Revert r233595, "MC: For variable symbols, maintain MCSymbol::Section as a cache."

llvm-svn: 233898

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/MC/MachObjectWriter.cpp b/llvm/lib/MC/MachObjectWriter.cpp
index 56cccab1d39..5e9e86f18a0 100644
--- a/llvm/lib/MC/MachObjectWriter.cpp
+++ b/llvm/lib/MC/MachObjectWriter.cpp
@@ -649,12 +649,33 @@ void MachObjectWriter::computeSectionAddresses(const MCAssembler &Asm,
   }
 }
 
+void MachObjectWriter::markAbsoluteVariableSymbols(MCAssembler &Asm,
+                                                   const MCAsmLayout &Layout) {
+  for (MCSymbolData &SD : Asm.symbols()) {
+    if (!SD.getSymbol().isVariable())
+      continue;
+
+    // Is the variable is a symbol difference (SA - SB + C) expression,
+    // and neither symbol is external, mark the variable as absolute.
+    const MCExpr *Expr = SD.getSymbol().getVariableValue();
+    MCValue Value;
+    if (Expr->EvaluateAsRelocatable(Value, &Layout, nullptr)) {
+      if (Value.getSymA() && Value.getSymB())
+        const_cast<MCSymbol*>(&SD.getSymbol())->setAbsolute();
+    }
+  }
+}
+
 void MachObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
                                                 const MCAsmLayout &Layout) {
   computeSectionAddresses(Asm, Layout);
 
   // Create symbol data for any indirect symbols.
   BindIndirectSymbols(Asm);
+
+  // Mark symbol difference expressions in variables (from .set or = directives)
+  // as absolute.
+  markAbsoluteVariableSymbols(Asm, Layout);
 }
 
 bool MachObjectWriter::