[Mips] 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.

Author: MaskRay

llvm/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "MCTargetDesc/MipsFixupKinds.h"
+#include "MCTargetDesc/MipsMCExpr.h"
 #include "MCTargetDesc/MipsMCTargetDesc.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/BinaryFormat/ELF.h"
@@ -161,6 +162,22 @@ unsigned MipsELFObjectWriter::getRelocType(MCContext &Ctx,
   if (Kind >= FirstLiteralRelocationKind)
     return Kind - FirstLiteralRelocationKind;
 
+  switch (Target.getRefKind()) {
+  case MipsMCExpr::MEK_DTPREL:
+  case MipsMCExpr::MEK_DTPREL_HI:
+  case MipsMCExpr::MEK_DTPREL_LO:
+  case MipsMCExpr::MEK_TLSLDM:
+  case MipsMCExpr::MEK_TLSGD:
+  case MipsMCExpr::MEK_GOTTPREL:
+  case MipsMCExpr::MEK_TPREL_HI:
+  case MipsMCExpr::MEK_TPREL_LO:
+    if (auto *S = Target.getSymA())
+      cast<MCSymbolELF>(S->getSymbol()).setType(ELF::STT_TLS);
+    break;
+  default:
+    break;
+  }
+
   switch (Kind) {
   case FK_NONE:
     return ELF::R_MIPS_NONE;

llvm/lib/Target/Mips/MCTargetDesc/MipsMCExpr.cpp

@@ -219,73 +219,6 @@ void MipsMCExpr::visitUsedExpr(MCStreamer &Streamer) const {
   Streamer.visitUsedExpr(*getSubExpr());
 }
 
-static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) {
-  switch (Expr->getKind()) {
-  case MCExpr::Target:
-    fixELFSymbolsInTLSFixupsImpl(cast<MipsMCExpr>(Expr)->getSubExpr(), Asm);
-    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: {
-    // We're known to be under a TLS fixup, so any symbol should be
-    // modified. There should be only one.
-    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 MipsMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
-  switch (getKind()) {
-  case MEK_None:
-  case MEK_Special:
-    llvm_unreachable("MEK_None and MEK_Special are invalid");
-    break;
-  case MEK_CALL_HI16:
-  case MEK_CALL_LO16:
-  case MEK_GOT:
-  case MEK_GOT_CALL:
-  case MEK_GOT_DISP:
-  case MEK_GOT_HI16:
-  case MEK_GOT_LO16:
-  case MEK_GOT_OFST:
-  case MEK_GOT_PAGE:
-  case MEK_GPREL:
-  case MEK_HI:
-  case MEK_HIGHER:
-  case MEK_HIGHEST:
-  case MEK_LO:
-  case MEK_NEG:
-  case MEK_PCREL_HI16:
-  case MEK_PCREL_LO16:
-    // If we do have nested target-specific expressions, they will be in
-    // a consecutive chain.
-    if (const MipsMCExpr *E = dyn_cast<const MipsMCExpr>(getSubExpr()))
-      E->fixELFSymbolsInTLSFixups(Asm);
-    break;
-  case MEK_DTPREL:
-  case MEK_DTPREL_HI:
-  case MEK_DTPREL_LO:
-  case MEK_TLSLDM:
-  case MEK_TLSGD:
-  case MEK_GOTTPREL:
-  case MEK_TPREL_HI:
-  case MEK_TPREL_LO:
-    fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
-    break;
-  }
-}
-
 bool MipsMCExpr::isGpOff(MipsExprKind &Kind) const {
   if (getKind() == MEK_HI || getKind() == MEK_LO) {
     if (const MipsMCExpr *S1 = dyn_cast<const MipsMCExpr>(getSubExpr())) {

llvm/lib/Target/Mips/MCTargetDesc/MipsMCExpr.h

@@ -74,8 +74,6 @@ class MipsMCExpr : public MCTargetExpr {
     return getSubExpr()->findAssociatedFragment();
   }
 
-  void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override;
-
   static bool classof(const MCExpr *E) {
     return E->getKind() == MCExpr::Target;
   }