[Bug libfortran/68743] [6 Regression] FAIL: gfortran.dg/aint_anint_1.f90 -O0 execution test

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68743

--- Comment #20 from John David Anglin <danglin at gcc dot gnu.org> ---
In the ccp1 pass, we had:

;; Function floorf (floorf, funcdef_no=22, decl_uid=167, cgraph_uid=114,
symbol_order=114)

__attribute__((nothrow, leaf, const))
floorf (float x)
{
  double _2;
  double _3;
  float _4;

  <bb 2>:
  _2 = (double) x_1(D);
  _3 = floor (_2);
  _4 = (float) _3;
  return _4;

}

Using c11 doesn't work.  "floor" is still transformed to "floorf" and
it also results in a number of implicit prototype warnings.

The -fno-builtin option works and gives the best code:

        stw %r2,-20(%r30)
        ldo 64(%r30),%r30
        .CALL ARGW0=FR,ARGW1=FU
        bl floor,%r2
        fcnvff,sgl,dbl %fr4L,%fr5
        fcnvff,dbl,sgl %fr4,%fr4L
        ldw -84(%r30),%r2
        bv %r0(%r2)
        ldo -64(%r30),%r30

The first approach in #16 can be made to work but one needs to assign
x to a volatile double instead of retval.  The code isn't too bad but
it introduces an unnecessary store/load pair:

float
floorf (float x)
{
  volatile double y = x;
  return (float) floor(y);
}

gives

        stw %r2,-20(%r30)
        fcnvff,sgl,dbl %fr4L,%fr4
        ldo 64(%r30),%r30
        ldo -64(%r30),%r28
        fstds %fr4,8(%r28)
        fldds 8(%r28),%fr5
        .CALL ARGW0=FR,ARGW1=FU
        bl floor,%r2
        nop

The code using the second approach is pretty bad but it works.

The third approach works but it introduces an extra call.