[Bug target/68674] New: ARM attribute target neon warning: incompatible implicit declaration of built-in function

[chrbr at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68674

            Bug ID: 68674
           Summary: ARM attribute target neon warning: incompatible
                    implicit declaration of built-in function
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chrbr at gcc dot gnu.org
  Target Milestone: ---

this test compiled with

cc1   -O2 test.c  -mcpu=cortex-a9 -mfloat-abi=hard -quiet -mfpu=neon

#include "arm_neon.h"

int8x8_t a, b;
int16x8_t e;

void
__attribute__ ((target("fpu=neon")))
foo(void)
{
  e = (int16x8_t)__builtin_neon_vaddlsv8qi (a, b);
}

ICEs with 

test.c:10:18: warning: incompatible implicit declaration of built-in function
'__builtin_neon_vaddlsv8qi'
   e = (int16x8_t)__builtin_neon_vaddlsv8qi (a, b);
                  ^~~~~~~~~~~~~~~~~~~~~~~~~

test.c:10:7: internal compiler error: in copy_to_mode_reg, at explow.c:595
   e = (int16x8_t)__builtin_neon_vaddlsv8qi (a, b);
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~