PPC64: Constant initializers with dynamic relocations go in .data.rel.ro.

This fixes warning messages observed in the oggenc application test in
projects/test-suite.  Special handling is needed for the 64-bit
PowerPC SVR4 ABI when a constant is initialized with a pointer to a
function in a shared library.  Because a function address is
implemented as the address of a function descriptor, the use of copy
relocations can lead to problems with initialization.  GNU ld
therefore replaces copy relocations with dynamic relocations to be
resolved by the dynamic linker.  This means the constant cannot reside
in the read-only data section, but instead belongs in .data.rel.ro,
which is designed for constants containing dynamic relocations.

The implementation creates a class PPC64LinuxTargetObjectFile
inheriting from TargetLoweringObjectFileELF, which behaves like its
parent except to place constants of this sort into .data.rel.ro.

The test case is reduced from the oggenc application.

llvm-svn: 181723

1 files changed, 32 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetObjectFile.h b/llvm/lib/Target/PowerPC/PPCTargetObjectFile.h
new file mode 100644
index 0000000..9203e23
--- /dev/null
+++ b/llvm/lib/Target/PowerPC/PPCTargetObjectFile.h
@@ -0,0 +1,32 @@
+//===-- PPCTargetObjectFile.h - PPC Object Info -----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TARGET_PPC_TARGETOBJECTFILE_H
+#define LLVM_TARGET_PPC_TARGETOBJECTFILE_H
+
+#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
+
+namespace llvm {
+
+  /// PPC64LinuxTargetObjectFile - This implementation is used for
+  /// 64-bit PowerPC Linux.
+  class PPC64LinuxTargetObjectFile : public TargetLoweringObjectFileELF {
+
+    virtual void Initialize(MCContext &Ctx, const TargetMachine &TM);
+
+    virtual const MCSection *
+    SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
+                           Mangler *Mang, const TargetMachine &TM) const;
+  };
+
+}  // end namespace llvm
+
+#endif