MCValue: Change getAccessVariant to return uint16_t

Some targets encode the relocation specifier within SymA using
MCSymbolRefExpr::SubclassData. They will cast the specifier
to *MCExpr::Specifier.

Migrate away from the confusing MCSymbolRefExpr::VariantKind.

Note: getAccessVariant is a deprecated method to get the relocation
specifier.

Author: MaskRay

llvm/include/llvm/MC/MCValue.h

@@ -65,7 +65,9 @@ class MCValue {
   /// Print the value to stderr.
   void dump() const;
 
-  MCSymbolRefExpr::VariantKind getAccessVariant() const;
+  // Get the relocation specifier from SymA. This is a workaround for targets
+  // that do not use MCValue::Specifier.
+  uint16_t getAccessVariant() const;
 
   static MCValue get(const MCSymbolRefExpr *SymA,
                      const MCSymbolRefExpr *SymB = nullptr,

llvm/lib/MC/MCValue.cpp

@@ -44,10 +44,10 @@ LLVM_DUMP_METHOD void MCValue::dump() const {
 }
 #endif
 
-MCSymbolRefExpr::VariantKind MCValue::getAccessVariant() const {
+uint16_t MCValue::getAccessVariant() const {
   const MCSymbolRefExpr *A = getSymA();
   if (!A)
-    return MCSymbolRefExpr::VK_None;
+    return 0;
 
-  return A->getKind();
+  return A->getSpecifier();
 }

llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp

@@ -69,7 +69,7 @@ unsigned WebAssemblyWasmObjectWriter::getRelocType(
   assert(RefA);
   auto& SymA = cast<MCSymbolWasm>(RefA->getSymbol());
 
-  MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
+  auto Modifier = Target.getAccessVariant();
 
   switch (Modifier) {
     case MCSymbolRefExpr::VK_GOT: