[RISCV] Use init_array instead of ctors for RISCV target, by default

Summary:
LLVM defaults to the newer .init_array/.fini_array scheme for static
constructors rather than the less desirable .ctors/.dtors (the UseCtors
flag defaults to false). This wasn't being respected in the RISC-V
backend because it fails to call TargetLoweringObjectFileELF::InitializeELF with the the appropriate
flag for UseInitArray.
This patch fixes this by implementing RISCVELFTargetObjectFile and overriding its Initialize method to call
InitializeELF(TM.Options.UseInitArray).

Reviewers: asb, apazos

Reviewed By: asb

Subscribers: mgorny, rbar, johnrusso, simoncook, jordy.potman.lists, sabuasal, niosHD, kito-cheng, shiva0217, llvm-commits

Differential Revision: https://reviews.llvm.org/D44750

llvm-svn: 328433

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVTargetObjectFile.h b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.h
new file mode 100644
index 00000000000..5467220301c
--- /dev/null
+++ b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.h
@@ -0,0 +1,25 @@
+//===-- RISCVTargetObjectFile.h - RISCV 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_LIB_TARGET_RISCV_RISCVTARGETOBJECTFILE_H
+#define LLVM_LIB_TARGET_RISCV_RISCVTARGETOBJECTFILE_H
+
+#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
+
+namespace llvm {
+class RISCVTargetMachine;
+
+/// This implementation is used for RISCV ELF targets.
+class RISCVELFTargetObjectFile : public TargetLoweringObjectFileELF {
+  void Initialize(MCContext &Ctx, const TargetMachine &TM) override;
+};
+
+} // end namespace llvm
+
+#endif