--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/CodeGen/libcalls-ld.c	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,19 @@
+// llvm-gcc -O1+ should run simplify libcalls, O0 shouldn't
+// and -fno-builtins shouldn't.
+// -fno-math-errno should emit an llvm intrinsic, -fmath-errno should not.
+// RUN: %clang_cc1 %s -emit-llvm -fno-math-errno -o - | grep {call.*exp2\\..*f}
+// RUN: %clang_cc1 %s -emit-llvm -fmath-errno -o - | grep {call.*exp2l}
+// RUN: %clang_cc1 %s -emit-llvm -O1 -o - | grep {call.*ldexp}
+// RUN: %clang_cc1 %s -emit-llvm -O3 -fno-builtin -o - | grep {call.*exp2l}
+
+// clang doesn't support this yet.
+// XFAIL: *
+
+// If this fails for you because your target doesn't support long double,
+// please xfail the test.
+
+long double exp2l(long double);
+
+long double t4(unsigned char x) {
+  return exp2l(x);
+}