[Bug target/78098] New: error: interrupt service routine can't be called directly

["hjl.tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78098

            Bug ID: 78098
           Summary: error: interrupt service routine can't be called
                    directly
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---

[hjl@gnu-6 repro]$ cat foo.c
void bar (int);

__attribute__((interrupt)) void foo1 (void *p)
{
  bar (0);
  *((int *)0xFEE00080) = 0;
}

__attribute__((interrupt)) void foo2 (void *p)
{
  bar (0);
  *((int *)0xFEE00080) = 0;
}
[hjl@gnu-6 repro]$ make foo.s
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -Os -mno-sse -mno-mmx
-mno-80387 -S -o foo.s foo.c
foo.c: In function ‘foo1’:
foo.c:3:33: error: interrupt service routine can't be called directly
 __attribute__((interrupt)) void foo1 (void *p)
                                 ^~~~
Makefile:21: recipe for target 'foo.s' failed
make: *** [foo.s] Error 1
[hjl@gnu-6 repro]$ 

The problem is the tail call:

;; Function foo1 (foo1, funcdef_no=3, decl_uid=1466, cgraph_uid=0,
symbol_order=0)

foo1 (void * p)
{
;;   basic block 2, loop depth 0
;;    pred:       ENTRY
  foo2 (p_2(D)); [tail call]
  return;
;;    succ:       EXIT

}