unittests/ASM: Adds test for FSCALE(0, +Inf) raising IE

unittests/ASM/FEX_bugs/FSCALE_zero_inf.asm

@@ -0,0 +1,30 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RBX":  "0x0001"
+  }
+}
+%endif
+
+; FSCALE(+0, +Inf) is 0 * 2^(+Inf) = 0 * Inf, which must raise the invalid
+; operation exception (IE=1).
+
+mov r15, 0xe0000000
+fninit
+
+mov dword [r15 + 0], 0x00000000
+mov dword [r15 + 4], 0x7ff00000
+
+fld qword [r15 + 0]
+fldz
+
+fscale
+
+fstp qword [r15 + 16]
+fstp st0
+
+fnstsw ax
+movzx rbx, ax
+and rbx, 1
+
+hlt