[Bug tree-optimization/65953] New: [5/6 Regression] undefined reference to static __thread variable

["trippels at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65953

            Bug ID: 65953
           Summary: [5/6 Regression] undefined reference to static
                    __thread variable
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
  Target Milestone: ---

A Gentoo user pointed me to a Mono build failure with gcc-5:

markus@x4 /tmp % cat mini.i
static __thread int *mono_jit_tls;
long mono_get_jit_tls_offset_foo;
int* mono_set_jit_tls_jit_tls;
void
fn1 ()
{
  __asm("movq $mono_jit_tls@TPOFF, %0" : "=r"(mono_get_jit_tls_offset_foo));
}

void
fn2 () { mono_jit_tls = mono_set_jit_tls_jit_tls; }

markus@x4 /tmp % gcc -nostdlib -O2 mini.i
/tmp/ccuc43K9.o:mini.i:function fn1: error: undefined reference to
'mono_jit_tls'
collect2: error: ld returned 1 exit status
markus@x4 /tmp % /usr/x86_64-pc-linux-gnu/gcc-bin/4.8.4/gcc -nostdlib -O2
mini.i
markus@x4 /tmp % /usr/x86_64-pc-linux-gnu/gcc-bin/4.9.2/gcc -nostdlib -O2
mini.i
markus@x4 /tmp % clang -nostdlib -O2 mini.i
markus@x4 /tmp % icc -nostdlib -O2 mini.i
markus@x4 /tmp %