[SystemZ] Use proper relocation for TLS variable debug info (#83975)

Debug info refering to a TLS variable via DW_OP_GNU_push_tls_address
needs to use a R_390_TLS_LDO64 relocation instead of R_390_64.

Fixed by adding a SystemZELFTargetObjectFile override class and proving
a getDebugThreadLocalSymbol implementation.

Author: uweigand

llvm/lib/Target/SystemZ/CMakeLists.txt

@@ -36,6 +36,7 @@ add_llvm_target(SystemZCodeGen
   SystemZShortenInst.cpp
   SystemZSubtarget.cpp
   SystemZTargetMachine.cpp
+  SystemZTargetObjectFile.cpp
   SystemZTargetTransformInfo.cpp
   SystemZTDC.cpp
 

llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp

@@ -11,6 +11,7 @@
 #include "SystemZ.h"
 #include "SystemZMachineFunctionInfo.h"
 #include "SystemZMachineScheduler.h"
+#include "SystemZTargetObjectFile.h"
 #include "SystemZTargetTransformInfo.h"
 #include "TargetInfo/SystemZTargetInfo.h"
 #include "llvm/ADT/StringRef.h"
@@ -83,7 +84,7 @@ static std::unique_ptr<TargetLoweringObjectFile> createTLOF(const Triple &TT) {
 
   // Note: Some times run with -triple s390x-unknown.
   // In this case, default to ELF unless z/OS specifically provided.
-  return std::make_unique<TargetLoweringObjectFileELF>();
+  return std::make_unique<SystemZELFTargetObjectFile>();
 }
 
 static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM) {

llvm/lib/Target/SystemZ/SystemZTargetObjectFile.cpp

@@ -0,0 +1,19 @@
+//===-- SystemZTargetObjectFile.cpp - SystemZ Object Info -----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "SystemZTargetObjectFile.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCValue.h"
+#include "llvm/Target/TargetMachine.h"
+
+using namespace llvm;
+
+const MCExpr *SystemZELFTargetObjectFile::getDebugThreadLocalSymbol(
+    const MCSymbol *Sym) const {
+  return MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext());
+}

llvm/lib/Target/SystemZ/SystemZTargetObjectFile.h

@@ -0,0 +1,27 @@
+//===-- SystemZTargetObjectFile.h - SystemZ Object Info ---------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_SYSTEMZ_SYSTEMZTARGETOBJECTFILE_H
+#define LLVM_LIB_TARGET_SYSTEMZ_SYSTEMZTARGETOBJECTFILE_H
+
+#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
+
+namespace llvm {
+
+/// This implementation is used for SystemZ ELF targets.
+class SystemZELFTargetObjectFile : public TargetLoweringObjectFileELF {
+public:
+  SystemZELFTargetObjectFile() {}
+
+  /// Describe a TLS variable address within debug info.
+  const MCExpr *getDebugThreadLocalSymbol(const MCSymbol *Sym) const override;
+};
+
+} // end namespace llvm
+
+#endif