[mips] Make TTypeEncoding indirect to allow .eh_frame to be read-only.

Summary:
Following on from r209907 which made personality encodings indirect, do the
same for TType encodings. This fixes the case where a try/catch block needs
to generate references to, for example, std::exception in the
.gcc_except_table.

This commit uses DW_EH_PE_sdata8 for N64 as far as is possible at the moment.
However, it is possible to end up with DW_EH_PE_sdata4 when a TargetMachine is
not available. There's no risk of issues with inconsistency here since the
tables are self describing but it does mean there is a small chance of the
PC-relative offset being out of range for particularly large programs.

Reviewers: petarj

Reviewed By: petarj

Subscribers: srhines, joerg, tberghammer, llvm-commits

Differential Revision: http://reviews.llvm.org/D9669

llvm-svn: 238190

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/lib/Target/Mips/MipsTargetObjectFile.cpp b/llvm/lib/Target/Mips/MipsTargetObjectFile.cpp
index 0f2db60..adbe526 100644
--- a/llvm/lib/Target/Mips/MipsTargetObjectFile.cpp
+++ b/llvm/lib/Target/Mips/MipsTargetObjectFile.cpp
@@ -37,6 +37,7 @@ ExternSData("mextern-sdata", cl::Hidden,
             cl::init(true));
 
 void MipsTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
+  this->TM = &static_cast<const MipsTargetMachine &>(TM);
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
   InitializeELF(TM.Options.UseInitArray);
 
@@ -45,7 +46,6 @@ void MipsTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
 
   SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
                                                ELF::SHF_WRITE | ELF::SHF_ALLOC);
-  this->TM = &static_cast<const MipsTargetMachine &>(TM);
 }
 
 // A address must be loaded from a small section if its size is less than the
@@ -146,3 +146,9 @@ MipsTargetObjectFile::getSectionForConstant(SectionKind Kind,
   // Otherwise, we work the same as ELF.
   return TargetLoweringObjectFileELF::getSectionForConstant(Kind, C);
 }
+
+unsigned MipsTargetObjectFile::SelectMipsTTypeEncoding() const {
+  return dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
+         (TM->getABI().ArePtrs64bit() ? dwarf::DW_EH_PE_sdata8
+                                      : dwarf::DW_EH_PE_sdata4);
+}