[12/12,RESEND] target-arm: fix neon shift helper functions

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 utilizes abs() function where applicable and otherwise
adds a test to ensure both arguments are positive before making the
aforementioned comparison.

Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
---
          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 >= 0 && tmp >= 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 (abs(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 >= 0 && tmp >= 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 >= 0 && tmp >= sizeof(src1) * 8) { \
          if (src1) \
              SET_QC(); \
          dest = src1 >> 31; \

On Wed, Oct 21, 2009 at 1:01 PM,  <Juha.Riihimaki@nokia.com> wrote:
> 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 utilizes abs() function where applicable and otherwise
> adds a test to ensure both arguments are positive before making the
> aforementioned comparison.

Why don't you instead cast sizeof to int?


Laurent

> Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
> ---
> diff --git a/target-arm/neon_helper.c b/target-arm/neon_helper.c
> index f32ecd6..0c95035 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 (abs(tmp) >= sizeof(src1) * 8) { \
>          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 >= 0 && tmp >= 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 >= 0 && tmp >= 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 (abs(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 >= 0 && tmp >= 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 >= 0 && tmp >= sizeof(src1) * 8) { \
>          if (src1) \
>              SET_QC(); \
>          dest = src1 >> 31; \
>

On Oct 22, 2009, at 10:57, ext Laurent Desnogues wrote:

> On Wed, Oct 21, 2009 at 1:01 PM,  <Juha.Riihimaki@nokia.com> wrote:
>> 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 utilizes abs() function where applicable and otherwise
>> adds a test to ensure both arguments are positive before making the
>> aforementioned comparison.
>
> Why don't you instead cast sizeof to int?

No reason, I'll make the v2 patch series use cast instead. It seems to  
work just as well.


Juha