[SystemZ] Use MVC to spill loads and stores

Try to use MVC when spilling the destination of a simple load or the source
of a simple store.  As explained in the comment, this doesn't yet handle
the case where the load or store location is also a frame index, since
that could lead to two simultaneous scavenger spills, something the
backend can't handle yet.  spill-02.py tests that this restriction kicks in,
but unfortunately I've not yet found a case that would fail without it.
The volatile trick I used for other scavenger tests doesn't work here
because we can't use MVC for volatile accesses anyway.

I'm planning on relaxing the restriction later, hopefully with a test
that does trigger the problem...

Tests @f8 and @f9 also showed that L(G)RL and ST(G)RL were wrongly
classified as SimpleBDX{Load,Store}.  It wouldn't be easy to test for
that bug separately, which is why I didn't split out the fix as a
separate patch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185434 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/Target/SystemZ/SystemZInstrInfo.h b/lib/Target/SystemZ/SystemZInstrInfo.h
index d6980f7171..8d9a3eaacf 100644
--- a/lib/Target/SystemZ/SystemZInstrInfo.h
+++ b/lib/Target/SystemZ/SystemZInstrInfo.h
@@ -111,6 +111,14 @@ public:
                          unsigned DestReg, int FrameIdx,
                          const TargetRegisterClass *RC,
                          const TargetRegisterInfo *TRI) const LLVM_OVERRIDE;
+  virtual MachineInstr *
+    foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
+                          const SmallVectorImpl<unsigned> &Ops,
+                          int FrameIndex) const;
+  virtual MachineInstr *
+    foldMemoryOperandImpl(MachineFunction &MF, MachineInstr* MI,
+                          const SmallVectorImpl<unsigned> &Ops,
+                          MachineInstr* LoadMI) const;
   virtual bool
     expandPostRAPseudo(MachineBasicBlock::iterator MBBI) const LLVM_OVERRIDE;
   virtual bool