Re: [Qemu-devel] [PATCH v2 10/10] target-arm: fix neon shift helper functions

[Laurent Desnogues <laurent.desnogues@gmail.com>]

On Sat, Oct 24, 2009 at 1:19 PM,  <juha.riihimaki@nokia.com> wrote:
> From: Juha Riihimäki <juha.riihimaki@nokia.com>
>
> Current code is broken at least on gcc 4.2, the result of a comparison
> "-1 >= sizeof(type) * 8" results true and causes wrong code path to
> be taken. The fix has been revised to use a type cast instead of
> abs() function and extra checks.
>
> Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
> ---
>  target-arm/neon_helper.c |   12 ++++++------
>  1 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/target-arm/neon_helper.c b/target-arm/neon_helper.c
> index f32ecd6..440b2ec 100644
> --- a/target-arm/neon_helper.c
> +++ b/target-arm/neon_helper.c
> @@ -392,7 +392,7 @@ NEON_VOP(abd_u32, neon_u32, 1)
>  #define NEON_FN(dest, src1, src2) do { \
>     int8_t tmp; \
>     tmp = (int8_t)src2; \
> -    if (tmp >= sizeof(src1) * 8 || tmp <= -sizeof(src1) * 8) { \
> +    if (tmp >= (int)sizeof(src1) * 8 || tmp <= -sizeof(src1) * 8) { \

You should also cast the sizeof in the second comparison.
With gcc 4.4.1, "1 <= -sizeof(uint32_t) * 8" is true.


Laurent

>         dest = 0; \
>     } else if (tmp < 0) { \
>         dest = src1 >> -tmp; \
> @@ -420,7 +420,7 @@ uint64_t HELPER(neon_shl_u64)(uint64_t val, uint64_t shiftop)
>  #define NEON_FN(dest, src1, src2) do { \
>     int8_t tmp; \
>     tmp = (int8_t)src2; \
> -    if (tmp >= sizeof(src1) * 8) { \
> +    if (tmp >= (int)sizeof(src1) * 8) { \
>         dest = 0; \
>     } else if (tmp <= -sizeof(src1) * 8) { \
>         dest = src1 >> (sizeof(src1) * 8 - 1); \
> @@ -453,7 +453,7 @@ uint64_t HELPER(neon_shl_s64)(uint64_t valop, uint64_t shiftop)
>  #define NEON_FN(dest, src1, src2) do { \
>     int8_t tmp; \
>     tmp = (int8_t)src2; \
> -    if (tmp >= sizeof(src1) * 8) { \
> +    if (tmp >= (int)sizeof(src1) * 8) { \
>         dest = 0; \
>     } else if (tmp < -sizeof(src1) * 8) { \
>         dest = src1 >> (sizeof(src1) * 8 - 1); \
> @@ -494,7 +494,7 @@ uint64_t HELPER(neon_rshl_s64)(uint64_t valop, uint64_t shiftop)
>  #define NEON_FN(dest, src1, src2) do { \
>     int8_t tmp; \
>     tmp = (int8_t)src2; \
> -    if (tmp >= sizeof(src1) * 8 || tmp < -sizeof(src1) * 8) { \
> +    if (tmp >= (int)sizeof(src1) * 8 || tmp < -sizeof(src1) * 8) { \
>         dest = 0; \
>     } else if (tmp == -sizeof(src1) * 8) { \
>         dest = src1 >> (tmp - 1); \
> @@ -528,7 +528,7 @@ uint64_t HELPER(neon_rshl_u64)(uint64_t val, uint64_t shiftop)
>  #define NEON_FN(dest, src1, src2) do { \
>     int8_t tmp; \
>     tmp = (int8_t)src2; \
> -    if (tmp >= sizeof(src1) * 8) { \
> +    if (tmp >= (int)sizeof(src1) * 8) { \
>         if (src1) { \
>             SET_QC(); \
>             dest = ~0; \
> @@ -579,7 +579,7 @@ uint64_t HELPER(neon_qshl_u64)(CPUState *env, uint64_t val, uint64_t shiftop)
>  #define NEON_FN(dest, src1, src2) do { \
>     int8_t tmp; \
>     tmp = (int8_t)src2; \
> -    if (tmp >= sizeof(src1) * 8) { \
> +    if (tmp >= (int)sizeof(src1) * 8) { \
>         if (src1) \
>             SET_QC(); \
>         dest = src1 >> 31; \
> --
> 1.6.5
>
>
>
>