[Bug c/63663] New: [NEON] wrong value when computing the leading zero of int16x4_t type at O2

[Bug c/63663] New: [NEON] wrong value when computing the leading zero of int16x4_t type at O2

[spf_zju at 126 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63663

            Bug ID: 63663
           Summary: [NEON] wrong value  when computing  the leading zero
                    of int16x4_t type  at O2
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: spf_zju at 126 dot com

the 1.c code is :

#include <arm_neon.h>
#include <stdio.h>
int main()
{
        int16x4_t vector_int16x4;
        int16x4_t vector_res_int16x4;
        vector_int16x4 = vdup_n_s16(0);
        vector_res_int16x4 = vclz_s16(vector_int16x4);
        return vector_res_int16x4[0];
}
compiled with :armeb-linux-gnueabi-gcc -S -O2 -mfloat-abi=softfp -mfpu=neon  
1.c 

the assembly:
main:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        mov     r0, #32
        bx      lr


the main should return #16,not #32.
this bug appears in the trunk snapshot 20141026.

[Bug c/63663] [NEON] wrong value when computing the leading zero of int16x4_t type at O2

[spf_zju at 126 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63663

--- Comment #1 from wind <spf_zju at 126 dot com> ---
I find this issue is related to the definition of a MACRO.

/* The arm5 clz instruction returns 32.  */
#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE)  ((VALUE) = 32, 1).

I am confused that in the armv7 NEON, the mode is HI ,it is also equal 32. Is
it right ? anyone can give me some explanation .

I should post a patch to fix this bug soon.

[Bug target/63663] [NEON] wrong value when computing the leading zero of int16x4_t type at O2

[ramana at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63663

Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|armeb-linux-gnueabi         |armeb-linux-gnueabi,
                   |                            |arm-none-linux-gnueabihf
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-10-28
                 CC|                            |michael.collison at linaro dot org
                   |                            |, ramana at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #2 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> ---
Patch being discussed here.

https://gcc.gnu.org/ml/gcc-patches/2014-10/msg00731.html

[Bug target/63663] [NEON] wrong value when computing the leading zero of int16x4_t type at O2

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63663

Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #3 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Fixed with:

https://gcc.gnu.org/ml/gcc-patches/2014-10/msg02311.html

[Bug target/63663] [NEON] wrong value when computing the leading zero of int16x4_t type at O2

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63663

Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |5.0