[PATCH, 7/16] Add pass_dominator_oacc_kernels

Tom de Vries Tom_deVries@mentor.com
Mon Nov 16 12:04:00 GMT 2015


On 11/11/15 12:05, Richard Biener wrote:
> On Mon, 9 Nov 2015, Tom de Vries wrote:
>
>> On 09/11/15 16:35, Tom de Vries wrote:
>>> Hi,
>>>
>>> this patch series for stage1 trunk adds support to:
>>> - parallelize oacc kernels regions using parloops, and
>>> - map the loops onto the oacc gang dimension.
>>>
>>> The patch series contains these patches:
>>>
>>>        1    Insert new exit block only when needed in
>>>           transform_to_exit_first_loop_alt
>>>        2    Make create_parallel_loop return void
>>>        3    Ignore reduction clause on kernels directive
>>>        4    Implement -foffload-alias
>>>        5    Add in_oacc_kernels_region in struct loop
>>>        6    Add pass_oacc_kernels
>>>        7    Add pass_dominator_oacc_kernels
>>>        8    Add pass_ch_oacc_kernels
>>>        9    Add pass_parallelize_loops_oacc_kernels
>>>       10    Add pass_oacc_kernels pass group in passes.def
>>>       11    Update testcases after adding kernels pass group
>>>       12    Handle acc loop directive
>>>       13    Add c-c++-common/goacc/kernels-*.c
>>>       14    Add gfortran.dg/goacc/kernels-*.f95
>>>       15    Add libgomp.oacc-c-c++-common/kernels-*.c
>>>       16    Add libgomp.oacc-fortran/kernels-*.f95
>>>
>>> The first 9 patches are more or less independent, but patches 10-16 are
>>> intended to be committed at the same time.
>>>
>>> Bootstrapped and reg-tested on x86_64.
>>>
>>> Build and reg-tested with nvidia accelerator, in combination with a
>>> patch that enables accelerator testing (which is submitted at
>>> https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01771.html ).
>>>
>>> I'll post the individual patches in reply to this message.
>>
>> this patch adds pass_dominator_oacc_kernels (which we may as well call
>> pass_dominator_no_peel_loop_headers. It doesn't do anything
>> oacc-kernels-specific), to be used in the kernels pass group.
>>
>> The reason I'm adding a new pass instead of using pass_dominator is that
>> pass_dominator uses first_pass_instance. So adding a pass_dominator instance A
>> before a pass_dominator instance B has the unexpected consequence that it may
>> change the behaviour of instance B. I've filed PR68247 - "Remove
>> pass_first_instance" to note this issue.
>
> This looks ok (minus my comments to patch #10)
>

AFAIU, if "Remove first_pass_instance from pass_dominator" get approved 
and committed, we can drop this patch, and use this pass instantiation 
instead in the oacc_kernels pass group:
...
   NEXT_PASS (pass_dominator, false /* may_peel_loop_headers_p */);
...

Thanks,
- Tom



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