1 files changed, 72 insertions, 3 deletions
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index e39c4a0..78ee215 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -665,6 +665,68 @@ void MCObjectStreamer::emitGPRel64Value(const MCExpr *Value) {
   DF->getContents().resize(DF->getContents().size() + 8, 0);
 }
 
+static Optional<std::pair<bool, std::string>>
+getOffsetAndDataFragment(const MCSymbol &Symbol, uint32_t &RelocOffset,
+                         MCDataFragment *&DF) {
+  if (Symbol.isVariable()) {
+    const MCExpr *SymbolExpr = Symbol.getVariableValue();
+    MCValue OffsetVal;
+    if(!SymbolExpr->evaluateAsRelocatable(OffsetVal, nullptr, nullptr))
+      return std::make_pair(false,
+                            std::string("symbol in .reloc offset is not "
+                                        "relocatable"));
+    if (OffsetVal.isAbsolute()) {
+      RelocOffset = OffsetVal.getConstant();
+      MCFragment *Fragment = Symbol.getFragment();
+      // FIXME Support symbols with no DF. For example:
+      // .reloc .data, ENUM_VALUE, <some expr>
+      if (!Fragment || Fragment->getKind() != MCFragment::FT_Data)
+        return std::make_pair(false,
+                              std::string("symbol in offset has no data "
+                                          "fragment"));
+      DF = cast<MCDataFragment>(Fragment);
+      return None;
+    }
+
+    if (OffsetVal.getSymB())
+      return std::make_pair(false,
+                            std::string(".reloc symbol offset is not "
+                                        "representable"));
+
+    const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*OffsetVal.getSymA());
+    if (!SRE.getSymbol().isDefined())
+      return std::make_pair(false,
+                            std::string("symbol used in the .reloc offset is "
+                                        "not defined"));
+
+    if (SRE.getSymbol().isVariable())
+      return std::make_pair(false,
+                            std::string("symbol used in the .reloc offset is "
+                                        "variable"));
+
+    MCFragment *Fragment = SRE.getSymbol().getFragment();
+    // FIXME Support symbols with no DF. For example:
+    // .reloc .data, ENUM_VALUE, <some expr>
+    if (!Fragment || Fragment->getKind() != MCFragment::FT_Data)
+      return std::make_pair(false,
+                            std::string("symbol in offset has no data "
+                                        "fragment"));
+    RelocOffset = SRE.getSymbol().getOffset() + OffsetVal.getConstant();
+    DF = cast<MCDataFragment>(Fragment);
+  } else {
+    RelocOffset = Symbol.getOffset();
+    MCFragment *Fragment = Symbol.getFragment();
+    // FIXME Support symbols with no DF. For example:
+    // .reloc .data, ENUM_VALUE, <some expr>
+    if (!Fragment || Fragment->getKind() != MCFragment::FT_Data)
+      return std::make_pair(false,
+                            std::string("symbol in offset has no data "
+                                        "fragment"));
+    DF = cast<MCDataFragment>(Fragment);
+  }
+  return None;
+}
+
 Optional<std::pair<bool, std::string>>
 MCObjectStreamer::emitRelocDirective(const MCExpr &Offset, StringRef Name,
                                      const MCExpr *Expr, SMLoc Loc,
@@ -698,10 +760,17 @@ MCObjectStreamer::emitRelocDirective(const MCExpr &Offset, StringRef Name,
                           std::string(".reloc offset is not representable"));
 
   const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*OffsetVal.getSymA());
-  if (SRE.getSymbol().isDefined()) {
-    // FIXME SRE.getSymbol() may not be relative to DF.
+  const MCSymbol &Symbol = SRE.getSymbol();
+  if (Symbol.isDefined()) {
+    uint32_t SymbolOffset = 0;
+    Optional<std::pair<bool, std::string>> Error;
+    Error = getOffsetAndDataFragment(Symbol, SymbolOffset, DF);
+
+    if (Error != None)
+      return Error;
+
     DF->getFixups().push_back(
-        MCFixup::create(SRE.getSymbol().getOffset() + OffsetVal.getConstant(),
+        MCFixup::create(SymbolOffset + OffsetVal.getConstant(),
                         Expr, Kind, Loc));
     return None;
   }