[AArch64] Add test case for r329797

Forgot to add a test case in the previous commit.

llvm-svn: 329805

test/CodeGen/AArch64/unreachable-emergency-spill-slot.mir

@@ -19,3 +19,20 @@ body: |
   bb.1:
     liveins: $x0, $x1, $x2, $x3, $x4, $x5, $x6, $x7, $x8, $x9, $x10, $x11, $x12, $x13, $x14, $x15, $x16, $x17, $x18, $x19, $x20, $x21, $x22, $x23, $x24, $x25, $x26, $x27, $x28, $fp, $lr
     RET_ReallyLR implicit $x21, implicit $x22, implicit $x23, implicit $x24, implicit $x25, implicit $x26, implicit $x27, implicit $x28
+...
+---
+name: fpDoesNotFit
+# CHECK-LABEL: name: fpDoesNotFit
+tracksRegLiveness: true
+frameInfo:
+  hasStackMap: true
+# set to true to force hasFP to true.
+stack:
+  - { id: 0, name: '', size: 4096, alignment: 8 }
+  - { id: 1, name: '', size: 32761, alignment: 8 }
+body: |
+  bb.0:
+    STRXui undef $x8, %stack.0, -34
+    ; Pick SP here. Picking FP will require scavenging a register.
+    ; CHECK: STRXui undef $x8, $sp, 4062
+    RET_ReallyLR