[Bug ipa/86695] New: Calls to builtins do not use visibility information

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86695

            Bug ID: 86695
           Summary: Calls to builtins do not use visibility information
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, visibility
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amonakov at gcc dot gnu.org
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

On the following testcase all 4 generated calls to memcpy/malloc should use
direct calls thanks to provided visibility attribute, but only the one in 'g2'
does. The other calls are assumed to be external and go via the PLT with the
corresponding size/speed penalty with -fpic -m32.

// gcc -O2 -fpic -m32
#pragma GCC visibility push(hidden)
void *memcpy(void *, const void *, __SIZE_TYPE__);
void *malloc(__SIZE_TYPE__);
#pragma GCC visibility pop

struct s {
  char c[1024*1024];
};

void f1(struct s a[2])
{
  a[1] = a[0];
}

void f2(struct s a[2])
{
  memcpy(a+1, a, sizeof *a);
}

void *g1()
{
  return __builtin_malloc(42);
}

void *g2()
{
  return malloc(42);
}