On Tue, Dec 13, 2016 at 9:43 AM, Eric Anholt <e...@anholt.net> wrote:
> Jason Ekstrand <ja...@jlekstrand.net> writes: > > > diff --git a/src/compiler/nir/nir_opt_copy_prop_vars.c > b/src/compiler/nir/nir_opt_copy_prop_vars.c > > new file mode 100644 > > index 0000000..728e476 > > --- /dev/null > > +++ b/src/compiler/nir/nir_opt_copy_prop_vars.c > > @@ -0,0 +1,799 @@ > > +/* > > + * Copyright © 2016 Intel Corporation > > + * > > + * Permission is hereby granted, free of charge, to any person > obtaining a > > + * copy of this software and associated documentation files (the > "Software"), > > + * to deal in the Software without restriction, including without > limitation > > + * the rights to use, copy, modify, merge, publish, distribute, > sublicense, > > + * and/or sell copies of the Software, and to permit persons to whom the > > + * Software is furnished to do so, subject to the following conditions: > > + * > > + * The above copyright notice and this permission notice (including the > next > > + * paragraph) shall be included in all copies or substantial portions > of the > > + * Software. > > + * > > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, > EXPRESS OR > > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF > MERCHANTABILITY, > > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT > SHALL > > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR > OTHER > > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, > ARISING > > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER > DEALINGS > > + * IN THE SOFTWARE. > > + */ > > + > > +#include "nir.h" > > +#include "nir_builder.h" > > + > > +/** > > + * Variable-based copy propagation > > + * > > + * Normally, NIR trusts in SSA form for most of its copy-propagation > needs. > > + * However, there are cases, especially when dealing with indirects, > where SSA > > + * won't help you. This pass is for those times. Specifically, it > handles > > + * the following things that the rest of NIR can't: > > + * > > + * 1) Copy-propagation on variables that have indirect access. This > includes > > + * propagating from indirect stores into indirect loads. > > + * > > + * 2) Dead code elimination of store_var and copy_var intrinsics based > on > > + * killed destination values. > > + * > > + * 3) Removal of redundant load_var intrinsics. We can't trust > regular CSE > > + * to do this because it isn't aware of variable writes that may > alias the > > + * value and make the former load invalid. > > + * > > + * Unfortunately, properly handling all of those cases makes this path > rather > > + * complex. In order to avoid additional complexity, this pass is > entirely > > + * block-local. If we tried to make it local the data-flow analysis > would > > I think here you wanted to say "make it global." > Thanks. Fixed locally. > I haven't reviewed the rest, I was just skimming to see what you were up > to. > > > + * rapidly get out of hand. Fortunately, for anything that is only ever > > + * accessed directly, we get SSA based copy-propagation which is > extremely > > + * powerful so this isn't that great a loss. > > + */ >
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