PR 49742: call lhs being ignored

Richard Guenther richard.guenther@gmail.com
Tue Jul 19 12:30:00 GMT 2011


On Tue, Jul 19, 2011 at 2:15 PM, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> In 49742, we have:
>
>  vect_array.21 = LOAD_LANES (MEM[(int[512] *)vect_pin.17_56]);
>  vect_var_.22_58 = vect_array.21[0];
>
> predcom doesn't think that there are any dependencies between
> the two statements, so hoists the second one as an invariant.
> This in turn is because get_references_in_stmt ignores the lhs
> of calls.
>
> Tested on x86_64-linux-gnu and arm-linux-gnueabi.  OK to install?

Ok.

Thanks,
Richard.

> Richard
>
>
> gcc/
>        PR tree-optimization/49742
>        * tree-data-ref.c (get_references_in_stmt): Treat the lhs of a call
>        as a potential write.
>
> Index: gcc/tree-data-ref.c
> ===================================================================
> --- gcc/tree-data-ref.c 2011-07-19 10:53:10.000000000 +0100
> +++ gcc/tree-data-ref.c 2011-07-19 13:08:12.000000000 +0100
> @@ -4158,33 +4158,37 @@ get_references_in_stmt (gimple stmt, VEC
>          ref->pos = op1;
>          ref->is_read = true;
>        }
> -
> -      if (DECL_P (*op0)
> -         || (REFERENCE_CLASS_P (*op0) && get_base_address (*op0)))
> -       {
> -         ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
> -         ref->pos = op0;
> -         ref->is_read = false;
> -       }
>     }
>   else if (stmt_code == GIMPLE_CALL)
>     {
> -      unsigned i, n = gimple_call_num_args (stmt);
> +      unsigned i, n;
>
> +      op0 = gimple_call_lhs_ptr (stmt);
> +      n = gimple_call_num_args (stmt);
>       for (i = 0; i < n; i++)
>        {
> -         op0 = gimple_call_arg_ptr (stmt, i);
> +         op1 = gimple_call_arg_ptr (stmt, i);
>
> -         if (DECL_P (*op0)
> -             || (REFERENCE_CLASS_P (*op0) && get_base_address (*op0)))
> +         if (DECL_P (*op1)
> +             || (REFERENCE_CLASS_P (*op1) && get_base_address (*op1)))
>            {
>              ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
> -             ref->pos = op0;
> +             ref->pos = op1;
>              ref->is_read = true;
>            }
>        }
>     }
> +  else
> +    return clobbers_memory;
>
> +  if (*op0
> +      && (DECL_P (*op0)
> +         || (REFERENCE_CLASS_P (*op0) && get_base_address (*op0))))
> +    {
> +      ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
> +      ref->pos = op0;
> +      ref->is_read = false;
> +    }
>   return clobbers_memory;
>  }
>
>



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