On Sat, 15 Nov 2014, Tom de Vries wrote:
> On 15-11-14 13:14, Tom de Vries wrote:
> > Hi,
> >
> > I'm submitting a patch series with initial support for the oacc kernels
> > directive.
> >
> > The patch series uses pass_parallelize_loops to implement parallelization of
> > loops in the oacc kernels region.
> >
> > The patch series consists of these 8 patches:
> > ...
> > 1 Expand oacc kernels after pass_build_ealias
> > 2 Add pass_oacc_kernels
> > 3 Add pass_ch_oacc_kernels to pass_oacc_kernels
> > 4 Add pass_tree_loop_{init,done} to pass_oacc_kernels
> > 5 Add pass_loop_im to pass_oacc_kernels
> > 6 Add pass_ccp to pass_oacc_kernels
> > 7 Add pass_parloops_oacc_kernels to pass_oacc_kernels
> > 8 Do simple omp lowering for no address taken var
> > ...
>
> This patch lowers integer variables that do not have their address taken as
> local variable. We use a copy at region entry and exit to copy the value in
> and out.
>
> In the context of reduction handling in a kernels region, this allows the
> parloops reduction analysis to recognize the reduction, even after oacc
> lowering has been done in pass_lower_omp.
>
> In more detail, without this patch, the omp_data_i load and stores are
> generated in place (in this case, in the loop):
> ...
> {
> .omp_data_iD.2201 = &.omp_data_arr.15D.2220;
> {
> unsigned intD.9 iD.2146;
>
> iD.2146 = 0;
> goto <D.2207>;
> <D.2208>:
> D.2216 = .omp_data_iD.2201->cD.2203;
> c.9D.2176 = *D.2216;
> D.2177 = (long unsigned intD.10) iD.2146;
> D.2178 = D.2177 * 4;
> D.2179 = c.9D.2176 + D.2178;
> D.2180 = *D.2179;
> D.2217 = .omp_data_iD.2201->sumD.2205;
> D.2218 = *D.2217;
> D.2217 = .omp_data_iD.2201->sumD.2205;
> D.2219 = D.2180 + D.2218;
> *D.2217 = D.2219;
> iD.2146 = iD.2146 + 1;
> <D.2207>:
> if (iD.2146 <= 524287) goto <D.2208>; else goto <D.2209>;
> <D.2209>:
> }
> ...
>
> With this patch, the omp_data_i load and stores for sum are generated at entry
> and exit:
> ...
> {
> .omp_data_iD.2201 = &.omp_data_arr.15D.2218;
> D.2216 = .omp_data_iD.2201->sumD.2205;
> sumD.2206 = *D.2216;
> {
> unsigned intD.9 iD.2146;
>
> iD.2146 = 0;
> goto <D.2207>;
> <D.2208>:
> D.2217 = .omp_data_iD.2201->cD.2203;
> c.9D.2176 = *D.2217;
> D.2177 = (long unsigned intD.10) iD.2146;
> D.2178 = D.2177 * 4;
> D.2179 = c.9D.2176 + D.2178;
> D.2180 = *D.2179;
> sumD.2206 = D.2180 + sumD.2206;
> iD.2146 = iD.2146 + 1;
> <D.2207>:
> if (iD.2146 <= 524287) goto <D.2208>; else goto <D.2209>;
> <D.2209>:
> }
> *D.2216 = sumD.2206;
> #pragma omp return
> }
> ...
>
>
> So, without the patch the reduction operation looks like this:
> ...
> *(.omp_data_iD.2201->sumD.2205) = *(.omp_data_iD.2201->sumD.2205) + x
> ...
>
> And with this patch the reduction operation is simply:
> ...
> sumD.2206 = sumD.2206 + x:
> ...
>
> OK for trunk?
I presume the reason you are trying to do that here is that otherwise
it happens too late? What you do is what loop store motion would
do.
Now - I can see how that is easily confused by the static chain
being address-taken. But I also remember that Eric did some
preparatory work to fix that, for nested functions, that is,
possibly setting DECL_NONADDRESSABLE_P? Don't remember exactly.
That said - the gimple_seq_ior_addresses_taken_op callback looks
completely broken. Consider &a.x which you'd fail to mark as
address-taken. It looks like the body is not yet in CFG form
when you apply all this?
That said - the functions do not belong to gimple.[ch] at least
as they are not going to work in general. I also question
why they are necessary - you do
+ if (gimple_code (stmt) == GIMPLE_OACC_KERNELS
+ && !bitmap_bit_p (addresses_taken, DECL_UID (var))
+ && INTEGRAL_TYPE_P (TREE_TYPE (var)))
but why don't you simply check TREE_ADDRESSABLE (var)? TREE_ADDRESSABLE
is conservative correct here.
And the above won't help for float reductions. So if, then you
should probably test is_gimple_reg_type (TREE_TYPE (var)) instead
of INTEGRAL_TYPE_P and you definitely should limit the number of
vars treated this way.
Oh - and the optimization should be somewhere more general - after
all it applies to all nested functions (thus move it to tree-nested.c?)
and to autopar loops as well. Not sure how much code the omp
lowering shares with unnesting - but hopefully enough.
Richard.
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendoerffer, HRB 21284
(AG Nuernberg)
Maxfeldstrasse 5, 90409 Nuernberg, Germany
