[PATCH] Fix PR81249

[Christophe Lyon]

Hi Richard,


On 29 June 2017 at 14:53, Richard Biener <rguenther@suse.de> wrote:
>
> Bootstrap and regtest running on x86_64-unknown-linux-gnu.
>
> Richard.
>
> 2017-06-29  Richard Biener  <rguenther@suse.de>
>
>         PR tree-optimization/81249
>         * tree-vect-loop.c (vect_create_epilog_for_reduction): Convert
>         condition reduction result to original scalar type.
>
>         * g++.dg/torture/pr81249.C: New testcase.
>

I think this patch (r249831) causes a regression on arm / aarch64:
    gcc.dg/vect/pr65947-10.c (internal compiler error)
    gcc.dg/vect/pr65947-10.c -flto -ffat-lto-objects (internal compiler error)

The regression appears between r249828 and 249831, which seems the
most likely guilty?

The log says:

/testsuite/gcc.dg/vect/pr65947-10.c: In function 'condition_reduction':
/testsuite/gcc.dg/vect/pr65947-10.c:12:1: error: invalid types in nop conversion
float
unsigned int
_47 = (float) _46;
during GIMPLE pass: vect
dump file: pr65947-10.c.159t.vect
/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/testsuite/gcc.dg/vect/pr65947-10.c:12:1:
internal compiler error: verify_gimple failed
0xbb9107 verify_gimple_in_cfg(function*, bool)
        /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/tree-cfg.c:5308
0xa7735c execute_function_todo
        /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/passes.c:1989
0xa770f5 execute_todo
        /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/passes.c:2043
Please submit a full bug report,

Christophe


> Index: gcc/tree-vect-loop.c
> ===================================================================
> --- gcc/tree-vect-loop.c        (revision 249780)
> +++ gcc/tree-vect-loop.c        (working copy)
> @@ -4833,12 +4858,9 @@ vect_create_epilog_for_reduction (vec<tr
>
>        /* Convert the reduced value back to the result type and set as the
>          result.  */
> -      tree data_reduc_cast = build1 (VIEW_CONVERT_EXPR, scalar_type,
> -                                    data_reduc);
> -      epilog_stmt = gimple_build_assign (new_scalar_dest, data_reduc_cast);
> -      new_temp = make_ssa_name (new_scalar_dest, epilog_stmt);
> -      gimple_assign_set_lhs (epilog_stmt, new_temp);
> -      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
> +      gimple_seq stmts = NULL;
> +      new_temp = gimple_convert (&stmts, scalar_type, data_reduc);
> +      gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);
>        scalar_results.safe_push (new_temp);
>      }
>    else if (STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info) == COND_REDUCTION
> @@ -4903,6 +4925,11 @@ vect_create_epilog_for_reduction (vec<tr
>               val = new_val;
>             }
>         }
> +      /* Convert the reduced value back to the result type and set as the
> +        result.  */
> +      gimple_seq stmts = NULL;
> +      val = gimple_convert (&stmts, scalar_type, val);
> +      gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);
>        scalar_results.safe_push (val);
>      }
>
>
> Index: gcc/testsuite/g++.dg/torture/pr81249.C
> ===================================================================
> --- gcc/testsuite/g++.dg/torture/pr81249.C      (nonexistent)
> +++ gcc/testsuite/g++.dg/torture/pr81249.C      (working copy)
> @@ -0,0 +1,25 @@
> +/* { dg-do compile } */
> +/* { dg-additional-options "-mavx2 -mprefer-avx128" { target x86_64-*-* i?86-*-* } } */
> +
> +typedef struct rtx_def *rtx;
> +union rtunion {
> +    rtx rt_rtx;
> +};
> +struct rtx_def {
> +    struct {
> +       rtunion fld[0];
> +    } u;
> +    rtx elem[];
> +} a;
> +int b, c, d;
> +rtx e;
> +int main() {
> +    for (;;) {
> +       d = 0;
> +       for (; d < b; d++)
> +         if (a.elem[d])
> +           e = a.elem[d]->u.fld[1].rt_rtx;
> +       if (e)
> +         c = 0;
> +    }
> +}