Test a tied operand following a fixed register operand.

The redefined tied value lives in the diverted register.

cranelift/filetests/regalloc/constraints.cton

@@ -44,3 +44,26 @@ ebb0:
 
     return v3
 }
+
+; Tied use of a diverted register.
+function %fixed_op_twice() -> i32 {
+ebb0:
+    ; check: ,%rax]
+    ; sameln: $v0 = iconst.i32 12
+    v0 = iconst.i32 12
+    v1 = iconst.i32 13
+    ; The dynamic shift amount must be in %rcx
+    ; check: regmove $v0, %rax -> %rcx
+    ; check: $v2 = ishl $v1, $v0
+    v2 = ishl v1, v0
+
+    ; Now v0 is globally allocated to %rax, but diverted to %rcx.
+    ; Check that the tied def gets the diverted register.
+    v3 = isub v0, v2
+    ; not: regmove
+    ; check: ,%rcx]
+    ; sameln: isub
+    ; Move it into place for the return value.
+    ; check: regmove $v3, %rcx -> %rax
+    return v3
+}