MC: Shrink MCSymbolRefExpr by only storing the bits we need.

32 -> 16 bytes on x86_64. NFC.

llvm-svn: 219574

2 files changed, 35 insertions, 22 deletions

diff --git a/llvm/include/llvm/MC/MCExpr.h b/llvm/include/llvm/MC/MCExpr.h
index 394a04737de..1d2e2950555 100644
--- a/llvm/include/llvm/MC/MCExpr.h
+++ b/llvm/include/llvm/MC/MCExpr.h
@@ -282,21 +282,20 @@ public:
   };
 
 private:
-  /// The symbol being referenced.
-  const MCSymbol *Symbol;
-
   /// The symbol reference modifier.
-  const VariantKind Kind;
+  const unsigned Kind : 16;
 
-  /// MCAsmInfo that is used to print symbol variants correctly.
-  const MCAsmInfo *MAI;
+  /// Specifies how the variant kind should be printed.
+  const unsigned UseParensForSymbolVariant : 1;
 
-  explicit MCSymbolRefExpr(const MCSymbol *_Symbol, VariantKind _Kind,
-                           const MCAsmInfo *_MAI)
-    : MCExpr(MCExpr::SymbolRef), Symbol(_Symbol), Kind(_Kind), MAI(_MAI) {
-    assert(Symbol);
-    assert(MAI);
-  }
+  // FIXME: Remove this bit.
+  const unsigned HasSubsectionsViaSymbols : 1;
+
+  /// The symbol being referenced.
+  const MCSymbol *Symbol;
+
+  explicit MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind,
+                           const MCAsmInfo *MAI);
 
 public:
   /// @name Construction
@@ -316,9 +315,12 @@ public:
   /// @{
 
   const MCSymbol &getSymbol() const { return *Symbol; }
-  const MCAsmInfo &getMCAsmInfo() const { return *MAI; }
 
-  VariantKind getKind() const { return Kind; }
+  VariantKind getKind() const { return static_cast<VariantKind>(Kind); }
+
+  void printVariantKind(raw_ostream &OS) const;
+
+  bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
 
   /// @}
   /// @name Static Utility Functions
diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
index c0396233c27..83a245602ce 100644
--- a/llvm/lib/MC/MCExpr.cpp
+++ b/llvm/lib/MC/MCExpr.cpp
@@ -49,12 +49,8 @@ void MCExpr::print(raw_ostream &OS) const {
     else
       OS << Sym;
 
-    if (SRE.getKind() != MCSymbolRefExpr::VK_None) {
-      if (SRE.getMCAsmInfo().useParensForSymbolVariant())
-        OS << '(' << MCSymbolRefExpr::getVariantKindName(SRE.getKind()) << ')';
-      else
-        OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
-    }
+    if (SRE.getKind() != MCSymbolRefExpr::VK_None)
+      SRE.printVariantKind(OS);
 
     return;
   }
@@ -150,6 +146,15 @@ const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
 
 /* *** */
 
+MCSymbolRefExpr::MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind,
+                                 const MCAsmInfo *MAI)
+    : MCExpr(MCExpr::SymbolRef), Kind(Kind),
+      UseParensForSymbolVariant(MAI->useParensForSymbolVariant()),
+      HasSubsectionsViaSymbols(MAI->hasSubsectionsViaSymbols()),
+      Symbol(Symbol) {
+  assert(Symbol);
+}
+
 const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
                                                VariantKind Kind,
                                                MCContext &Ctx) {
@@ -442,6 +447,13 @@ MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
     .Default(VK_Invalid);
 }
 
+void MCSymbolRefExpr::printVariantKind(raw_ostream &OS) const {
+  if (UseParensForSymbolVariant)
+    OS << '(' << MCSymbolRefExpr::getVariantKindName(getKind()) << ')';
+  else
+    OS << '@' << MCSymbolRefExpr::getVariantKindName(getKind());
+}
+
 /* *** */
 
 void MCTargetExpr::anchor() {}
@@ -679,7 +691,6 @@ bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
   case SymbolRef: {
     const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
     const MCSymbol &Sym = SRE->getSymbol();
-    const MCAsmInfo &MCAsmInfo = SRE->getMCAsmInfo();
 
     // Evaluate recursively if this is a variable.
     if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
@@ -688,7 +699,7 @@ bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
         const MCSymbolRefExpr *A = Res.getSymA();
         const MCSymbolRefExpr *B = Res.getSymB();
 
-        if (MCAsmInfo.hasSubsectionsViaSymbols()) {
+        if (SRE->hasSubsectionsViaSymbols()) {
           // FIXME: This is small hack. Given
           // a = b + 4
           // .long a