Re-apply r211399, "Generate native unwind info on Win64" with a fix to ignore SEH pseudo ops in X86 JIT emitter.

--
This patch enables LLVM to emit Win64-native unwind info rather than
DWARF CFI.  It handles all corner cases (I hope), including stack
realignment.

Because the unwind info is not flexible enough to describe stack frames
with a gap of unknown size in the middle, such as the one caused by
stack realignment, I modified register spilling code to place all spills
into the fixed frame slots, so that they can be accessed relative to the
frame pointer.

Patch by Vadim Chugunov!

Reviewed By: rnk

Differential Revision: http://reviews.llvm.org/D4081

llvm-svn: 211691
diff --git a/llvm/lib/Target/X86/X86CodeEmitter.cpp b/llvm/lib/Target/X86/X86CodeEmitter.cpp
index b275a9c..a3ae7ee 100644
--- a/llvm/lib/Target/X86/X86CodeEmitter.cpp
+++ b/llvm/lib/Target/X86/X86CodeEmitter.cpp
@@ -1131,6 +1131,16 @@
     case TargetOpcode::IMPLICIT_DEF:
     case TargetOpcode::KILL:
       break;
+
+    case X86::SEH_PushReg:
+    case X86::SEH_SaveReg:
+    case X86::SEH_SaveXMM:
+    case X86::SEH_StackAlloc:
+    case X86::SEH_SetFrame:
+    case X86::SEH_PushFrame:
+    case X86::SEH_EndPrologue:
+      break;
+
     case X86::MOVPC32r: {
       // This emits the "call" portion of this pseudo instruction.
       MCE.emitByte(BaseOpcode);