Re: [PATCH, PR68460] Always call free_stmt_vec_info_vec in gather_scalar_reductions

[Richard Biener <richard.guenther@gmail.com>]

On Fri, Nov 20, 2015 at 4:57 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
> [ was: Re: [PATCH] Fix parloops gimple_uid usage ]
>
> On 09/10/15 23:09, Tom de Vries wrote:
>>
>> @@ -2392,6 +2397,9 @@ gather_scalar_reductions (loop_p loop,
>> reduction_info_table_type *reduction_list
>>     loop_vec_info simple_inner_loop_info = NULL;
>>     bool allow_double_reduc = true;
>>
>> +  if (!stmt_vec_info_vec.exists ())
>> +    init_stmt_vec_info_vec ();
>> +
>>     simple_loop_info = vect_analyze_loop_form (loop);
>>     if (simple_loop_info == NULL)
>>       return;
>> @@ -2453,9 +2461,16 @@ gather_scalar_reductions (loop_p loop,
>> reduction_info_table_type *reduction_list
>>     destroy_loop_vec_info (simple_loop_info, true);
>>     destroy_loop_vec_info (simple_inner_loop_info, true);
>>
>> +  /* Release the claim on gimple_uid.  */
>> +  free_stmt_vec_info_vec ();
>> +
>
>
> With the src/libgomp/testsuite/libgomp.c/pr46886.c testcase, compiled in
> addition with -ftree-vectorize, I ran into an ICE:
> ...
> src/libgomp/testsuite/libgomp.c/pr46886.c:8:5: internal compiler error: in
> init_stmt_vec_info_vec, at tree-vect-stmts.c:8250
>  int foo (void)
>      ^~~
>
> 0x1196082 init_stmt_vec_info_vec()
>         src/gcc/tree-vect-stmts.c:8250
> 0x11c3ed4 vectorize_loops()
>         src/gcc/tree-vectorizer.c:510
> 0x10a7ea5 execute
>         src/gcc/tree-ssa-loop.c:276
> ...
>
> The ICE is caused by the fact that init_stmt_vec_info_vec is called at the
> start of vectorize_loops, while stmt_vec_info_vec is not empty. I traced
> this back to gather_scalar_reduction, where we call init_stmt_vec_info_vec,
> but we skip free_stmt_vec_info_vec if we take the early-out for
> simple_loop_info == NULL.
>
> This patch fixes the ICE by making sure we always call
> free_stmt_vec_info_vec in gather_scalar_reduction.
>
> Passes cc1/f951 rebuild and autopar testing.
>
> OK for stage3 trunk if bootstrap and regtest succeeds?

Ok.

Richard.

> Thanks,
> - Tom