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

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-systemz

Author: Ulrich Weigand (uweigand)

<details>
<summary>Changes</summary>

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.

---
Full diff: https://github.com/llvm/llvm-project/pull/83975.diff


4 Files Affected:

- (modified) llvm/lib/Target/SystemZ/CMakeLists.txt (+1) 
- (modified) llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp (+2-1) 
- (added) llvm/lib/Target/SystemZ/SystemZTargetObjectFile.cpp (+20) 
- (added) llvm/lib/Target/SystemZ/SystemZTargetObjectFile.h (+27) 


``````````diff
diff --git a/llvm/lib/Target/SystemZ/CMakeLists.txt b/llvm/lib/Target/SystemZ/CMakeLists.txt
index 0614e07bde8ac1..063e5bcd44171e 100644
--- a/llvm/lib/Target/SystemZ/CMakeLists.txt
+++ b/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
 
diff --git a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp b/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
index 121512d5a7e589..2491bd2ee2c12c 100644
--- a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
+++ b/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) {
diff --git a/llvm/lib/Target/SystemZ/SystemZTargetObjectFile.cpp b/llvm/lib/Target/SystemZ/SystemZTargetObjectFile.cpp
new file mode 100644
index 00000000000000..14ab59d278d7f6
--- /dev/null
+++ b/llvm/lib/Target/SystemZ/SystemZTargetObjectFile.cpp
@@ -0,0 +1,20 @@
+//===-- 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());
+}
+
diff --git a/llvm/lib/Target/SystemZ/SystemZTargetObjectFile.h b/llvm/lib/Target/SystemZ/SystemZTargetObjectFile.h
new file mode 100644
index 00000000000000..b840e14f448be0
--- /dev/null
+++ b/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

``````````

</details>


https://github.com/llvm/llvm-project/pull/83975