Add test

Author: Prabhuk

llvm/test/CodeGen/X86/rex-profile-test.ll

@@ -0,0 +1,18 @@
+;; Test that the UEFI and Windows targets set the rex64 correctly.
+; RUN: llc -mtriple x86_64-uefi %s -o - | FileCheck %s -check-prefix=REX
+; RUN: llc -mtriple x86_64-windows-msvc %s -o - | FileCheck %s -check-prefix=REX
+; RUN: llc -mtriple x86_64-unknown-linux %s -o - | FileCheck %s -check-prefix=NOREX
+
+define void @test_tailjmp(ptr %fptr) {
+; REX-LABEL:    test_tailjmp:           # @test_tailjmp
+; REX:          # %bb.0:                # %entry
+; REX-NEXT:     rex64 jmpq	*%rcx       # TAILCALL
+;
+; NOREX-LABEL:  test_tailjmp:           # @test_tailjmp
+; NOREX:        .cfi_startproc
+; NOREX-NEXT:   # %bb.0:                # %entry
+; NOREX-NEXT:   jmpq	*%rdi           # TAILCALL
+entry:
+  tail call void %fptr()
+  ret void
+}