From: Pete Cooper <peter_cooper@apple.com>
Date: Wed, 1 Jul 2015 21:57:51 +0000 (+0000)
Subject: Pack MCSymbol::Flags in to the bitfield with other members.  NFC.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=f89e1bdc1a54c3bf211e86132af7c51bac8a7374;p=oota-llvm.git

Pack MCSymbol::Flags in to the bitfield with other members.  NFC.

All file formats only needed 16-bits right now which is enough to fit
in to the padding with other fields.

This reduces the size of MCSymbol to 24-bytes on a 64-bit system.  The
layout is now

   0 | class llvm::MCSymbol
   0 |   class llvm::PointerIntPair SectionOrFragmentAndHasName
   0 |     intptr_t Value
     |   [sizeof=8, dsize=8, align=8
     |    nvsize=8, nvalign=8]

   8 |   unsigned int IsTemporary
   8 |   unsigned int IsRedefinable
   8 |   unsigned int IsUsed
   8 |   _Bool IsRegistered
   8 |   unsigned int IsExternal
   8 |   unsigned int IsPrivateExtern
   8 |   unsigned int Kind
   9 |   unsigned int IsUsedInReloc
   9 |   unsigned int SymbolContents
   9 |   unsigned int CommonAlignLog2
  10 |   uint32_t Flags
  12 |   uint32_t Index
  16 |   union
  16 |     uint64_t Offset
  16 |     uint64_t CommonSize
  16 |     const class llvm::MCExpr * Value
     |   [sizeof=8, dsize=8, align=8
     |    nvsize=8, nvalign=8]

     | [sizeof=24, dsize=24, align=8
     |  nvsize=24, nvalign=8]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241196 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/MC/MCSymbol.h b/include/llvm/MC/MCSymbol.h
index e52a34601b0..17e6b857cf2 100644
--- a/include/llvm/MC/MCSymbol.h
+++ b/include/llvm/MC/MCSymbol.h
@@ -117,6 +117,11 @@ protected:
   static const unsigned NumCommonAlignmentBits = 5;
   unsigned CommonAlignLog2 : NumCommonAlignmentBits;
 
+  /// The Flags field is used by object file implementations to store
+  /// additional per symbol information which is not easily classified.
+  static const unsigned NumFlagsBits = 16;
+  mutable uint32_t Flags : NumFlagsBits;
+
   /// Index field, for use by the object file implementation.
   mutable uint32_t Index = 0;
 
@@ -131,10 +136,6 @@ protected:
     const MCExpr *Value;
   };
 
-  /// The Flags field is used by object file implementations to store
-  /// additional per symbol information which is not easily classified.
-  mutable uint32_t Flags = 0;
-
 protected: // MCContext creates and uniques these.
   friend class MCExpr;
   friend class MCContext;
@@ -152,7 +153,7 @@ protected: // MCContext creates and uniques these.
       : IsTemporary(isTemporary), IsRedefinable(false), IsUsed(false),
         IsRegistered(false), IsExternal(false), IsPrivateExtern(false),
         Kind(Kind), IsUsedInReloc(false), SymbolContents(SymContentsUnset),
-        CommonAlignLog2(0) {
+        CommonAlignLog2(0), Flags(0) {
     Offset = 0;
     SectionOrFragmentAndHasName.setInt(!!Name);
     if (Name)
@@ -402,10 +403,14 @@ protected:
   uint32_t getFlags() const { return Flags; }
 
   /// Set the (implementation defined) symbol flags.
-  void setFlags(uint32_t Value) const { Flags = Value; }
+  void setFlags(uint32_t Value) const {
+    assert(Value < (1U << NumFlagsBits) && "Out of range flags");
+    Flags = Value;
+  }
 
   /// Modify the flags via a mask
   void modifyFlags(uint32_t Value, uint32_t Mask) const {
+    assert(Value < (1U << NumFlagsBits) && "Out of range flags");
     Flags = (Flags & ~Mask) | Value;
   }
 };
diff --git a/lib/MC/MCSymbol.cpp b/lib/MC/MCSymbol.cpp
index 2655a181a23..affc57471fd 100644
--- a/lib/MC/MCSymbol.cpp
+++ b/lib/MC/MCSymbol.cpp
@@ -20,6 +20,7 @@ using namespace llvm;
 MCSection *MCSymbol::AbsolutePseudoSection = reinterpret_cast<MCSection *>(1);
 
 const unsigned MCSymbol::NumCommonAlignmentBits;
+const unsigned MCSymbol::NumFlagsBits;
 
 void *MCSymbol::operator new(size_t s, const StringMapEntry<bool> *Name,
                              MCContext &Ctx) {