From 532facc78e075255afde69f2d86f26e4d4dd4c7f Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Sat, 7 Jun 2025 23:32:18 -0700
Subject: [PATCH] ARMMCExpr: Migrate to MCSpecifierExpr

---
 .../Target/ARM/MCTargetDesc/ARMAsmBackend.cpp |  4 +--
 .../ARM/MCTargetDesc/ARMELFStreamer.cpp       |  2 +-
 .../ARM/MCTargetDesc/ARMMCCodeEmitter.cpp     |  2 +-
 .../lib/Target/ARM/MCTargetDesc/ARMMCExpr.cpp |  4 ---
 llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h  | 34 +++----------------
 5 files changed, 8 insertions(+), 38 deletions(-)

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 075fe8687b5a..a7320eea80b0 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -619,7 +619,7 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
     // Offset by 8 just as above.
     if (const MCSymbolRefExpr *SRE =
             dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
-      if (getSpecifier(SRE) == ARMMCExpr::VK_TLSCALL)
+      if (SRE->getSpecifier() == ARMMCExpr::VK_TLSCALL)
         return 0;
     return 0xffffff & (Value >> 2);
   case ARM::fixup_t2_uncondbranch: {
@@ -746,7 +746,7 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
     uint32_t offset = (Value - 4) >> 2;
     if (const MCSymbolRefExpr *SRE =
             dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
-      if (getSpecifier(SRE) == ARMMCExpr::VK_TLSCALL)
+      if (SRE->getSpecifier() == ARMMCExpr::VK_TLSCALL)
         offset = 0;
     uint32_t signBit = (offset & 0x400000) >> 22;
     uint32_t I1Bit = (offset & 0x200000) >> 21;
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
index 7884b10a48a9..49b89cad6d47 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -590,7 +590,7 @@ public:
   /// necessary.
   void emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value)) {
-      if (getSpecifier(SRE) == ARMMCExpr::VK_SBREL && !(Size == 4)) {
+      if (SRE->getSpecifier() == ARMMCExpr::VK_SBREL && !(Size == 4)) {
         getContext().reportError(Loc, "relocated expression must be 32-bit");
         return;
       }
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
index 7fa4baac9970..e79cdbde62ca 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
@@ -1191,7 +1191,7 @@ uint32_t ARMMCCodeEmitter::getHiLoImmOpValue(const MCInst &MI, unsigned OpIdx,
   // :lower0_7: assembly prefixes.
   const MCExpr *E = MO.getExpr();
   MCFixupKind Kind;
-  if (E->getKind() == MCExpr::Target) {
+  if (E->getKind() == MCExpr::Specifier) {
     const ARMMCExpr *ARM16Expr = cast<ARMMCExpr>(E);
     E = ARM16Expr->getSubExpr();
 
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.cpp
index 6230491a7b01..b5e17e3c2da0 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.cpp
@@ -48,7 +48,3 @@ void ARMMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const {
   if (Expr->getKind() != MCExpr::SymbolRef)
     OS << ')';
 }
-
-void ARMMCExpr::visitUsedExpr(MCStreamer &Streamer) const {
-  Streamer.visitUsedExpr(*getSubExpr());
-}
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h
index 9b959ce12f64..bcd92de3434a 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCExpr.h
@@ -13,9 +13,10 @@
 
 namespace llvm {
 
-class ARMMCExpr : public MCTargetExpr {
+class ARMMCExpr : public MCSpecifierExpr {
 public:
-  enum Specifier {
+  using Specifier = uint16_t;
+  enum {
     VK_None,
     VK_HI16 =
         MCSymbolRefExpr::FirstTargetSpecifier, // The R_ARM_MOVT_ABS relocation
@@ -57,16 +58,10 @@ public:
   };
 
 private:
-  const Specifier specifier;
-  const MCExpr *Expr;
-
   explicit ARMMCExpr(Specifier S, const MCExpr *Expr)
-      : specifier(S), Expr(Expr) {}
+      : MCSpecifierExpr(Expr, S) {}
 
 public:
-  /// @name Construction
-  /// @{
-
   static const ARMMCExpr *create(Specifier S, const MCExpr *Expr,
                                  MCContext &Ctx);
 
@@ -94,33 +89,12 @@ public:
     return create(VK_LO_0_7, Expr, Ctx);
   }
 
-  /// @}
-  /// @name Accessors
-  /// @{
-
-  Specifier getSpecifier() const { return specifier; }
-  const MCExpr *getSubExpr() const { return Expr; }
-
-  /// @}
-
   void printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const override;
   bool evaluateAsRelocatableImpl(MCValue &Res,
                                  const MCAssembler *Asm) const override {
     return false;
   }
-  void visitUsedExpr(MCStreamer &Streamer) const override;
-  MCFragment *findAssociatedFragment() const override {
-    return getSubExpr()->findAssociatedFragment();
-  }
-
-  static bool classof(const MCExpr *E) {
-    return E->getKind() == MCExpr::Target;
-  }
 };
-
-static inline ARMMCExpr::Specifier getSpecifier(const MCSymbolRefExpr *SRE) {
-  return ARMMCExpr::Specifier(SRE->getKind());
-}
 } // end namespace llvm
 
 #endif