asm test: Ensure predicate cache is reset when control flow leaves block

unittests/ASM/X87/MemcopyWithCPUID.asm

@@ -0,0 +1,36 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RBX": "0x8000000000000000",
+    "RCX": "0x3fff"
+  }
+}
+%endif
+
+; Related to #4274 - ensures that if cpuid clobbers the predicate register,
+; we reset the predicate cache.
+
+section .data
+align 8
+
+data:
+  dt 1.0
+
+section .bss
+align 8
+
+data2:
+  resb 10
+
+section .text
+lea r8, [rel data]
+fld tword [r8]
+
+mov rax, 0x0
+cpuid ; Will this instruction clobber the predicate register?
+
+fstp tword [rel data2]
+
+mov rbx, [rel data2]
+mov rcx, [rel data2+8]
+hlt