The x86 jit doesn't generate a def_cfa_offset unwind instruction after the

pushes in the function prolog if the function doesn't have any stack space,
i.e. for a prolog like:

0x40011870:     push %r15
0x40011872:     push %r14
0x40011874:     push %rbx

Patch by Zoltan!

llvm-svn: 77919

llvm/lib/Target/X86/X86RegisterInfo.cpp

@@ -1059,7 +1059,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
       emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, TII);
   }
 
-  if (!HasFP && needsFrameMoves && NumBytes) {
+  if (!HasFP && needsFrameMoves) {
     // Mark end of stack pointer adjustment.
     unsigned LabelId = MMI->NextLabelID();
     BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(LabelId);