[Sparc] Move fixELFSymbolsInTLSFixups to getRelocType

fixELFSymbolsInTLSFixups walks the expression tree, which is complex and
unnecessary. As the expression must be relocatable, we can move the code
to getRelocType and just set SymA. The behavior is similar to GNU
assembler.

__tls_get_addr registery (https://reviews.llvm.org/D43271) is unnecessary
now.  SparcMCExpr::visitUsedExpr registers the symbol.

Author: MaskRay

llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp

@@ -46,6 +46,30 @@ unsigned SparcELFObjectWriter::getRelocType(MCContext &Ctx,
   if (Kind >= FirstLiteralRelocationKind)
     return Kind - FirstLiteralRelocationKind;
 
+  switch (Target.getRefKind()) {
+  case SparcMCExpr::VK_Sparc_TLS_GD_HI22:
+  case SparcMCExpr::VK_Sparc_TLS_GD_LO10:
+  case SparcMCExpr::VK_Sparc_TLS_GD_ADD:
+  case SparcMCExpr::VK_Sparc_TLS_LDM_HI22:
+  case SparcMCExpr::VK_Sparc_TLS_LDM_LO10:
+  case SparcMCExpr::VK_Sparc_TLS_LDM_ADD:
+  case SparcMCExpr::VK_Sparc_TLS_LDO_HIX22:
+  case SparcMCExpr::VK_Sparc_TLS_LDO_LOX10:
+  case SparcMCExpr::VK_Sparc_TLS_LDO_ADD:
+  case SparcMCExpr::VK_Sparc_TLS_IE_HI22:
+  case SparcMCExpr::VK_Sparc_TLS_IE_LO10:
+  case SparcMCExpr::VK_Sparc_TLS_IE_LD:
+  case SparcMCExpr::VK_Sparc_TLS_IE_LDX:
+  case SparcMCExpr::VK_Sparc_TLS_IE_ADD:
+  case SparcMCExpr::VK_Sparc_TLS_LE_HIX22:
+  case SparcMCExpr::VK_Sparc_TLS_LE_LOX10:
+    if (auto *S = Target.getSymA())
+      cast<MCSymbolELF>(S->getSymbol()).setType(ELF::STT_TLS);
+    break;
+  default:
+    break;
+  }
+
   if (const SparcMCExpr *SExpr = dyn_cast<SparcMCExpr>(Fixup.getValue())) {
     if (SExpr->getKind() == SparcMCExpr::VK_Sparc_R_DISP32)
       return ELF::R_SPARC_DISP32;

llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.cpp

@@ -17,6 +17,7 @@
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCObjectStreamer.h"
 #include "llvm/MC/MCSymbolELF.h"
+#include "llvm/MC/MCValue.h"
 #include "llvm/Support/Casting.h"
 
 using namespace llvm;
@@ -183,71 +184,11 @@ Sparc::Fixups SparcMCExpr::getFixupKind(SparcMCExpr::VariantKind Kind) {
 bool SparcMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
                                             const MCAssembler *Asm,
                                             const MCFixup *Fixup) const {
-  return getSubExpr()->evaluateAsRelocatable(Res, Asm, Fixup);
-}
-
-static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) {
-  switch (Expr->getKind()) {
-  case MCExpr::Target:
-    llvm_unreachable("Can't handle nested target expr!");
-    break;
-
-  case MCExpr::Constant:
-    break;
-
-  case MCExpr::Binary: {
-    const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr);
-    fixELFSymbolsInTLSFixupsImpl(BE->getLHS(), Asm);
-    fixELFSymbolsInTLSFixupsImpl(BE->getRHS(), Asm);
-    break;
-  }
-
-  case MCExpr::SymbolRef: {
-    const MCSymbolRefExpr &SymRef = *cast<MCSymbolRefExpr>(Expr);
-    cast<MCSymbolELF>(SymRef.getSymbol()).setType(ELF::STT_TLS);
-    break;
-  }
-
-  case MCExpr::Unary:
-    fixELFSymbolsInTLSFixupsImpl(cast<MCUnaryExpr>(Expr)->getSubExpr(), Asm);
-    break;
-  }
-
-}
-
-void SparcMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
-  switch(getKind()) {
-  default: return;
-  case VK_Sparc_TLS_GD_CALL:
-  case VK_Sparc_TLS_LDM_CALL: {
-    // The corresponding relocations reference __tls_get_addr, as they call it,
-    // but this is only implicit; we must explicitly add it to our symbol table
-    // to bind it for these uses.
-    MCSymbol *Symbol = Asm.getContext().getOrCreateSymbol("__tls_get_addr");
-    Asm.registerSymbol(*Symbol);
-    auto ELFSymbol = cast<MCSymbolELF>(Symbol);
-    if (!ELFSymbol->isBindingSet())
-      ELFSymbol->setBinding(ELF::STB_GLOBAL);
-    [[fallthrough]];
-  }
-  case VK_Sparc_TLS_GD_HI22:
-  case VK_Sparc_TLS_GD_LO10:
-  case VK_Sparc_TLS_GD_ADD:
-  case VK_Sparc_TLS_LDM_HI22:
-  case VK_Sparc_TLS_LDM_LO10:
-  case VK_Sparc_TLS_LDM_ADD:
-  case VK_Sparc_TLS_LDO_HIX22:
-  case VK_Sparc_TLS_LDO_LOX10:
-  case VK_Sparc_TLS_LDO_ADD:
-  case VK_Sparc_TLS_IE_HI22:
-  case VK_Sparc_TLS_IE_LO10:
-  case VK_Sparc_TLS_IE_LD:
-  case VK_Sparc_TLS_IE_LDX:
-  case VK_Sparc_TLS_IE_ADD:
-  case VK_Sparc_TLS_LE_HIX22:
-  case VK_Sparc_TLS_LE_LOX10: break;
-  }
-  fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
+  if (!getSubExpr()->evaluateAsRelocatable(Res, Asm, Fixup))
+    return false;
+  Res =
+      MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(), getKind());
+  return true;
 }
 
 void SparcMCExpr::visitUsedExpr(MCStreamer &Streamer) const {

llvm/lib/Target/Sparc/MCTargetDesc/SparcMCExpr.h

@@ -101,8 +101,6 @@ class SparcMCExpr : public MCTargetExpr {
     return getSubExpr()->findAssociatedFragment();
   }
 
-  void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override;
-
   static bool classof(const MCExpr *E) {
     return E->getKind() == MCExpr::Target;
   }