[RISCV] 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/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp

@@ -55,6 +55,17 @@ unsigned RISCVELFObjectWriter::getRelocType(MCContext &Ctx,
   unsigned Kind = Fixup.getTargetKind();
   if (Kind >= FirstLiteralRelocationKind)
     return Kind - FirstLiteralRelocationKind;
+
+  switch (Target.getRefKind()) {
+  case RISCVMCExpr::VK_RISCV_TPREL_HI:
+  case RISCVMCExpr::VK_RISCV_TLS_GOT_HI:
+  case RISCVMCExpr::VK_RISCV_TLS_GD_HI:
+  case RISCVMCExpr::VK_RISCV_TLSDESC_HI:
+    if (auto *S = Target.getSymA())
+      cast<MCSymbolELF>(S->getSymbol()).setType(ELF::STT_TLS);
+    break;
+  }
+
   if (IsPCRel) {
     switch (Kind) {
     default:

llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp

@@ -169,49 +169,6 @@ StringRef RISCVMCExpr::getVariantKindName(VariantKind Kind) {
   llvm_unreachable("Invalid ELF symbol kind");
 }
 
-static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) {
-  switch (Expr->getKind()) {
-  case MCExpr::Target:
-    llvm_unreachable("Can't handle nested target expression");
-    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 RISCVMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
-  switch (getKind()) {
-  default:
-    return;
-  case VK_RISCV_TPREL_HI:
-  case VK_RISCV_TLS_GOT_HI:
-  case VK_RISCV_TLS_GD_HI:
-  case VK_RISCV_TLSDESC_HI:
-    break;
-  }
-
-  fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
-}
-
 bool RISCVMCExpr::evaluateAsConstant(int64_t &Res) const {
   MCValue Value;
   if (Kind != VK_RISCV_LO && Kind != VK_RISCV_HI)

llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.h

@@ -76,8 +76,6 @@ class RISCVMCExpr : public MCTargetExpr {
     return getSubExpr()->findAssociatedFragment();
   }
 
-  void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override;
-
   bool evaluateAsConstant(int64_t &Res) const;
 
   static bool classof(const MCExpr *E) {