT_OBJECT);
 
   if (Symbol->getBinding() == ELF::STB_LOCAL) {
-    MCSection *Section = getAssembler().getContext().getELFSection(
-        ".bss", ELF::SHT_NOBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
-
-    AssignSection(Symbol, Section);
-
     struct LocalCommon L = {Symbol, Size, ByteAlignment};
     LocalCommons.push_back(L);
   } else {
@@ -630,7 +625,8 @@ void MCELFStreamer::Flush() {
     const MCSymbol &Symbol = *i->Symbol;
     uint64_t Size = i->Size;
     unsigned ByteAlignment = i->ByteAlignment;
-    MCSection &Section = Symbol.getSection();
+    MCSection &Section = *getAssembler().getContext().getELFSection(
+        ".bss", ELF::SHT_NOBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
 
     getAssembler().registerSection(Section);
     new MCAlignFragment(ByteAlignment, 0, 1, ByteAlignment, &Section);

diff --git a/lib/MC/MCExpr.cpp b/lib/MC/MCExpr.cpp
index 042fd1c72a28be6c5a1e8faae72f6ca3ed8ccee5..916e505c4b9309862de73fae1475338ce5136f26 100644 (file)
--- a/lib/MC/MCExpr.cpp
+++ b/lib/MC/MCExpr.cpp
@@ -477,7 +477,8 @@ static void AttemptToFoldSymbolOffsetDifference(
   if (!Asm->getWriter().isSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
     return;
 
-  if (SA.getFragment() == SB.getFragment()) {
+  if (SA.getFragment() == SB.getFragment() && !SA.isVariable() &&
+      !SB.isVariable()) {
     Addend += (SA.getOffset() - SB.getOffset());
 
     // Pointers to Thumb symbols need to have their low-bit set to allow
@@ -606,7 +607,7 @@ bool MCExpr::evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const {
                                    true);
 }
 
-static bool canExpand(const MCSymbol &Sym, const MCAssembler *Asm, bool InSet) {
+static bool canExpand(const MCSymbol &Sym, bool InSet) {
   const MCExpr *Expr = Sym.getVariableValue();
   const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
   if (Inner) {
@@ -616,9 +617,7 @@ static bool canExpand(const MCSymbol &Sym, const MCAssembler *Asm, bool InSet) {
 
   if (InSet)
     return true;
-  if (!Asm)
-    return false;
-  return !Asm->getWriter().isWeak(Sym);
+  return !Sym.isInSection();
 }
 
 bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
@@ -643,7 +642,7 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
 
     // Evaluate recursively if this is a variable.
     if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None &&
-        canExpand(Sym, Asm, InSet)) {
+        canExpand(Sym, InSet)) {
       bool IsMachO = SRE->hasSubsectionsViaSymbols();
       if (Sym.getVariableValue()->evaluateAsRelocatableImpl(
               Res, Asm, Layout, Fixup, Addrs, InSet || IsMachO)) {
@@ -775,45 +774,41 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
   llvm_unreachable("Invalid assembly expression kind!");
 }
 
-MCSection *MCExpr::findAssociatedSection() const {
+MCFragment *MCExpr::findAssociatedFragment() const {
   switch (getKind()) {
   case Target:
     // We never look through target specific expressions.
-    return cast<MCTargetExpr>(this)->findAssociatedSection();
+    return cast<MCTargetExpr>(this)->findAssociatedFragment();
 
   case Constant:
-    return MCSymbol::AbsolutePseudoSection;
+    return MCSymbol::AbsolutePseudoFragment;
 
   case SymbolRef: {
     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
     const MCSymbol &Sym = SRE->getSymbol();
-
-    if (Sym.isDefined())
-      return &Sym.getSection();
-
-    return nullptr;
+    return Sym.getFragment();
   }
 
   case Unary:
-    return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedSection();
+    return cast<MCUnaryExpr>(this)->getSubExpr()->findAssociatedFragment();
 
   case Binary: {
     const MCBinaryExpr *BE = cast<MCBinaryExpr>(this);
-    MCSection *LHS_S = BE->getLHS()->findAssociatedSection();
-    MCSection *RHS_S = BE->getRHS()->findAssociatedSection();
+    MCFragment *LHS_F = BE->getLHS()->findAssociatedFragment();
+    MCFragment *RHS_F = BE->getRHS()->findAssociatedFragment();
 
-    // If either section is absolute, return the other.
-    if (LHS_S == MCSymbol::AbsolutePseudoSection)
-      return RHS_S;
-    if (RHS_S == MCSymbol::AbsolutePseudoSection)
-      return LHS_S;
+    // If either is absolute, return the other.
+    if (LHS_F == MCSymbol::AbsolutePseudoFragment)
+      return RHS_F;
+    if (RHS_F == MCSymbol::AbsolutePseudoFragment)
+      return LHS_F;
 
     // Not always correct, but probably the best we can do without more context.
     if (BE->getOpcode() == MCBinaryExpr::Sub)
-      return MCSymbol::AbsolutePseudoSection;
+      return MCSymbol::AbsolutePseudoFragment;
 
-    // Otherwise, return the first non-null section.
-    return LHS_S ? LHS_S : RHS_S;
+    // Otherwise, return the first non-null fragment.
+    return LHS_F ? LHS_F : RHS_F;
   }
   }
 

diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index 0f65d51bb73b8b51f95c0a4eb64ab160a5e35778..50ee08fa1f9eec742fb6315a88d1bb4ebfbf56ce 100644 (file)
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -180,8 +180,6 @@ void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
 
-  // isSymbolLinkerVisible uses the section.
-  AssignSection(Symbol, getCurrentSection().first);
   // We have to create a new fragment if this is an atom defining symbol,
   // fragments cannot span atoms.
   if (getAssembler().isSymbolLinkerVisible(*Symbol))
@@ -415,8 +413,6 @@ void MCMachOStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
   if (ByteAlignment != 1)
     new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, Section);
 
-  AssignSection(Symbol, Section);
-
   MCFragment *F = new MCFillFragment(0, 0, Size, Section);
   Symbol->setFragment(F);
 
@@ -460,7 +456,8 @@ void MCMachOStreamer::FinishImpl() {
   // defining symbols.
   DenseMap<const MCFragment *, const MCSymbol *> DefiningSymbolMap;
   for (const MCSymbol &Symbol : getAssembler().symbols()) {
-    if (getAssembler().isSymbolLinkerVisible(Symbol) && Symbol.getFragment()) {
+    if (getAssembler().isSymbolLinkerVisible(Symbol) && Symbol.isInSection() &&
+        !Symbol.isVariable()) {
       // An atom defining symbol should never be internal to a fragment.
       assert(Symbol.getOffset() == 0 &&
              "Invalid offset in atom defining symbol!");

diff --git a/lib/MC/MCObjectStreamer.cpp b/lib/MC/MCObjectStreamer.cpp
index caee5da47a0321e7c08051477cc276ed3731242f..992b2cfe359ac4e5cef428f488ba5fc49f4941d8 100644 (file)
--- a/lib/MC/MCObjectStreamer.cpp
+++ b/lib/MC/MCObjectStreamer.cpp
@@ -58,7 +58,8 @@ void MCObjectStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi,
                                               const MCSymbol *Lo,
                                               unsigned Size) {
   // If not assigned to the same (valid) fragment, fallback.
-  if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment()) {
+  if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment() ||
+      Hi->isVariable() || Lo->isVariable()) {
     MCStreamer::emitAbsoluteSymbolDiff(Hi, Lo, Size);
     return;
   }
@@ -155,7 +156,6 @@ void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
   MCStreamer::EmitLabel(Symbol);
 
   getAssembler().registerSymbol(*Symbol);
-  assert(!Symbol->getFragment() && "Unexpected fragment on symbol data!");
 
   // If there is a current fragment, mark the symbol as pointing into it.
   // Otherwise queue the label and set its fragment pointer when we emit the

diff --git a/lib/MC/MCObjectWriter.cpp b/lib/MC/MCObjectWriter.cpp
index 347903408737ecfe479ac581e4d10fb69f3c54c5..e84f74ae81d6c7cd21d0d9ec65f48173101f8398 100644 (file)
--- a/lib/MC/MCObjectWriter.cpp
+++ b/lib/MC/MCObjectWriter.cpp
@@ -33,8 +33,14 @@ bool MCObjectWriter::isSymbolRefDifferenceFullyResolved(
   if (!SA.getFragment() || !SB.getFragment())
     return false;
 
-  return isSymbolRefDifferenceFullyResolvedImpl(Asm, SA, *SB.getFragment(),
-                                                InSet, false);
+  return isSymbolRefDifferenceFullyResolvedImpl(Asm, SA, SB, InSet);
+}
+
+bool MCObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
+    const MCAssembler &Asm, const MCSymbol &A, const MCSymbol &B,
+    bool InSet) const {
+  return isSymbolRefDifferenceFullyResolvedImpl(Asm, A, *B.getFragment(), InSet,
+                                                false);
 }
 
 bool MCObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(

diff --git a/lib/MC/MCSection.cpp b/lib/MC/MCSection.cpp
index 9152f2b42a48578abc5eecffb1a58259dc269e8b..e0d29bbd6600ae5d754c39e974b62be8e19e47eb 100644 (file)
--- a/lib/MC/MCSection.cpp
+++ b/lib/MC/MCSection.cpp
@@ -21,7 +21,7 @@ using namespace llvm;
 
 MCSection::MCSection(SectionVariant V, SectionKind K, MCSymbol *Begin)
     : Begin(Begin), BundleGroupBeforeFirstInst(false), HasInstructions(false),
-      IsRegistered(false), Variant(V), Kind(K) {}
+      IsRegistered(false), DummyFragment(this), Variant(V), Kind(K) {}
 
 MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
   if (!End)

diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index d6b44a0297d5e2129c68653277cb18043e81eeef..5d7685177b2b3187097a70fe12de7dec35c95890 100644 (file)
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -188,9 +188,9 @@ void MCStreamer::InitSections(bool NoExecStack) {
   SwitchSection(getContext().getObjectFileInfo()->getTextSection());
 }
 
-void MCStreamer::AssignSection(MCSymbol *Symbol, MCSection *Section) {
-  assert(Section);
-  Symbol->setSection(*Section);
+void MCStreamer::AssignFragment(MCSymbol *Symbol, MCFragment *Fragment) {
+  assert(Fragment);
+  Symbol->setFragment(Fragment);
 
   // As we emit symbols into a section, track the order so that they can
   // be sorted upon later. Zero is reserved to mean 'unemitted'.
@@ -200,7 +200,8 @@ void MCStreamer::AssignSection(MCSymbol *Symbol, MCSection *Section) {
 void MCStreamer::EmitLabel(MCSymbol *Symbol) {
   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
   assert(getCurrentSection().first && "Cannot emit before setting section!");
-  AssignSection(Symbol, getCurrentSection().first);
+  assert(!Symbol->getFragment() && "Unexpected fragment on symbol data!");
+  Symbol->setFragment(&getCurrentSectionOnly()->getDummyFragment());
 
   MCTargetStreamer *TS = getTargetStreamer();
   if (TS)

diff --git a/lib/MC/MCSymbol.cpp b/lib/MC/MCSymbol.cpp
index 125380a9d14066aea4508f4a35d8f37b9366512e..c7d6213bc192257752b9924e9e1bbfcab7345037 100644 (file)
--- a/lib/MC/MCSymbol.cpp
+++ b/lib/MC/MCSymbol.cpp
@@ -16,8 +16,9 @@
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
-// Sentinel value for the absolute pseudo section.
-MCSection *MCSymbol::AbsolutePseudoSection = reinterpret_cast<MCSection *>(1);
+// Sentinel value for the absolute pseudo fragment.
+MCFragment *MCSymbol::AbsolutePseudoFragment =
+    reinterpret_cast<MCFragment *>(4);
 
 void *MCSymbol::operator new(size_t s, const StringMapEntry<bool> *Name,
                              MCContext &Ctx) {

diff --git a/lib/MC/MachObjectWriter.cpp b/lib/MC/MachObjectWriter.cpp
index 94d71f1116d243f3c0358b3a31cb028b4bf2c275..d5184f1d9a48d9dd26341221339f8960522d0d89 100644 (file)
--- a/lib/MC/MachObjectWriter.cpp
+++ b/lib/MC/MachObjectWriter.cpp
@@ -625,6 +625,18 @@ void MachObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
   bindIndirectSymbols(Asm);
 }
 
+bool MachObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
+    const MCAssembler &Asm, const MCSymbol &A, const MCSymbol &B,
+    bool InSet) const {
+  // FIXME: We don't handle things like
+  // foo = .
+  // creating atoms.
+  if (A.isVariable() || B.isVariable())
+    return false;
+  return MCObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(Asm, A, B,
+                                                                InSet);
+}
+
 bool MachObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
     const MCAssembler &Asm, const MCSymbol &SymA, const MCFragment &FB,
     bool InSet, bool IsPCRel) const {

diff --git a/lib/MC/WinCOFFStreamer.cpp b/lib/MC/WinCOFFStreamer.cpp
index 40c242ce86651b8391a9f4013de65fa71688d287..02814fa7d28d000d3f57ba78eadd6e7e5fc57b0a 100644 (file)
--- a/lib/MC/WinCOFFStreamer.cpp
+++ b/lib/MC/WinCOFFStreamer.cpp
@@ -245,8 +245,6 @@ void MCWinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
   getAssembler().registerSymbol(*Symbol);
   Symbol->setExternal(false);
 
-  AssignSection(Symbol, Section);
-
   if (ByteAlignment != 1)
     new MCAlignFragment(ByteAlignment, /*Value=*/0, /*ValueSize=*/0,
                         ByteAlignment, Section);

diff --git a/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp b/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp
index 29a903fd9f1539e7f2fd2b71b60a6e1862342976..a540f49866a9e0826de08591ecec9e8f1162e304 100644 (file)
--- a/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp
+++ b/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp
@@ -85,7 +85,7 @@ void AArch64MCExpr::visitUsedExpr(MCStreamer &Streamer) const {
   Streamer.visitUsedExpr(*getSubExpr());
 }
 
-MCSection *AArch64MCExpr::findAssociatedSection() const {
+MCFragment *AArch64MCExpr::findAssociatedFragment() const {
   llvm_unreachable("FIXME: what goes here?");
 }
 

diff --git a/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h b/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h
index b111e7c2dedb722b7c2697a9522ac6bc2679ad8a..db36a65564ce8db4800d96c423e95424bd2dd547 100644 (file)
--- a/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h
+++ b/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h
@@ -149,7 +149,7 @@ public:
 
   void visitUsedExpr(MCStreamer &Streamer) const override;
 
-  MCSection *findAssociatedSection() const override;
+  MCFragment *findAssociatedFragment() const override;
 
   bool evaluateAsRelocatableImpl(MCValue &Res, const MCAsmLayout *Layout,
                                  const MCFixup *Fixup) const override;

diff --git a/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h b/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h
index 9146d4def75ad2f05fbeb5fdfb00d3b72ce65877..75dde8008fca0613978e56b601fa829971fcc23a 100644 (file)
--- a/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h
+++ b/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h
@@ -63,8 +63,8 @@ public:
     return false;
   }
   void visitUsedExpr(MCStreamer &Streamer) const override;
-  MCSection *findAssociatedSection() const override {
-    return getSubExpr()->findAssociatedSection();
+  MCFragment *findAssociatedFragment() const override {
+    return getSubExpr()->findAssociatedFragment();
   }
 
   // There are no TLS ARMMCExprs at the moment.

diff --git a/lib/Target/Hexagon/MCTargetDesc/HexagonMCELFStreamer.cpp b/lib/Target/Hexagon/MCTargetDesc/HexagonMCELFStreamer.cpp
index bf51c3515e95116f8d01c5004bf9cf92091f8ab7..1bec375f33ee045425d56dadfb8720f00f6a392b 100644 (file)
--- a/lib/Target/Hexagon/MCTargetDesc/HexagonMCELFStreamer.cpp
+++ b/lib/Target/Hexagon/MCTargetDesc/HexagonMCELFStreamer.cpp
@@ -114,7 +114,7 @@ void HexagonMCELFStreamer::HexagonMCEmitCommonSymbol(MCSymbol *Symbol,
     MCSection *Section = getAssembler().getContext().getELFSection(
         SectionName, ELF::SHT_NOBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
     SwitchSection(Section);
-    AssignSection(Symbol, Section);
+    AssignFragment(Symbol, getCurrentFragment());
 
     MCELFStreamer::EmitCommonSymbol(Symbol, Size, ByteAlignment);
     SwitchSection(CrntSection);

diff --git a/lib/Target/Mips/MCTargetDesc/MipsMCExpr.h b/lib/Target/Mips/MCTargetDesc/MipsMCExpr.h
index fd2ed17ee785e77277ac663a56760e3680c5b71d..e889972c5c0e8d121df49e0f9a365d9b0b7c2a1c 100644 (file)
--- a/lib/Target/Mips/MCTargetDesc/MipsMCExpr.h
+++ b/lib/Target/Mips/MCTargetDesc/MipsMCExpr.h
@@ -51,8 +51,8 @@ public:
                                  const MCAsmLayout *Layout,
                                  const MCFixup *Fixup) const override;
   void visitUsedExpr(MCStreamer &Streamer) const override;
-  MCSection *findAssociatedSection() const override {
-    return getSubExpr()->findAssociatedSection();
+  MCFragment *findAssociatedFragment() const override {
+    return getSubExpr()->findAssociatedFragment();
   }
 
   // There are no TLS MipsMCExprs at the moment.

diff --git a/lib/Target/NVPTX/NVPTXMCExpr.h b/lib/Target/NVPTX/NVPTXMCExpr.h
index 46b4b33e7e4004ded6caa2ddd28de4171fbed4a5..81a606d7535cbb24e2255b71b5552651f070ffef 100644 (file)
--- a/lib/Target/NVPTX/NVPTXMCExpr.h
+++ b/lib/Target/NVPTX/NVPTXMCExpr.h
@@ -68,7 +68,7 @@ public:
     return false;
   }
   void visitUsedExpr(MCStreamer &Streamer) const override {};
-  MCSection *findAssociatedSection() const override { return nullptr; }
+  MCFragment *findAssociatedFragment() const override { return nullptr; }
 
   // There are no TLS NVPTXMCExprs at the moment.
   void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override {}
@@ -110,7 +110,7 @@ public:
     return false;
   }
   void visitUsedExpr(MCStreamer &Streamer) const override {};
-  MCSection *findAssociatedSection() const override { return nullptr; }
+  MCFragment *findAssociatedFragment() const override { return nullptr; }
 
   // There are no TLS NVPTXMCExprs at the moment.
   void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override {}

diff --git a/lib/Target/PowerPC/MCTargetDesc/PPCMCExpr.h b/lib/Target/PowerPC/MCTargetDesc/PPCMCExpr.h
index a641780516b3f76e2548d0be8aa6f940cfffc789..d42a111cc43ede3156d27a8c1da23f254fe9620f 100644 (file)
--- a/lib/Target/PowerPC/MCTargetDesc/PPCMCExpr.h
+++ b/lib/Target/PowerPC/MCTargetDesc/PPCMCExpr.h
@@ -82,8 +82,8 @@ public:
                                  const MCAsmLayout *Layout,
                                  const MCFixup *Fixup) const override;
   void visitUsedExpr(MCStreamer &Streamer) const override;
-  MCSection *findAssociatedSection() const override {
-    return getSubExpr()->findAssociatedSection();
+  MCFragment *findAssociatedFragment() const override {
+    return getSubExpr()->findAssociatedFragment();
   }
 
   // There are no TLS PPCMCExprs at the moment.

diff --git a/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h b/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h
index d08ad86dbe042a0ed68b7c8fdca32e2d2508e944..13f08195c7644ac91b4996b2e2d13b133151e7f6 100644 (file)
--- a/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h
+++ b/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h
@@ -90,8 +90,8 @@ public:
                                  const MCAsmLayout *Layout,
                                  const MCFixup *Fixup) const override;
   void visitUsedExpr(MCStreamer &Streamer) const override;
-  MCSection *findAssociatedSection() const override {
-    return getSubExpr()->findAssociatedSection();
+  MCFragment *findAssociatedFragment() const override {
+    return getSubExpr()->findAssociatedFragment();
   }
 
   void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override;

diff --git a/test/MC/COFF/alias.s b/test/MC/COFF/alias.s
index 2293d43c5750c09354da7a97a1bf38aa8de77e43..369bbe8d8444c07341704df85dff707b196f6828 100644 (file)
--- a/test/MC/COFF/alias.s
+++ b/test/MC/COFF/alias.s
@@ -21,9 +21,9 @@ weak_aliased_to_external = external2
         .long weak_aliased_to_external
 
 // CHECK:      Relocations [
-// CHECK:        0x0 IMAGE_REL_I386_DIR32 local1
+// CHECK:        0x0 IMAGE_REL_I386_DIR32 external_aliased_to_local
 // CHECK:        0x4 IMAGE_REL_I386_DIR32 external1
-// CHECK:        0x8 IMAGE_REL_I386_DIR32 local2
+// CHECK:        0x8 IMAGE_REL_I386_DIR32 global_aliased_to_local
 // CHECK:        0xC IMAGE_REL_I386_DIR32 external2
 // CHECK:      ]
 // CHECK:      Symbols [

diff --git a/test/MC/ELF/relocation.s b/test/MC/ELF/relocation.s
index 34f1a4038131b62e58c40a1075e53176d35f2368..0fec76792818bdfc5c045f227743ee8fc4727b5b 100644 (file)
--- a/test/MC/ELF/relocation.s
+++ b/test/MC/ELF/relocation.s
@@ -55,6 +55,11 @@ bar:
         .quad  pr23272_2 - pr23272
         .quad  pr23272_3 - pr23272
 
+       .global pr24486
+pr24486:
+       pr24486_alias = pr24486
+       .long pr24486_alias
+
         .code16
         call pr23771
 
@@ -94,6 +99,7 @@ bar:
 // CHECK-NEXT:       0xD4 R_X86_64_SIZE32 blah 0xFFFFFFFFFFFFFFE0
 // CHECK-NEXT:       0xD8 R_X86_64_GOTPCREL foo 0x0
 // CHECK-NEXT:       0xDC R_X86_64_PLT32 foo 0x0
-// CHECK-NEXT:       0xF1 R_X86_64_PC16 pr23771 0xFFFFFFFFFFFFFFFE
+// CHECK-NEXT:       0xF0 R_X86_64_32 .text 0xF0
+// CHECK-NEXT:       0xF5 R_X86_64_PC16 pr23771 0xFFFFFFFFFFFFFFFE
 // CHECK-NEXT:     ]
 // CHECK-NEXT:   }