Spread some const around for non-mutating uses of MCSymbolData.

I discovered this const-hole while attempting to coalesnce the Symbol
and SymbolMap data structures. There's some pending issues with that,
but I figured this change was easy to flush early.

llvm-svn: 207124
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 1db517f..c16b355 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -603,7 +603,7 @@
   // the offset when the destination has the same MCFragment.
   if (A && (unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_bl) {
     const MCSymbol &Sym = A->getSymbol().AliasedSymbol();
-    MCSymbolData &SymData = Asm.getSymbolData(Sym);
+    const MCSymbolData &SymData = Asm.getSymbolData(Sym);
     IsResolved = (SymData.getFragment() == DF);
   }
   // We must always generate a relocation for BL/BLX instructions if we have
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
index 3bf5cf1..f2e4532 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
@@ -156,7 +156,7 @@
 
   // See <reloc.h>.
   const MCSymbol *A = &Target.getSymA()->getSymbol();
-  MCSymbolData *A_SD = &Asm.getSymbolData(*A);
+  const MCSymbolData *A_SD = &Asm.getSymbolData(*A);
 
   if (!A_SD->getFragment())
     Asm.getContext().FatalError(Fixup.getLoc(),
@@ -170,7 +170,7 @@
   FixedValue += SecAddr;
 
   if (const MCSymbolRefExpr *B = Target.getSymB()) {
-    MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
+    const MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
 
     if (!B_SD->getFragment())
       Asm.getContext().FatalError(Fixup.getLoc(),
@@ -259,7 +259,7 @@
 
   // See <reloc.h>.
   const MCSymbol *A = &Target.getSymA()->getSymbol();
-  MCSymbolData *A_SD = &Asm.getSymbolData(*A);
+  const MCSymbolData *A_SD = &Asm.getSymbolData(*A);
 
   if (!A_SD->getFragment())
     Asm.getContext().FatalError(Fixup.getLoc(),
@@ -272,7 +272,7 @@
   uint32_t Value2 = 0;
 
   if (const MCSymbolRefExpr *B = Target.getSymB()) {
-    MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
+    const MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
 
     if (!B_SD->getFragment())
       Asm.getContext().FatalError(Fixup.getLoc(),
@@ -378,7 +378,7 @@
   }
 
   // Get the symbol data, if any.
-  MCSymbolData *SD = 0;
+  const MCSymbolData *SD = 0;
   if (Target.getSymA())
     SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());
 
diff --git a/llvm/lib/Target/ARM64/MCTargetDesc/ARM64MachObjectWriter.cpp b/llvm/lib/Target/ARM64/MCTargetDesc/ARM64MachObjectWriter.cpp
index 1695b39..9d2dcb6 100644
--- a/llvm/lib/Target/ARM64/MCTargetDesc/ARM64MachObjectWriter.cpp
+++ b/llvm/lib/Target/ARM64/MCTargetDesc/ARM64MachObjectWriter.cpp
@@ -183,11 +183,11 @@
     }
   } else if (Target.getSymB()) { // A - B + constant
     const MCSymbol *A = &Target.getSymA()->getSymbol();
-    MCSymbolData &A_SD = Asm.getSymbolData(*A);
+    const MCSymbolData &A_SD = Asm.getSymbolData(*A);
     const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
 
     const MCSymbol *B = &Target.getSymB()->getSymbol();
-    MCSymbolData &B_SD = Asm.getSymbolData(*B);
+    const MCSymbolData &B_SD = Asm.getSymbolData(*B);
     const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
 
     // Check for "_foo@got - .", which comes through here as:
@@ -267,7 +267,7 @@
     Type = MachO::ARM64_RELOC_SUBTRACTOR;
   } else { // A + constant
     const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
-    MCSymbolData &SD = Asm.getSymbolData(*Symbol);
+    const MCSymbolData &SD = Asm.getSymbolData(*Symbol);
     const MCSymbolData *Base = Asm.getAtom(&SD);
     const MCSectionMachO &Section = static_cast<const MCSectionMachO &>(
         Fragment->getParent()->getSection());
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp
index bbafe2e..4b8f325 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp
@@ -206,7 +206,7 @@
 
   // See <reloc.h>.
   const MCSymbol *A = &Target.getSymA()->getSymbol();
-  MCSymbolData *A_SD = &Asm.getSymbolData(*A);
+  const MCSymbolData *A_SD = &Asm.getSymbolData(*A);
 
   if (!A_SD->getFragment())
     report_fatal_error("symbol '" + A->getName() +
@@ -219,7 +219,7 @@
   uint32_t Value2 = 0;
 
   if (const MCSymbolRefExpr *B = Target.getSymB()) {
-    MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
+    const MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
 
     if (!B_SD->getFragment())
       report_fatal_error("symbol '" + B->getSymbol().getName() +
@@ -324,7 +324,7 @@
 
   // this doesn't seem right for RIT_PPC_BR24
   // Get the symbol data, if any.
-  MCSymbolData *SD = 0;
+  const MCSymbolData *SD = 0;
   if (Target.getSymA())
     SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());
 
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
index 1a35ced..8bfb7d5 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
@@ -146,13 +146,13 @@
     const MCSymbol *A = &Target.getSymA()->getSymbol();
     if (A->isTemporary())
       A = &A->AliasedSymbol();
-    MCSymbolData &A_SD = Asm.getSymbolData(*A);
+    const MCSymbolData &A_SD = Asm.getSymbolData(*A);
     const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
 
     const MCSymbol *B = &Target.getSymB()->getSymbol();
     if (B->isTemporary())
       B = &B->AliasedSymbol();
-    MCSymbolData &B_SD = Asm.getSymbolData(*B);
+    const MCSymbolData &B_SD = Asm.getSymbolData(*B);
     const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
 
     // Neither symbol can be modified.
@@ -220,7 +220,7 @@
     Type = MachO::X86_64_RELOC_SUBTRACTOR;
   } else {
     const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
-    MCSymbolData &SD = Asm.getSymbolData(*Symbol);
+    const MCSymbolData &SD = Asm.getSymbolData(*Symbol);
     const MCSymbolData *Base = Asm.getAtom(&SD);
 
     // Relocations inside debug sections always use local relocations when
@@ -369,7 +369,7 @@
 
   // See <reloc.h>.
   const MCSymbol *A = &Target.getSymA()->getSymbol();
-  MCSymbolData *A_SD = &Asm.getSymbolData(*A);
+  const MCSymbolData *A_SD = &Asm.getSymbolData(*A);
 
   if (!A_SD->getFragment())
     report_fatal_error("symbol '" + A->getName() +
@@ -382,7 +382,7 @@
   uint32_t Value2 = 0;
 
   if (const MCSymbolRefExpr *B = Target.getSymB()) {
-    MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
+    const MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
 
     if (!B_SD->getFragment())
       report_fatal_error("symbol '" + B->getSymbol().getName() +
@@ -465,7 +465,7 @@
   unsigned IsPCRel = 0;
 
   // Get the symbol data.
-  MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol());
+  const MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol());
   unsigned Index = SD_A->getIndex();
 
   // We're only going to have a second symbol in pic mode and it'll be a
@@ -476,7 +476,8 @@
     // If this is a subtraction then we're pcrel.
     uint32_t FixupAddress =
       Writer->getFragmentAddress(Fragment, Layout) + Fixup.getOffset();
-    MCSymbolData *SD_B = &Asm.getSymbolData(Target.getSymB()->getSymbol());
+    const MCSymbolData *SD_B =
+        &Asm.getSymbolData(Target.getSymB()->getSymbol());
     IsPCRel = 1;
     FixedValue = (FixupAddress - Writer->getSymbolAddress(SD_B, Layout) +
                   Target.getConstant());
@@ -524,7 +525,7 @@
   }
 
   // Get the symbol data, if any.
-  MCSymbolData *SD = 0;
+  const MCSymbolData *SD = 0;
   if (Target.getSymA())
     SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());