Issue with extendhfsf2_test.c in compiler-rt

Hi all,

I have a issue when I’m running “extendhfsf2_test.c” (in “compiler-rt/test/builtins/Unit”) with llvm9.0.1.
I’m getting this output message (and the test return 1):

error in test__extendhfsf2(0x7e00) = nan, expected nan

I’m compile the test by hand (“clang -O2 extendhfsf2_test.c -o extendhfsf2_test”)
I’ve also looked at the generated asm code, and it seems that clang decided at compile time that the test will fail as it will always print the message and return 1 as shown below:

0000000000400580 main:
400580: 50 pushq %rax
400581: bf 00 7e 00 00 movl $32256, %edi
400586: e8 25 00 00 00 callq 37 <__extendhfsf2>
40058b: f3 0f 5a c0 cvtss2sd %xmm0, %xmm0
40058f: f2 0f 10 0d 21 01 00 00 movsd 289(%rip), %xmm1
400597: bf c0 06 40 00 movl $4196032, %edi
40059c: be 00 7e 00 00 movl $32256, %esi
4005a1: b0 02 movb $2, %al
4005a3: e8 58 fe ff ff callq -424 printf@plt
4005a8: b8 01 00 00 00 movl $1, %eax
4005ad: 59 popq %rcx
4005ae: c3 retq
4005af: 90 nop

If I force the compiler to do the test at runtime (by adding a “attribute((noinline))” at the right place in the code), the test return with success.

Am I doing something wrong here? Or it is a known bug?