[Bug target/65374] New: [SH] Tail call optimization not done for libcalls

[olegendo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65374

            Bug ID: 65374
           Summary: [SH] Tail call optimization not done for libcalls
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: olegendo at gcc dot gnu.org
            Target: sh*-*-*

This example function:

unsigned int test (unsigned int x)
{
  return __builtin_clz (x);
}

Compiled with -m4 -O2:

_test:
        mov.l   .L3,r0
        sts.l   pr,@-r15
        jsr     @r0
        nop
        lds.l   @r15+,pr
        rts    
        nop
.L4:
        .align 2
.L3:
        .long   ___clzsi2


For some reason, tail call optimization is not performed in this case.