[MIPS] Update sandboxing changes for LLVM on MIPS.

This change

- resolves conflicts from previous merges;
- prevents delay slot filler to use instructions that could be masked;
- generates calls to __nacl_read_tp to access thread pointer;
- removes previous (now obsolete) sandboxing code of unaligned loads and stores;
- propagates relocation model to MipsELFObjectWriter, so that it can set
  flag ELF::EF_MIPS_PIC (small hack).

BUG= http://code.google.com/p/nativeclient/issues/detail?id=2275
TEST= pnacl/build.sh all

Review URL: https://codereview.chromium.org/11115013
Patch from Petar Jovanovic <petarj@mips.com>.

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp b/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
index 5d240fe847..6ad8669d04 100644
--- a/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
+++ b/lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp
@@ -18,6 +18,13 @@
 #include "llvm/Support/ErrorHandling.h"
 #include <list>
 
+// @LOCALMOD-START
+// TODO(petarj): HACK! Find better way to set ELF::EF_MIPS_PIC flag.
+// See also file lib/MC/MCObjectFileInfo.cpp.
+#include "llvm/Support/CodeGen.h"
+extern llvm::Reloc::Model RelocModelOption;
+// @LOCALMOD-END
+
 using namespace llvm;
 
 namespace {
@@ -71,6 +78,10 @@ unsigned MipsELFObjectWriter::getEFlags() const {
     Flag |= ELF::EF_MIPS_ARCH_64R2;
   else
     Flag |= ELF::EF_MIPS_ARCH_32R2;
+  /* @LOCLAMOD-START */
+  if (RelocModelOption == Reloc::PIC_ || RelocModelOption == Reloc::Default)
+    Flag |= ELF::EF_MIPS_PIC;
+  /* @LOCLAMOD-END */
   return Flag;
 }