Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/optimize.c | 39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 110b3d1cc2..faedbdbfb8 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -888,6 +888,25 @@ static bool fold_eqv(OptContext *ctx, TCGOp *op)
     return fold_const2(ctx, op);
 }
 
+static bool fold_extract2(OptContext *ctx, TCGOp *op)
+{
+    if (arg_is_const(op->args[1]) && arg_is_const(op->args[2])) {
+        uint64_t v1 = arg_info(op->args[1])->val;
+        uint64_t v2 = arg_info(op->args[2])->val;
+        int shr = op->args[3];
+
+        if (op->opc == INDEX_op_extract2_i64) {
+            v1 >>= shr;
+            v2 <<= 64 - shr;
+        } else {
+            v1 = (uint32_t)v1 >> shr;
+            v2 = (int32_t)v2 << (32 - shr);
+        }
+        return tcg_opt_gen_movi(ctx, op, op->args[0], v1 | v2);
+    }
+    return false;
+}
+
 static bool fold_exts(OptContext *ctx, TCGOp *op)
 {
     return fold_const1(ctx, op);
@@ -1726,23 +1745,6 @@ void tcg_optimize(TCGContext *s)
             }
             break;
 
-        CASE_OP_32_64(extract2):
-            if (arg_is_const(op->args[1]) && arg_is_const(op->args[2])) {
-                uint64_t v1 = arg_info(op->args[1])->val;
-                uint64_t v2 = arg_info(op->args[2])->val;
-                int shr = op->args[3];
-
-                if (opc == INDEX_op_extract2_i64) {
-                    tmp = (v1 >> shr) | (v2 << (64 - shr));
-                } else {
-                    tmp = (int32_t)(((uint32_t)v1 >> shr) |
-                                    ((uint32_t)v2 << (32 - shr)));
-                }
-                tcg_opt_gen_movi(&ctx, op, op->args[0], tmp);
-                continue;
-            }
-            break;
-
         default:
             break;
 
@@ -1777,6 +1779,9 @@ void tcg_optimize(TCGContext *s)
         CASE_OP_32_64(eqv):
             done = fold_eqv(&ctx, op);
             break;
+        CASE_OP_32_64(extract2):
+            done = fold_extract2(&ctx, op);
+            break;
         CASE_OP_32_64(ext8s):
         CASE_OP_32_64(ext16s):
         case INDEX_op_ext32s_i64:
-- 
2.25.1

On Fri, 29 Oct 2021 at 05:59, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  tcg/optimize.c | 39 ++++++++++++++++++++++-----------------
>  1 file changed, 22 insertions(+), 17 deletions(-)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index 110b3d1cc2..faedbdbfb8 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -888,6 +888,25 @@ static bool fold_eqv(OptContext *ctx, TCGOp *op)
>      return fold_const2(ctx, op);
>  }

Hi; Coverity warns about a shift in here (CID 1465220):

>
> +static bool fold_extract2(OptContext *ctx, TCGOp *op)
> +{
> +    if (arg_is_const(op->args[1]) && arg_is_const(op->args[2])) {
> +        uint64_t v1 = arg_info(op->args[1])->val;
> +        uint64_t v2 = arg_info(op->args[2])->val;
> +        int shr = op->args[3];
> +
> +        if (op->opc == INDEX_op_extract2_i64) {
> +            v1 >>= shr;
> +            v2 <<= 64 - shr;
> +        } else {
> +            v1 = (uint32_t)v1 >> shr;
> +            v2 = (int32_t)v2 << (32 - shr);

Here we do the shift at 32-bits and then assign it into a 64-bit
variable, which triggers Coverity's usual OVERFLOW_BEFORE_WIDEN
heuristic. Is the 32-bitness intentional?

> +        }
> +        return tcg_opt_gen_movi(ctx, op, op->args[0], v1 | v2);
> +    }
> +    return false;
> +}

-- PMM

On 11/9/21 5:52 PM, Peter Maydell wrote:
> On Fri, 29 Oct 2021 at 05:59, Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
>> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   tcg/optimize.c | 39 ++++++++++++++++++++++-----------------
>>   1 file changed, 22 insertions(+), 17 deletions(-)
>>
>> diff --git a/tcg/optimize.c b/tcg/optimize.c
>> index 110b3d1cc2..faedbdbfb8 100644
>> --- a/tcg/optimize.c
>> +++ b/tcg/optimize.c
>> @@ -888,6 +888,25 @@ static bool fold_eqv(OptContext *ctx, TCGOp *op)
>>       return fold_const2(ctx, op);
>>   }
> 
> Hi; Coverity warns about a shift in here (CID 1465220):
> 
>>
>> +static bool fold_extract2(OptContext *ctx, TCGOp *op)
>> +{
>> +    if (arg_is_const(op->args[1]) && arg_is_const(op->args[2])) {
>> +        uint64_t v1 = arg_info(op->args[1])->val;
>> +        uint64_t v2 = arg_info(op->args[2])->val;
>> +        int shr = op->args[3];
>> +
>> +        if (op->opc == INDEX_op_extract2_i64) {
>> +            v1 >>= shr;
>> +            v2 <<= 64 - shr;
>> +        } else {
>> +            v1 = (uint32_t)v1 >> shr;
>> +            v2 = (int32_t)v2 << (32 - shr);
> 
> Here we do the shift at 32-bits and then assign it into a 64-bit
> variable, which triggers Coverity's usual OVERFLOW_BEFORE_WIDEN
> heuristic. Is the 32-bitness intentional?

Yep.  I'll add another cast.


r~