[mips] Fix inconsistent .cprestore behaviour between direct object emission and assembling.

Summary:
Direct object emission has an initialization order problem where an
InitMCObjectFile is called after MipsTargetELFStreamer determines whether
PIC is enabled by default or not. There doesn't seem to be point that
initializes all cases so split the responsibility between
MipsTargetELFStreamer and MipsAsmPrinter.

Reviewers: sdardis

Subscribers: dsanders, llvm-commits, sdardis

Differential Revision: http://reviews.llvm.org/D19728

llvm-svn: 268737

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
index 58c1f0ee4ee..23c46351b82 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsTargetStreamer.cpp
@@ -652,6 +652,14 @@ MipsTargetELFStreamer::MipsTargetELFStreamer(MCStreamer &S,
                                              const MCSubtargetInfo &STI)
     : MipsTargetStreamer(S), MicroMipsEnabled(false), STI(STI) {
   MCAssembler &MCA = getStreamer().getAssembler();
+
+  // It's possible that MCObjectFileInfo isn't fully initialized at this point
+  // due to an initialization order problem where LLVMTargetMachine creates the
+  // target streamer before TargetLoweringObjectFile calls
+  // InitializeMCObjectFileInfo. There doesn't seem to be a single place that
+  // covers all cases so this statement covers most cases and direct object
+  // emission must call setPic() once MCObjectFileInfo has been initialized. The
+  // cases we don't handle here are covered by MipsAsmPrinter.
   Pic = MCA.getContext().getObjectFileInfo()->getRelocM() == Reloc::PIC_;
 
   const FeatureBitset &Features = STI.getFeatureBits();