[llvm] 2ada0c1 - [AArch64] Move fixELFSymbolsInTLSFixups to getRelocType

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2025-03-15T00:10:55-07:00
New Revision: 2ada0c1e6163502a8b3fd6485c290eca26ce8748

URL: https://github.com/llvm/llvm-project/commit/2ada0c1e6163502a8b3fd6485c290eca26ce8748
DIFF: https://github.com/llvm/llvm-project/commit/2ada0c1e6163502a8b3fd6485c290eca26ce8748.diff

LOG: [AArch64] 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.

Added: 
    

Modified: 
    llvm/include/llvm/MC/MCExpr.h
    llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
    llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp
    llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/MC/MCExpr.h b/llvm/include/llvm/MC/MCExpr.h
index 6186e472a8c52..2017b34b246cb 100644
--- a/llvm/include/llvm/MC/MCExpr.h
+++ b/llvm/include/llvm/MC/MCExpr.h
@@ -571,7 +571,9 @@ class MCTargetExpr : public MCExpr {
   virtual void visitUsedExpr(MCStreamer& Streamer) const = 0;
   virtual MCFragment *findAssociatedFragment() const = 0;
 
-  virtual void fixELFSymbolsInTLSFixups(MCAssembler &) const = 0;
+  // Deprecated way to set the type of referenced ELF symbols to STT_TLS when
+  // the derived MCELFObjectTargetWriter::getRelocType does not update symbols.
+  virtual void fixELFSymbolsInTLSFixups(MCAssembler &) const {}
 
   static bool classof(const MCExpr *E) {
     return E->getKind() == MCExpr::Target;

diff  --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
index 947ec401238e2..19d04b4e83c23 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
@@ -126,6 +126,19 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
           Target.getSymB()->getKind() == MCSymbolRefExpr::VK_None) &&
          "Should only be expression-level modifiers here");
 
+  switch (SymLoc) {
+  case AArch64MCExpr::VK_DTPREL:
+  case AArch64MCExpr::VK_GOTTPREL:
+  case AArch64MCExpr::VK_TPREL:
+  case AArch64MCExpr::VK_TLSDESC:
+  case AArch64MCExpr::VK_TLSDESC_AUTH:
+    if (auto *S = Target.getSymA())
+      cast<MCSymbolELF>(S->getSymbol()).setType(ELF::STT_TLS);
+    break;
+  default:
+    break;
+  }
+
   if (IsPCRel) {
     switch (Kind) {
     case FK_Data_1:

diff  --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp
index 53e4e1730f070..172f0fe6610cc 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.cpp
@@ -120,50 +120,6 @@ bool AArch64MCExpr::evaluateAsRelocatableImpl(MCValue &Res,
   return true;
 }
 
-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 AArch64MCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
-  switch (getSymbolLoc(Kind)) {
-  default:
-    return;
-  case VK_DTPREL:
-  case VK_GOTTPREL:
-  case VK_TPREL:
-  case VK_TLSDESC:
-  case VK_TLSDESC_AUTH:
-    break;
-  }
-
-  fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
-}
-
 const AArch64AuthMCExpr *AArch64AuthMCExpr::create(const MCExpr *Expr,
                                                    uint16_t Discriminator,
                                                    AArch64PACKey::ID Key,

diff  --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h
index 3f9a85d634d8f..e91a9bcfc1d84 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCExpr.h
@@ -178,8 +178,6 @@ class AArch64MCExpr : public MCTargetExpr {
   bool evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
                                  const MCFixup *Fixup) const override;
 
-  void fixELFSymbolsInTLSFixups(MCAssembler &Asm) const override;
-
   static bool classof(const MCExpr *E) {
     return E->getKind() == MCExpr::Target;
   }