Add back r203962, r204028 and r204059.

This reverts commit r204137.

This includes a fix for handling aliases of aliases.

llvm-svn: 204178

1 files changed, 22 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCSymbol.cpp b/llvm/lib/MC/MCSymbol.cpp
index 24165254e56..6876cb165dc 100644
--- a/llvm/lib/MC/MCSymbol.cpp
+++ b/llvm/lib/MC/MCSymbol.cpp
@@ -9,6 +9,7 @@
 
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCValue.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
@@ -51,6 +52,27 @@ const MCSymbol &MCSymbol::AliasedSymbol() const {
   return *S;
 }
 
+const MCSymbol *MCSymbol::getBaseSymbol(const MCAsmLayout &Layout) const {
+  // FIXME: shouldn't EvaluateAsRelocatable be responsible for following as many
+  // variables as possible?
+
+  const MCSymbol *S = this;
+  while (S->isVariable()) {
+    const MCExpr *Expr = S->getVariableValue();
+    MCValue Value;
+    if (!Expr->EvaluateAsRelocatable(Value, &Layout))
+      return nullptr;
+
+    if (Value.getSymB())
+      return nullptr;
+    const MCSymbolRefExpr *A = Value.getSymA();
+    if (!A)
+      return nullptr;
+    S = &A->getSymbol();
+  }
+  return S;
+}
+
 void MCSymbol::setVariableValue(const MCExpr *Value) {
   assert(!IsUsed && "Cannot set a variable that has already been used.");
   assert(Value && "Invalid variable value!");