MCAssembler: Move SubsectionsViaSymbols; to MCObjectWriter

Author: MaskRay

llvm/include/llvm/MC/MCAssembler.h

@@ -65,7 +65,6 @@ class MCAssembler {
 
   bool HasLayout = false;
   bool RelaxAll = false;
-  bool SubsectionsViaSymbols = false;
 
   SectionListType Sections;
 
@@ -204,10 +203,6 @@ class MCAssembler {
   // Layout all section and prepare them for emission.
   void layout();
 
-  // FIXME: This does not belong here.
-  bool getSubsectionsViaSymbols() const { return SubsectionsViaSymbols; }
-  void setSubsectionsViaSymbols(bool Value) { SubsectionsViaSymbols = Value; }
-
   bool hasLayout() const { return HasLayout; }
   bool getRelaxAll() const { return RelaxAll; }
   void setRelaxAll(bool Value) { RelaxAll = Value; }

llvm/include/llvm/MC/MCObjectWriter.h

@@ -38,6 +38,7 @@ class MCObjectWriter {
   std::string CompilerVersion;
   std::vector<const MCSymbol *> AddrsigSyms;
   bool EmitAddrsigSection = false;
+  bool SubsectionsViaSymbols = false;
 
   struct CGProfileEntry {
     const MCSymbolRefExpr *From;
@@ -114,6 +115,10 @@ class MCObjectWriter {
   std::vector<const MCSymbol *> &getAddrsigSyms() { return AddrsigSyms; }
   SmallVector<CGProfileEntry, 0> &getCGProfile() { return CGProfile; }
 
+  // Mach-O specific: Whether .subsections_via_symbols is enabled.
+  bool getSubsectionsViaSymbols() const { return SubsectionsViaSymbols; }
+  void setSubsectionsViaSymbols(bool Value) { SubsectionsViaSymbols = Value; }
+
   /// Write the object file and returns the number of bytes written.
   ///
   /// This routine is called by the assembler after layout and relaxation is

llvm/lib/MC/MCAssembler.cpp

@@ -90,7 +90,6 @@ MCAssembler::~MCAssembler() = default;
 
 void MCAssembler::reset() {
   RelaxAll = false;
-  SubsectionsViaSymbols = false;
   Sections.clear();
   Symbols.clear();
   ThumbFuncs.clear();
@@ -1095,7 +1094,7 @@ bool MCAssembler::relaxLEB(MCLEBFragment &LF) {
   // Use evaluateKnownAbsolute for Mach-O as a hack: .subsections_via_symbols
   // requires that .uleb128 A-B is foldable where A and B reside in different
   // fragments. This is used by __gcc_except_table.
-  bool Abs = getSubsectionsViaSymbols()
+  bool Abs = getWriter().getSubsectionsViaSymbols()
                  ? LF.getValue().evaluateKnownAbsolute(Value, *this)
                  : LF.getValue().evaluateAsAbsolute(Value, *this);
   if (!Abs) {

llvm/lib/MC/MCELFStreamer.cpp

@@ -88,18 +88,6 @@ void MCELFStreamer::emitLabelAtPos(MCSymbol *S, SMLoc Loc, MCDataFragment &F,
 void MCELFStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {
   // Let the target do whatever target specific stuff it needs to do.
   getAssembler().getBackend().handleAssemblerFlag(Flag);
-  // Do any generic stuff we need to do.
-  switch (Flag) {
-  case MCAF_SyntaxUnified: return; // no-op here.
-  case MCAF_Code16: return; // Change parsing mode; no-op here.
-  case MCAF_Code32: return; // Change parsing mode; no-op here.
-  case MCAF_Code64: return; // Change parsing mode; no-op here.
-  case MCAF_SubsectionsViaSymbols:
-    getAssembler().setSubsectionsViaSymbols(true);
-    return;
-  }
-
-  llvm_unreachable("invalid assembler flag!");
 }
 
 // If bundle alignment is used and there are any instructions in the section, it

llvm/lib/MC/MCMachOStreamer.cpp

@@ -220,7 +220,7 @@ void MCMachOStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {
   case MCAF_Code32: return; // Change parsing mode; no-op here.
   case MCAF_Code64: return; // Change parsing mode; no-op here.
   case MCAF_SubsectionsViaSymbols:
-    getAssembler().setSubsectionsViaSymbols(true);
+    getWriter().setSubsectionsViaSymbols(true);
     return;
   }
 }

llvm/lib/MC/MCObjectWriter.cpp

@@ -22,6 +22,8 @@ MCObjectWriter::~MCObjectWriter() = default;
 void MCObjectWriter::reset() {
   FileNames.clear();
   AddrsigSyms.clear();
+  EmitAddrsigSection = false;
+  SubsectionsViaSymbols = false;
   CGProfile.clear();
 }
 

llvm/lib/MC/MachObjectWriter.cpp

@@ -744,7 +744,7 @@ bool MachObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
     if (!hasReliableSymbolDifference) {
       if (!SA.isInSection() || &SecA != &SecB ||
           (!SA.isTemporary() && FB.getAtom() != SA.getFragment()->getAtom() &&
-           Asm.getSubsectionsViaSymbols()))
+           SubsectionsViaSymbols))
         return false;
       return true;
     }
@@ -894,7 +894,7 @@ uint64_t MachObjectWriter::writeObject(MCAssembler &Asm) {
 
   // Write the prolog, starting with the header and load command...
   writeHeader(MachO::MH_OBJECT, NumLoadCommands, LoadCommandsSize,
-              Asm.getSubsectionsViaSymbols());
+              SubsectionsViaSymbols);
   uint32_t Prot =
       MachO::VM_PROT_READ | MachO::VM_PROT_WRITE | MachO::VM_PROT_EXECUTE;
   writeSegmentLoadCommand("", NumSections, 0, VMSize, SectionDataStart,