ARM: Add missing test coverage for windows frexp libcalls (#146690)

fp128 case crashes, so left off. Also didn't just add to the
other frexp test, since update_llc_test_checks seems to just
ignore this case for some reason, and the other windows tests
are also separated into this subdirectory.

Author: arsenm

llvm/test/CodeGen/ARM/Windows/frexp.ll

@@ -0,0 +1,28 @@
+; RUN: llc -mtriple thumbv7--windows-itanium < %s | FileCheck %s
+
+; CHECK-LABEL: test_frexp_f16_i32:
+; CHECK: bl __gnu_h2f_ieee
+; CHECK: vcvt.f64.f32 d0, s0
+; CHECK: bl frexp
+; CHECK: vcvt.f32.f64 s0, d0
+; CHECK: bl __gnu_f2h_ieee
+define { half, i32 } @test_frexp_f16_i32(half %a) {
+  %result = call { half, i32 } @llvm.frexp.f16.i32(half %a)
+  ret { half, i32 } %result
+}
+
+; CHECK-LABEL: test_frexp_f32_i32:
+; CHECK: vcvt.f64.f32
+; CHECK: bl frexp
+; CHECK: vcvt.f32.f64	s0, d0
+define { float, i32 } @test_frexp_f32_i32(float %a) {
+  %result = call { float, i32 } @llvm.frexp.f32.i32(float %a)
+  ret { float, i32 } %result
+}
+
+; CHECK-LABEL: test_frexp_f64_i32:
+; CHECK: bl frexp
+define { double, i32 } @test_frexp_f64_i32(double %a) {
+  %result = call { double, i32 } @llvm.frexp.f64.i32(double %a)
+  ret { double, i32 } %result
+}