Pack the MCSymbolELF bit fields into MCSymbol's Flags.

This reduces MCSymolfELF from 64 bytes to 56 bytes on x86_64.

While at it, also make getOther/setOther easier to use by accepting unshifted
STO_* values.

llvm-svn: 239006

1 files changed, 135 insertions, 38 deletions

diff --git a/llvm/lib/MC/MCSymbolELF.cpp b/llvm/lib/MC/MCSymbolELF.cpp
index f4d3d176c3a..33542f99e1d 100644
--- a/llvm/lib/MC/MCSymbolELF.cpp
+++ b/llvm/lib/MC/MCSymbolELF.cpp
@@ -16,27 +16,71 @@ namespace llvm {
 
 namespace {
 enum {
-  ELF_STT_Shift = 0, // Shift value for STT_* flags
-  ELF_STB_Shift = 4, // Shift value for STB_* flags
-  ELF_STV_Shift = 8, // Shift value for STV_* flags
-  ELF_STO_Shift = 10 // Shift value for STO_* flags
+  // Shift value for STT_* flags. 7 possible values. 3 bits.
+  ELF_STT_Shift = 0,
+
+  // Shift value for STB_* flags. 4 possible values, 2 bits.
+  ELF_STB_Shift = 3,
+
+  // Shift value for STV_* flags. 4 possible values, 2 bits.
+  ELF_STV_Shift = 5,
+
+  // Shift value for STO_* flags. 3 bits. All the values are between 0x20 and
+  // 0xe0, so we shift right by 5 before storing.
+  ELF_STO_Shift = 7,
+
+  // One bit.
+  ELF_IsSignature_Shift = 10,
+
+  // One bit.
+  ELF_WeakrefUsedInReloc_Shift = 11,
+
+  // One bit.
+  ELF_UsedInReloc_Shift = 12,
+
+  // One bit.
+  ELF_BindingSet_Shift = 13
 };
 }
 
 void MCSymbolELF::setBinding(unsigned Binding) const {
-  BindingSet = true;
-  assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
-         Binding == ELF::STB_WEAK || Binding == ELF::STB_GNU_UNIQUE);
-  uint32_t OtherFlags = getFlags() & ~(0xf << ELF_STB_Shift);
-  setFlags(OtherFlags | (Binding << ELF_STB_Shift));
+  setIsBindingSet();
+  unsigned Val;
+  switch (Binding) {
+  default:
+    llvm_unreachable("Unsupported Binding");
+  case ELF::STB_LOCAL:
+    Val = 0;
+    break;
+  case ELF::STB_GLOBAL:
+    Val = 1;
+    break;
+  case ELF::STB_WEAK:
+    Val = 2;
+    break;
+  case ELF::STB_GNU_UNIQUE:
+    Val = 3;
+    break;
+  }
+  uint32_t OtherFlags = getFlags() & ~(0x3 << ELF_STB_Shift);
+  setFlags(OtherFlags | (Val << ELF_STB_Shift));
 }
 
 unsigned MCSymbolELF::getBinding() const {
   if (isBindingSet()) {
-    uint32_t Binding = (getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
-    assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
-           Binding == ELF::STB_WEAK || Binding == ELF::STB_GNU_UNIQUE);
-    return Binding;
+    uint32_t Val = (getFlags() & (0x3 << ELF_STB_Shift)) >> ELF_STB_Shift;
+    switch (Val) {
+    default:
+      llvm_unreachable("Invalid value");
+    case 0:
+      return ELF::STB_LOCAL;
+    case 1:
+      return ELF::STB_GLOBAL;
+    case 2:
+      return ELF::STB_WEAK;
+    case 3:
+      return ELF::STB_GNU_UNIQUE;
+    }
   }
 
   if (isDefined())
@@ -51,26 +95,58 @@ unsigned MCSymbolELF::getBinding() const {
 }
 
 void MCSymbolELF::setType(unsigned Type) const {
-  assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
-         Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
-         Type == ELF::STT_COMMON || Type == ELF::STT_TLS ||
-         Type == ELF::STT_GNU_IFUNC);
-
-  uint32_t OtherFlags = getFlags() & ~(0xf << ELF_STT_Shift);
-  setFlags(OtherFlags | (Type << ELF_STT_Shift));
+  unsigned Val;
+  switch (Type) {
+  default:
+    llvm_unreachable("Unsupported Binding");
+  case ELF::STT_NOTYPE:
+    Val = 0;
+    break;
+  case ELF::STT_OBJECT:
+    Val = 1;
+    break;
+  case ELF::STT_FUNC:
+    Val = 2;
+    break;
+  case ELF::STT_SECTION:
+    Val = 3;
+    break;
+  case ELF::STT_COMMON:
+    Val = 4;
+    break;
+  case ELF::STT_TLS:
+    Val = 5;
+    break;
+  case ELF::STT_GNU_IFUNC:
+    Val = 6;
+    break;
+  }
+  uint32_t OtherFlags = getFlags() & ~(0x7 << ELF_STT_Shift);
+  setFlags(OtherFlags | (Val << ELF_STT_Shift));
 }
 
 unsigned MCSymbolELF::getType() const {
-  uint32_t Type = (getFlags() & (0xf << ELF_STT_Shift)) >> ELF_STT_Shift;
-  assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
-         Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
-         Type == ELF::STT_COMMON || Type == ELF::STT_TLS ||
-         Type == ELF::STT_GNU_IFUNC);
-  return Type;
+  uint32_t Val = (getFlags() & (0x7 << ELF_STT_Shift)) >> ELF_STT_Shift;
+  switch (Val) {
+  default:
+    llvm_unreachable("Invalid value");
+  case 0:
+    return ELF::STT_NOTYPE;
+  case 1:
+    return ELF::STT_OBJECT;
+  case 2:
+    return ELF::STT_FUNC;
+  case 3:
+    return ELF::STT_SECTION;
+  case 4:
+    return ELF::STT_COMMON;
+  case 5:
+    return ELF::STT_TLS;
+  case 6:
+    return ELF::STT_GNU_IFUNC;
+  }
 }
 
-// Visibility is stored in the first two bits of st_other
-// st_other values are stored in the second byte of get/setFlags
 void MCSymbolELF::setVisibility(unsigned Visibility) {
   assert(Visibility == ELF::STV_DEFAULT || Visibility == ELF::STV_INTERNAL ||
          Visibility == ELF::STV_HIDDEN || Visibility == ELF::STV_PROTECTED);
@@ -86,31 +162,52 @@ unsigned MCSymbolELF::getVisibility() const {
   return Visibility;
 }
 
-// Other is stored in the last six bits of st_other
-// st_other values are stored in the second byte of get/setFlags
 void MCSymbolELF::setOther(unsigned Other) {
-  uint32_t OtherFlags = getFlags() & ~(0x3f << ELF_STO_Shift);
+  assert((Other & 0x1f) == 0);
+  Other >>= 5;
+  assert(Other <= 0x7);
+  uint32_t OtherFlags = getFlags() & ~(0x7 << ELF_STO_Shift);
   setFlags(OtherFlags | (Other << ELF_STO_Shift));
 }
 
 unsigned MCSymbolELF::getOther() const {
   unsigned Other = (getFlags() & (0x3f << ELF_STO_Shift)) >> ELF_STO_Shift;
-  return Other;
+  return Other << 5;
 }
 
 void MCSymbolELF::setUsedInReloc() const {
-  UsedInReloc = true;
+  uint32_t OtherFlags = getFlags() & ~(0x1 << ELF_UsedInReloc_Shift);
+  setFlags(OtherFlags | (1 << ELF_UsedInReloc_Shift));
 }
 
 bool MCSymbolELF::isUsedInReloc() const {
-  return UsedInReloc;
+  return getFlags() & (0x1 << ELF_UsedInReloc_Shift);
 }
 
-void MCSymbolELF::setIsWeakrefUsedInReloc() const { WeakrefUsedInReloc = true; }
+void MCSymbolELF::setIsWeakrefUsedInReloc() const {
+  uint32_t OtherFlags = getFlags() & ~(0x1 << ELF_WeakrefUsedInReloc_Shift);
+  setFlags(OtherFlags | (1 << ELF_WeakrefUsedInReloc_Shift));
+}
 
-bool MCSymbolELF::isWeakrefUsedInReloc() const { return WeakrefUsedInReloc; }
+bool MCSymbolELF::isWeakrefUsedInReloc() const {
+  return getFlags() & (0x1 << ELF_WeakrefUsedInReloc_Shift);
+}
 
-void MCSymbolELF::setIsSignature() const { IsSignature = true; }
+void MCSymbolELF::setIsSignature() const {
+  uint32_t OtherFlags = getFlags() & ~(0x1 << ELF_IsSignature_Shift);
+  setFlags(OtherFlags | (1 << ELF_IsSignature_Shift));
+}
 
-bool MCSymbolELF::isSignature() const { return IsSignature; }
+bool MCSymbolELF::isSignature() const {
+  return getFlags() & (0x1 << ELF_IsSignature_Shift);
+}
+
+void MCSymbolELF::setIsBindingSet() const {
+  uint32_t OtherFlags = getFlags() & ~(0x1 << ELF_BindingSet_Shift);
+  setFlags(OtherFlags | (1 << ELF_BindingSet_Shift));
+}
+
+bool MCSymbolELF::isBindingSet() const {
+  return getFlags() & (0x1 << ELF_BindingSet_Shift);
+}
 }